ICAR 2017 Abstract Authors: 19-23 June, 28th International Conference on Arabidopsis Research, St. Louis, USA

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Abdel-Hameed, Amira: abstract 57 Abdollahzadeh, Azam: abstract 209 Abe, Tomoko: abstract 159 Abraham J. Koo: abstract 204 Ackerman, Arlyn: abstract 269 Adamchek Christopher: abstract 283, 288 Adams, Er: abstract 71 Aguirre, Lyndsey: abstract 128 Ahmed Sheaza: abstract 107 Akintayo, Adedotun: abstract 185 Alassimone, Julien: abstract 87 Albert, Andreas: abstract 53 Albrecht, Tessa: abstract 263 Alonso, Jose: abstract 1, 181, 198 Altmann, Melina: abstract 200 Altmann, Stefan: abstract 200 Aluru, Maneesha: abstract 185 Aluru, Srinivas: abstract 185 An Chuanfu: abstract 43 Anderson, Jeff: abstract 193, 241 Anderson, Justin E.: abstract 7 Anderson, Ryan: abstract 258 Anderson, Stacy A.: abstract 118 Ane, Jean-Michel: abstract 269 Annamalai, Raja: abstract 269 Aquea F.: abstract 228 Arce-Johnson P.: abstract 228 Argueso, Cris: abstract 263 Arida, Emily: abstract 269 Ariyaratne, Menaka: abstract 107 Armbruster, Ute: abstract 290 Arrial, Alexis: abstract 105 Assmann, Sarah.: abstract 51 Augustin Sebastian: abstract 303 Aung, Kyaw: abstract 252, 276 Austin, Ryan: abstract 137 Avilla, Julian: abstract 127 Axtell Michael J.: abstract 169, 267 Ayre Brian G: abstract 216 Azodi Christina: abstract 44, 226 Azpeitia, Eugenio: abstract 102 Babaei Amameh, Mohammad: abstract 275 Baekelandt, Alexandra: abstract 154 Baer, John: abstract 120 Bagman Anne-Maarit: abstract 49 Bai, Mei: abstract 85 Bailey-Serres, Julia: abstract 9, 27, 59, 296 Bajic, Marko: abstract 9, 152, 153 Baldrich, Patricia: abstract 174, 230 Balkunde, Rachappa: abstract 110 Ballard, Keith: abstract 292 Barrett, Jennifer: abstract 233 Bartels, Arthur: abstract 143 Baskar Ramamurthy: abstract 73 Bassham, Diane: abstract 66, 86, 295 Basu, Debarati: abstract 244 Baten Abdul: abstract 139 Bäurle, Isabel: abstract 32 Baxter Ivan: abstract 227, 233 Beard, Katherine FM: abstract 298 Behera Sumita: abstract 158 Beilstein, Mark A.: abstract 224 Belkhadir, Youssef: abstract 281 Belmonte, Mark F: abstract 70 Ben Khaled Sara: abstract 11 Bender, Judith: abstract 275 Benfey Philip N.: abstract 79, 191 Bennett Eric J.: abstract 288 Berckhan, Sophie: abstract 289

Berger, Frederic: abstract 36 Bergmann, Dominique: abstract 87 Beric, Aleksandra: abstract 167 Berry, Hannah: abstract 263 Betegon, Isabel: abstract 191 Bethke, Gerit: abstract 259, 261 Bevilacqua, Philip: abstract 51 Beyer, Andreas: abstract 229 Bhan, Aishwarya: abstract 143 Bhandari, Deepak: abstract 196, 238 Bhatnagar Pooja: abstract 319 Biener Gabriel: abstract 98 Bindbeutel, Rebecca: abstract 89 Björklund, Stefan: abstract 62 Blakley, Ivory: abstract 103 Blancaflor, Elison: abstract 81 Blomberg, Jeanette: abstract 62 Blomster, Tiina: abstract 202 Bobokalonova Anastassia: abstract 29 Boeckx, Tinne: abstract 289 Boerjan, Wout: abstract 312 Boheler, Kenneth: abstract 231 Bohmer Erica: abstract 115 Bonaldi Katia: abstract 266 Bonasio, Roberto: abstract 137 Bonnard April C: abstract 239 Bordiya, Yogendra: abstract 239 Boudaoud, Arezki: abstract 25 Bourdais Gildas: abstract 11 Boutrot, Freddy: abstract 276 Bouyer, Daniel: abstract 10 Bowers, John: abstract 321 Brady, Siobhan: abstract 9, 49, 173, 311 Brandizzi, Federica: abstract 64 Brandt Benjamin: abstract 303 Brennan, Benjamin: abstract 295 Brenner, Caitlin: abstract 304 Briggs, Steven: abstract 237 Brimeyer, Nathaniel: abstract 269 Brooks, Ashley: abstract 145 Brose, Julia: abstract 167 Bullock, David: abstract 198 Burgie, Ernest: abstract 302 Burgie, Sethe: abstract 211 Busch, Wolfgang: abstract 21, 91, 194 Busscher-Lange, Jacqueline: abstract 214 Butenko Melinka: abstract 303 Butler-Smith, Tiara: abstract 97 Caballero, Mélodie: abstract 234 Caillieux, Erwann: abstract 10 Cakir, Ozkan: abstract 300 Calviello Lorenzo: abstract 79 Campos Marcelo L.: abstract 164 Campos Roya: abstract 117 Caño-Delgado, Ana: abstract 191 Cao, Jun: abstract 76 Cao, Xiaofeng: abstract 24 Carballo Valentina: abstract 29 Carianopol, Carina: abstract 113 Carpita, Nicholas: abstract 78 Carrington James C.: abstract 230, 265 Carter Clay: abstract 182 Carvalho Viana, Américo José: abstract 218 Castroverde, Christian Danve M: abstract 251 Cejda, Nic: abstract 122 Cejudo, Francisco Javier: abstract 290 Celenza, John: abstract 270, 275 Chaabouni, Salma: abstract 126

Chan Agnes: abstract 310 Chan, Aaron: abstract 113 Chang, Chiung-Yun: abstract 166 Chang, Jeff: abstract 276 Chen Jin: abstract 273, 279 Chen, Cheng: abstract 84 Chen, Haodong: abstract 297 Chen, Jiani: abstract 192, 295 Chen, Li-Qing: abstract 83 Chen, Meng: abstract 41, 76 Chen, Wen: abstract 168 Chen, Xiangsong: abstract 135, 136 Chen, Yang: abstract 65 Chen, Yi-Chun: abstract 180 Cheng, Jianlin: abstract 241 Cheng, Ling: abstract 15 Cherkis, Karen: abstract 258 Chia, Ju-Chen: abstract 42, 46 Chiara, Matteo: abstract 106, 106 Chica, Claudia: abstract 10 Chitwood, Daniel: abstract 80, 320 Chiu, Rex Shun: abstract 113 Cho, Sung Ki: abstract 300 Chockalingam, Sriram: abstract 185 Choi Hyong Woo: abstract 239 Chory, Joanne: abstract 41 Chung, Yuhee: abstract 130 Clark-Wiest, Caitlin: abstract 173 Clark, Greg: abstract 54 Clark, Natalie: abstract 97, 114 Clarke, Kurtis: abstract 172 Clavel Marion: abstract 174, 299 Clemens, Stephan: abstract 7 Cobine Paul: abstract 205 Collins, Carina: abstract 193 Collura, Vincent: abstract 105 Colot, Vincent: abstract 10 Concia, Lorenzo: abstract 145 Coneva, Viktoriya: abstract 80 Conn, Caitlin: abstract 187 Contrino, Sergio: abstract 310 Coolen, Silva: abstract 222 Corneillie, Sander: abstract 312 Coronel Josue: abstract 310 Coruh, Ceyda: abstract 267 Coruzzi Gloria M: abstract 146 Cosson, Patrick: abstract 234 Costa-Nunes, Pedro: abstract 230 Cousins Asaph: abstract 227 Cox, Kevin: abstract 163 Crawford, Tim: abstract 62 Criqui, Marie-Claire: abstract 174 Cristina Alexandre: abstract 149 Cruz, Mariel: abstract 209 Cruz, Neiman: abstract 173 Cui, Fuhao: abstract 253 Cui, Sujuan: abstract 137 Cuperus, Josh: abstract 149 Dalis, Morgan: abstract 183 Dang, H Jonathan: abstract 82 Dangl, Jeff: abstract 258 Daniels, Erin: abstract 313 Daron, Josquin: abstract 140 Darrow, Paige: abstract 270 Dassanayake Maheshi: abstract 219 Davila Olivas, Nelson: abstract 222 Davis, Thomas: abstract 122 Day Patrick: abstract 122 Dazhong Zhao: abstract 98 de Lorenzo, Laura: abstract 296

ICAR 2017 Abstract Authors: 19-23 June, 28th International Conference on Arabidopsis Research, St. Louis, USA

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de Luis Balaguer, Maria A, abstract 80, 97, 114 de Melo, J. Romario F.: abstract 7 de Oliveira Ferreira Dalton: abstract 164 de Pamphilis, Claude W., P: abstract 267 Deal, Roger: abstract 9, 150, 151, 152, 153 DeFraia Christopher T.: abstract 255 Delplace, Florent: abstract 242 Deng, Xingwang: abstract 297 Derbyshire Paul: abstract 127, 245 Derrien Benoît: abstract 299 Des Lauriers Stephen: abstract 195 DeShields Alison: abstract 49, 132 Deslandes, Lauren: abstract 238 DesMarais, David: abstract 19 Devoto Alessandra: abstract 45 DeZwaan, Todd: abstract 316 Diallo, Aissata: abstract 275 Dicke, Marcel: abstract 222 Ding Yezhang: abstract 256 Dinneny, José: abstract 40, 58, 111, 219 Dixit, Ram: abstract 5, 110 Djami-Tchatchou, A. T.: abstract 322 Djander, Selma: abstract 105 Dolf Weijers: abstract 114 Dommel, Matthew: abstract 256 Dong Jie: abstract 297 Dong, Xinnian, abstract 260 Dooley, Rion: abstract 310 Dorrity Michael W: abstract 149 Downes, Brian: abstract 304 Downie, A. Bruce: abstract 157 Dressano, Keini: abstract 237 Drews Gary N.: abstract 165 Drysdale, Samantha: abstract 133 Duan, Lina: abstract 111 Duarte, Gustavo T: abstract 207 Dubiella, Ullrich: abstract 242 Dubois Marieke: abstract 299 Dumond, Mathilde: abstract 25 Duxbury, Zane: abstract 245 Dwyer, Matthew: abstract 123 Eaton Nathan: abstract 98 Ebert Berit: abstract 90 Edger, Patrick: abstract 20 Egan Matthew: abstract 115 Ekanayake, Gayani: abstract 268 Ellsworth Patrick: abstract 227 Elshobaky, Ahmed: abstract 47 Elton, Samuel: abstract 96 Enganti, Ramya: abstract 300 Esfahanian, Malihe: abstract 313 Estelle, Mark: abstract 63 Falavigna, Agostino: abstract 321 Falter-Braun, Pascal: abstract 200 Farcot Etienne: abstract 102 Faure Lionel: abstract 197 Fei Zhangjun: abstract 42, 46, 239, 253 Feke Ann: abstract 283, 288 Feldman, Max: abstract 227 Feng Wei: abstract 40 Ferlanti, Erik: abstract 310 Fernandez, Donna: abstract 118 Fernando, V C Dilukshi: abstract 70 Fernie, Alisdair R: abstract 298 Feuerborn, Tatiana: abstract 223 Fields Stanley: abstract 149 Filiault, Daniele: abstract 194 Fisher Adam: abstract 97, 114 Floyd, Brice: abstract 86

Fouracre, Jim: abstract 109 Fowler Mary: abstract 293 Fowler, John: abstract 144 Frank Mary: abstract 49 Frank, Margaret: abstract 80, 320 Friso, Giulia: abstract 112 Frommer, Wolf: abstract 35, 83 Fujiwara, Masayuki: abstract 213 Fukao, Yoichiro: abstract 213 Gallagher, Kim: abstract 13 Gallavotti, Andrea: abstract 309 Galli, Mary: abstract 309 Gao, Fei, abstract 282 Garner, Christopher: abstract 208, 280 Garrick, M Jacqueline: abstract 82 Gassmann, Walter: abstract 208, 254, 280, 282 Gazzarrini, Sonia: abstract 113 Gebraegziabher, Habtamu: abstract 214 Geem, KyoungRok: abstract 271 Geert De Jaeger: abstract 154 Gehring, Mary: abstract 28 Geigenberger, Peter: abstract 290 Geldner, Niko: abstract 6 Gemperline, David C.: abstract 291 Gendron, Joshua: abstract 283, 288 Genschik, Pascal: abstract 174, 299 George Kapali: abstract 164 Georgii, Elisabeth: abstract 53 Gibon, Yves: abstract 234 Gilmour Sarah J.: abstract 43 Gladstone, Natasha: abstract 289 Glazebrook, Jane: abstract 259, 261 Glenn, Weslee: abstract 59 Gnesutta, Nerina: abstract 106, 171 Godin Christophe: abstract 102 Goertzen, Leslie R: abstract 183 Goeschl, Christian: abstract 194 Goff Jason: abstract 117 Gohlke, Jochen: abstract 168 Gómez Cano, Lina Andrea: abstract 209 Gong, Yan: abstract 87 Gonzalez Nathalie: abstract 154 Gonzalez-Garcia, Mary Paz: abstract 191 Goodrich, Justin: abstract 137 Goossens Alain: abstract 154 Gou Mingyue: abstract 284 Graf, Alexander: abstract 298 Green, Kim: abstract 233 Greene, George: abstract 260 Groenendijk, John: abstract 321 Grotewold, Erich: abstract 209 Grover Jeffrey W.: abstract 139, 168 Guan, Daogang: abstract 231 Guerinot, Mary Lou: abstract 16 Guerra, Damian: abstract 292 Guo Hanqing: abstract 225 Guo, Li: abstract 257 Guo, Pin: abstract 159 Guo, Qiang: abstract 164 Guo, Xining: abstract 72 Gupta, Shibu: abstract 93 Guzman, Michael: abstract 58 Hacquard, Thibaut: abstract 299 Hadia Mohamed Raafat Ahmed: abstract 281 Hadju, Dawn: abstract 263 Hahn Michael G.: abstract 90 Haining Brianna: abstract 227 Halder, Vivek: abstract 196

Hallmark, H. Tucker: abstract 183 Hamant, Olivier: abstract 25 Hamilton Eric: abstract 131 Han Diane: abstract 311 Han, Minwoo: abstract 71 Han, Qiang: abstract 143 Han, Soon-Ki: abstract 82 Hangarter, Roger: abstract 123 Hanley-Bowdoin, Linda: abstract 145 Harkess, Alex: abstract 321 Hasezawa, Seiichiro: abstract 36 Haswell Elizabeth: abstract 131, 244 Hauser, Marie-Theres: abstract 315 He Ping: abstract 163, 272 He, Hanjun: abstract 85 He, Ping: abstract 253 He, Sheng-Yang: abstract 37, 164, 236, 251, 273, 276, 279 Heazlewood, Joshua: abstract 90 Heber, Steffen: abstract 181 Heese, Antje: abstract 193, 268 Helariutta, Ykä: abstract 126, 129 Helliwell, Chris: abstract 137 Helm, Matthew: abstract 278 Henderson, Ian R.: abstract 223 Herud, Ole: abstract 189 Higaki, Takumi: abstract 36 Higashiyama, Tetsuya: abstract 36, 91, 274 Hisashi, Koiwa: abstract 101 Hobson, Eric: abstract 270 Höcker, Birte: abstract 189 Hoereth, Stephan: abstract 7 Hofstetter, K Alex: abstract 82 Hohenstein Jessica D.: abstract 262 Holdsworth, Michael J.: abstract 289 Holehouse, Alex: abstract 203 Holt, Ben F. III: abstract 50, 106, 124, 171 Hong, Lilan: abstract 25 Horner, David: abstract 106 Hothorn, Michael: abstract 31, 303 Hou, Jie: abstract 241 Howe Gregg A.: abstract 164 Howell, Stephen: abstract 66 Howton, Timothy: abstract 281 Hsia, Mon Mandy: abstract 96 Hsieh, Ming-Hsiun: abstract 166 Hsieh, Tzung-Fu: abstract 143 Hsieh, Wei-Yu: abstract 166 Hsu, Polly: abstract 79 Hu Tieqiang: abstract 141 Hu, Wei: abstract 317 Hu, Weiming: abstract 211, 302 Hu, Yanting: abstract 85 Hua, Jian: abstract 246, 248 Hua, Jingmin: abstract 231 Hua, Zhihua: abstract 286 Huang Yanmei: abstract 29 Huang, Chien Yu: abstract 247 Huang, He: abstract 89 Huang, Jian: abstract 98 Huang, Ping-Ping: abstract 222 Huang, Rong: abstract 42 Huard-Chauveau: abstract 242 Huet, Gaelle: abstract 238 Huffaker, Alisa: abstract 237 Hughes, Ariel: abstract 183, 205 Huh, Sung Un: abstract 245 Hunt, Arthur G.: abstract 296 Huot, Bethany: abstract 236, 251

ICAR 2017 Abstract Authors: 19-23 June, 28th International Conference on Arabidopsis Research, St. Louis, USA

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Huq, Enamul: abstract 155 Husband, Brian: abstract 221 Huynh Ha: abstract 115 Hwang, Inhwan: abstract 308 Iba, Koh: abstract 39, 220 Imai Hiroyuki: abstract 61 Imaizumi, Takato: abstract 33 Innes, Roger W.: abstract 235, 243, 278 Inzé Dirk: abstract 154 Irish, Vivian: abstract 78 Ishida Junko: abstract 45 Islam, Kazi: abstract 277 Islam, Soliman: abstract 241 Issakidis-Bourguet, Emmanuelle: abstract 290 Itaya, Tomotaka: abstract 91, 274 Ito, Masaki: abstract 82 Iuchi, Satoshi: abstract 232 Izaguirre Sierra, Mario: abstract 133 Jawahir, Vanessica: abstract 206 Jean-Baptiste Ken: abstract 149 Jensen Gregory: abstract 131 Jez, Joseph: abstract 30, 203 Ji, Hao: abstract 315 Ji, Lexiang: abstract 144 Jia Mengyuan: abstract 182 Jia Zongchao: abstract 65 Jiang, Hao: abstract 188 Jiang, Lingyan: abstract 241 Jiang, Nan: abstract 209 Jiao Chen: abstract 42, 46 Jin Hailing: abstract 247 Jin, Ming: abstract 53 Jin, Run: abstract 137 John, Florian: abstract 92 Johnson, Evan: abstract 313 Johnson, Nathan: abstract 267 Jones B.: abstract 228 Jones, Alexander: abstract 35, 116, 201 Jones, Daniel: abstract 108, 122, 171 Jones, Jonathan D G: abstract 245 Judd, Rika: abstract 217 Jupin, Isabelle: abstract 105 Jürgens, Gerd: abstract 189 Jurkowski, Melissa: abstract 227, 233 Juveland, Katelyn: abstract 156 Kaiser, Markus: abstract 196 Kajala, Kaisa: abstract 9 Kakuta, Chikako: abstract 213 Kanawati, Basem: abstract 53 Kang Hong Gu: abstract 239 Kapoor Meenu: abstract 177 Kapoor, Suraj: abstract 187 Karamat, Fazeelat: abstract 62 Karunadasa, Sumudu: abstract 201 Kasavajhala, Prasad: abstract 57 Katagiri, Fumiaki: abstract 259 Katari Manpreet S: abstract 146 Kataya, Amr R.A.: abstract 47 Kawai-Yamada, Maki: abstract 213 Kawamura Yukio: abstract 61 Kawashima, Tomokazu: abstract 36 Kay Steve: abstract 288 Kayastha, Sandipty: abstract 132 Kendall Timmy: abstract 139 Kent, Tyler, abstract 20 Kepinski, Stefan: abstract 63 Keshishian, Erika: abstract 52, 183 Kessler, Sharon: abstract 108, 122 Khakhar, Arjun: abstract 190

Khan, Bibi Rafeiza: abstract 81 Khandelia, Himanshu: abstract 71 Khosla, Aashima: abstract 187 Kieber, Joseph: abstract 180 Kieffer, Martin: abstract 63 Kim Jong-Myong: abstract 45 Kim Jonghwan: abstract 239 Kim Minsoo: abstract 293 Kim To Taiko: abstract 45 Kim, Dae Heon: abstract 271 Kim, Gunjune: abstract 267 Kim, Minsoo: abstract 56 Kim, Sang Hee: abstract 282 Kim, Taesung: abstract 48 Kim, Yong Sig: abstract 43 Kimata, Yusuke: abstract 36 Kimura Sachie: abstract 285 King Graham J.: abstract 139 Kinser Joshua: abstract 115 Kirik, Viktor: abstract 156 Klessig Daniel F: abstract 239 Kliebenstein, Daniel: abstract 173 Klinkenberg Peter: abstract 182 Kloth, Karen: abstract 222 Kobayashi, Masatomo: abstract 232 Kochian, Leon: abstract 42, 46 Koichi Sugimoto: abstract 164 Kojima, Mikiko: abstract 39 Komatsuzaki, Tamiki: abstract 25 Kombrink, Erich: abstract 196 Kondo Mariko: abstract 61 Kopischke Michaela: abstract 11, 249 Korasick, David: abstract 203, 305 Korolev, Sergey: abstract 304 Koroleva, Olga: abstract 304 Kosentka, Pawel: abstract 99 Kotomi Yago: abstract 61 Kovakova, Viera: abstract 229 Kragler, Friedrich: abstract 231 Krahn, Jan Henrik: abstract 196 Krämer, Ute: abstract 7 Krishnakumar, Vivek: abstract 310 Krizek, Beth: abstract 103 Kruijer, Willem: abstract 222 Kucukoglu, Melis: abstract 126 Kudhla Jörg: abstract 40 Kühn, Kristina: abstract 56 Kumimoto, Roderick: abstract 50, 106, 171 Kurepa, Jasmina: abstract 68, 201 Kurihara, Daisuke: abstract 36 Kusano, Miyako: abstract 71 Kwon, Taegun: abstract 81 Lagarias, J Clark: abstract 317 Lai, YaShiuan: abstract 64 LaMontagne, Erica: abstract 193 Lanctot, Amy: abstract 190 Lange, Birgit: abstract 53 Lapin, Dmitry: abstract 229, 238 Le Masson Marie: abstract 102 LeBlanc, Chantal: abstract 145 Lee Bum Kyu: abstract 239 Lee, Chin-Mei: abstract 283, 288 Lee, Dong Wook: abstract 308 Lee, Gwonjin: abstract 7 Lee, Han Yong: abstract 180 Lee, Kwang-Hee, abstract 291 Lee, Travis: abstract 27, 59 Lee, Un-Sa: abstract 148 Leebens-Mack, James: abstract 321 Lehotai, Nóra, abstract 62

Lei KaiJian: abstract 69 Lei, Jiaxin: abstract 264 Leyser, Ottoline: abstract 96 Li Fay-Wei: abstract 79 Li Man-Wah: abstract 288 Li Zheng: abstract 266 Li Zhiyong: abstract 98 Li, Baohua: abstract 173 Li, Chun-Biu: abstract 25 Li, Faqiang: abstract 104 Li, Jiankun: abstract 83 Li, Li: abstract 287 Li, Ling: abstract 262 Li, Man-Wah: abstract 283 Li, Mao: abstract 80 Li, Qi: abstract 147 Li, Yimin: abstract 38 Li, Ying: abstract 146 Li, Zhang: abstract 279 Li, Zhaohu: abstract 295 Li, Zixing: abstract 60 Liao, Jo-Chien: abstract 166 Liao, Jui-Yun: abstract 112 Likai Wang: abstract 170 Lilley, Kathryn: abstract 100 Lillo, Cathrine: abstract 47 Lin, Jingyu: abstract 315 Lindbäck, Louise: abstract 55 Lingling, An: abstract 165 Liseron-Monfils Christophe: abstract 49 Liu Wei: abstract 288 Liu Xunliang: abstract 12 Liu, Chang-Jun: abstract 284 Liu, Chenglong: abstract 253 Liu, Fen: abstract 104 Liu, Jiangxin: abstract 76 Liu, Wei: abstract 283 Liu, Wusheng: abstract 315 Liu, Wuzhen: abstract 38 Liu, Xiaotong: abstract 259 Liu, Xiaoyi: abstract 86, 186 Lloyd Alan: abstract 165 Lloyd M. Smith: abstract 135 Locke, Anna: abstract 27 Lomax Aaron: abstract 135 Loraine, Ann: abstract 103 Lozano-Elena, Fidel: abstract 191 Lu, Li: abstract 135, 136 Lu, Xiaolong: abstract 304 Lu, You: abstract 259 Luesse, Darron: abstract 115, 161, 162 Luis Joe: abstract 158 Lutz, Kerry: abstract 88 Lye, Shu-Hui: abstract 211, 302 Ma, Li-Jun: abstract 257 Ma, Wenxiu: abstract 41 Ma, Yan: abstract 245 Mabry, Makenzie: abstract 167 Mabuchi, Atsushi: abstract 39, 220 Mabuchi, Kaho: abstract 91 MacIntosh, Gustavo: abstract 86, 262 Madison, Imani: abstract 199 Maes, Michal: abstract 127 Maher, Kelsey: abstract 9, 151, 152 Maherali, Hafiz: abstract 221 Mähönen, Ari Pekka: abstract 126, 202 Major Ian T.: abstract 164 Maki, Hiromasa: abstract 91 Maliga, Pal: abstract 88 Malley, Konstantin: abstract 304

ICAR 2017 Abstract Authors: 19-23 June, 28th International Conference on Arabidopsis Research, St. Louis, USA

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Mantovani, Roberto: abstract 106, 171 Maradiaga, Richard: abstract 99 Marin, Nora: abstract 200 Marks, M. David: abstract 313 Marshall, Richard: abstract 291 Martienssen, Robert: abstract 145, 146 Martin, Pascal: abstract 160 Matiolli, Cleverson: abstract 218 Matsui Akihiro: abstract 45 Matsushita, Tomonao: abstract 274 Matte, Juan: abstract 228 Mayer Kevin S.: abstract 135 Mazarei, Mitra,: abstract 315 Mazzoni-Putman, Serina: abstract 181 McCombie W. Richard: abstract 146 McDonald Tami R.: abstract 225 McDowell, John: abstract 277 McFarlane, Heather: abstract 100 McGinn, Michaela: abstract 313 McLoughlin, Fionn: abstract 291, 293 McLoughlin, Katrice: abstract 211, 302 McNinch, Colton: abstract 185 Meinke, David: abstract 215 Meng, Zhe: abstract 64 Menke, Frank L H: abstract 127, 245 Mercati, Francesco: abstract 321 Merchant, Sabeeha: abstract 4 Meyers, Blake C: abstract 167, 174, 230, 320, 321 Michaels, Scott D: abstract 160 Micklem, Gos: abstract 310 Millwood, Reginald: abstract 315 Min, Yunsook: abstract 125 Mitchell-Olds, Tom: abstract 20 Miyamoto, Koji: abstract 175 Miyashima, Shunsuke: abstract 129 Miyazaki, Takae: abstract 71 Mock, Stephen: abstract 310 Mogami, Junro: abstract 67, 301 Mohanty, Devasantosh: abstract 158 Monaghan, Jacqueline: abstract 14 Monda, Keina: abstract 39, 220 Mondal Hossain Ali: abstract 158 Montano, Sherwin: abstract 306 Montgomery, Beronda L.: abstract 251 Moore, Christy: abstract 156 Morao, Ana Karina: abstract 10 Morffy, Nicholas: abstract 197 Morikami, Atsushi: abstract 91 Morley, Stewart: abstract 307 Morris Paul: abstract 107 Morriss, Stephanie: abstract 86 Mosher, Rebecca A.: abstract 12, 139, 168, 224 Moss, Britney: abstract 309 Mou, Zhonglin: abstract 255 Moutel, Sandrine: abstract 105 Mueller, Caroline, abstract 7 Muhammad, DurreShahwar: abstract 65, 318 Mukherjee Indrani: abstract 146 Mukhtar, M. Shahid: abstract 250, 281 Myers, Zachary: abstract 50, 171 Nagano, Minoru: abstract 213 Nagashima, Yukihiro: abstract 101 Nagatani, Akira: abstract 41 Nair, Pooja abstract 143 Nam, Ji Chul: abstract 239, 282 Nebenführ, Andreas: abstract 95 Negi, Juntaro: abstract 39, 220

Nelson, David: abstract 8, 187, 197 Nemhauser Jennifer L: abstract 18, 149, 178, 184, 190 Nettleton Dan: abstract 262 Neubauer, Matthew: abstract 235 Newton, Allison: abstract 161 Nghia Le Tri: abstract 285 Ngo, Richard: abstract 173 Nguyen, Thomas: abstract 97 Ni, Weimin, U: abstract 297 Niblack, Terry: abstract 318 Niefind, Karsten: abstract 238 Nielsen, Brent: abstract 307 Nieminen, Kaisa: abstract 126 Nikoloski, Zoran: abstract 298 Nilsson, Ove: abstract 74, 126 Nimchuk, Zachary: abstract 75 Ninck, Sabrina: abstract 196 Nishimura, Marc: abstract 258 Noble Jennifer: abstract 12 Nolan, Trevor: abstract 185, 295 Nomoto, Mika: abstract 91, 274 Nomura, Kinya: abstract 276 Novak, Ondrej:abstract 52, 183 Ntushelo, K: abstract 322 Nusinow, Dmitri: abstract 89 O'Conner, Seth: abstract 142 O'Connor, Devin: abstract 96 O'Lexy Ruthsabel: abstract 13 O'Malley, Ronan, abstract 44, 226 O’Neill, Kathryn: abstract 55 Obata, Toshihiro: abstract 298 Odom Matt: abstract 95 Ogura, Takako: abstract 194 Oh Dong-Ha: abstract 219 Ohler Uwe: abstract 79 Okada, Kazunori: abstract 175 Olichon, Aurélien: abstract 105 Olsen Andrew: abstract 49 Oney, Matthew: abstract 236 Orellana Ariel: abstract 90 Orozco-Nunnelly, Danielle: abstract 65, 318 Orville, Allen M: abstract 302 Osaki, Jackie: abstract 58 Osteryoung, Katherine W.: abstract 84 Pacey, Evan: abstract 221 Pajerowska-Mukhtar, Karolina: abstract 186 Palme, Julius: abstract 200 Panchy, Nicholas: abstract 226 Panda, Gurudutta: abstract 200 Panda, Kaushik: abstract 144 Pandey, Sona: abstract 26, 179 Panivelu, Ravi: abstract 12 Pappu, Rohit: abstract 203 Parcy Francois: abstract 102 Park Sunchung: abstract 43 Park, Thomas: abstract 318 Parker, Jane: abstract 229, 238 Parker, Nicole: abstract 215 Parsons, Harriet: abstract 100 Pasoreck, Elise: abstract 41 Patel Jigar: abstract 107 Patel, Monika: abstract 240 Patharkar, Rahul: abstract 254 Pauluzzi, Germain: abstract 9, 27 Pauwels Laurens: abstract 154 Payne, Thomas: abstract 95 Peaucelle Alexis: abstract 40

Peck, Scott: abstract 193, 241 Pedmale, Ullas: abstract 55 Peng, Yanhui: abstract 315 Perez, Franck: abstract 105 Perkins, Patrick: abstract 181 Perry Sharyn: abstract 157 Pham, Vinh: abstract 155 Piñeros Miguel: abstract 46 Pires, J. Chris: abstract 20, 167 Plačková, Lenka: abstract 52, 183 Platts, Adrian: abstract 20 Poethig, Scott: abstract 109, 141 Polydore, Seth: abstract 169 Porri, Aimone: abstract 7 Porter, Katie: abstract 84 Portugal Vieira, João Guilherme: abstract 207 Pottinger, Sarah: abstract 278 Poudel, Arati: abstract 204 Powell, Rachel V., abstract 183 Powers, Samantha: abstract 199, 203 Prabhakaran-Mariyamma, Neema: abstract 172 Pruneda-Paz, Jose: abstract 137, 266, 288 Pu, Yunting: abstract 66 Putarjunan, Aarthi: abstract 128 Qi Mingsheng: abstract 262 Qi, Xingyun: abstract 82 Qian, Shuiming: abstract 135 Qian, Shuiming: abstract 136 Qian, Weiqiang: abstract 147 Qin Xiaobo: abstract 247 Qiu, Yonjian: abstract 41 Queitsch Christine: abstract 149 Raicu Valerica: abstract 98 Rain, Jean-Christophe: abstract 105 Ramu, Umamaheswari: abstract 145 Ran, Di: abstract 165 Rasheed Sultana: abstract 45 Rashotte, Aaron: abstract 52, 183, 205 Ratcliffe, R George: abstract 298 Rautengarten Carsten: abstract 90 Reddy, Amit: abstract 41 Reddy, Anireddy: abstract 57 Reinders Anke: abstract 225 Rengarajan, Shruthi: abstract 275 Reuter-Carlson, Ursula: abstract 318 Revers, Frédéric: abstract 234 Reynoso, Mauricio A.: abstract 9, 27 Riccardi, Paolo: abstract 321 Rickerd, Trevor: abstract 156 Rickett Lydia: abstract 11 Ringli, Christoph: abstract 92, 93 Rizza, Annalisa: abstract 35, 116, 210 Robatzek, Silke: abstract 11, 249 Roby, Dominique: abstract 242 Rodriguez-Medina Joel: abstract 49 Rodriguez, Sastre: abstract 270, 275 Roeder, Adrienne: abstract 25 Rogan, Conner: abstract 280 Rokka Anne: abstract 285 Roman Octavia: abstract 303 Romero, Andres: abstract 133 Rose Annkatrin: abstract 132 Roszak, Pawel: abstract 129 Rothfels Carl: abstract 79 Roudier, Francois: abstract 10 Roux, Fabrice: abstract 234, 242 Roux, Stanley: abstract 54 Rowan, Beth: abstract 223

ICAR 2017 Abstract Authors: 19-23 June, 28th International Conference on Arabidopsis Research, St. Louis, USA

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Roy Rahul: abstract 182 Rubeck, Sara: abstract 269 Ruberti, Cristina: abstract 64 Rubio, Bernadette: abstract 234 Ruffel Sandrine: abstract 146 Rutter, Brian: abstract 243 Růžička, Kamil: abstract 202 Rytz, Therese C.: abstract 294 Rzasa, Rebecca: abstract 132 Saffer, Adam: abstract 78 Saini, Ramswaroop: abstract 73 Saito, Kazuki: abstract 71 Sakakibara, Hitoshi: abstract 39 Sakaoka, Satomi: abstract 91 Sako Kaori: abstract 45 Sakuraba, Yasuhito: abstract 220 Saleem, Muhammad: abstract 315 Salvador, Felipe: abstract 263 Sanchez Oscar Lorenzo: abstract 114 Sanchez Rangel Diana: abstract 247 Santiago, Julia: abstract 303 Santibañez:C. abstract 228 Sapala, Aleksandra: abstract 25 Sarkar, Soumik: abstract 185 Sarowar Sujon: abstract 158 Sarris, Panagiotis F: abstract 245 Sato, Karin: abstract 301 Sato, Yoshikatsu, abstract 36 Sato, Yuta: abstract 67, 301 Savageau Michael: abstract 311 Scalf, Mark: abstract 135, 291, 294 Schaeffner, Anton R.: abstract 53 Schaufelberger, Myriam: abstract 92 Schei, Edit: abstract 47 Schläppi, Michael: abstract 134 Schmitt-Kopplin, Philippe: abstract 53 Schmitt, Anthony: abstract 182 Schmitz, Robert J.: abstract 144 Schmutz, Jeremy: abstract 20 Schnable, Patrick: abstract 185 Schornack, Sebastian: abstract 3 Schranz, Eric: abstract 20 Schreiber, Katherine: abstract 203 Schreuder, Marielle: abstract 214 Schroeder, Dana: abstract 70 Schroeder, Julian: abstract 60 Schultz Eric: abstract 244 Schultz, Elizabeth: abstract 172 Schulz, Vincent: abstract 56 Schumaker Karen S.: abstract 165 Schurdi-Levraud, Valérie: abstract 234 Schwartz, Kacey: abstract 55 Sedbrook, John: abstract 313 Seelig, Georg: abstract 190 Segonzac, Cecile: abstract 245 Seki, Motoaki: abstract 45 Seroka, Adam: abstract 273 Serrano Irene: abstract 235 Sevilem, Iris: abstract 126, 129 Shah Jyoti: abstract 158 Shah, Dilip: abstract 277 Shahid, Saima: abstract 267 Shaikh, Mearaj: abstract 216 Shan, Libo: abstract 163, 253, 264, 272 Shang, Baoshuan: abstract 72 Shao, Yuanhua: abstract 315 Shapulatov, Umidjon: abstract 214 Sharma, Gunjan: abstract 289 Shashank, Sane: abstract 74 Shaw, Sidney: abstract 121, 123

Shen Bo: abstract 49 Shen, Zhouxin: abstract 237 Sheng, Huajin: abstract 42 Shikha Malik: abstract 98 Shin, Kihye: abstract 15 Shin, Ryoung: abstract 71 Shinozaki, Kazuo: abstract 67, 301 Shippen, Dorothy: abstract 133 Shiu, Shin-Han: abstract 44, 226 Shpak, Elena: abstract 99, 119 Shull, Timothy: abstract 68 Sieberer Tobias: abstract 94 Sijacic, Paja: abstract 152, 153 Siligato, Riccardo: abstract 202 Simonini Sara: abstract 130 Singh Amit Kumar: abstract 73 Sinha, Neelima: abstract 9 Siqueira R.: abstract 228 Siriwardana, Chamindika: abstract 50, 106, 171 Sirohi, Gunjan: abstract 177 Skaggs Megan I.: abstract 165 Skelly, Michael: abstract 274 Sklenar, Jan: abstract 127, 245 Slotkin, R. Keith: abstract 140, 144 Smakowska Elwira: abstract 281 Smalle, Jan A.: abstract 68, 201 Smith, Benjamin, abstract 108 Smith, John M.: abstract 268 Smith, Lloyd M., abstract 291, 294 Smith, Richard: abstract 25 Sohn, Kee Hoon: abstract 245 Soma, Fumiyuki: abstract 67, 301 Somers, David: abstract 48 Sonawala, Unnati: abstract 277 Song, Chun-Peng: abstract 69 Song, Jawon: abstract 145 Sorenson, Reed: abstract 296 Sorkin, Maria: abstract 89 Sorour, Ahmed A. A.: abstract 7 Sousa Correia, Cristina: abstract 289 Sozzani, Rosangela: abstract 80, 97, 114 Spalding, Edgar: abstract 195 Sparks, J. Alan: abstract 81 Spears, Benjamin: abstract 208, 282 Spoel, Steven: abstract 274 Srivastava, Renu: abstract 66 Stefanini, Kristina: abstract 270 Stein, Ricardo J.: abstract 7 Stepanova, Anna: abstract 181, 198 Stevens, Tim: abstract 100 Stewart, C. Neal, Jr.: abstract 315 Stiel, Andre: abstract 189 Stolpe, Clemens: abstract 7 Strader, Lucia: abstract 2, 193, 199, 203 Strand, Åsa: abstract 62 Stubbs, Joe: abstract 310 Su, Jianbin: abstract 208 Su, Zhao: abstract 51 Sullivan Alessandra M: abstract 149 Sun Yali: abstract 281 Sun, Tai-Ping: abstract 76 Sun, Yali: abstract 250 Sun, Ying: abstract 219 Sung, Tzu-Ying: abstract 166 Sunseri, Francesco: abstract 321 Suo, Bangxia: abstract 156 Suraj Kapoor: abstract 197 Suzuki, Takamasa: abstract 91, 274 Swain, Swadhin: abstract 106

Swart, Corné: abstract 298 Swarup, Roy Choudhury: abstract 26, 179 Sweetlove, Lee J: abstract 298 Swinnen Gwen: abstract 154 Tack, David: abstract 51 Tada, Yasuomi: abstract 91, 274 Tafelmeyer, Petra: abstract 105 Takahashi Daisuke: abstract 61 Takahashi, Fuminori: abstract 67, 301 Takahashi, Sho: abstract 39, 220 Takebayashi, Yumiko: abstract 39 Tamborski, Janina: abstract 249 Tan, Ek Han: abstract 138 Tanaka Maho: abstract 45 Tang, Michelle: abstract 173 Tang, Yin: abstract 51 Tanner, John: abstract 305 Tanurdzic Milos: abstract 146 Tao, Kai: abstract 253 Taylor Nigel: abstract 26 Taylor-Teeples, Mallorie: abstract 178 Taylor, Isaiah: abstract 120 Teng, Chong: abstract 230 Tetlow Mary: abstract 11 Theisen, Nickolas: abstract 269 Thieme, Christoph: abstract 231 Thnaibat, Nayfah: abstract 318 Thoen, Manus: abstract 222 Thomashow Michael F.: abstract 43 Thompson, William F.: abstract 145 Thormählen, Ina: abstract 290 Thum, Karen E: abstract 146, 160 Tian, Ran: abstract 157 Tichtinsky Gabrielle: abstract 102 Tirrell, David: abstract 59 Tohmori, Ryoma.: abstract 39 Toperzer, Jody: abstract 300 Torii, Keiko U.: abstract 34, 82, 127, 128 Torrens-Spence Michael P: abstract 29 Torres, Shannon: abstract 150 Town, Chris: abstract 310 Toyokura, Koichi: abstract 129 Traw, M. Brian: abstract 315 Treffon, Patrick: abstract 292 Trolet, Adrien: abstract 174, 299 Trost, Toria: abstract 162 True, Jillian: abstract 121 Truebridge, Ian: abstract 292 Trujillo, Joshua: abstract 224 Truman, William: abstract 259 Tsai, Allen Yi-Lun: abstract 113 Tseng, Ching-Chih: abstract 166 Tsugawa, Satoru: abstract 25 Tsukagoshi, Hironaka: abstract 91, 274 Tsukaya, Hirokazu, T: abstract 159 Turco, Gina: abstract 311 Tyler, Brett: abstract 253 Tylka Gregory L.: abstract 262 Ueda Minoru: abstract 45 Ueda, Minako: abstract 36 Uemura Matsuo: abstract 61 Umesh Yadav: abstract 216 Uribe-Romeo Francisco: abstract 266 Urton James R: abstract 149 Uygun, Sahra: abstract 44 Vahldick Hannah: abstract 311 Valea, Ioana: abstract 175 Van der Hulst, Ron: abstract 321 Van der Krol, Sander: abstract 214 Van Doorsselaere Jan: abstract 154

ICAR 2017 Abstract Authors: 19-23 June, 28th International Conference on Arabidopsis Research, St. Louis, USA

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van Eeuwijk, Fred: abstract 222 van Heerwaarden, Joost: abstract 222 van Hoogdalem, Mark: abstract 214 Van Ieperen, Wim: abstract 214 Van Norman, Jaimie: abstract 117 van Wijk, Klaas J.: abstract 112 Vanholme, Bartel: abstract 312 Varathanajah, Kresanth: abstract 113 Vatamaniuk, Olena: abstract 42, 46 Vaughn, Matthew: abstract 145, 310 Veenendaal, Janelle: abstract 172 Veerappa, Roopadarshini: abstract 54 Vejlupkova, Zuzana: abstract 144 Velásquez, André C.: abstract 236, 251, 276 Vellosillo, Tamara: abstract 58 Venkateshwaran, Muthusubramanian: abstract 269 Vernoux, Teva: abstract 17 Vert, Greg: abstract 77 Vescio, Kathryn: abstract 257 Vibe Scheller Henrik: abstract 90 Vidal-Melgosa, Silvia, abstract 100 Vierling, Elizabeth: abstract 56, 292, 293 Vierstra, Richard D.: abstract 104, 211, 291, 293, 294, 302 Vijayakumar Anitha: abstract 26 Vilarrasa-Blasi, Josep: abstract 58 Villalba, Alondra: abstract 133 Vincentz, Michel, C: abstract 207, 218 Vogel, John: abstract 96 von Arnim, Albrecht: abstract 300 Von Kannon Donald: abstract 115 Vu, William: abstract 286 Waadt, Rainer UC San Diego: abstract 60 Wafula, Eric K.: abstract 267 Wagner, Doris: abstract 130, 137, 148 Walia, Ankit: abstract 35, 116, 210 Walker, John C.: abstract 120, 254 Walley, Justin: abstract 295 Wan, Ying: abstract 241 Wang Chenggang: abstract 255 Wang Dongfang: abstract 165 Wang Fangfang: abstract 157 Wang Ling: abstract 43 Wang Shu: abstract 248 Wang Yanbing: abstract 12 Wang Yongsheng: abstract 255 Wang, Feng: abstract 267 Wang, He: abstract 76 Wang, Nu: abstract 225 Wang, Ping: abstract 272 Wang, Renhou: abstract 63 Wang, Wei: abstract 314 Wang, Wenfei: abstract 15 Wang, Xiaokang: abstract 147 Wang, Xin: abstract 126 Wang, Xuelu: abstract 295 Wang, Yanbing: abstract 131 Wang, Yixing: abstract 215 Wang, Zhiyong: abstract 15 Ward John M.: abstract 225 Ware Doreen: abstract 49 Warpeha Katherine M: abstract 65, 318 Washburn, Jacob: abstract 20 Wassenaar, Maarten: abstract 214 Watanabe, Etsuko: abstract 61 Watson, Ruthie: abstract 263 Wear, Emily: abstract 145 Webb Kristofor: abstract 288

Weckwerth, Philipp: abstract 237 Wei, Ning: abstract 297 Weigel, Delef: abstract 20, 76, 149, 223 Welch, Kendell: abstract 269 Welsch, Ralf: abstract 287 Weng, Jing-Ke: abstract 29 Wenguang Zheng: abstract 262 Westwood, James H., abstract 267 Wheeler, Emily: abstract 145 Whitham Steven A.: abstract 262 Wildhagen Mari: abstract 303 Willats, William: abstract 100 William Schryver: abstract 161 Williams Ashley: abstract 65 Williams Cranos: abstract 114 Willoughby, Andrew: abstract 122, 124 Wing, Rod: abstract 20 Winkler, J. Barbro: abstract 53 Winship Eamon: abstract 226 Winte, Sonja: abstract 27 Woll, Arthur: abstract 42 Wright Clay: abstract 184 Wright, Stephen: abstract 20 Wrzaczek, Michael: abstract 285 Wu Larry H.: abstract 79 Wu Miin-Feng: abstract 130 Wu Shuang: abstract 13 Wu, Hong: abstract 85 Wu, Lizhu: abstract 272 Wurtele Eve Syrkin: abstract 262 Xia, Yiji: abstract 38, 231 Xiao, Jun: abstract 137 Xiao, Wenyan: abstract 143 Xie Deyu: abstract 217 Xie, Zhouli: abstract 188 Xin, Xiu-Fang: abstract 164 Xin, Xiufang: abstract 276 Xing, Denghui: abstract 57 Xiong Erhui: abstract 98 Xu, Chunyan: abstract 321 Xu, Guoyong: abstract 260 Xu, Mingli: abstract 141 Xu, Shouling: abstract 15 Xu, Shu: abstract 236 Yadegari Ramin: abstract 165 Yamada, Tomomi: abstract 36 Yamaguchi-Shinozaki, Kazuko: abstract 67, 301 Yamaguchi, Ayako: abstract 148 Yamaguchi, Takahiro: abstract 159 Yamamoto, Yoshiharu: abstract 274 Yan, Bin: abstract 231 Yan, Jiapei: abstract 42, 46, 248 Yanagisawa, Shuichi: abstract 220 Yang, Emily Jie-Ning: abstract 76 Yang, Leiyun: abstract 246 Yang, Mengran: abstract 295 Yang, Ming: abstract 85 Yang, Saiqi: abstract 94 Yang, Xiaojing: abstract 306 Yang, Yue: abstract 84 Yanjuan Jiang: abstract 279 Yao, Jian: abstract 276 Ye, Lingling: abstract 126 Yeoh-Wang Jenny: abstract 146 Yin, Yanhai: abstract 185, 188, 295 Yoo, Chan Yul: abstract 76 Yoo, Hyunjin: abstract 125 Yoon, Gyeong Mee: abstract 180 York, Samuel: abstract 294

Yoshida Yuki: abstract 164 Yu, Hong: abstract 63 Yu, Qiguo: abstract 88 Yu, Renbo: abstract 297 Yu, Xiang: abstract 137 Yu, Xuhong: abstract 160 Yu, Yunqing: abstract 51 Yuan, Hui Yuan: abstract 287 Yuan, Jing: abstract 108, 122 Zahde, Mais: abstract 156 Zaheer, Shamaila: abstract 318 Zahler, Mollye: abstract 184 Zambrano, Jose Alfredo: abstract 74 Zavodna, Tetiana-Olena: abstract 42 Zayed, Omar: abstract 212 Zebell, Sophia: abstract 260 Zeeman, Samuel C.: abstract 92 Zeng Weiqing: abstract 279 Zeng, Xiaoli: abstract 306 Zhan Li: abstract 248 Zhang Huajian: abstract 165 Zhang Lifang: abstract 49 Zhang, Hailei: abstract 38 Zhang, Liang: abstract 119 Zhang, Mingcai: abstract 295 Zhang, Shanshan: abstract 165 Zhang, Shoudong: abstract 231 Zhang, Xiao: abstract 72 Zhang, Xiaoyu: abstract 137 Zhang, Xudong: abstract 255, 256 Zhang, Xuebin: abstract 284 Zhang, Yi: abstract 63 Zhang, Youjun: abstract 298 Zhang, Zhenzhen: abstract 15 Zhao Catherine Z.: abstract 98 Zhao, Bo: abstract 170 Zhao, Chunzhao: abstract 212 Zhao, Jin: abstract 53 Zhao, Kaihong: abstract 306 Zhao, Qingzhen: abstract 291 Zhao, Xuefeng: abstract 262 Zhao, Zhongying: abstract 231 Zheng Qiaolin: abstract 157 Zheng Yi: abstract 239 Zheng, Xingguo: abstract 265 Zhong, Huan: abstract 38 Zhong, Ren: abstract 306 Zhong, Xuehua: abstract 22, 135, 136 Zhonglin Mou: abstract 256 Zhou, Man: abstract 259 Zhou, Mian: abstract 314 Zhou, Pei: abstract 76 Zhou, Xiangjun: abstract 287 Zhou, Xue: abstract 173 Zhu, Hailong: abstract 231 Zhu, Jia-Ying: abstract 15 Zhu, Ziqiang: abstract 176 Ziegler, Greg: abstract 227, 233 Zilberman, Daniel: abstract 23 Zipfel, Cyril: abstract 276 Zolj, Sanda: abstract 270, 275 Zolman, Bethany K.: abstract 206 Zwack, Paul: abstract 205, 260

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28thInternationalConferenceonArabidopsisResearch

ICAR201719-23JUNE2017HYATTREGENCYATTHEST.LOUISARCH

St.Louis,Missouri,UnitedStatesofAmericaOrganizedbytheNorthAmericanArabidopsisSteeringCommittee(NAASC)

LocalHosts:TheDonaldDanforthPlantScienceCenter

ListofAbstractsandAuthors

InvitedSpeakers:Abstracts1–37(Startingpage1inthispdf)AbioticInteractions:Abstracts38–70(Startingpage12inthispdf)Applied:Biotechnology,MolecularBreeding,Human/SocietalHealth:Abstracts71–74(Startingpage23inthispdf)CellandDevelopmentalBiology:Abstracts75–133(Startingpage25inthispdf)EducationandOutreach:Abstract134(Startingpage45inthispdf)EpigeneticsandChromatin:Abstracts135–153(Startingpage45inthispdf)GeneRegulation:Abstracts154–174(Startingpage52inthispdf)HormoneSignaling:Abstracts175–208(Startingpage59inthispdf)MetabolismandBiochemistry:Abstracts209–218(Startingpage71inthispdf)NaturalVariation,Evolution,Ecology:Abstracts219–227(Startingpage75inthispdf)NovelTools,TechniquesandResources:Abstracts228–233(Startingpage78inthispdf)PlantDefenseandBioticinteractions:Abstracts234–282(Startingpage80inthispdf)Post-TranslationalRegulation:Abstracts283–301(Startingpage97inthispdf)StructuralBiology:Abstract302–306(Startingpage104inthispdf)SystemsorSyntheticBiology,Bioinformatics,Modeling:Abstracts307–311(Startingpage106inthispdf)TranslationalBiology:Abstracts312–321(Startingpage108inthispdf)LateAbstracts:Abstracts322-323(Startingpage111inthispdf)

InvitedSpeakers:Abstract#1.Translationregulationofplanthormoneresponses.(Submission257)JoseAlonso11NCSU,UnitedStatesSurvivalofplantsgreatlydependsontheabilityofthesesessileorganismstotunetheirhardwireddevelopmentalprogramstotheconstantenvironmentalchanges.Althoughitisclearthatplanthormonesplayacentralroleinthissignalintegrationprocess,theexactmolecularmechanismsinvolvedarestilllargelyunknown.Untilrecently,moststudieshaveapproachedthisquestionbyexaminingtheeffectsofdifferentplanthormoneregimensontranscriptlevels.Ourrecentworkhastakenadvantageofthedevelopmentofgenome-widetranslationprofiling(theRibo-seq)touncoveranovellevelofregulationintheplantresponsetothehormoneethylene.Specifically,wehavefoundthatthesignalingmoleculeEIN2andthenonsense-mediateddecayproteinsUPFsplayacentralroleinapreviouslyuncharacterizedethylene-inducedtranslationalresponse.Currently,weareinvestigatingtheroleofotherplanthormonesingene-specifictranslationalregulation.Ourstudiesarerevealingnewnodesofinteractionbetweenhormones,aswellasimplicating3’UTRsand5’uORFsofspecifictranscriptsintheregulationofplantresponsestokeygrowthregulators.Keywords:Ribo-Seq;Auxin;Ethylene;Translation;Planthormones.Abstract#2.RegulationofAuxinResponseFactors(Submission307)LuciaStrader11WashingtonUniversityinSt.Louis,UnitedStatesThephytohormoneauxinisacentralregulatorofplantgrowthanddevelopment.TheAUXINRESPONSEFACTOR(ARF)familyoftranscriptionfactorsmediatestranscriptionalresponsestoauxinandalterationofARFactivityoftenleadstoseveredevelopmentalconsequences.Usingacombinationofstructural,molecular,andcellbiology,wehaveidentifiedamechanismtoregulatecellular

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competencetorespondtoauxin,basedonARFactivity.Keywords:Auxin;TranscriptionFactorsAbstract#3.Structuresandprocessesimpactingonthemicrobialcolonisationofplants(Submission269)SebastianSchornack11UniversityofCambridge,SainsburyLaboratory(SLCU),UnitedKingdomThestudyofplant-bioticinteractionshasunravelledimportantimmunitymechanismswhichrestrictmicrobialinvasion.Conceptually,successfulpathogensandsymbioticplantcolonisingmicrobessuppressimmunityandbenefitfromorexploitadditionalhostmechanismsfortheirentryandestablishment.RemarkableexamplesforbroadhostmicrobesarePhytophthorapalmivoraoomyceteswhichcaninfecthundredsofhostspeciesanddiverseorgansandtissues.ArbuscularMycorrhizafungiestablishsymbioticinteractionswiththemajorityofalllandplantsandspeciesofRhizobacteriacanformanitrogenfixingnodulesymbiosisinmostlegumes.Byutilisingthesemicrobesandtheirinteractionswithlegumes,tobacco,barleyandArabidopsisweaimtodiscover,understandandmodulategeneralplantmechanismsformicrobialcolonisation.Time-resolveddualtranscriptomicsofP.palmivorarootcolonisationhashelpedustoidentifyinfectionrelevantinducedmicrobialeffectorproteinsaswellasearlyinducedplantgenesinvolvedinmicrobialsensingandsignalling.Furthermore,wefoundaconservedeukaryoticproteinwhichimpactsonmicrobialentrybyalteringbiochemicalandphysicalpropertiesoftheplantcellwall.Thesefindingsaddtoourunderstandingofcommonandspecificplantcolonisationmechanismsandmayprovidealternativestrategiesforquantitativeplantdiseaseresistance.Keywords:symbiosis;plant-microbeinteractions;Phytophthora,arbuscularmycorrhizafungi;Medicago,Nicotiana

Abstract#4.AdayinthelifeofChlamydomonasandotherstories(Submission298)SabeehaMerchant11UCLA,UnitedStatesTechnologicaladvancesinthelastdecadepresentenormousopportunitiesforbiologists.Wearenolongerrestrictedtoahandfulofreference/modelorganismsforaviewoffundamentalpathwaysinplants,animalsandmicrobeswithmolecularresolution.Wecansamplethediversityofextantlifeforaretrospectiveviewofadaptationandevolution,givingusdeepermechanisticunderstandingoffunction,andsub-cellularstructuresandinteractionscanbevisualizedwithatomicresolution.Thereisgreatpotentialforcontinueddiscovery,forexpandingourknowledgebase,ultimatelyforimprovingthequalityoflife.Threevignetteswillbepresented:1)acollaborationwiththeNiyogiandPellegrinigroupsinwhichwebringapreviouslyuncharacterizedorganism,Chromochloriszofingiensis,tothestatusofamodelorganismwithahighqualitygenomeassemblyandimagingofintracellularstructures,2)acollaborationwithRalletovisualizeintracellularmetalstoresinChlamydomonaswithhighspatialresolution,revealinghighlyorganizedstructures,and3)useofDOEuserfacilitiesfortemporalresolutionofmacromolecularandcentralmetabolismduringtheChlamydomonascellcycle.Keywords:Chlamydomonas,metalions,chloroplast,metabolism,lysosome-relatedorganelleAbstract#5.TendingtheMicrotubuleGarden:Pruners,ProtectorsandGrowers(Submission295)RamDixit11WashingtonUniversityinSaintLouis,UnitedStatesInplants,thecorticalmicrotubulecytoskeletondeterminescellshapebyspatiallyorganizingthedepositionofcellwallmaterial.Toperformthismorphogeneticfunction,corticalmicrotubulesneedtobearrangedintodefinedstructuresdependingonthecelltypeanddevelopmentalstate.Thisfeatisachievedbyahostofmicrotubule-associatedproteinsthatregulatepolymernumber,lengthandturnover.Here,Iwillpresentourfindingsonthemechanismsthatregulatethemicrotubuleseveringproteinkataninandthediscoveryofnewplus-endtrackingproteinsinArabidopsisthaliana.WehavediscoveredthatseveringactivityisregulatedbyphosphorylationofthreeserineresiduesintheN-terminaldomainofp60katanin.Mutatingallthreeresiduestoaspartatecompletelyinhibitsseveringactivityinvitro,whereasmutatingtheseresiduestoalaninedidnotalterseveringactivitycomparedtowild-typep60.Furthermore,wefoundthatthemicrotubulebundlingprotein,MAP65-1,isapotentinhibitorofkatanin-mediatedmicrotubuleseveringinvitro.WefoundthattheSPR2protein,whichhasbeenproposedtoinhibitseveringatmicrotubuleintersections,alsoinhibitsseveringinvitro,althoughtoalesserextentcomparedtoMAP65-1.Unexpectedly,liveimagingrevealedthatSPR2hasbothmicrotubuleplus-endandminus-endtrackingactivity.IntheArabidopsisspr2-2mutant,corticalmicrotubuleplus-endsarestuckinthegrowthstate,whereastheminusendsdepolymerizemuchmorerapidlythaninwild-typeplantsdemonstratingthatSPR2differentiallyregulatesthedynamicsofmicrotubuleplusandminusends.Recently,wealsodiscoveredseveralnewArabidopsisEB1b-bindingpartnersasputativemicrotubuleplus-endtrackingproteins.OneofthesecalledMicrotubuleEndbindingProtein1(MEP1)isamemberofanovelfamilyof+TIPsthatlocalizetogrowingplus-endsofcorticalmicrotubulesinvivoandareimplicatedinvasculardevelopmentand/orfunction.Keywords:Plantmorphogenesis;microtubulecytoskeleton;fluorescencemicroscopy;katanin;plus-endtracking

Abstract#6.Endodermaldifferentiation-walkingthethinlinebetweenprotectionandexchange(Submission284)NikoGeldner11UniversityofLausanne,SwitzerlandRootsmustmanagetheopposingaimsofprovidingforuptakeofnutrientsandwaterfromthesoilontheonehandandprovidingprotectionfrompotentiallyharmfulmicroorganismandtoxicelementsontheother.Theendodermis,themainbarriercelllayerofroots,

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playsapivotalroleinthiscontinuoustug-of-war.Thehighlylocalisednetworkofcellwallimpregnationsbetweenendodermalcells-theCasparianstrips-appearoptimisedforeffectivelyblockingapoplasticdiffusionintothestelewhilemaximisingendodermalplasmamembranesurfaceforuptake.Yet,inlaterstages,endodermalcellscloseofftheirsurfacebysurroundingthemselveswithlayersofhydrophobicsuberinlamellae,forfeitinguptakecapacityforstronglyincreasedprotection.Recently,wehavebeenabletodemonstratethatrootsareabletochangespeedanddegreeofsuberisation,dependingonthespecificnutrientdeficiencythattheyexperience.Thisplasticityisnotonlyduetoregulatedbiosynthesis,butalsoduetoincreaseddegradationofpre-existingsuberinundercertainconditions,revealinganunexpectedlevelofcontrolofrootsovertheirprotectivebarrier.Intriguingly,eveninfullysuberizedrootzones,somecellsremainentirelyunsuberised.Theselong-described,suberisation-resistantcellswereintuitivelytermed“passagecells”andnotedtoalwaysoccurabovexylempoles.Wewereabletodemonstratethatpassagecellformationisprecedbydifferentiationofendodermalcellsintophloem/xylempoleendodermis.Symmetrybreakingiscausedbylocaldifferencesofcytokininandauxinsignalling,dueinparttothemovementofthecytokininrepressorAHP6fromthesteleintoendodermalcells.Moreover,weshowthatpassagecellsareindeedprivilegedsitesoftransporterexpressionandappeartoexertaneffectonsurroundingcorticalandepidermalcells.Iwillreportonourlatestideasonthefunctionalrelevanceofthishighlyconservedcelltypeinroots.Keywords:roots;nutrientuptake;endodermis;Abstract#7.Arabidopsishalleri–amodelspeciestostudylocaladaptation(Submission293)UteKrämer1,Anderson,JustinE.,RuhrUniversityBochum,Sorour,AhmedA.A.,RuhrUniversityBochum,deMelo,J.RomarioF.,RuhrUniversityBochum,Lee,Gwonjin,RuhrUniversityBochum,Porri,Aimone,RuhrUniversityBochum,Stein,RicardoJ.,RuhrUniversityBochum,Hoereth,Stephan,UniversityofBayreuth,Stolpe,Clemens,BielefeldUniversity,Mueller,Caroline,BielefeldUniversity,Clemens,Stephan,UniversityofBayreuth1RuhrUniversityBochum,GermanyBackground:Ourgoalistoidentifythealterationsinmolecularfunctionsthatunderlieevolutionaryadaptations.Wepursuecomparativeapproachesfocusedonmetal-relatedextremetraitsinthezinc(Zn)andcadmium(Cd)hyperaccumulatorspeciesArabidopsishalleri,acloserelativeofA.thaliana.A.halleriisaperennialstoloniferousoutcrossingspeciescapableofcolonizingtoxicmetalliferoussoilsthatcontainhighlevelsofZn,Cd,leadandcopper.Intheirnaturalhabitats,onmetalliferoussoilsandalsoonordinary,non-metalliferous,soils,A.hallericanenrichheavymetalstoconcentrationsabove0.3%Znand0.01%Cdinleafdrybiomass–concentrationsthatjustifytheclassificationofthisspeciesamongmorethan500knownmetalhyperaccumulatortaxa.LeafmetalconcentrationsinA.halleriareordersofmagnitudehigherthaninotherplantsonthesamesoilsandfarexceedcriticaltoxicitythresholdsofA.thaliana.Materialsandmethods:Wecombinelaboratory-basedgenetic,genomic,molecularandcellbiology,physiologyandphenotypingapproacheswithcommongardenexperiments,fieldworkandpopulationgenomics.Results:Genome-widecross-speciestranscriptomicsstudiesofA.halleriandcloselyrelatednon-hyperaccumulatorspeciesledtoworkingmodelsofthemolecularmechanismsofmetalhyperaccumulationandassociatedmetalhypertolerance.ThefunctionsofseveralkeycandidategenesandtheirvariantswereanalyzedupontransferintotheA.thalianageneticbackground,aswellasinA.halleristablytransformedwithRNAinterferenceandpromoter-reportergeneconstructs.Toaddresswithin-speciesphenotypictraitvariation,weconductedalargefieldsurveyofA.halleri,withmulti-elementanalysisofleavesandrhizospheresoilfromabout2,000plantindividualssampledintheirnaturalhabitats(Steinetal.,2017).Asubsetof850individualsweretransferredintoourgreenhousetoformanedaphicallyandionomicallyindexedbiodiversitycollection.Genotyping-by-sequencingdataallowedinitialgenome-wideassociationstudies.Toexpandthisapproach,phenotypingoffield-collectedindividualsisinprogressunderstandardizedgrowthchamberconditions.Reciprocalfieldtransplantandcommongardenexperimentsdemonstratedlocaladaptationandprovidedinsightsontheecologicalrelevanceofintra-speciesvariationinmetalhomeostasisofA.halleri.Conclusions:Naturallyselectedmetalhyperaccumulationandhypertolerancearetheresultoftheenhancementofpre-existinggenefunctionsatkeypositionsinthemetalhomeostasisnetwork.NaturalselectionactsinacomplexwayonmetalhomeostasisofA.halleri,andaspectsofthisareworthexaminingalsoinnon-accumulatorplantspecies.Ourworkisrelevantforthedevelopmentofphytominingandphytoremediationtechnologiesandmayeducateapproachestowardscropsafetyandbio-fortification.References:Steinetal.(2017)NewPhytol.213:1274-86.Keywords:Arabidopsisrelatives;extremophile;heavymetal;genome-wideassociationmapping;molecularecology

Abstract#8.Fire,phosphate,friends,andfoes:theevolutionofkarrikinandstrigolactonesignaling(Submission300)DavidNelson11UniversityofCalifornia,Riverside,UnitedStatesKarrikinsareaclassofcompoundsfoundinsmokethatstimulategerminationofmanyspeciesafterfire.Karrikinscanalsoinfluenceseedlinggrowth,andinsomespecieshavebeenreportedtoenhanceseedlingvigorandsurvivalunderstressfulgrowthconditions.GeneticstudiesrevealedthatkarrikinresponsesrequiretheF-boxproteinMAX2,whichisalsonecessaryforstrigolactonesignaling.Strigolactonesareplanthormoneswithdiverserolesindevelopmentthatarealsoexudedintosoil,wheretheyserveasrecruitmentsignalsforsymbioticinteractionswitharbuscularmycorrhizalfungiunderlowphosphorusornitrogenconditions.RootparasiticweedsintheOrobanchaceaehavecapitalizedonthissymbiosisbyevolvingtheabilitytousestrigolactonesinsoilasgerminationcues.Thecorecomponentsofthekarrikinandstrigolactonesignalingpathwayshavebeenidentifiedoverthepastseveralyears,revealingmechanismsofligand-activatedproteolysisthatareanalogoustoseveralotherplanthormonesignalingsystems.Remarkably,karrikinandstrigolactonesignalinginvolvehomologouscomponents.Wediscoveredthatstrigolactonereceptorsinparasiticplantsevolvedfrom

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geneduplicationandneofunctionalizationofthereceptorKAI2,whichisnecessaryforkarrikinresponsesinArabidopsis.However,increasingevidencepointstoanunknownendogenousligandforKAI2andthatkarrikinsmayfortuitouslymimicthissignalinArabidopsis.WearenowpursuingtheidentificationoftheunknownKAI2ligandandexploringtheevolutionofspecializedkarrikinresponsesinfire-followingspecies.

Abstract#9.Definingthetranscriptionalregulatorystructureofplantgenomes(Submission258)RogerDeal1,Maher,Kelsey,EmoryUniversity,Bajic,Marko,EmoryUniversity,Kajala,Kaisa,UCDavis,Reynoso,Mauricio,UCRiverside,Pauluzzi,Germain,UCRiverside,Bailey-Serres,Julia,UCRiverside,NeelimaSinha,UCDavis,SiobhanBrady,UCDavis1EmoryUniversity,UnitedStatesComparedtoanimalgenomes,thecis-regulatorystructureofplantgenomesremainspoorlydefined.Itiscurrentlyunclearhowmanyenhancerelementsexistinplantgenomes,wheretheseelementslieinrelationtotheirtargetpromoters,andhowmanyelementsaretypicallyusedtoregulateeachgene.Toaddresstheseissues,wehaveemployedtheassayfortransposaseaccessiblechromatin(ATAC-seq)infourdifferentplantspecies(Arabidopsis,Medicago,Tomato,andRice)todelineateopenchromatinregionsandtranscriptionfactorbindingsitesacrosseachgenome.Despitemajorvariationsingenomesizeandevolutionarydivergence,wefindthatthedistributionofopenchromatinsitesishighlysimilaracrossspecies.Themajorityofintergenicopenchromatinsitesoccurwithin3kbupstreamofatranscriptionstartsite(TSS)inallfourspecies.Nearly70%ofgenesinArabidopsis,Medicago,andRicehaveasingleputativeenhancerregionupstreamoftheTSS,whileasimilarpercentageofTomatogeneshave2-5suchelements.WehavealsousedATAC-seqprofilingofspecificcelltypesinArabidopsistoaddressthedifferentialutilizationofregulatoryelementsduringcelldifferentiation.Wefindthatwhileclosely-relatedcelltypesoftenhavequalitativelyindistinguishableopenchromatinprofiles,quantitativeanalysisofchromatinaccessibilityrevealsfunctionallyrelevantdifferencesbetweencelltypes.Furthermore,bycombiningchromatinaccessibilitydatawithtranscriptionfactor(TF)expressionandgenomicbindingdata,wecanidentifyTFnetworksactingatahighleveltocontroltranscriptionaloutputinspecificcelltypes.Theseputativeregulatorynetworkstheninformfurtherexperimentationandhypothesistesting.InthistalkIwilldiscussthekeyfindingsofthisworkandfuturegoalsfordecipheringtranscriptionalcontrolinplants.Keywords:transcriptionalregulation,ATAC-seq,transcriptionfactor,enhancer

Abstract#10.ThemultiplefacetsofPolycombRepressiveComplexe2(Submission314)FrancoisRoudier1,Morao,AnaKarina,IBENS,Chica,Claudia,IBENS,Caillieux,Erwann,IBENS,Bouyer,Daniel,IBENS,Colot,Vincent,IBENS,Roudier,François,IBENS-RDP1FrancePolycombgroupproteinsplayamajorroleinmaintainingthetranscriptionalrepressionoftargetgenesbyregulatingtheirchromatinstructure.PolycombRepressiveComplex2(PRC2)isresponsibleforthetrimethylationofhistoneH3lysine27(H3K27me3)andexistsinmultipleformsdifferingbytheirsubunitcomposition.Bycombiningmolecular,geneticandgenomicapproaches,weshowthattheinterplaybetweendistinctPRC2sisnecessarytoregulatetheactivityofthemeristemandthetimingofcelldifferentiation,aswellasthemaintenanceofcellidentity.Inaddition,ourworkrevealsthatPRC2complexescontainingeitherofthetworelatedmethyltransferasesCLForSWNregulatecommonaswellasspecificsetsofgenesthroughdistinctmechanisms,includinganon-canonicalfunction.Furthermore,ourresultsindicatethatthefunctionaldifferencesbetweenCLF-PRC2andSWN-PRC2rely,atleastinpart,onthenon-catalyticsubunittheyareinteractingwith.Takentogether,ourdataindicatethatdistinctPRC2complexescooperatetoorchestratethetranscriptionalnetworksthatcoordinatemeristemactivityandcelldifferentiationduringrootdevelopment.

Abstract#11.Howmembranetraffickingregulatesimmunity(Submission146)SilkeRobatzek1,SaraBenKhaled,GildasBourdais,MichaelaKopischke,LydiaRickett,MaryTetlow1TheSainsburyLaboratory,UnitedKingdomOurmainresearchfocushasbeenhowcellsdefendthemselvesagainstinfectionoftheirextracellularspacebymicrobialpathogens.Conservedmicrobialpatternsactivatecellsurfacereceptorsthatareessentialforhostimmunity,andinducetheirinternalization.Overtheyearswehavecharacterizedimmunereceptor-mediatedendocytosis,aprocessconservedacrossdifferentreceptorfamilymembers.Yet,thesignificanceofreceptor-mediatedendocytosisintheregulationofimmunesignallingremainedcontroversial.Werecentlyhaverevealedthatendocytosisofcellsurfaceimmunereceptorsisamechanismforsustainingcellularresponsivenesstomicrobialpatterns,asitexistsinnaturalencountersofplantswiththeirbioticenvironment,toconferlong-termanti-bacterialimmunity.ThisworkissupportedbytheGatsbyCharitableFoundationandtheEuropeanResearchCouncil(ERC).Keywords:pattern-triggeredimmunity,flagellin,EF-Tu,FLS2,EFR

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Abstract#12.Closingthedeal:ArabidopsisLORELEIisrequiredforpollentubereceptionbythefemalegametophyte(Submission387)RaviPanivelu1,YanbingWang,XunliangLiu,JenniferNoble,RebeccaA.Mosher1UniversityofArizona,UnitedStatesDoublefertilizationrequiressuccessfulspermcelldeliverybythemalegametophyte(pollentube)tothefemalegametophyte(embryosac).WeisolatedanullalleleofLORELEI(LRE)andimplicateditininducingpollentubereceptionbythesynergidcellsofthefemalegametophyte.LREfusedtocitrineyellowfluorescentprotein(LRE-cYFP)remainsfunctionalandlocalizestothesynergidplasmamembrane-richfiliformapparatus,thefirstpointofcontactbetweenthepollentubeandthefemalegametophyte.LREcontainsdomainsthatarecriticalforaddingaglycosylphosphatidylinositol(GPI)anchortothepre-proteininER.Consistentwiththeseobservations,deletionofGPIanchoradditiondomainsledtodecreasedlocalizationofLRE-cYFPinthefiliformapparatus.Biochemicalanalysisofectopically-expressedLRE-cYFPexpressedinleavesdemonstratedthatLREisindeedaGPI-anchoredmembraneprotein.EctopicallyexpressedanddeliveredLRE-cYFPfrompollentubescouldnon-cell-autonomouslycomplementthepollentubereceptiondefectinlrefemalegametophytes,onlyiftheyexpressedFERONIA,areceptor-likekinase,indicatingthatLREandFERONIAjointlyfunctioninpollentubereceptionattheinterfaceofthesynergidcellandpollentube.ExpressionanalysisshowedthatLREisexpressedinthefemalegametophytebeforefertilizationandthedevelopingseedupto24hoursafterpollination.Interestingly,LREexpressionisimprinted:theLORELEImatrigenicallelecontributesnearlyalltheLORELEIexpressionafterfertilization,makingitarareimprintedgenethatfunctionsimmediatelyafterdoublefertilization.OurresultsshowthatastrictmaternalandmatrigenicexpressionofLORELEIinthefemalegametophyteandfertilizedovules,respectively,allowsthematernalparenttocontroltwocriticalevents–pollentubereceptionandinitiationofseeddevelopment–justbeforeandsoonafterdoublefertilizationusingthesamegene.Abstract#13.Symplasticsignalingduringrootdevelopment(Submission249)KimGallagher1,ShuangWu,RuthsabelO'Lexy1UnitedStatesPlantdevelopmentreliesonpositionalinformationforthecoordinationofcellularpatterningandmorphogenesis.Asinanimals,mechanicalsignals,secretedpeptidesandhormonescanallconveyinformationbetweencells.However,uniquetoplantsistheabilityofcellstodirectlysignaltheirneighborsviaplasmodesmata.Transcriptionfactors,smallRNAsandmetabolitescanallmovebetweencellsintheplant.HereweexploitanoveltoolthateffectivelyblocksmovementofproteinsandsmallRNAsbetweencellstoshowthatcell-to-cellsignalingisimportantforthecoordinationofcelldivisionsandcellpolaritybetweencelllayersintheroot.Tissuespecificinhibitionofplasmodesmataintheendodermisresultsinadeformationofthecorticalcelllayerandafailureofcellsintheendodermallineagetoswitchfromastem(founder)cellfatetoatransitamplifyingfate.

Abstract#14.Interplaybetweenphosphorylationandubiquitinationinplantimmunesignaling(Submission299)JacquelineMonaghan11Queen'sUniversity,CanadaPlantshaveevolvedamulti-facetedimmunesystemtofightagainstpathogeninfection.Whilenecessaryforsurvival,pathogenperceptionandtheactivationofimmuneresponsesareenergeticallytaxingforthehostandhavebeenlinkedtoconsiderablefitnesscosts.Althoughdefensesignalingpathwaysmustthereforebetightlyregulated,verylittleisknownaboutthebiochemicalmechanismsthattailorsignalingtomaintaincellularhomeostasis.OurnewresearchprogramatQueen’sUniversityfocusesonunderstandingthebasicmechanismsunderlyingplantimmunitywithafocusonkinase-mediatedsignaltransduction.Currentprojectsaddresstheroleofandinterplaybetweendifferentpost-translationalmodificationsonproteinsinvolvedinimmunehomeostasis.WepreviouslyfoundthattheCa2+-dependentproteinkinaseCPK28associateswithandphosphorylatesthekeyimmunekinaseBIK1,affectingBIK1turnoverthroughtheubiquitin-proteasomesystem.Wearecurrentlyinvestigatingsite-specificmodificationsonBIK1andCPK28thatregulatetheirfunctioninimmunesignaling.Ongoingworkinvolvingtheidentificationofinvivopost-translationalmodificationsoftheseregulatorswillbepresented.

Abstract#15.Post-translationalmechanismsofbrassinosteroidandsugarresponses(Submission391)ZhiyongWang1,Zhu,Jia-Ying,CarnegieInstitutionforScience,Zhang,Zhenzhen,FujianAgricultureandForestryUniversity,Wang,Wenfei,FujianAgricultureandForestryUniversity,Xu,Shouling,CarnegieInstitutionforScience,Shin,Kihye,FujianAgricultureandForestryUniversity,Cheng,Ling,FujianAgricultureandForestryUniversity1UnitedStatesPlantgrowthisregulatedbynotonlyenvironmentalandhormonalsignalsbutalsobysugar,whichisnotonlytheessentialsourceforenergyandmetabolismbutalsoaregulatorysignal.Integrationofsugarsignalwithenvironmentalandhormonalsignalsiscrucialforhomeostasis.Plantcellelongationisregulatedbybrassinosteroid(BR),auxin,gibberellin(GA),light,andtemperaturesignalsthroughacentralnetworkofinteractingtranscriptionalregulators,includingtheBR-activatedBZR1familytranscriptionfactors,theauxinresponsefactors(ARF),thephytochrome-interactingfactors(PIFs),andtheGA-sensitiveDELLAproteins(theso-calledBAP/Dgrowthmodule).BRsignallingthroughthereceptorkinaseBRI1leadstoinhibitionoftheGSK3-likekinaseBIN2anddephosphorylationoftheBZR1familyoftranscriptionfactors.BR-inducedinactivationofBIN2involvesitsubiquitinationmediatedbytheF-boxproteinKIB1.SugaraffectsBRresponsesinlight-dependentmanners.Indarkconditions,sugarpromotesBZR1accumulationthroughtheTargetOfRapamycin(TOR)pathwayandanautophagy-dependentmechanism.However,inlight-grownplants,ahighlevelofsugarattenuatesBR-inducedBZR1

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dephosphorylationandinhibitsBRresponses.Sugarisalsoknowntomodulategrowththroughglycosylationofregulatoryproteins.Wehaveidentified262proteinsmodifiedbyO-linkedN-acetylglucosamine(O-GlcNAc)inArabidopsis.Theseincludemostlynuclearproteinsinvolvedintranscriptionalregulation,RNA-processing,andhormoneresponses.Aframeworkforintegratingsugarandhormonalresponsesthroughpost-translationalmechanismswillbepresented.Keywords:Sugarresponse,TOR,brassinosteroid,ubiquitination,O-GlcNAcmodifications

Abstract#16.IonometoGenome:TalesofGeneDiscovery(Submission390)MaryLouGuerinot11DartmouthCollege,UnitedStatesUnderstandinghowseeds,oftentheedibleportionoftheplant,obtainandstorenutrientsiskeytodevelopingcropswithhigheragronomicandnutritionalvalue.Mostofourworkhasbeenfocusedontheessentialmicronutrientsiron,manganeseandzinc.Combininggenetics,highthroughputelementalanalysisviaICP-MSandhighresolutionimagingviasynchrotronX-rayfluorescence,wehaveidentifiedandcharacterizedanumberofArabidopsismutantsthathaveincreasedtolerancetoirondeficientgrowthconditionsandhaveincreasedironaccumulationrelativetowildtypeplants.Oneofthese,Ig14,hasasimilarmetalcontenttowildtypewhengrownonnormalsoil,butthrivesonalkalinesoil,accumulatingsignificantlymoreironinitsshootandseeds.Atriplemutantofthreecloselyrelatednegativeregulatorsoftheirondeficiencyresponsehasincreasedtolerancetoirondeficientgrowthconditionsandincreasedironaccumulationwithoutresultingtoxicity.Wehavealsouncovereduniquepatternsofironandmanganeselocalizationinseedsandhavenowidentifiedthegenesresponsibleforsettingupthesepatterns,allowingustodeterminewhetherthepatternsarebiologicallysignificantand,ultimately,whethertheycanbealteredinsupportofbiofortificationofstaplecrops.Wearealsotakingsimilarapproachestodeterminehowarsenic,anon-threshold,Class1humancarcinogen,accumulatesinplants.Rice,astaplefoodforoverhalftheworld’spopulation,representsasignificantdietarysourceofarsenic.Itisimperativethatstrategiestoreducegrainarsenicaredeveloped,andidentifyingthemechanismsthatenablearsenictoreachandaccumulatewithinthericegrainiskeytothisendeavor.Keywords:essentialmicronutrients;iron;manganese;arsenic;seeds

Abstract#17.Towardsaquantitativeunderstandingofhowsignalsdrivecellfatedecision-makingattheshootapicalmeristem(Submission294)TevaVernoux11ENSdeLyon,FrancePlantorgansareinitiatedattheshootapexinprecisespatio-temporalpatternsthataretheprimarydeterminantsofphyllotaxis,thegeometricarrangementoforgansalongthestem.Acombinationofmodelingandwetexperimentshasshownovertheyearsthatauxin-basedinhibitoryfieldsarecentraltothedynamicsofmorphogenesisattheshootapex.Sofarourunderstandingofhowauxin-basedinhibitoryfieldspatterntheshootapexislargelyqualitativeandnoformalanalysishasbeenconductedtoanalyzetheirdynamicsandtheirvariability.Wehavenowusedaratiometricbiosensorforauxinandlive-imagingtoconductaquantitativeanalysisofauxin4Ddistributionintheshootapexandtorelateittoidentitymarkersdynamicsandtotissuegrowth.Iwilldiscusshowbothauxintransportandgrowthcontributetoshapeinhibitoryfieldsthatallowefficientcontrolofpatterningdynamicsattheshootapexandgenerationoftheshootprimaryarchitecture.

Abstract#18.Hopefulmonstersandplantsyntheticbiology(Submission274)JenniferNemhauser11UWashington,UnitedStatesLifeintheAnthropocenehasmanychallenges,amongthemosturgentiswidespreadglobalhungerandmalnourishment.Whatifeverycommunityofsmall-holdfarmerscouldimprovetheirownheritagecropstotheirownspecifications?RealizingthisDIYvisionwouldrequireradicalinnovationsinthewayweconceptualizeandexecutecropimprovement.Syntheticbiology,sittingatoneoftheintersectionsofengineeringandbiology,offerstheoreticalandpracticaltoolstoguidesuchefforts.Mygroupisinterestedinexploringthelimitsofrationalre-tuningofdevelopmentalpathwaystocustomizeplantformforlocalagriculturalconditions.Todate,themajorityofoureffortshavefocusedontheauxinresponsepathway.Oursyntheticexperimentsrecapitulatingauxinresponseinyeastinformandareinformedbyexperimentsinplants.Thisworkhasledtothehypothesisthatauxinsetscontext-specificdevelopmentaltimers.Weareactivelytestingthishypothesisbyresettingauxinresponsedynamicsthroughexpressionofvariantsinpathwaycomponentsandquantificationoftheimpactsonshootandrootarchitecture.

Abstract#19.Topologicalfeaturesofageneco-expressionnetworkpredictpatternsofnaturaldiversityinenvironmentalresponse(Submission360)DavidDesMarais11HarvardUniversity,UnitedStatesGenesneitherfunctionnorevolveinisolation.Thetranscriptionalactivitiesofgenesareoftenhighlycorrelatedwithoneanother,forminghierarchicalgeneregulatorynetworks(GRNs)comprisedoffunctionallyrelatedmodules.WithinGRNs,somegenes--“nodes”–havestrongerormoreinteractions--“edges”–thandoothergenes.Becausetheeffectsizeofmutationsisstronglyassociatedwiththeirevolutionaryfate,andbecauseGRNpositioncaninfluencethephenotypicbreadthofamutation’seffect,propertiesofGRNswilllikely

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affectselectionactingonindividualcomponentgenes.Here,Iinvestigatedthenetworktopologyofgenesinvolvedinresponsetotwoabioticstressors—droughtandcold—inArabidopsisthaliana.Ishowthatthepositionsofgenesexhibitinggeneticvariationindroughtresponse(GxE)aremoreperipheralandcoldGxEgenesaremorecentralinGRNsthangenesnotinvolvedineitherresponse.Isuggestthattheobservedtopologiesreflectdifferentconstraintsonregulatorypathwaysinvolvedintheassayedphenotypes.Mynetwork-basedanalysisalsorevealsfunctionalenrichmentsofdroughteGxEgeneswhichwerenotdetectedinpastanalyses,thussuggestingthepowerofthisapproachfordetectingmeaningfulbiologicalpatternsincomplexdata.Keywords:abioticstress,genotypebyenvironmentinteraction,genereguation

Abstract#20.NaturalVariationWithinAndAmongSpecies:IntegratingPopulationGenomicsandComparativeGenomicsofBrassicaandRelatives(Submission75)J.ChrisPires1,Kent,Tyler,UniversityofToronto,Edger,Patrick,MichiganStateUniversity,Platts,Adrian,NewYorkUniversity,Washburn,Jacob,UniversityofMissouri,Schmutz,Jeremy,HudsonAlpha,Mitchell-Olds,Tom,DukeUniversity,Schranz,Eric,WageningenUniversity,Weigel,Detlef,MPI,Wing,Rod,UniversityofArizona,Wright,Stephen,UniversityofToronto1UniversityofMissouri,UnitedStatesTheBrassicalesMapAlignmentProject(BMAP)hassequenced19genomesaspartofaDepartmentofEnergy(DOE)JointGenomesInstitute(JGI)CommunitySequencingProgram(CSP)initiative.Ourinternationalteamhasmorethandoubledtheexistinggenomicresourcesforthemustardfamily(Brassicaceae).Specifically,weareaddingonegenomeintheCleomaceae(Cleomeviolacea)and18genomesintheBrassicaceae:Cakilemaritima,Caulanthusamplexicaulis,Crambehispanica,Descurania(twospecies),Diptychocarpusstrictus,Erucavesicaria,Euclidiumsyriacum,Iberisamara,Isatistinctoria,Lepidiumsativum,Lunariaannua,Malcomiamartima,Myagrumperfoliatum,Rorippaislandica,Sinapisalba,Stanleyapinnata,andThlaspiarvense.WhilepreviousgenomesequencingintheBrassicaceaehasfocusedonrelativesofArabidopis,Brassica,andafewextremophiles,thesegenomesequencesarephylogeneticallydispersedamongallthemainlineagesofthemustardfamily.Collectively,theBrassicaceaearethemodelfloweringplantfamilymorephenotypesofinterestincludingabioticstress(salt,flooding,drought,cold,heavy-metalsoils),bioticstress(herbivory,fungalassociations),vegetativeandreproductivedevelopment,self-incompatibility,seedcompositionanddormancy,andotherstraitsofagronomicorevolutionarysignificance.Wewillpresentcomprehensiveanalysesofthesegenomeswithexistingpublishedhigh-qualitygenomesoftheBrassicaceae.Ouranalysesincludeathoroughcharacterizationofgenomestructure(genomesize,repetitiveelements,conservednoncodingregions,geneandgenomeduplications,etc.)evolutionaryandphylogenomicanalyses,andsystems/networkanalyses.Keywords:ComparativeGenomics;Phylogenomics;Polyploidy;GenomeSizeEvolution;MetabolicNetworksAbstract#21.UsingNaturalVariationtoUncovertheGeneticBasisofRootTraitsinArabidopsis(Submission289)WolfgangBusch11SalkInstitute,UnitedStatesHiddenfromview,rootsplayacrucialroleforplantsurvivalandproductivity.Differentsoilsandclimatesconstitutetremendouschallengesforrootsystems,aswaterandnutrientdistributioncangreatlydiffer.Nevertheless,ArabidopsisthalianasuccessfullycolonizedlargepartsofEurasiathatdisplayvastvariationsofclimatesandsoils.Supposedly,rootsystemshadtostronglyadapttoallowforthisandconsistentlywithanadaptiveroleofroots,naturalaccessionsofArabidopsisshowpronouncedvariationofrootgrowthanditsresponsestotheenvironment.Butwhatarethegenesandgeneticvariantsresponsibleforroottraitvariation,andwheredotheyfitinwithwhatwealreadyknowaboutrootgrowthanddevelopment?Wehaveapproachedthisproblemusingasystemsgeneticsapproachthatintegrateshighthroughputphenotyping,genomewideassociationmappingandfunctionalgenomicapproaches.Wehaveidentifiedmultiplemechanismsthatunderliethenaturalvariationofroottraits.Moreover,westudiedtherelationofgenevariants,roottraits,climateandsoilparameters.Finally,westartedtoinvestigatethemolecularmechanismofsomeofthesegenes.AmongthemostoutstandingmechanismsisasignalingmoduleofLeucine-Rich-Receptor-Like-Kinasesinwhichnaturalgeneticvariationdeterminesrootgrowthresponsestolowironlevels.Interestingly,thesegenesarealsoinvolvedindefenseresponses.Overall,ourworkdemonstratesthatsystemsgeneticsapproachesharnessingexistingnaturalgeneticvariationaswellasmodernpost-genome-eraapproaches,allowustounderstandgeneticandmolecularmechanismsthatunderliephenotypicvariationandmostlikelycontributetolocaladaption.Keywords:genetics;naturalvariation;root;phenotyping;GWAS

Abstract#22.Epigeneticregulationofgenomeexpression,environmentalanddevelopmentalinteraction(Submission261)XuehuaZhong11UniversityofWisconsin-Madison,UnitedStatesEpigeneticregulationofgeneexpressionplayscriticalrolesinmaintaininggenomeintegrity,imprinting,cellulardifferentiation,normalgrowthanddevelopment,diseaseformationaswellasinrespondingversatileenvironmentalsignals.OuroverallresearchgoalistounderstandhowepigeneticmodificationsofDNAandhistonesmodulatechromatinstructuraldynamicstoregulategeneexpression.Wearealsointerestedinunderstandinghowepigeneticmodulationofchromatinstructureandgeneexpressiondictateresponsestoenvironmentalchangesandhowenvironmentconditionsfeedbacktoshapetheepigeneticlandscape.Ourlabrecentlydiscoveredanepigeneticcomplexasanovelplayerinplantageingaswellasanepigeneticswitchtriggeringdevelopmentalphasetransition.Iwilldiscussthedatadescribingourlatestunderstandingoftheunderlyingmechanism.

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Abstract#23.EpigeneticinheritanceofDNAmethylationpatterns(Submission354)DanielZilberman11UCBerkeley,UnitedKingdomCytosinemethylationprovidesamechanismtoheritablyalterthegenomewithoutpermanentmodificationoftheDNAsequence.Infloweringplants,DNAmethylationpatternsarefaithfullyreproducedacrossgenerations,sothatmethylationshapestheinheritanceofplanttraits.Epigeneticmutationsthatdisruptmethylationataparticularlocuscancausesubstantialdevelopmentalabnormalities.IwillpresentourrecentresultsthatelucidatehowplantsensuretheaccurateandreliableinheritanceofDNAmethylation.

Abstract#24.InsightofhistonedemethylasestargetinginArabidopsis(Submission254)XiaofengCao11InstituteofGeneticsandDevelopmentalBiology,ChineseAcademyofSciences,ChinaTranscriptionactivityofchromatinisregulatedbycovalentmodificationsonnucleosomesandDNA.Recenteffortshaveidentifiedalotofchromatinmodifiers,whichplayimportantrolesinvariousaspectsofbiologicalprocesses.Thesechromatinmodifiersnormallybindasubsetofspecificgenomicloci.Discoveringthemechanismsofrecruitingthesemodifiersisessentialforunderstandingthebiologicalfunctionofthem.WepreviouslyidentifiedArabidopsisJMJ14andJMJ12/REF6asH3K4andH3K27-specifichistonedemethylases,whichusetwodistinctmechanismstotheirgenome-widetargets.TheC-terminalFYRdomainofJMJ14interactswithapairofNACdomaincontainingtranscriptionfactors,whichbringJMJ14totheircommontargetgenes;whereasREF6recognizesitstargetlocibydirectrecognizingspecificDNAsequencethroughitstandemC2H2-Zincfingerdomains.Inthistalk,IwillprovideadditionalinformationtoillustratehowREF6actsingenome-widetargetinginArabidopsis.

Abstract#25.SpatiotemporalaveragingofvariablecellgrowthproducesregularArabidopsissepals(Submission129)AdrienneRoeder1,Hong,Lilan,CornellUniversity,Dumond,Mathilde,ENSdeLyon,Tsugawa,Satoru,HokkaidoUniversity,Sapala,Aleksandra,MaxPlanckInstituteforPlantBreedingResearch,Hamant,Olivier,ENSdeLyon,Smith,Richard,MaxPlanckInstituteforPlantBreedingResearch,Komatsuzaki,Tamiki,HokkaidoUniversity,Li,Chun-Biu,StockholmUniversity,Boudaoud,Arezki,ENSdeLyon1CornellUniversity,UnitedStatesFlowersformwithremarkableconsistencyofsizeandshapeinArabidopsis.Thisconsistencyisstrikingbecausethegrowthanddivisionofcellsmakingupthoseorgansishighlyvariable.Toidentifygenesinvolvedinproducingreproduciblefloralorgans,wescreenedformutantswithvariablysizedandshapedfloralorgansandrecoveredsixmutationsintheFtsH4gene.Surprisingly,wefoundthattherateofcellgrowthwaslessvariableinftsh4sepalsthaninwildtype.Tounderstandhowreducingcellularvariabilitycouldincreaseorganvariability,wesimulatedamechanicalmodelofthesepal.Inourmodel,varyingthestiffnessofthetissueonlyinspaceproducedhighlyirregularsepals.Incontrast,ifwevariedthestiffnessofthetissuenotonlyinspacebutalsointime,themodelproducedregularsepals.Thus,themodelsuggestedthatcellularvariabilityinbothspaceandtimeaveragesouttoproduceregularorgans.Inwild-typesepals,weobservedthisspatiotemporalaveragingintheprincipaldirectionsofgrowthofthecells.Forexample,ifacellgrewalittlebittowardtherightandthengrewalittlebittotheleft,theoverallgrowthaveragedtostraight.Incontrast,spatiotemporalaveragingfailedinftsh4mutantsepals,andtheprincipaldirectionsofgrowthofthecellsdidnotbecomestraightovertime.FtsH4encodesamitochondriali-AAAprotease,andftsh4mutantshaveabnormalandincreasedaccumulationofreactiveoxygenspecies(ROS).Dippingwildtypeflowersinhydrogenperoxideproducedirregularsepalsizes,whereasreducingROSintheftsh4mutantbyoverexpressingCATALASE2(CAT2)restoredconsistentsepalsizes;thesedataindicatethatabnormalROSaccumulationcausestheformationofirregularorgans.Thus,spatiotemporalaveragingofcellularvariabilityisrequiredforprecisionandreproducibilityinorganshapeandsize.Keywords:spatiotemporalaveraging;sepal;cellgrowth;size;shape

Abstract#26.ManipulatingheterotrimericG-proteinsignalingtoimproveplantyieldandstresstolerance(Submission287)SonaPandey1,JagdeepKaur,SwarupRoyChoudhury,AnithaVijayakumar,NigelTaylor1DonaldDanforthPlantScienceCenter,UnitedStatesHeterotrimericG-proteinscomprisedofthreedissimilarsubunitsGα,GβandGγ,areimportantregulatorsofmultiplegrowthanddevelopmentalpathwaysinalleukaryotes.Inplants,theinvolvementofG-proteinshasbeenestablishedinregulationofamultitudeoffundamentalgrowthanddevelopmentpathwayssuchasphytohormonesignalingandcross-talk,controlofcelldivisionandorganshape,bioticandabioticstressresponsesandreproductivetraitplasticity.Theplant-specifictypeIIIGγproteins,exemplifiedbyAGG3inArabidopsis,haveemergedasakeytargetforincreasingyieldofcropplants,whilereducinginputandimprovingstresstolerance,whichistheultimategoalofmostplantscienceresearch.FunctionalanalysisofArabidopsisAGG3showsitsinvolvementinG-proteinmediatedabscisicacidsignalingprocesses.TargetedmanipulationofAGG3geneinArabidopsisandCamelinahasalsoestablisheditasapositiveregulatoroforgansize.Furthermore,geneticanalysisofvariousriceandbarleypopulationshasidentifiedtheAGG3homologsDEP1andGS3astheQTLforgrainlength,paniclebranchingandnitrogenuseefficiency.Theregulationofmultipleimportanttraitssuchasseedsize,shapeandnumber,aswellasstressresponsesandnutrientuseefficiencybythetypeIIIGγproteinsmakethemakeytargetforbiotechnologicalapplications.Howevermajorgapsexistinourknowledgeabouttheirmechanisticdetails.Theresultsobtainedfromtheanalysisofnaturallyoccurringvariationsinriceandbarleyareconfoundingandtheextenttowhichtheobservedeffectsareduetothehigherexpressionoftheseproteinsversusthepresenceofspecificmodificationsortruncationsremainsunclear.Toaddressthis,wehave

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overexpressedtheAGG3geneinSetariaitalica(amodelmonocot)andanalyzedthetransgenicplantsfortheirimprovedagronomictraits.OurresultsconfirmtheroleoftypeIIIGγproteinsasapositiveregulatorofyield.Keywords:TypeIIIGγproteins,AGG3,HeterotrimericG-proteins,stressresponse,yield

Abstract#27.Lowoxygenandenergy:Multi-scalegeneregulatoryresponsesinArabidopsisandrice(Submission278)JuliaBailey-Serres1,Reynoso,MauricioA.,UCRiverside,Pauluzzi,Germain,UCRiverside,Lee,Travis,UCRiverside,Locke,Anna,UCRiverside,Winte,Sonja,UCRiverside1UCRiverside,UnitedStatesArealityoftheincreaseintheEarth’saveragesurfaceairtemperatureismorefrequentextremesinwateravailabilityinnaturalandagriculturalecosystems.Poortoleranceofcropstowaterextremesisaleadingcauseofstagnationingrainproductivityandcontributestofoodinsecurity.TheintegrationoffundamentalknowledgefromcropsandArabidopsiscanhastentherecognitionofconservedgeneticmechanismsthatmightbeengineeredtostabilizefitnessinvariableenvironments.TheexceptionaldevelopmentalplasticityofriceplantstosloworrapidfloodsisdeterminedbySUBMERGENCE1AorSNORKEL1/2loci,respectively,membersofanethylene-responsivetranscriptionfactorfamily(ERF-VIIs).ERF-VIIaccumulationinArabidopsisrequiresadeclineincellularoxygenlevels,duetoturnovermediatedbyanoxygen-dependentbranchoftheN-endrulepathway.ArabidopsisERF-VIIsbindanhypoxia-responsivepromoterelement(HRPE)toactivategenesassociatedwithanaerobicmetabolismaswellasrestrictERF-VIIfunctionandaccumulation.Thiscounterbalancedresponseiscriticaltolimitenergyinefficientanaerobicmetabolismasoxygenlevelsrecover.Athirdricelocus,TREHALOSE6-PPHOSPHATASE7enhancesseedlingsurvivaloffloodingbylimitinggrowthtothecoleoptile.Fromtheselociweunderstandthatfloodingsurvivalinvolvesregulationofwhetherenergyreserveswillbe:(1)depletedtomaximizegrowthtoregainaccesstooxygen,or(2)re-allocatedfromsourcetosinktomaintainviabilityofstemorothercells.Tobetterunderstandprioritizationoftheseoptionsinspecificcellstoinfluencedevelopmentalplasticity,wehaveperformedcomparativemulti-scalestudiesofArabidopsisandrice.ThisentailedadaptionofINTACT(IsolationofNucleiTAggedinspecificCellTypes)andTRAP(TranslatingRibosomeAffinityPurification)torice.Withthesewehavemonitoreddynamicsinchromatinaccessibility,nuclear,andribosome-boundmRNAsfromtheorgantothecell-typelevel,recognizingsimilaritiesanddistinctionbetweencelltypesandspeciesindynamicsofresponseandenergymanagement.SupportedbyNSFPGRPPlasticity(IOS-1238243)andPGRPSecretome(IOS-1546879)projects.Keywords:transcriptionalregulation,chromatin,abioticstress,waterextremes,rice

Abstract#28.Mechanismsandevolutionofimprintinginplants(Submission273)MaryGehring11WhiteheadInstitute,UnitedStatesInplants,imprintingoccursintheendosperm,anessentialseedtissueformedfromoneoftwofertilizationeventsthatcharacterizefloweringplantreproduction.Theendospermistriploid,withtwomaternallyandonepaternallyinheritedgenomes.Mostgenesareexpressedinamaternal:paternalratioof2:1,but100+genesareimprinted,meaningtheyareexpressedpreferentiallyeitherfromthematernallyorthepaternallyinheritedalleles.ThistalkwillfocusonourlatestunderstandingoftheroleofDNAmethylationdynamics,transposableelements,andnaturalepigeneticvariationinestablishingandmaintainingimprintedexpression,andwilldiscussinsightsderivedfromcomparativeevolutionarystudiesofimprinting.Keywords:DNAmethylation,imprinting,endosperm

Abstract#29.Hormonemetabolismandbiasedligandsignalinginplants(Submission313)Jing-KeWeng1,MichaelPTorrens-Spence,ValentinaCarballo,AnastassiaBobokalonova,YanmeiHuang1WhiteheadInstituteandMIT,UnitedStatesTraditionalviewsofcellsignalingoftendepicthormoneperceptionmechanismsassimpleon-offswitchesinaone-ligand-one-receptormodel,whereinaparticularreceptorproteinisactivatedsolelybyitspairinghormonewithperfectedbindingkinetics.However,anincreasingbodyofevidencessuggeststhathormone-receptorinteractionsinvivoaremoresophisticatedthanpreviouslythought,whichmayinvolvedynamicinteractionsbetweenaseriesofstructurallyrelatedhormonemoleculesandafamilyofdivergentreceptorproteinssubjecttospatialandtemporalregulation.Hormonemetabolismnotonlygivesrisetothebiosynthesisofoneactivehormoneform,butalsoyieldaseriesofrelatedmetabolites,includingtheprecursorintermediatesprecedinghormonebiosynthesisaswellasthecompoundsthatarefurthermetabolizedfromthemostcommonlyrecognizedactivehormoneform.Historically,thesignalingpropertiesoftheseadditionalhormone-relatedmetaboliteswereatlargeoverlookedwithoutmuchscrutiny,yetsomeofthesemetaboliteshaveindeedbeenexploitedevolutionarilytoserveasnewsignalingmolecules,oftenina“biasedfashion”,contributingtothesignalingcomplexitywithinthesameorganismoracrossdivergentlineages.Phytohormonesarehighlyspecializedmetabolites,thebiosynthesisofwhichisdependentofmetabolicpathwaysuniquelyevolvedinlandplants.Inthistalk,Idiscusstheroleofbiasedligands,derivedfromevolutionarilyelaboratedhormonemetabolicsystems,incomplexsignalingregulationinplants.

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Abstract#30.MolecularControlsinPlantHormoneSignaling(Submission256)JoeJez11WashingtonUniversityinSt.Louis,UnitedStatesPlantsrespondtodevelopmentalcuesandabioticandbioticstressesbycontrollingboththelevelandactivityofphytoormones.Recentstructuralbiologystudiesprovidenewinsightsoncontrolmechanismbeforeandafterbindingofauxinandjasmonatestotheirrespectivereceptors.Pre-receptoractionbyacylacidamidosynthetasesoftheGH3familymodulatehormonelevelsbyaminoacidconjugation.Thefirstcrystalstructuresofbenzoate-specificArabidopsisthalianaAtGH3.12/PBS3andjasmonicacid(JA)-specificAtGH3.11/JAR1,combinedwithbiochemicalanalysis,definefeaturesfortheconjugationofaminoacidstodiverseacylacidsubstratesandhighlighttheimportanceofconformationalchangesintheC-terminaldomainforcatalysis.Theseresultsdemonstratehowahighlyadaptablethree-dimensionalscaffoldisusedfortheevolutionofpromiscuousactivityacrossanenzymefamilyformodulationofplantsignalingmolecules.Asecondmolecularcontrolmechanisminauxinresponsesinvolvesprotein-proteininteractionsmediatedbythePhox/Bem1p(PB1)domainsofAuxinResponseFactors(ARF)andAux/IAAco-repressorstoregulatetranscriptionaleventsmodulatedbythephytohormoneauxin.Thesestructuresrevealatwo-prongedinteractionandevolutionarilyconservationofthiscorerecognitionfeature,alongwithco-varyinginterfacesequencesallowsforversatilePB1-mediatedinteractionsinauxinsignaling.Combinedstructural,functional,andsequenceanalysisprovidesnewmolecularinsightsonplanthormoneresponsesystems.

Abstract#31.InositolpyrophosphatesignalingmoleculescontrolplantphosphatehomeostasisbybindingtoSPXsensordomains(Submission255)MichaelHothorn11SwitzerlandPhosphorusisamacronutrienttakenupbycellsasinorganicphosphate(Pi).HowcellssensecellularPilevelsispoorlycharacterized.IwillreportthatSPXdomains,whicharefoundineukaryoticphosphatetransporters,signalingproteins,andinorganicpolyphosphatepolymerases,provideabasicbindingsurfaceforinositolpolyphosphatesignalingmolecules(InsPs),theconcentrationsofwhichchangeinresponsetoPiavailability.SubstitutionsofcriticalbindingsurfaceresiduesimpairInsPbindinginvitro,inorganicpolyphosphatesynthesisinyeast,andPitransportinArabidopsis.Inplants,InsPstriggertheassociationofSPXproteinswithtranscriptionfactorstoregulatePistarvationresponses.ThesefindingssuggestthatInsPscommunicatecytosolicPilevelstoSPXdomainsandenablethemtointeractwithamultitudeofproteinstoregulatePiuptake,transport,andstorage.Keywords:phosphatemetabolism;inositolpyrophosphates;SPXdomain;transcriptionalregulation;structuralbiologyAbstract#32.Chromatinregulationofheatstressmemory(Submission283)IsabelBäurle11UniversitätPotsdam,GermanyInnature,plantsoftenencounterchronicorrecurringstressfulconditions.Anincreasingnumberofobservationssuggestthatplantscanrememberapastexposuretostresstobebetterpreparedforafuturestressincident.Mylabstudiesheatstressmemoryinplantsasamodelcaseforenvironmentalstressmemory.Seedlingsacquirethermotolerancethroughaheattreatmentatsublethaltemperatures(primingheatstress(HS))thatenablesthemtosurviveanotherwiselethalHS.Thisthermotoleranceisactivelymaintainedforseveraldaysasindicatedbytheexistenceofmutantswhichareabletoestablishthermotolerance,butfailtomaintainit.WehavebeenexploringthemolecularbasisofHSmemoryinArabidopsis.WehavefoundthatHSinducessustainedhistonemethylationatHSmemory-relatedlocithatoutlaststhetranscriptionalactivityoftheselociandhencemarksthemasrecentlytranscriptionallyactive(1).Atsomeloci,thisiscorrelatedwithhyper-inductionofgeneexpressionuponarecurringHS,-asignaturereadoutoftranscriptionalmemory.Inaddition,nucleosomeremodelingcontrolssustainedactivityofmemorygenes.SustainedlownucleosomeoccupancyismediatedbythehighlyconservedFORGETTER1proteinthroughdirectinteractionwithchromatinremodelingproteins(2).Insummary,thephysiologicalHSmemoryhasamolecularequivalentinthetranscriptionalmemoryandchangesinthechromatinstructureatasubsetofheat-responsivegenes.(1)LämkeJ,BrzezinkaK,AltmannS,BäurleI(2016).Ahit-and-runheatshockfactorgovernssustainedhistonemethylationandtranscriptionalstressmemory.EMBOJ.35,162-175.(2)BrzezinkaK,AltmannS,CzesnickH,NicolasP,GórkaM,BenkeE,KabelitzT,JähneF,GrafA,KappelC,BäurleI(2016).ArabidopsisFORGETTER1mediatesstress-inducedchromatinmemorythroughnucleosomeremodeling.eLife5,e17061.doi:10.7554/eLife.17061.Keywords:heatstress;chromatin;primingAbstract#33.CircadianTimingMechanismsinSeasonalFlowering(Submission302)TakatoImaizumi11UnitedStatesManyorganismsdisplayvariousseasonaldevelopmentalchangesthroughouttheyear.Toknowtheprecisetimeoftheseason,theymeasurechangesindaylength(=photoperiod)asahighlypredictableenvironmentalvariant.Photoperiodinformationisprocessedthroughanintricatenetworkcontrolledbythecircadianclock.Inmylab,weareinterestedinelucidatingthemechanismsbywhichorganismsmeasureseasonalchange.WeparticularlystudyphotoperiodicfloweringtimeregulationinArabidopsis.Inmytalk,Iwillintroducetwonewattemptstounderstandthemolecularmechanismsbywhichthecircadianclockpreciselytimesflowering.1)Inthispathway,oneofthecrucialmechanismsiscircadianclockregulatedtimingofCONSTANS(CO)transcription.WeidentifiedthatTEOSINTE

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BRANCHED1/CYCLOIDEA/PROLIFERATINGCELLNUCLEARANTIGENFACTOR4(TCP4)andrelatedclassIITCPsdirectlyactastranscriptionactivatorsofCO.WealsodemonstratedthatTCP4physicallyinteractswithanotherfloweringregulator,GIGANTEA(GI),andinducesCOexpressioninaGI-dependentmanner.2)Evenwhenphotoperiodsremainthesame,higherlightintensityinducesearlierflowering,however,theunderlyingmechanismforthishadremainedelusive.WefoundthatthephotoperiodicphotoreceptorFLAVIN-BINDING,KELCHREPEAT,F-BOX1(FKF1)proteinmodulateslevelsofphotorespiration-derivedhydrogenperoxide,whichcontrolscelldeathandaltersfloweringtimeinArabidopsis.FKF1interactswithCATALASE(CAT)proteinsthatbreakdownhydrogenperoxide.Hydrogenperoxideaccumulatesunderlong-dayhigh-lightconditionsandactsasasignaltoincreaseFLOWERINGLOCUST(FT)levels.Therefore,plantsintegratelightintensityinformationcapturedthroughphotosynthesis/photorespirationmechanismsintotheday-lengthsensingpathway.Takentogether,plantsusethesemechanismstopreciselyregulatefloweringtime.

Abstract#34.Breakingthesilence:Makingdecisionsintheworldofuncertainty(Submission268)KeikoTorii11HHMIandUniversityofWashington,UnitedStatesIthasbecomeevidentthatplantsuseamyriadofsecretedpeptidesandsmallchemicalstocoordinatetheirgrowth,development,andresponsetoenvironmentalinsults.Thesesignalscouldworkforlong-distance,ashoot-to-rootcommunicationforphysiologicaladjustment,ashort-distanceparacrinemanner,oranautocrinemannertocoordinatedevelopmentalpotentialofplanttissuepatterning.Owingtotheimportanceofplantsforourenvironmentandsustenance,newapproachesareneededtofurtherunderstandandmanipulateplantgrowthanddevelopment.Tothisend,weareformingacross-disciplinaryteamofscientists,includingsyntheticorganicchemists,structuralchemists,andplantbiologiststodevelopartificialligandsandreceptorstoprobe,understand,andmanipulateplantgrowthanddevelopment.Iwilldescribeourcollaborativeefforttomoveforward,andhowourtoolsprovidesconclusiveevidenceforaclassic,unresolvedquestioninplantsignaling.Keywords:receptor;hormonesignaling;chemicalbiology;growthanddevelopment

Abstract#35.Dynamicregulationofcellulargibberellindistributionsinfluencingplantgrowthpatterning(Submission270)AlexanderJones1,Rizza,Annalisa,SainsburyLaboratory,CambridgeUniversity,Walia,Ankit,SainsburyLaboratory,CambridgeUniversity,Frommer,Wolf,UniversitätDüsseldorf1SainsburyLaboratoryCambridgeUniversity,UnitedKingdomThephytohormonegibberellin(GA)isakeyregulatorofplantgrowthanddevelopment.AlthoughtheupstreamregulationanddownstreamresponsestoGAvaryacrosscellsandtissues,developmentalstages,andenvironmentalconditions,thespatiotemporaldistributionofgibberellininvivoremainsunclear.Weengineeredanoptogeneticbiosensor,GibberellinPerceptionSensor1(GPS1),thatsensesnanomolarlevelsofbioactivegibberellins(Kd=24nMforGA4).ArabidopsisthalianaplantsexpressinganuclearlocalisedGPS1reportongibberellinsatthecellularlevel.GAgradientswerecorrelatedwithgradientsofcelllengthinrapidlyelongatingrootsanddark-grownhypocotyls.Inroots,accumulationofexogenouslyappliedGAalsocorrelatedwithcelllength,suggestingthatarootGAgradientcanbeestablishedindependentlyofGAbiosynthesis.Inhypocotyls,GAlevelswerereducedinaphytochromeinteractingfactor(PIF)quadruplemutantinthedarkandincreasedinaphytochromedoublemutantinthelight,indicatingthatPIFselevateGAinthedarkandthatphytochromeinhibitionofPIFscouldlowerGAinthelight.AsGAsignallingdirectshypocotylelongationlargelythroughpromotingPIFactivity,PIFpromotionofGAaccumulationrepresentsapositivefeedbackloopwithinthemolecularframeworkdrivingrapidhypocotylgrowth.VisualisationofinvivoGAgradientsprovidesanimportantsteptowardsunderstandinghowGAintegratesupstreamsignallinginputsanddirectsdownstreamgrowthprogramminganddevelopment.Keywords:GibberellinPerceptionSensor1;cellgrowth;GAhormone;FRETbiosensor;phytochromeinteractingfactor

Abstract#36.Live-cellimagingoftheintracellulardynamicsduringzygotepolarization(Submission98)MinakoUeda1,Kimata,Yusuke,NagoyaUniversity,Kurihara,Daisuke,NagoyaUniversity,Higaki,Takumi,TokyoUniversity,Kawashima,Tomokazu,UniversityofKentucky,Yamada,Tomomi,NagoyaUniversity,Sato,Yoshikatsu,NagoyaUniversity,Hasezawa,Seiichiro,TokyoUniversity,Berger,Frederic,GregorMendelInstitute,Higashiyama,Tetsuya,NagoyaUniversity1NagoyaUniversity,JapanAxisformationisoneofthefundamentaleventsinplantembryogenesis.InArabidopsisthaliana,theapical-basalbodyaxisisinitiatedbytheasymmetriccelldivisionofthepolarizedzygote.Inspiteofitsimportance,thereal-timedynamicsofthezygotepolarizationstepswaspoorlyunderstood,becausethezygotedevelopsdeepintheflower.Thereforeweestablishedalive-cellimagingsystemthatenablesustoobservetheintracellulardynamicsofthezygotethroughtheovule.Byusingthissystem,wevisualizedvariousstructures,suchascytoskeletonsandorganelles,indevelopingzygote.Basedontheseresults,wewouldliketodiscusstheefficiencyofthisapproachtounderstandthedevelopmentaleventfromthecellbiologicalaspect.Keywords:live-cellimaging;zygote;embryoAbstract#37.“Disease-climate-microbiome”trianglesinthephyllosphere(Submission263)ShengYangHe11MichiganStateUniversity,UnitedStatesOneofthemostsignificantchallengesofthe21stcenturyistodiscoverinnovativewaysofincreasingglobalcropproductiontomeetthe

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demandsforfoodfromthegrowinghumanpopulation.Amajorroadblocktoglobalfoodsufficiencyispersistentlossofstaplecropstopathogeninfections.Greatereffortsareneededtoacceleratethebuildupofacomprehensiveknowledgebasethatexplainshowplantdiseasesoccur;howplantsdefendagainstmicrobialpathogens;andhowdynamicclimateconditionsimpactplants,microbes,andtheirinteractions.In1960,RBStevens(PlantPathology,anAdvancedTreatise.Vol.3,AcademicPress,NewYork)formulatedthefamous“DiseaseTriangle”concept,proposingthatplantdiseaseoutbreaksrequirenotonlyasusceptibleplantandavirulentpathogen,butalsoconduciveenvironmentalconditions.Forpracticalreasons,however,mostcontemporaryinvestigationsintoplant-pathogeninteractionsatthemolecularleveldevotelittleefforttounderstandingwhyclimaticconditions,suchashumidityandtemperature,haveaprofoundeffectonpathogenvirulenceandhostsusceptibility.Moreover,thesestudiesoftenignorethepotentiallypervasiveeffectaplant’sendogenousmicrobiomemayhaveonbasicplanthealthandhost-pathogeninteractions.Inthistalk,Iwillgiveanexampleofinterplaysbetweendisease,humidityandmicrobiotaduringPseudomonassyringaeinfectionofArabidopsisthalianaleaves.Futurestudiesofplant-pathogeninteractionsshouldincreasinglyconsiderthemulti-dimensionalnatureof“disease-environment-microbiome”interactionsthataremorereflectiveofwhatoccurincropfieldsandnaturalecosystems.Keywords:Plant-pathogenBioticstressAbioticstressMicrobiomePlantimmunity

AbioticInteractions:Abstract#38.Tworedox-sensitivebZIPtranscriptionfactorsmodulatethebalancebetweenstresstoleranceandgrowth(Submission46)YijiXia1,Li,Yimin,HongKongBaptistUniversity,Liu,Wuzhen,HongKongBaptistUniversity,Zhong,Huan,HongKongBaptistUniversity,Zhang,Hailei,HongKongBaptistUniversity1HongKongBaptistUniversity,HongKongToadapttoadverseenvironments,itisvitalforplantstore-establishhomeostasistobalancegrowthandstresstoleranceinaccordancewithenvironmentalconditions.Acommonthemeofenvironmentalstresssignalingistheinvolvementofreactiveoxygenspeciesintherelayofstresssignals.Ourredoxproteomicanalysisrevealedthatmultiplegroup-GbZIPtranscriptionfactors,includingbZIP16andbZIP68,undergoreversibleoxidativemodificationsinArabidopsiscellsunderoxidativestress.bZIP68wasfoundtobelocalizedinthenucleusundernormalconditions,butunderoxidativestressitundergoesnucleocytoplasmicshuttlingwhichisdependentonitsredox-sensitivecysteine.TheknockoutmutantsofthesebZIPgenesdonotcauseastrikingphenotypicdifferenceundernormalgrowthconditions.However,theydisplayedgrowthdefectundervariousabioticstressconditionsandhadalteredresponsestoexogenousABAandstarvation.OurstudysuggeststhatthesebZIPproteinsarepartsofatranscriptionalregulatorycircuitthatconsolidatessignalsfromdifferentstresssignalingpathwaysintoacoordinatedtranscriptionalreprogrammingtobalancegrowthandstresstolerance.Keywords:redoxsignaling;bZIP16;bZIP68;stressresponse;growthAbstract#39.IsolationofArabidopsismutantswithabnormalitiesinstomatalresponsetohumidity,light,orCO2(Submission52)KeinaMonda1,Takahashi,Sho,KyushuUniv.,Negi,Juntaro,KyushuUniv.,Tohmori,Ryoma,KyushuUniv.,Mabuchi,Atsushi,KyushuUniv.,Kojima,Mikiko,RIKENCSRS,Takebayashi,Yumiko,RIKENCSRS,Sakakibara,Hitoshi,RIKENCSRS,Iba,Koh,KyushuUniv.1KyushuUniversity,JapanPlantshavedevelopedtheabilitytoadapttooptimizegrowthundervariousenvironmentalconditions,forexample,humidity,light,andCO2concentration.Plantssensechangesintheirnaturalenvironments,alteringtheirdevelopmentandphysiologyinresponsetothesechanges.Guardcellsplayakeyroleinrespondingtoenvironmentalchanges,regulatingstomatalaperturesbyintegratingenvironmentalsignalsandendogenoushormonestimuli.Inthisstudy,weexploredgeneticmutationsinArabidopsisthalianarelatedtotheabscisicacid(ABA)-independentsignalingpathwaysinguardcells.First,wescreened108mutantswithabnormalstomatalresponsivenesstoCO2concentrationsand/orhumidityfromapproximately8,000M2plantsusingleafthermalimagingtechniques.Second,weselectedtwenty-twomutantsfromthese,whichexhibitedsufficientabilityinABAsynthesisandABAresponse,inordertoexcludemutantswithABAsignaltransductionpathwayabnormalities.Theisolatedmutantsarecategorizedintothreegroupsaccordingtotheirphenotypes:reducedstomatalresponseto(i)humidity,(ii)light,and(iii)CO2concentrations.Here,wereportthestomatalcharacteristicsoftheisolatedmutantsindetail.Keywords:guardcellsAbstract#40.TheFERONIAreceptor-likekinasemaintainscellintegrityduringsaltstressthroughCa2+signaling(Submission55)JoséDinneny1,WeiFeng,AlexisPeaucelle,JörgKudhla1CarnegieInstitutionforScience,DepartmentofPlantBiology,UnitedStatesGrowthplacesacellinaprecarioussituation.Duringcellexpansion,structuralcomponentsthatlimitthesizeofthecellmustbeweakened,whileatthesametime,homeostaticmechanismsmustacttopreventalossincellintegrity.Howsuchmechanismsactatthecellularandtissuescaleduringthegrowthofanorganiscurrentlyachallengingquestion,butonethatiscommontomanymulticellularsystems.Plantrootsprovideapowerfulsystemforexploringthebasisforgrowthcontrolinamulticellularcontextduetothespatialseparationofcellularprocessesassociatedwithgrowthalongthelongitudinalaxisoftheorgan.Ascellsaredisplacedfromtheroottip,

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theirgrowthisrapidlyinducedthroughorganizedcellwalllooseningandwateruptake.Rootsexposedtohighsaltmediaexhibitatemporaryarrestingrowthfollowedbyacclimationandgrowthrecovery.Wehavefoundthatthesechangesingrowthratearetightlyassociatedwithtransientspikesinintracellularcalciumthatoccurinindividualcellswithinthegrowthzone.Suppressionofcalciuminfluxleadstocellburstingsuggestingthatsuchtransientsarenecessarytomaintaincellintegrityduringrecovery.WehaverecentlyidentifiedanessentialrolefortheFERONIAreceptor-likekinaseinenablingplantcellstorecovergrowthunderhighsalinity.Inferoniamutants,cellsinthegrowthzoneoftherootviolentlyexploderatherthanundergoingcontrolledcellelongation.PastworkhasdemonstratedthatFERONIAplaysanessentialroleinmechano-signaltransductioninrootsandinmaintenanceofcellintegrity.Ournewfindingssuggestthatmechano-sensingisnecessaryduringsaltstresstodetectdamagetothewallinducedbysodiumions.Thesefindingshighlightanovelapoplastictoxicityofsaltandopenupnewareasofinvestigationtounderstandhowplantsacclimatetoenvironmentalstress.Keywords:Salinity,rootdevelopment,cellwall,abioticstress,growthAbstract#41.Mechanismofearlylightsignalingbythecarboxy-terminaloutputmoduleofArabidopsisphytochromeB(Submission73)YONGJIANQIU1,Pasoreck,Elise,DukeUniversity,Reddy,Amit,DukeUniversity,Nagatani,Akira,KyotoUniversity,Ma,Wenxiu,UCRiverside,Chory,Joanne,TheSalkInstituteforBiologicalStudies,Chen,Meng,UCRiverside1UniversityofCalifornia,Riverside,UnitedStatesPhytochromesareredandfar-redphotoreceptorsthatcontrolalldevelopmentaltransitionsfromseedgerminationtofloralinitiation.Theprototypicalphytochromeisahomodimer;eachmonomercontainsanN-terminalphotosensorymoduleandaC-terminaloutputmodule,whichincludesaHistidineKinase-RelatedDomain(HKRD)thatexhibitshighsequencesimilaritytobacterialhistidinekinases.However,whilebacterialphytochromesarebonafidehistidinekinasesensorsthatutilizetheirhistidinekinasedomainassignalingoutputdomaintorelayphototransductionthroughautophosphorylationofanactive-sitehistidine,plantphytochromeslacktheconservedactive-sitehistidineandhistidinekinaseactivity.IthasbeenwidelyacceptedthattheHKRDisdispensableforphytochromesignaling.Here,weprovideevidencedemonstratingthattheHKRDplaysanessentialroleinphytochromeBsignalinginArabidopsisthroughitsdimerization.AD1040Vmutation,whichdisruptsthedimerizationofHKRDabrogatestheearlylightsignalingevents,includingphytochromeBnuclearaccumulation,photobodybiogenesis,anddegradationoftheantagonistically-actinglightsignalingfactor-Phytochrome-InteractingFactor3(PIF3).ThedimerformofHKRDcommunicateswiththePAS-repeatdomainintheC-terminalmoduleofphytochromeBtopromotetheactivityofphytochromeBinnuclearaccumulation,photobodylocalization,aswellasinteractionwithPIF3.Together,thisstudyunravelsanewmechanismforphytochromesignalingthatdespitelackinghistidinekinaseactivity,plantphytochromesutilizetheHKRDassignalingoutputmoduleinmediatingearlylightsignalingeventsofphytochromesubnuclearlocalizationandPIF3degradation.Keywords:phytochromes;phytochrome-interactingfactors;lightsignaling;seedlingdevelopment;photobodyAbstract#42.NewInsightsintoCrosstalkbetweenCopperHomeostasisandJasmonicAcidBiosynthesisandItsRoleinReproductionofA.thaliana(Submission83)JiapeiYan1,Chia,Ju-Chen,Cornell,Sheng,Huajin,Cornell,Zavodna,Tetiana-Olena,Cornell,Huang,Rong,Cornell,Woll,Arthur,Cornell,Jiao,Chen,BoyceThompsonInstituteforPlantResearch,Fei,Zhangjun,BoyceThompsonInstituteforPlantResearch,Kochian,Leon,USDA-ARS,Vatamaniuk,Olena,Cornell1CornellUniversity,UnitedStatesGlobalfoodsecurityurgesthedevelopmentofhigh-yieldingcropsandtheutilizationofmarginallandsforagriculturalpurposes.Deficiencyforamicronutrientcopperthatdevelopsinalkalinesoilsandorganicsoils,causesupto20%ofcropyieldreduction.Ithasbeenknownfordecadesthatinadditiontothestuntedgrowthandchlorosisofleaves,copperstarvationreducesplantfertilityandseed/grainset.However,ourknowledgeoftheunderlyingmoleculardeterminantsthatlinkcopperwithplantreproduction,issurprisinglylimited.UsingRNA-seq-basedanalysesoftheresponseoftheArabidopsisthalianaflowertranscriptometocopperdeficiency,weidentifiedanovelcopper-responsivetranscriptionfactor,CIT1.FunctionalgeneticstudiesshowedthatCIT1isrequiredforgrowthanddevelopmentofA.thalianaundercopperlimitedconditionsandthatCIT1functionsinacomplexinteractingpathwaywithamasterregulatorofcopperhomeostasis,SPL7.WealsofoundthatCIT1andSPL7co-regulatetheexpressionofthehigh-affinityrootcopperuptakesystemandthus,thelossoftheCIT1-SPL7pathwayleadstoseedlinglethality.Supplementationofthegrowthmediumwithcopperrescuedtheseedlinglethalityofthecit1spl7doublemutantbutthemutantremainedmale-infertile.Usingsynchrotronx-rayfluorescentmicroscopy,weshowedthatcopperlocalizesmainlytoanthers,thesitesofpollendevelopment,andthatcopperdeliverytoanthersrequiresCIT1andSPL7.Further,ourdatasuggestedinteractionsbetweencopperhomeostasisandthesynthesisofjasmonicacid(JA),aplantsignalingmoleculethatisincreasinglyrecognizedforitsroleinplantfertility.Specifically,wefoundthatcopperdeficiencystimulatedJAsynthesisandthattheSPL7-CIT1pathwaywasrequiredforJAproduction.Further,male-infertile,JA-deficientA.thalianamutantlackingCIT1andSPL7downstreamtargetsLOX3andLOX4wasmoresensitivetocopperdeficiencyandaccumulatedlesscopperinanthers.TherelationshipbetweenCIT1-SPL7-mediatedcopperhomeostasisandJAmetabolicpathwayaspertainstoplantfertilitywillbediscussed.

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Keywords:Copperhomeostasis;Jasmonicacidbiosynthesis;Plantfertility;Pollensterility;TranscriptionalregulationAbstract#43.MutationalAnalysisofArabidopsisCAMTA3ActivityinresponsetoLowTemperatureandPathogenInfection(Submission102)YongSigKim1,ChuanfuAn,SunchungPark,SarahJ.Gilmour,LingWang,MichaelF.Thomashow1TexasTechUniversity,UnitedStatesPlantsarebeingconstantlychallengedwithvariousenvironmentfactorssuchasabioticandbioticstresses.Inresponsetovariousstimuli,plantshavedevelopedcalciumsignalingnetworksfordecodingandrelayingsignals.PreviousstudieshavedemonstratedthatArabidopsishasfunctionallyredundantCalmodulin-bindingTranscriptionActivator(CAMTA)1,2,and3genesinvolvedinregulatingsalicylicacidproductionatwarmtemperatureaswellasunderlong-termcoldconditions.TounderstandhowArabidopsisCAMTAsmediatesignalsinresponsetolong-termcoldconditionsandpathogenattack,wegeneratedmutantsofCAMTA3,whichwereanalyzedinthecamta2camta3doublemutantbackground.Itwasreconfirmedthatamutationinthecalmodulinbindingdomain(CAMTA3K907E)abolishedtheactivityofCAMTA3,andthatasemi-dominantmutationintheIQdomain(CAMTA3A855V)didnotaffectactivityofCAMTA3.Interestingly,CAMTA3A855VoverrodetheeffectofCAMTA3K907EinaCAMTA3A855V/K907Edoublemutation.Inaddition,thephosphorylationstatusonthe454thand964thserineresiduesaffectedtheCAMTA3activityatwarmtemperature.Atruncatedversion(CAMTA3-334)containingonlytheDNA-bindingandtranscriptiondomainsshoweddominantsuppressiveactivityonSA-relatedgeneexpressionunderlong-termcoldconditions.WesternblotanalysesshowedthatstabilityoftheCAMTA3proteinwasnotinvolvedinregulationofCAMTA3activityundercoldconditions.CAMTA3A855V,CAMTA3A855V/K907E,andCAMTA3-334showedincreasedsusceptibilitytopathogenattackandreducedpathogen-inducedgeneexpressionatbothwarmandcoldtemperatures.TheseresultssuggestthattheN-terminusofCAMTA3containingDNA-bindingandtranscriptionactivationdomainsareacriticalpartofitsactivity,andthattheremainderoftheproteinmaybeinvolvedinregulationofCAMTA3activityviainteractionwithotherproteinsormodificationofphosphorylationstatus.Keywords:Coldtemperature;CAMTA3;Mutationalanalysis;Plantdefense;FunctionaldomainAbstract#44.Uncoveringthecis-regulatorycodeofplantresponsetocombinedabioticstressusingmulti-dimensionaldataintegrationandmachinelearning(Submission108)ChristinaAzodi1,Uygun,Sahra,MichiganStateUniversity,O'Malley,Ronan,DOEJointGenomeInstitute,Shiu,Shin-Han,MichiganStateUniversity,1MichiganStateUniversity,UnitedStatesPlantsacclimatetoanenvironmentalstressusinghighlytailoredresponsepathways.Whenmultiplestressesoccuratonce,acclimationmayrequireconflictingorentirelydifferentresponsescomparedtotheresponsestoeachstressalone.Previousworkhasshownthatconflictingandnovelresponsesarecommon,with>60%ofgenesrespondingtocombinedstressantagonisticallyorsynergisticallycomparedtotheirresponsetothestressesindividually.Whilemultiplecombinedstressstudieshaveobservedthesenon-additiveresponses,theregulatorybasesfortheseresponsesarestilllargelyunknown.Inthisstudy,weidentified197putativecis-regulatoryelements(pCREs)associatedwithantagonisticandsynergisticresponsestocombineddroughtandheatstressinArabidopsisthaliana.ThesepCREsperformbetteratpredictingagene’sresponsepatternthannotonlyrandomexpectation,butalsoknowntranscriptionfactor(TF)bindingmotifsandsites.ToidentifywhichofthesepCREsaremostlikelytobeinvolvedinregulation,additionalcriteriasuchaschromatinaccessibility,histonemarks,sequenceconservation,andlocationanddistributioninthepromoterwereconsidered.Usingthesecriteria,wepareddownourlistto31highconfidencepCREs.Ofthese,48%sharesignificantsequencesimilaritywithknownTFbindingmotifs,includingTFsfromthebZIP,HSF,andbHLHTFfamilies.Theremaining52%couldrepresentnovelTFbindingmotifs.AsubsetofthesehighconfidencepCREsisbeingexperimentallyverified.Theseresultssupportthehypothesisthatcombinationsofstresseselicitregulatorymechanismsnotinducedbythestressesindividually.Thiscontributiontoourunderstandingofhowplantsregulatetheirresponsetomorecomplexenvironmentalstressesisanimportantstepasweworktowardimprovingcropresilienceinthefaceofachangingclimate.Keywords:abioticstress;combinedstress;transcriptionalregulation;machinelearning,bioinformaticsAbstract#45.NovelEpigeneticandAntisenseRNARegulationinPlantAbioticStressAdaptation(Submission127)MotoakiSeki1,Jong-MyongKim,AkihiroMatsui,KaoriSako,MinoruUeda,KhurramBashir,SultanaRasheed,JunkoIshida,MahoTanaka,TaikoKimTo,AlessandraDevoto1RIKENCSRS,JapanPlantsrespondandadapttodrought,heat,coldandhigh-salinitystressesinordertosurvive.Manyabioticstress-regulatedgeneshavebeenidentifiedbygeneticandtranscriptomeanalysis,anditsfunctioninthestressresponseshasbeenelucidated.However,wethinkthatnovelmechanismsinvolvingepigeneticandRNAregulationhaveadditionalfunctions.Recently,wefoundthatthefollowingnovelregulationmechanismsfunctioninplantabioticstressadaptation.1)ArabidopsisHistoneDeacetylase6(HDA6)isamasterregulatorofnoveldroughtstressresponsenetwork.HDA6regulatesconversionofcentralmetabolicpathwayfromglycolysistoaceticacid

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biosynthesisunderwaterdeficitcondition.Furthermore,aceticacidpretreatmentenhancesplantdroughttolerance.2)Treatmentwithhistonedeacetylase(HDAC)inhibitors,suchasKy-2andSAHA,enhanceshigh-salinitystresstolerance.3)Abioticstress-responsivenon-codingantisenseRNAsaresynthesizedfromsensetranscriptsofprotein-codinggeneswithouttheinvolvementofknownsiRNAbiosynthesisbyRNA-dependentRNApolymerases(RDRs)andfunctionindroughtstressadaptation.Inthismeeting,Iwillpresentourrecentfindingsintheabioticstressadaptation.Keywords:AbioticStress,EpigeneticRegulation,Non-codingRNAAbstract#46.Oligopeptidetransporter3,OPT3,isrequiredforcopperhomeostasisinArabidopsisthaliana(Submission128)Ju-ChenChia1,JiapeiYan,ChenJiao,ZhangjunFei,MiguelPiñeros,LeonV.Kochian,OlenaK.Vatamaniuk1CornellUniversity,UnitedStatesCopper(Cu)isanessentialelementforplantgrowthanddevelopmentbutistoxicwhenaccumulatedincellsinaccess.Thus,plantsdevelopedsophisticatedmechanismstoregulatecellularCuacquisitionandsource-to-sinkdeliverytoavoiddeficiencyandpreventtoxicity.ItisknownthatCuacquisitionintorootepidermalcellsismediatedbyhigh-affinityCutransportsystemsincludingCutransportersCOPT1,COPT2,andcupricreductasesFRO4andFRO5.However,transportsystemsresponsibleforthephloem-basedCudeliverytosinktissuesremainpoorlyunderstood.Here,weshowthatphloem-localizedArabidopsisthalianairon(Fe)transporter,OPT3,recognizedforitsroleinsource-to-sinkFedeliveryandshoot-to-rootcommunicationofFestatus,alsocontributestoCutransport.Specifically,wefoundthatOPT3transportedCuionsinXenopuslaevisoocytes,suggestingthatinadditiontoFe,OPT3mightbealsoinvolvedinsource-to-sinkCudelivery.Consistentwiththissuggestionwasfindingthatyoungleavesoftheopt3-3mutantcontained80%lessCuthanyoungleavesofwildtypeplants,whileCuconcentrationinmatureleavesoftheopt3-3mutantwassimilartothatofmatureleavesofwildtype.Inaddition,RNA-seqanalysesrevealedthatyoungleaves(sinks)oftheopt3-3mutantsmanifestedthemolecularsymptomsofCudeficiencyincludingtheupregulationoftheexpressionofgenesinvolvedincellularCuacquisitionandthedownregulationoftheexpressionofCubindingproteinsinvolvedinthemetabolicre-utilizationofcellularcopperreserves.Finally,wefoundthattheopt3-3mutantwasmoresensitivetoCudeficiencythanwildtypeplantsre-informingtheroleofOPT3inCuhomeostasisinA.thaliana.Together,ourdataassignanovelfunctiontoOPT3insource-to-sinksdeliveryofCu.TheroleofOPT3incrosstalkbetweenFeandCuhomeostasisinA.thalianawillbealsodiscussed.Keywords:copperhomeostasis,ironhomeostasis,oligopeptidetransporter,source-to-sinktransportAbstract#47.Trehalose-6-phosphatephosphataseIharborsanovelperoxisomalsignalandisimplicatedinabioticstressanddevelopment(Submission133)AmrR.A.kataya1,Elshobaky,Ahmed,Schei,Edit,Lillo,Cathrine1UniversityofStavanger,NorwayDetectionoflow-abundantproteinsandinducibleperoxisomalproteinscruciallydependingontheadvancementofbioinformaticalpredictionmethods.Usingavailablepredictiontoolsandconservationstudies,aputativenon-canonicalperoxisomaltargetingsignaltype1(PTS1)Pro-Arg-Met>wasidentifiedintheextremeC-terminusoftrehalose-6-phosphatephosphatase(TPP)I.TPPcatalyzesthefinalstepoftrehalosemechanismthatwasnotassociatedwithperoxisomesbefore.HereweshowexperimentallythattheTPPIC-terminaldomainendingwithPro-Arg-Met>canindeedfunctionasaPTS1.Upontransientexpressionintwoplantexpressionsystems,thefreeCandN-terminalendledtothefull-lengthTPPItargetingtoperoxisomesandchloroplasts,respectively.Moreover,nucleusandnucleolustargetingofthefull-lengthTPPIwasobservedinbothcases.ThehomozygousT-DNAinsertionlineofTPPIwasisolatedandtheplantsshowedseveralphenotypesaschangesinleafanatomy,shorterroot,delayedflowering,hypersensitivitytosalt,andasucrosedependentdevelopment.OurresultsidentifyanovelPTS1sandTPPIasaproteinmulti-targetedtoperoxisomes,chloroplasts,nucleus,andnucleolus.AllofwhichindicatearoleforTPPsinperoxisomes,plantdevelopment,abioticstressandreproduction.Keywords:Arabidopsisthaliana,Peroxisomes,Abioticstress,SignaltransductionAbstract#48.GIGANTEAandZEITLUPEinteractionsunderlieamolecularbasisfortemperaturecompensationinthecircadianclock(Submission137)DavidSomers1,Kim,Taesung,OhioStateUniversity1OhioStateUniversity,UnitedStatesTemperaturecompensationisapropertyofcircadiansystemsthathelpsorganismsmaintainsimilarfree-runningperiodsoverawiderangeofphysiologicallytolerableambienttemperatures.Thisispresumedtoconferanadaptiveadvantagebysustainingappropriatecircadianphasingofkeyphysiologicalandmetabolicprocessesatdifferenttemperatures.Themechanism(s)oftemperaturecompensationareunknownandarelikelymultifactorial.Mutationsincertainknownclock-associatedgenescanmanifestasseveredisruptionsintemperaturecompensationofperiod.PreviousQTLstudiesofthenaturalvariationintemperaturecompensationmechanismsinArabidopsishaveimplicatedrolesforGIGANTEA(GI)andZEITLUPE(ZTL).OurcurrentworksupportsthesefindingsandidentifiesamolecularbasisforunderstandinghowtheCapeVerdeIslands(Cvi)Arabidopsisecotypemaintainsstrongtemperaturecompensationathighertemperatures.Usingintrogressednearisogeniclines(NILs)weshowthattheGICviallele(GI(Cvi))confersa

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significantlyshortercircadianperiodatalltemperatures,relativetotheLandsbergerecta(Ler)allele,regardlessoftheZTLbackground.However,theGI(Cvi)ZTL(Cvi)allelicpairingexhibitsthemoststableperiodatalltemperatures.DifferencesinperiodbetweenNILscanpartlybeattributedtodifferentlevelsofZTLproteinlevels,whichcorrelatewithdifferencesinGI-ZTLinteractabilityamongthedifferentalleliccombinationsofGI(Col/Ler,Cvi)andZTL(Col/Ler,Cvi).FurtherinspectionandtestingidentifiedaLRR-likemotifinGIthatfacilitatesZTLinteractionandaffectsnuclearlocalization.ExaminationofZTLandGIsequencesinnumerousArabidopsisaccessionsrevealsthatthespecificGI(Cvi)andZTL(Cvi)allelesareonlyfoundpairedintheCviecotype.Takentogether,thefindingssuggestthatepistaticselectionmayhaveoccurredatthislocationtostronglyenhancethetemperaturecompensationresponseinthisenvironment.Keywords:circadianclock;epistaticselection;GIGANTEA;ZEITLUPE;temperaturecompensationAbstract#49.Transcriptionalregulationofnitrogenmetabolism(Submission140)SiobhanBrady1,AllisonGaudinier,LifangZhang,ChristopheLiseron-Monfils,JoelRodriguez-Medina,Anne-MaaritBagman,AndrewOlsen,DoreenWare,MaryFrank,BoShen1UCDavis,UnitedStatesRegulationofplantdevelopmentrequiresintricatecommunicationwithbothprimaryandspecializedmetabolisminordertofuelgrowth.Whiletranscriptionalregulationofmetabolismisevidentfrommyriadwholegenome-expressionanalyses,ourunderstandingofwhichtranscriptionalregulatorsareresponsibleforthesechangesaswellastheirunderlyingmodeofactionisunclear.Iwillhighlightoureffortsonsystematicmappingoftranscriptionalregulatorsofnitrogenmetabolism.Networkanalysesincorporatingprotein-DNAinteractiondata,geneexpressionandconnectivitywereusedtoidentifycriticalregulators,mostofwhichwereshowntoregulaterootgrowthanddevelopmentinresponsetochangesinavailablenitrogeninplanta.Finally,theseanalyseshaveshedlightonmodularitywithinthesepathwaysandglobalperspectivesonthisadditionalmodeofplantmetabolicregulation.Keywords:nitrogen,transcriptionalnetwork,systemsbiology,generegulationAbstract#50.RolesoftheNUCLEARFACTORY(NF-Y)aspositiveregulatorsoflight-mediateddevelopment(Submission148)ZacharyMyers1,Kumimoto,Roderick,UCDavis,Siriwardana,Chamindika,UniversityofOklahoma,Holt,BenF.III,UniversityofOklahoma1UniversityofOklahoma,UnitedStatesPlantsintegratelightsignalstocoordinatemanydevelopmentalandphysiologicalprocessesthroughouttheirlifecycle.Lightisperceivedbyarelativelysmallgroupofphoto-receptiveproteinswhichstabilizephotomorphogenictranscriptionfactorsandelicitvastchangesingeneexpression.WepreviouslyidentifiedthreeNUCLEARFACTOR-YC(NF-YC)proteinsthatfunctionredundantlytocontrolphotoperiodicflowering.Inthisstudy,wedemonstratethatthosesameNF-YCproteinsarealsonecessaryforphotomorphogenicgrowth,andlossofselectNF-YCsresultsinaninabilitytoinhibithypocotylelongationinresponsetolight.Thismutantisalsoabletopartiallysuppresstheshorthypocotylphenotypeofconstitutivephotomorphogenic1(cop1),anE3ubiquitinligasethatnegativelyregulateslightsignalingbyfacilitatingthedegradationofpositiveregulators,suggestingthattheNF-YCsarefunctioningaspositiveregulatorsofphotomorphogenesis.InordertobetterunderstandthisNF-Ymediatedsignaltransductionpathway,wegeneratedcrossesbetweennf-ycandelongatedhypocotyl5(hy5)mutants.Thesemutantswerelessabletoinhibithypocotylelongationthaneitherparentalmutant,suggestingthattheseselectNF-YCsfunctionindependentofHY5,awell-describedregulatorofphotomorphogenesis.Wearenowintheprocessofextendingthisapproachtoincludeotherwell-describedlightsignalingcomponentsinordertomorefullyunderstandwhethertheNF-Yconstituteanovelbranchoflightsignaling.Addinganotherlayerofcomplexity,theNF-Yfunctionasheterotrimerictranscriptionfactorcomplexes,andassuch,alteringtheabundanceofanindividualsubunitdirectlyimpactsthepotentialNF-Ycomplexesthatcanform.Withthisinmind,wehavealsobegunexploringpost-translationalregulationoftheNF-YAfamily,whichimpartssequencespecificitytotheNF-Ycomplex,tobetterunderstandthemechanisticfunctionofNF-Yinlight-mediateddevelopment.Keywords:photomorphogenesis;lightsignaling;geneticregulationofdevelopmentAbstract#51.SaltstressinducesvarianceintheRNAstructuromeofArabidopsisthaliana.(Submission150)DavidTack1,Tang,Yin,PennState.,Su,Zhao,PennState.,Yu,Yunqing,PennState.,Bevilacqua,Philip,PennState.,Assmann,Sarah,PennState.1ThePennsylvaniaStateUniversity,UnitedStatesOsmoticregulationisofcriticalimportanceforplants,frombothanagronomicandanevolutionaryperspective.Whensubjectedtosaltstress,plantcellsbecomeosmoticallybufferedagainstthisdesiccatingenvironmentviatheproductionofseveralmetabolites,notablyproline.However,prolineandothermetabolitesareknowndenaturantsofRNA.TheoutcomeofintroducingtheseosmoticaonRNAstructurehasnotbeenstudiedonagenome-widescale.Structure-seqisaninnovativeandefficientmethodtoresolvetheinvivoRNA-structurome.UsingStructure-seqonbothunstressedandsaltstressedArabidopsisplants,wesurveyedbothshootandroottissueforchangesintheRNA-structuromebetweenconditions.Wefindthatsaltstressdoesnotinvokemajordirectionalchangestothestructuromeineithertissue,withroottissueshowingaslightlystrongershifttowardslessoverallsecondarystructure.However,saltstressintroducesasignificantamountofvariancetotheRNA-structuromeinbothtissues.Undersalttreatment,thetranscriptomeshowsincreasedvariabilityandunevennessintheamountandthedistributionoftranscriptsecondarystructure,bothwithinindividual

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transcriptsandamongdifferenttranscripts.SeveralgroupsofgenesdirectlyimplicatedinthesaltresponseexhibitlargechangesinmRNAstructurebetweencontrolandsaltconditions,highlightingprospectstofurtherunderstandingtheirregulation.Manyothertranscripts,notcurrentlydefinedaspartofthesaltresponse,alsoundergopronouncedchangesintheirstructureundersaltstress,suggestingtheymayplayasofyetunidentifiedrolesinthesaltstressresponse.Keywords:Saltstress;Structure-seq;RNAStructure;DMSReactivity;AbioticStressAbstract#52.CRF2modulatescytokininlevelsinresponsetosaltstress(Submission163)ErikaKeshishian1,Plačková,Lenka,PalackyUniversityandInstituteofExperimentalBotany,Novak,Ondrej,PalackyUniversityandInstituteofExperimentalBotany,Rashotte,AaronM,AuburnUniversity1AuburnUniversity,UnitedStatesCytokininisaplanthormoneknowntobeinvolvedingrowthanddevelopment,regulatingsuchprocessesasresponsetolight,maintenanceofapicaldominance,andonsetofsenescence.Asub-familyoftheAP2/ERFtranscriptionfactorscalledCytokininResponseFactors(CRFs)hasbeenshowntobeasidebranchofthecytokininsignalingpathwayandisconservedacrossplants.Inadditiontoplayingaroleinthecanonicalcytokininprocesses,CRFsarelinkedtoseveraldifferentabioticstressresponses.Onesub-grouporcladeofCRFsareCRF1andCRF2,whichwereoriginallylinkedonlytocytokininresponse,butwehavealsoshownareregulatedinthepresenceofhighsalt(NaCl)andosmoticstressconditions.AlthoughmanycytokininsignalingpathwaygenesincludingtheCRFsarefunctionallyredundant,wefinddifferencesinstressresponsivenessbetweenCRF1andCRF2.Whencytokininlevelsweremeasuredincrf1,crf2,andWTplantsexposedtoacontrolbuffer,littletonosignificantdifferenceswereseen.However,afterasaltstresstreatment(150mMNaCl)cytokininlevelsincreasedforcrf1inamannersimilartoWT.Intriguinglyforcrf2cytokininlevelsfollowaverydifferentpatternofchangeandarelargelyreduced.Anexaminationoftranscriptlevels,viaRNAseqconductedinparallelwithcytokininmeasurementsrevealedthatgenesinvolvedincytokininbiosynthesisarealteredinresponsetosaltstressandimportantlythatCRF2hasaroleinconvertingcytokinintoseveralofitsinactiveconjugatedforms.Keywords:abioticstress,salt(NaCl),cytokinin,CytokininResponseFactors(CRFs)Abstract#53.Transcriptome-metabolomeco-analysisrevealstemperature-andairhumidity-relatedheatcomponentsandnovelnetworksindrought-heatscenarios(Submission167)AntonR.Schaeffner1,Zhao,Jin,HelmholtzZentrumMuenchen,Lange,Birgit,HelmholtzZentrumMuenchen,Jin,Ming,HelmholtzZentrumMuenchen,Kanawati,Basem,HelmholtzZentrumMuenchen,Schmitt-Kopplin,Philippe,HelmholtzZentrumMuenchen,Albert,Andreas,HelmholtzZentrumMuenchen,Winkler,J.Barbro,HelmholtzZentrumMuenchen,Georgii,Elisabeth,HelmholtzZentrumMuenchen1HelmholtzZentrumMuenchen,GermanyElevatedtemperatureandreducedwateravailabilityarefrequentlylinkedabioticstressesthatmayprovokedistinctaswellasinteractingmolecularresponses.Thisstudyaimedatadata-drivenelucidationofrelationshipsbetweendrought(sevendayswithoutwatering)andheat(33°Cfor6h)scenariosbasedonnon-targetedmetabolomicandtranscriptomicdatasetsfromArabidopsisrosettes.Wefirstdecomposedtheresponsetoacombinedstressscenariorelativetosinglestresses.Additivecombinationsofindependentdroughtandheateffectscouldbedistinguishedfromresponsesindicatinginteractioneffectswheretheregulationincombinedstresssignificantlydeviatedfromtheadditivelevel.E.g.,theinteractioneffectsincludeenhancedgeneexpressionrelatedtoproteinfoldingandgrowthinhibition.Applyingheatstresswithandwithoutsupplementedairhumidityallowedseparatingtemperature-andairhumidity-relatedcomponentsofaheatscenario.The“dryair”componentofheatspecificallycomprisesJA-andABA-relatedresponsestowaterdeprivationpreviouslyassociatedwith“heat”stress.Remarkably,the"dryair”effectseemstobetheprimarytriggerofthemetabolomicresponsetoheat,whereasthetranscriptomicresponseisdominatedbythetemperaturecomponent.Canonicalcorrelationanalysisandnetworkminingoftranscriptomicandmetabolomicchangesacrossallstressexperimentspredictednovel,highlycorrelatedmetabolite/genenetworks.Thesenetworksincludee.g.complementarycellwallinvertasesandinvertaseinhibitorrelationshipsornovelstress-relatedmetabolicfeatures.Hypothesesbasedontheseresultswillassistmechanisticstudiesontherelationshipbetweentranscriptsandmetabolites,theannotationofpreviouslyuncharacterizedfeaturesandtheanalysisofputative,newdroughtandheatstress-relatedpathways.Keywords:systemsbiology,heat-droughtinteraction,stressdecomposition,airhumidityeffect,data-drivenhypothesesAbstract#54.EctopicexpressionofpsNTP9,anapyrasegenefromPisumsativumimprovesrootsystemarchitectureandimpartsdroughttoleranceintransgenicArabidopsis(Submission168)RoopadarshiniVeerappa1,GregClark,UniversityofTexas,Austin,StanleyRoux,UniversityofTexas,Austin1UniversityofTexasatAustin,UnitedStatesApyraseenzymesbelongtoaconservedfamilyofnucleosidetriphosphate-diphosphohydrolases(NTPDases)thatcanremovetheterminalphosphatefromNTPsandNDPs,butnotfromnucleotidemonophosphates.Theycontroldiversefunctionsincells,includingproteinglycosylationintheGolgiofyeast,andthehydrolysisoftheextracellularnucleotidesthatactivatepurinoceptors,whichisakey

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regulatoryfunctionontheplasmamembranesofanimalsandplants.Apeaapyrase,psNTP9,purifiedfromnucleiofpeas,wasamongthefirststructurallycharacterizedapyrasesinplants.EctopicexpressionofpsNTP9inArabidopsisimproveditsrootsystemarchitecture,includingprimaryrootlength,lateralrootlength,lateralrootdensity,roothairlength,androothairdensity.TheseresultsledustoexaminewhetherpsNTP9-overexpressingArabidopsisplantsalsohadimproveddroughttoleranceatbothseedlingandmatureplantstages.Thetransgenicplantswereremarkablylessaffectedbywater-deficitconditions,withlesswilting,andahigherbiomassandseedyieldthanthewild-typecontrolplants.Theyalsohadimprovedrootgrowthunderosmoticstressconditionsintheinitialstagesofseedlingdevelopment.TheseresultssuggestafunctionofpsNTP9inimprovingplants’rootsystemarchitectureunderbothcontrolandosmoticstressconditions,and,perhapsasaresult,alsodroughttoleranceinArabidopsis.ThesenovelresultshighlightthepotentialofpsNTP9inthedevelopmentofcropsthatareresistanttodroughtstress,oneofthemostimportantenvironmentalconstraintslimitingplantgrowthandagriculturalproductivity.SupportedbygrantsfromNSFandTexasCropSciencetoSJRandGC.Keywords:Apyrase,rootsystemarchitecture,osmotictolerance,droughttolerance,Abstract#55.Theredsandthebluesoftheshadeavoidanceresponse(Submission171)UllasPedmale1,Lindbäck,Louise,ColdSpringHarborLaboratory,NY11724.,Schwartz,Kacey,ColdSpringHarborLaboratory,NY11724.,O’Neill,Kathryn,ColdSpringHarborLaboratory,NY11724.1ColdSpringHarborLaboratory,UnitedStatesPlantsadjusttheirbodyplaninresponsetoambientenvironmentalconditions.Lightisamongthemostrelevantenvironmentalsignalsbecauselightnotonlydrivesphotosynthesisbutalsoprovidescriticalinformationaboutthelocalgrowthenvironmentaswellasdiurnalandseasonaltime.Lightisperceivedbyacomplexarrayofphotoreceptors,definedbythecoloroflighttheyabsorb.Theseincludethered/far-red-absorbingphytochromes(phyA-E),theblue/UV-A-absorbingcryptochromes(CRY1-2),phototropins(phot1-2),andZTL-family,andaUV-B-absorbingreceptor.Plantshavedevelopedvariousadaptiveresponsesininterpretingandutilizelightdirectionality,quantity,andquality.Onesuchadaptiveresponseistheabilityofsun-lovingplantstosenseandavoidvegetationalshadingbynearbyplants.Invegetationalorcanopyshading,plantsperceiveadecreaseintheratioofredtofar-redlight(R:FR),andthereisalsoareductioninbluelightandtheavailablephotosyntheticallyactiveradiation(PAR).CRYscontrolthephenotypicplasticityofplantsinresponsetochangesinbluelight.Despitetheirimportance,verylittleisknownaboutthemechanismsbywhichCRYsaffectgrowthprograms.Wepresentdatatoshowthatwhenplantsaredeprivedofbluelightunderashadedcanopy,CRY1/2perceivethischangeandrespondbydirectlycontactingtwobHLHtranscriptionfactors,PIF4andPIF5.Shadeavoidanceresponsesleadtocontrastinggrowthresponsesindifferentorgansoftheplant;forexample,thestemandpetioleelongateattheexpenseofotherstructuressothattheplantcancapturemorelightthanitsneighbors.However,themolecularmechanismsunderlyingthiscontrastingresponseisnotwellunderstood.Herewewilldescribethemolecularbasisofhowdifferentorgansandtissuesrespondtothesameshadestimuliduringthisimportantadaptiveresponsewhichisofsignificantagriculturalimportance.Keywords:photobiology;shadeavoidance;plant-environmentinteractions;phytochrome;cryptochrome;Abstract#56.MolecularmechanismofthermotolerancecausedbyamutationinanmTERF(mitochondrialTranscriptiontERminationFactor)protein(Submission176)MinsooKim1,Schulz,Vincent,HumboldtUniversityofBerlin,Kühn,Kristina,HumboldtUniversityofBerlin,Vierling,Elizabeth,UMassAmherst1UMassAmherst,UnitedStatesMitochondriaplaycriticalrolesnotonlyinprimarymetabolismasacentralorganelleforATPgeneration,butalsoinsensingbiotic/abioticstressesandrelayinginformationtothenucleusforaneffectiveresponse.Maintainingmitochondrialhomeostasisrequiresmanynucleus-encodedproteins,whichincludefactorsthatregulatetheexpressionofmitochondrial-encodedproteinssuchasthePPR(PentatricopeptideRepeat)andmTERF(mitochondrialTranscriptiontERminationFactor)familiesofproteins.ThefoundingmemberofthemTERFfamily,humanmTERF1,bindsspecificsitesinthemitochondrialgenomeandregulatestranscriptionterminationandinitiation.StudiesofothermTERFproteinsrevealthatmTERFmotifsarealsoinvolvedinbindingtospecificorganellarRNAs.Unlikeanimals,thathavealimitednumberofmTERFs(fourinhumans),plantshaveundergoneadramaticexpansionofthefamilyduringevolution,with35membersinArabidopsis,mostofwhicharetargetedtoplastidsand/ormitochondria.WepreviouslyidentifiedamutationintheArabidopsisMTERF18/SHOT1(Suppressorofhot1-41)geneinascreenforasuppressorofaheatsensitivemutant,adominant-negativealleleofchaperoneHSP101(hot1-4).Althoughshot1mutantssurvivebetterunderheatstress,presumablyduetoreducedoxidativedamage,theexactmolecularmechanismofthermotolerancehasnotbeenrevealed.shot1mutationscauseanoverallincreaseinmitochondria-encodedtranscriptsandtranslationrate,whichislikelyacompensatoryresponsetoovercomereducedoxidativephosphorylation(OXPHOS).Proteomicsanalysisofshot1-2comparedtowildtypedetected22mitochondrial-encodedproteins.Amongthem,proteinsinvolvedinOXPHOSweredecreased,whileribosomalproteinswereincreasedinshot1-2.WealsoidentifiedSHOT1-interactingproteinsbyimmunoprecipitationfollowedbymassspectrometry.FindingthedirecttargetsofSHOT1willhelpelucidatemTERFfunctionandtheroleofmitochondriainregulatingoxidativestressandthethermotolerancemechanism.Keywords:HeatStress;Mitochondria;MTERF;OxidativeStress

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Abstract#57.GlobalgeneexpressionanalysisusingRNA-sequncoveredanewroleforSR1/CAMTA3transcriptionfactorinsaltstress(Submission182)AmiraAbdel-Hameed1,Kasavajhala,Prasad,ColoradoStateUniversity,Xing,Denghui,ColoradoStateUniversity,Reddy,Anireddy,ColoradoStateUniversity1ColoradoStateUniversity,UnitedStatesAbioticandbioticstressescausesignificantyieldlossesinallcrops.Acquisitionofstresstoleranceinplantsrequiresrapidreprogrammingofgeneexpression.SR1/CAMTA3,amemberofsignalresponsivetranscriptionfactors(TFs),functionsbothasapositiveandanegativeregulatorofbioticstressresponsesandasapositiveregulatorofcoldstress-inducedgeneexpression.UsinghighthroughputRNA-seq,weidentified~3000SR1-regulatedgenes.Promotersofabout60%ofthedifferentiallyexpressedgeneshaveaknownDNAbindingsiteforSR1,suggestingthattheyarelikelydirecttargets.GeneontologyanalysisofSR1-regulatedgenesconfirmedpreviouslyknownfunctionsofSR1anduncoveredapotentialroleforthisTFinsaltstress.OurresultsshowedthatSR1mutantismoretoleranttosaltstressthanthewildtypeandcomplementedline.Improvedtoleranceofsr1seedlingstosaltisaccompaniedwiththeinductionofsalt-responsivegenes.Furthermore,ChIP-PCRresultsshowedthatSR1bindstopromotersofseveralsalt-responsivegenes.TheseresultssuggestthatSR1actsasanegativeregulatorofsalttolerancebydirectlyrepressingtheexpressionofsalt-responsivegenes.Overall,thisstudyidentifiedSR1-regulatedgenesgloballyanduncoveredapreviouslyuncharacterizedroleforSR1insaltstressresponse.Keywords:AbioticStress;SaltStress;RNA-Seq;CAMTA;TranscriptionFactorsAbstract#58.Identificationandcharacterizationofwatersensingmechanismsinplants(Submission184)TamaraVellosillo1,Vilarrasa-Blasi,Josep,CarnegieInstitutionforScience,Guzman,Michael,CarnegieInstitutionforScience,Osaki,Jackie,CarnegieInstitutionforScience,Dinneny,José,CarnegieInstitutionforScience1CarnegieInstitutionforScience,UnitedStatesWatersensingandhomeostasisisnecessaryforsurvivalofallorganisms.Whileosmo-sensingpathwayshavebeendefinedinbacteria,yeastandanimals,howplantsperceivewaterandorchestrateadaptiveresponsesremainslargelyunknown.Theincreasingneedtoprovidesustainablefoodsourcestoagrowingworldpopulation,combinedwithclimatechange,putswateravailabilityandmanagementatcenterstageasanimportantareaforresearch.Inordertouncoverthesensingmechanismsandidentifykeyregulatorsofosmo-signaling,weperformedageneticscreeningforosmo-sensitivemutantsusingagenome-wideindexedmutantlibraryinChlamydomonasreinhardtii,aunicellularalgawhichprovidesasimplifiedsystemavoidingcomplexinteractionsassociatedwithmulticellularity.Wehaveidentifiedalargenumberofmutantsusingdifferentosmoticregimesandaregeneratingtranscriptomicandproteomicdatasetsoftheosmoticstressresponsetodevelopasystems-levelunderstandingoftheprocess.TheOSCA1-likeandMSL3-likegenes,whichwerepreviouslyshowninArabidopsistofunctionintheosmo-sensorypathway,havesignificantdefectsingrowthunderhyperosmoticstresswhenmutatedinChlamydomonasrevealingbroadconservationforthesepathwaysingreenplants.Orthologousgenesofnovelcomponentsoftheosmo-sensorypathwayarecurrentlybeingcharacterizedinChlamydomonasandinArabidopsistodecipherthewatersensingmechanismsinplants.Keywords:Osmo-sensingpathway;Chlamydomonasreinhardtii;mutantscreening;hyperosmoticstress;conservationingreenplantsAbstract#59.Walkingthedog(ma)inlowoxygen:FromDNAtoRNAtoproteinsynthesisinresponsetoandrecoveryfromhypoxia(Submission191)TravisLee1,Glenn,Weslee,CaliforniaInstituteofTechnology,Tirrell,David,CaliforniaInstituteofTechnology,Bailey-Serres,Julia,UCRiverside1UniversityofCalifornia,Riverside,UnitedStatesAhallmarkofplantplasticityistheabilitytoregulateandaltermetabolismanddevelopmentinresponsetoexternalstimuli.Thecellulartranscriptome,assayedbypolyA+mRNA-sequencing,providesinformationaboutgeneregulatorydynamics,thoughnotablysteady-statemRNAlevelsreflectthebalanceofnascentsynthesisanddegradation.Classicalstudiespublished40yearsagobyGoldbergandothersrecognizedthatnuclearRNApopulationsaremorecomplexthanpolysomalpolyA+mRNApopulations,suggestingthatnotallnascenttranscriptsareprocessedintomaturemRNA,exportedtothecytoplasm,andengagedintranslation.Further,proteinsynthesiscanbeinferredbytrackingribosome-associatedmRNAs,whereasthemorerecenttechnologybiorthogonalnoncanonicalaminoacidtagging(BONCAT)enablesthedirectglobalmonitoringofdenovoproteinsynthesis.Here,transcriptionalandnucleartranscriptdynamics,aswellasnascentproteinsynthesisweremonitoredinseedlingsdifferingincellularoxygenavailability:control(non-stressed),lowoxygen(hypoxia)-stressed,andstress-recovered.GeneactivitywasassayedattheDNAlevelthroughagenome-widesurveyofopenchromatinregionsbyAssayforTransposaseAccessibleChromatin-sequencing(ATAC-seq).Additionally,transcriptionalelongation,nuclearRNAabundance,andnascentproteinsynthesisweresurveyedbyChIP-seqofCarboxyTerminalDomainSerine-2phosphorylatedRNAPolymeraseII(RNAPII-Ser2P),nuclearRNA-sequsingisolationofnucleitaggedinspecificcelltypes(INTACT),andBONCAT,respectively.ThesereadoutswerecomparedtopolyA+andpolysomalmRNA-seqdata.WefoundthathypoxiaandreoxygenationrapidlymodulateRNAPII-Ser2Ppresencealonggenebodies,nuclearpre-RNAlevels,andthenascentproteome.Moreover,RNAPIIelongationandnascentRNAsynthesisprecedeelevationofsomestress-associatedmRNAs,indicatingmultiplescalesofregulationrelevanttoplantacclimation

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responses.Keywords:hypoxia;ATAC-seq;ChIP-seq;nuclearRNA-seq;BONCATAbstract#60.ReleaseofRopGEF-ROPMediatedDown-RegulationofAbscisicAcidSignalTransductionthroughABA-InducedRapidDegradationofRopGEFs(Submission217)ZixingLi1,Waadt,RainerUCSanDiego,Schroeder,JulianUCSanDiego1UniversityofCaliforniaSanDiego,UnitedStatesThephytohormoneabscisicacid(ABA)iscriticaltoplantdevelopment,droughtstressanddroughtavoidanceresponses.AbioticwaterstresstriggersanABAsignaltransductioncascade,whichiscomprisedofthecorecomponentsPYL/RCARABAreceptors,PP2C-typeproteinphosphatases,andproteinkinases.SmallGTPasesoftheROP/RACfamilyactasnegativeregulatorsofABAsignaltransduction.However,themechanismsbywhichABAcontrolsthebehaviorofROP/RACshaveremainedunclear.OurresearchresultsshowthatanArabidopsisguaninenucleotideexchangefactorproteinRopGEF1israpidlysequesteredtointracellularparticlesinresponsetoABA.GFP-RopGEF1issequesteredviatheendosome-prevacuolarcompartmentpathwayandisdegraded.RopGEF1directlyinteractswithseveralcladeAPP2Cproteinphosphatases,includingABI.Interestingly,RopGEF1undergoesconstitutivedegradationinpp2cquadrupleabi1/abi2/hab1/pp2camutantplants,revealingthatactivePP2CproteinphosphatasesprotectandstabilizeRopGEF1fromABA-mediateddegradation.Notably,ABA-mediateddegradationofRopGEF1alsoplaysanimportantroleinABA-mediatedinhibitionoflateralrootgrowthwhichisakeyrootdevelopmentresponsetodrought.EvidenceindicatesthatGEF-ROPregulationmayprovideamechanismforcrosstalkwithauxinsignalinginthisresponse.ThepresentedfindingspointtoaPP2C-RopGEF-ROP/RACcontrolloopmodelthatisproposedtoaidinshuttingoffABAsignaltransductionundernon-water-stressconditions,tocounteractleakyABAsignaltransductioncausedby“monomeric”PYL/RCARABAreceptorsintheabsenceofstress,andfacilitatesignalinginresponsetoABAinresponseabioticstresscondition.FurthermorenewfindingswillbereportedshowingadirectandkeyroleforCa2+andaCa2+bindingproteininregulationoftheGEF1-ROP-PP2CcontrolloopandthusABAsignaling.Keywords:ABA;RopGEF;ROP;PP2Cphosphatase;Calcium-dependentproteinkinaseAbstract#61.PlasmaMembraneProteomicanalysisrevealstheroleofArabidopsisDRP1EDuringColdAcclimationinAssociationwithFreezingToleranceDevelopment(Submission219)EtsukoWatanabe1,KotomiYago,MarikoKondo,HiroyukiImai,DaisukeTakahashi,MatsuoUemura,YukioKawamura1IwateUniversity,JapanThefreezingtoleranceofplantsincreasesafterbeingexposedtolowtemperatures,aprocesscalledcoldacclimation(CA).Thedynamin-relatedprotein(DRP)family,whichisaGTPaseconservedwidelyinorganisms,playsrolesindivisionoforganelles,cytokinesandpathogenentrybyregulatingthemembranetraffickingpathway.DRP1Ewasexpectedtohavearoleforreconstitutingtheplasmamembrane(PM)compositionduringCA,sincedynaminfunctionsinpinchingvesiclesofffromthecellmembrane.WepreviouslydemonstratedthatDRP1EfunctionwasassociatedwithfreezingtoleranceafterCAsuggestingDRP1E’sfunctionforreorganizingthePMcomposition(1).AlthoughDRP1EmightaffectchangesofPMproteinsduringCA,detailedanalysisandPMproteomeassociatedwithDRP1Eisnotperformedsofar.TounderstandtheroleofDRP1EinmoredetailandhowthePMproteinsareregulatedinassociationwithDRP1Efunction,weperformedtheelectrolyteleakage(EL)analysisusingdrp1emutantandPMproteomeinassociationwithfreezingtolerancedevelopmentduringCAwithnanoLC-MS/MS.First,weshowedthatDRP1EismorefunctionalinnewleavesthanoldleavesbyELanalysissuggestingthatDRP1Eworksinnewleavesforfreezingtolerance.Next,weidentified640proteinswithPMproteome.Theabundancesofavarietyofproteins,suchasPMchannels,cellstructure,signaltransductionrelatedproteinswereaffectedbyCA.Wealsofoundthat460proteinschangedtorespondedtoCA(ANOVAp<0.05).AmongtheCA-responsiveproteins,136proteinsincreased(>2-fold)and178proteinsdecreased(<0.5-fold)inbothofWTanddrp1emutant.Ofthese,60increasedand123decreasedCA-responsiveproteinswereidentifiedinWTanddrp1emutant.OurPMcomparativeproteomicanalysistoCAresponseinWTanddrp1emutantuncovertheDRP1E’sroleinsignallingpathways.(1)Minamietal,PlantJournal(2015)Keywords:Freezingtolerance;Coldacclimation;Proteome;Dynamin;nanoLC-MS/MSAbstract#62.ExploringtheroleofMediatorsubunitsinArabidopsisresponsestoabioticstresses(Submission228)FazeelatKaramat1,Lehotai,Nóra,Umeåuniversity,Crawford,Tim,Umeåuniversity,Blomberg,Jeanette,Umeåuniversity,Strand,Åsa,Umeåuniversity,Björklund,Stefan,Umeåuniversity1UmeåUniversity,SwedenMediatorisamulti-subunitcomplex,whichisessentialfortranscriptionalregulationineukaryoticcells.Itservesasaninterfacebetweenpromoter-boundtranscriptionfactorsandRNApolymeraseII,totransducesignalsforactivationandrepressionofgenesinresponsetochangesintheenvironment,suchasdifferenttypesofstress.StudiesofthefunctionsofMediatorsubunitsinplantsundervariousabioticstressesisimportantinordertounderstandhowtheregulationofstressresponsegenesiscontrolledandcoordinated.WehaveselectedfourArabidopsisthalianamediatorsubunitmutants(med9,med16,med18andcdke1)andthecorrespondingwildtype(Col-0)tostudyhowtheyareinvolvedintheresponsetothreedifferenttypesofstress;cold,heatandsalt.Plantsweregrownundershort-day

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conditionsfor5weeksinsoilforeitherheatorcoldstress,andinhydroponicmediaforsaltstress.Initialphenotypicevaluationofplantswasperformedandshorterphenotypesforseedlingsofmed18andcdke1wereobserved.Forsaltstress,plantswereexposedtodifferentconcentrationsofNaCl,while37°Cand4°Cwereusedforinducingheatandcoldstressinplants,respectively.AnumberofmarkergeneswereselectedforRT-qPCRtechniquetoevaluatethedifferentialgeneexpressionpatternsbetweenthedifferentgenotypes.Forsaltstress,(i)RD29A(ii)Atskipand(iii)MoCosulfurasewereevaluated.Cold-inducedgenes(i)COR15a(ii)COR47and(iii)CBF1werestudiedtounderstandtheirexpressionpatternsinplantstreatedwith4°C.Tostudytheeffectofheattreatmentongeneexpressionlevels(i)DREB2A(ii)ZAT12and(iii)MBFCwerequantified.Differentexpressionpatternsforselectedgeneswereobservedinthevariousgenotypesunderdifferenttypesofstress.Foraglobalviewofdifferentialgeneexpressionpatterns,high-throughputtechniqueswillbeutilizedandresultswillbepresented.Keywords:plantmediator:abioticstresses:generegulationAbstract#63.HSP90andSGT1regulatetemperature-dependentplantgrowthinArabidopsis(Submission251)RenhouWang1,Zhang,Yi,UCSanDiego,Kieffer,Martin,UniversityofLeeds,Yu,Hong,UCSanDiego,Kepinski,Stefan,UniversityofLeeds,Estelle,Mark,UCSanDiego1UniversityofCaliforniaSanDiego,UnitedStatesAssessileorganisms,plantsareparticularlysensitivetochangesinenvironmentaltemperature.Evenamildincreaseinambienttemperaturecancausedrasticchangesinplantgrowthanddevelopment.Hereweshowthatinadditiontotheirrolesinplantresponsetoheatstress,HEATSHOCKPROTEIN90(HSP90)anditsco-chaperoneSGT1arealsoimportantforambienttemperature-regulatedplantgrowth.AsmallelevationinambienttemperatureleadstoaccumulationofHSP90,which,togetherwithSGT1,stabilizesauxinco-receptorTRANSPORTINHIBITORRESPONSE1(TIR1)bypreventingitsdegradationthroughthe26Sproteasome.HighlevelsofTIRsenhanceauxinsignaling,thusstimulatingarangeofauxin-mediatedgrowthprocessesinwarmenvironments.OurresultsindicatethatHSP90andSGT1integratetemperatureandauxinsignalinginordertoregulateplantgrowthinachangingenvironment.Keywords:HSP90;hightemperature;auxin;TIR1;plantgrowthAbstract#64.SignalingcircuitryforERstressresolutioninplants(Submission267)CristinaRuberti1,Lai,YaShiuan,PlantResearchLaboratory,DepartmentofEnergy,MichiganStateUniversity,Meng,Zhe,PlantResearchLaboratory,DepartmentofEnergy,MichiganStateUniversity,Brandizzi,Federica,PlantResearchLaboratory,DepartmentofEnergy,MichiganStateUniversity1MSU,UnitedStatesSignalingcircuitryforERstressresolutioninplantsCristinaRuberti,YaShiuanLai,ZheMeng,FedericaBrandizziMSU-DOEPlantResearchLabandPlantBiologyDepartment,MichiganStateUniversity,EastLansing,MI,48824,USA.Theendoplasmicreticulum(ER)playsapivotalroleinsensingandrespondingtoachangingenvironment.StressconditionsleadtoanaccumulationofunfoldedproteinsintheER(ERstress),thattriggersanevolutionarilyconservedmechanismtermedtheunfoldedproteinresponse(UPR),toensureoptimalfunctioningandgrowthundermild-shortstressconditions,ortoleadtocelldeathunderprolongedandseverestressconditions.AmongtheERstresstransducers,onlytheERtrans-membraneinositolrequiringenzyme-1(IRE1)ishighlyconservedinyeast,animalsandplants.Interestingly,inanimals,IRE1adifferentiallytriggersdifferentUPRsdependingonneed.IRE1aindeed(1)increasestheproteinfoldingcapacityduringtheadaptivephase;(2)itincreasestheintensityoftheERstressthroughmRNAdecayofselectiveUPRtargetgenesinthetransitionphasebetweentheadaptiveandapoptoticresponse;and(3)itinitiatescelldeathduringapoptosis.HowIRE1adeterminescellfateunderERstressremainsunknown.Inthelightofthesefindings,weareelucidatingthecourseofUPRsinplantsunderERstress.TheviabilityofArabidopsisERstresstransducersmutantlinesallowsperforminginvivoanalysesoftheroleofeachERstresssensorwithrespecttotheotherUPRarmsinanintactmodelsystem.WholegenomenextgenerationRNA-sequencinganalyseswereperformedtoexaminethetranscriptionalprofilinginwildtypeandmutantlinesexposedtoERstress.QuantitativeRT-PCRwereusedtoconfirmtheRNAseqresultsinordertodefinethemolecularmechanismsbywhicheachERstresstransducercontrolstheUPR.Finally,phenotypicalanalysesintheUPR-deficientplantswereperformedtoevaluatetherequirementofeachUPReffectorsinERstressandacriticalplayerinvolvedinERstressmanagementhasbeenidentified.ThisworkwasprimarilysupportedbyNationalInstitutesofHealthwithcontributingsupportfromU.S.DepartmentofEnergyandAgBioResearch.Keywords:Arabidopsis;UnfoldedProteinResponse;ERstressAbstract#65.Pirin1controlsbluelight-inducedtranscriptionofseveralgenesinearlydevelopment(Submission336)YangChen1,AshleyWilliams,DanielleOrozco-Nunnelly,DurreShahwarMuhammad,ZongchaoJia,KatherineMWarpeha1UniversityofIllinoisatChicago,UnitedStatesAssessileorganisms,plantsdevelopuniquemechanismstoaccommodateenvironmentalchanges.ArabidopsisPirin1(PRN1,AT3G59220),acupinsuperfamilymember,playsanimportantroleinseedlingearlydevelopment.PRN1isreportedtoactasatranscriptioncofactorinresponsetobluelightinregulatingLhcb1.3transcription,throughthenuclearfactorY(NFY,aCCAATboxbindingproteincomplex;Warpehaetal.2007).PRN1alsocleavesquercetininvitro(Orozco-Nunnellyetal.2014),aUV-inducibleflavonoid,

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whichisabundantinseedlingshootapexandepidermis.Recently,weperformedqPCRandexploredgenesthatbothhaveaCCAATboxandarebluelightinduced.OurdataindicatesthatPRN1canregulategenesofthiscategoryotherthanLhcb1.3.Pirinsarehighlyconservedfromhumantobacteria.SimilartoPRN1,humanPirin(hPir)alsocleavesquercetininvitro.Interestingly,wefoundthathPirwasunabletorescuetheprn1mutanttranscriptiondefect,withorwithoutbluelight.ModelsareproposedhowPRN1mayaccommodateitsfunctionalaction.PRN1isalsorequiredfornormalcellsizeattheseedlingstageinnormalwhite-lightdrivengrowthanddevelopment.TheevolutionarycontextofPirinsisexplored.Abstract#66.IRE1blinksERstresstoautophagyinArabidopsisbydegradingRNAsencodingproteinsthatnegativelyregulateautophagy(Submission340)SteveHowell1,Pu,Yunting,IowaStateUniversity,DepartmentofGenetics,DevelopmentandCellBiology,Srivastava,Renu,IowaStateUniversity,PlantSciencesInstitute,Howell,Stephen,IowaStateUniversity,PlantSciencesInstitute,Bassham,Diane,IowaStateUniversity,DepartmentofGenetics,DevelopmentandCellBiology1IowaStateUniversity,UnitedStatesAutophagyisaconservedprocessineukaryotesthatcontributestocellsurvivalinresponsetostress.Previously,wefoundthatERstressinducesautophagyviaapathwaydependentuponIRE1b,anERmembrane-associatedfactorinvolvedinthesplicingofbZIP60mRNA.IRE1isadualproteinkinaseandribonuclease,andherewedeterminedtheinvolvementoftheproteinkinasecatalyticdomain,nucleotidebindingandRNasedomainsofIRE1binactivatingautophagy.AutophagywasassessedintransgenicseedlingsbearingmutationsinthevariousIRE1bdomains,andnucleotidebindingandRNaseactivityofIRE1barerequiredforERstress-mediatedautophagy.TheRNaseactivityisinvolvedinIRE1bmRNAsplicingfunction,butitsprincipalsplicingtarget,bZIP60,isnotinvolvedinIRE1binducedautophagy,andwethereforeconsideredotherrolesforIRE1bintheactivationofautophagy.ClusteringofERlocalizedIRE1b-YFPwasobservedwhenseedlingsweresubjectedtoERstress,buttheRNaseknockoutmutationinIRE1bstillundergoesclustering,suggestingthatIRE1bclusteringdoesnotinduceautophagy.UponERstress,theRNaseofIRE1hasbeenfoundtoengageinanotheractivitycalledRegulatedIre1-DependentDecayofMessengerRNA(RIDD),whichisthepromiscuousdegradationofmRNAbyIRE1inresponsetoERstress.12RIDDtargetgeneswereselectedfromRNA-seqdatafortestingtheirroleininhibitingautophagy,andthreeofthem,beta-glucosidase21(beta-GLU21),MD2relatedlipidrecognitionprotein(ML)andperoxidase14(PR14)werefoundtobenegativeregulatorsofautophagyinducedbyERstress.Thus,inresponsetoERstress,IRE1bdegradestheRNAsofnegativeregulatorsofautophagy.SupportedbyNSFIOS1353867.Keywords:abioticstress;ERstress;autophagy;RegulatedIre1-DependentDecayofMessengerRNA;ribonucleaseAbstract#67.IdentificationofupstreamkinasesofVCSunderosmoticstressconditionsinArabidopsis(Submission349)FumiyukiSoma1,Mogami,Junro,GraduateSchoolofAgriculturalandLifeSciences,TheUniversityofTokyo,Sato,Yuta,GraduateSchoolofAgriculturalandLifeSciences,TheUniversityofTokyo,Takahashi,Fuminori,RIKENCenterforSustainableResourceScience,Shinozaki,Kazuo,RIKENCenterforSustainableResourceScience,Yamaguchi-Shinozaki,Kazuko,GraduateSchoolofAgriculturalandLifeSciences,TheUniversityofTokyo1TheUniversityofTokyo,JapanPlantssenseosmoticstresses,suchasdroughtandhighsalinity,andcontrolgrowthanddevelopmentunderthesestressconditions.SnRK2s(SNF1-relatedproteinkinase2)playacriticalroleinosmoticstresssignalinginplants.WepreviouslyreportedthatABA-unresponsivesubclassISnRK2sinteractedwithandphosphorylatedadecappingactivatorVARICOSE(VCS)underosmoticstressconditions.WealsoshowedthatthesubclassISnRK2sandVCSregulatedmRNAdecayunderosmoticstressconditions.TheseresultsindicatedthatthesubclassISnRK2andVCSplayedanimportantroleintheosmoticstresssignaling.However,Resultsoftheingelkinaseassayindicatedthatproteinkinase(s)otherthansubclassISnRK2scouldalsophosphorylateVCSunderosmoticstressconditions.Inthisstudy,toelucidatenovelpost-transcriptionalregulationmediatedbyphosphorylationofVCSunderosmoticstressconditions,weidentifiedaproteinkinasenamedVCSKthatcanphosphorylateVCS.Ourin-gelandinvitrokinaseassaysrevealedthatVCSKphosphorylatesVCSunderosmoticstressconditions.WealsoshowedthatVCSKinteractswithVCSinP-bodies.OurpreviousstudyindicatedthatamutantlackingallfunctionalsubclassISnRK2s(srk2abgh)showedgrowthretardationunderosmoticstressconditions.Notably,amutantlackingsubclassISnRK2sandVCSKshowedseverergrowthretardationthanthesrk2abghmutantunderosmoticstressconditions.WewillcheckmRNAstabilityinthevcskmutanttoclarifywhetherphosphorylationofVCSbyVCSKaffectsthemRNAdecayunderosmoticstressconditions.Keywords:osmoticstress;proteinkinases;mRNAdecayAbstract#68.ModulationofAutophagyImpactsNanoharvestingYieldinA.Thaliana(Submission356)TimothyShull1,Kurepa,Jasmina,UniversityofKentucky,Smalle,JanA.,UniversityofKentucky1UniversityofKentucky,UnitedStatesInrecentyears,flavonoidshavegarneredattentionduetotheirpotentialuseasnaturaldyesaswellastheiranti-inflammatoryandcancer-preventativeproperties.Conventionally,recoveringflavonoidsrequiresdestructionofplanttissue.Recentlywedevelopedananoparticle-basedtechniquetoisolateflavonoidsfromlivingplanttissue,whichistermednanoharvesting.Thisapproachinvolves

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incubatingplanttissuewithTiO2nanoparticleswhichentercells,bindtoflavonoidsandareextrudedasflavonoid-nanoparticleconjugates.Isolatingflavonoidsfromplanttissueusingthisprocessreliesupontheso-called“surfacedefects”ofanataseTiO2nanoparticlessmallerthan20nmindiameterthatpossessahighaffinityforcompoundscontainingenediolandespeciallycatecholgroups.Previouslyitwasshownthatnanoharvestingisabiologicallyactiveprocessandleavesplantcellsviable.Hereweshowthatnanoparticlesinduceautophagyinplantsandthatautophagycontributestothenanoharvestingphenomenon.Autophagyisahousekeepingmechanismandstress-responsepathwaythatinvolvesengulfingcytoplasmiccomponentsinadouble-membranedstructure,ultimatelyleadingtodegradationoftheengulfedcargointhevacuole.Additionally,weshowthatthechemicalactivationorinhibitionofautophagyinfluencesnanoharvestingyield.Keywords:nanoparticles;flavonoids;autophagy;nanoharvestingAbstract#69.ModulationofthePhosphate-DeficientResponsesbyMicroRNA156anditsTargetedSQUAMOSAPROMOTERBINDINGPROTEIN-LIKE3inArabidopsis(Submission357)Chun-PengSong1,KaiJianLei1HenanUniversity,ChinaThemicroRNA156(miR156)-modulatedSQUAMOSAPROMOTERBINDINGPROTEIN-LIKE(SPL)isinvolvedindiversebiologicalprocessesthatincludegrowth,development,andmetabolism.Here,wereportthattheArabidopsismiR156andSPL3asregulatorsplayimportantrolesinphosphate(Pi)deficiencyresponse.MiR156wasinducedduringPistarvationwhereasSPL3expressionwasrepressed.Phenotypesofreducedrhizosphereacidificationanddecreasedanthocyaninaccumulationwereobservedin35S:MIM156(viatargetmimicry)transgenicplantsunderPideficiency.ThecontentanduptakeofPiin35S:MIM156Arabidopsisplantswereincreasedcomparedwithwild-type(Col-0ecotype)plants.35S:rSPL3seedlingsshowedsimilaranthocyaninaccumulationandPicontentphenotypestothoseof35S:MIM156plants.ChromatinimmunoprecipitationandanelectrophoreticmobilityshiftassayindicatedthattheSPL3proteindirectlyboundtoGTACmotifsinthePLDZ2,Pht1;5andmiR399fpromoters.TheexpressionofseveralPistarvation-inducedgeneswasincreasedin35S:MIM156and35S:rSPL3plants,includinghigh-affinityPitransporters,Mt4/TPS1-likegenes,andphosphatases.Collectively,ourresultssuggestthatthemiR156-SPL3-Pht1;5(-PLDZ2and-miR399f)pathwaysconstituteacomponentofthePideficiency-inducedregulatorymechanismofArabidopsis.Keywords:MicroRNA156;MicroRNA399;Phosphorusdeficient;Piuptake;Rhizosphereacidification;SPLAbstract#70.RoleofArabidopsisABFgenesduringdet1germinationinsaltandosmoticstressconditions(Submission366)DanaSchroeder1,Fernando,VCDilukshi,UniversityofManitoba,Belmonte,MarkF,UniversityofManitoba,Schroeder,DanaF,UniversityofManitoba1UniversityofManitoba,CanadaWhileDE-ETIOLATED1(DET1)iswellknownasanegativeregulatoroflightdevelopment,det1mutantsalsoexhibitalteredresponsestosaltandosmoticstress,suchassaltandmannitolresistantgermination.LONGHYPOCOTYL5(HY5)positivelyregulatesbothlightandABAsignalling.hy5suppressedthedet1saltandmannitolresistantgerminationphenotype,thus,det1stressresistantgerminationrequiresHY5.PublicallyavailablemicroarraydatawereanalyzedtoidentifygenesdownstreamofHY5andthataredifferentiallyexpressedindet1mutants.ThisanalysisrevealedthatABAregulatedgenes,includingABARESPONSIVEELEMENTBINDINGFACTOR3(ABF3),aredownregulatedindet1.TheroleofABF3andhomologuesABF4andABF1indet1stressphenotypeswasinvestigated.Doublemutantanalysisindicatedthatabf4andabf1suppressthedet1salt/osmoticstressresistantgerminationphenotype.MolecularanalysisrevealedthatwhileABF3isinducedbysaltinwildtypeseeds,ABF4andABF1arerepressed,andthatallthreeofthesegenesareunderexpressedindet1seeds.Indet1abf1anddet1abf4doublemutantseedsABF3levelsareelevated,consistentwiththereducedgerminationobservedintheselines.ThusregulationoftheABFgenesappearstocontributetodet1salt/osmoticstressresponsephenotypes.Keywords:DET1,ABF,salt,germinationApplied:Biotechnology,MolecularBreeding,Human/SocietalHealth:Abstract#71.AnovelroleformethylcysteinateandcysteineincesiumaccumulationandresponseinArabidopsis(Submission220)RyoungShin1,Adams,Er,RIKENCenterforSustainableResourceScience,Miyazaki,Takae,RIKENCenterforSustainableResourceScience,Han,Minwoo,RIKENCenterforSustainableResourceScience,Kusano,Miyako,RIKENCenterforSustainableResourceScience,Saito,Kazuki,RIKENCenterforSustainableResourceScience,Khandelia,Himanshu,UniversityofSouthernDenmark1RIKENCenterforSustainableResourceScience,JapanTheaccidentattheFukushimanuclearpowerplantinJapanfollowingthegreatearthquakein2011resultedinthespreadofradiocesiumoverthesurroundingareasincludingfarmland.Insubsequentyears,techniquestoremediatethelandandensuresecurityofagriculturalproductsusingplantshavebecomethefocusofattention.Cesiumisavaluablemetalwhileradioactiveisotopesofcesiumcanbehazardous.Inordertoestablishamoreefficientphytoremediationsystem,smallmoleculeswhichpromoteplantstoaccumulatecesium

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wereinvestigated.Throughchemicallibraryscreening,of10,000chemicalstested,14chemicalswereisolatedascesiumaccumulatorsinArabidopsis.Ofthose,methylcysteinate,aderivativeofcysteinewasfurtheranalyzed.Themethylcysteinatetreatmentresultedinincreasingcesiumaccumulationandthecysteinetreatmentalsoledtocesiumaccumulationtoalesserextentcomparedtomethylcysteinate.Fromthemetabolicprofiling,cysteinelevelsinArabidopsiswereshowntoincreaseinresponsetocesiumtreatment.Thecesiumaccumulationeffectwasnotobservedforothercysteinederivativesoraminoacidsonthecysteinemetabolicpathwaytested.Ourresultssuggestthatmethylcysteinateandcysteinemaybindwithcesiumonthesurfaceoftherootsorinsideplantcellsandimprovephytoremediation.Keywords:cesium,potassium,phytoremediationAbstract#72.Genome-wideidentificationandexpressionanalysisofCCCHzincfingerfamilyincotton(Submission262)BaoshuanShang1,XiningGuo,InstituteofStressBiology,HenanUniversity,XiaoZhang,InstituteofStressBiology,HenanUniversity1HenanUniversity,ChinaTheCCCHzincfingerproteinsplaydiverserolesinplantdevelopmentandstressresponse,withuniquefeaturesasRNA-bindingproteins.AlthoughtheidentificationofCCCHsascandidatesofstresstoleranceregulatorisunderpaceinmodelorganisms,littleisknownabouttheCCCHfamilyincotton.Inthisstudy,membersoftheCCCHgenefamilywereidentifiedinGossypiumhirsutum,Gossypiumarboretum,andGossypiumraimondii.Comprehensiveanalysisrevealedthechromosomaldistribution,genestructure,phylogeny,andproteinmotifsoftheCCCHgenesincotton.Theseresultsrevealedtheorigin,integration,geneduplication,andsystemicevolutionaryofcottonCCCHgenefamily.ExpressionpatternprofilingoftheGhCCCHgenesinvarioustissuesdecipheredtheirdistinctspatiotemporalpattern.Additionally,expressionanalysisindicatedthatcertainGhCCCHsresponsetodrought,salinity,andcoldtreatment,implicatingtheircrucialrolesfortheimprovementofcottoncultivartolerancetoabioticstress.Takentogether,ourresultsprovidethefoundationforfurtheridentificationofCCCHsaskeyregulatorsincottontolerancetoabioticstress,andshedlightontheimprovementofmulti-agriculturaltraitsofelitecottoncultivars.Keywords:Abioticstress,GhCCCH,RNAprocessing,GossypiumhirsutumAbstract#73.EffectofparentalageonmeioticrecombinationratesinArabidopsis(Submission312)RamswaroopSaini1,AmitKumarSingh,RamamurthyBaskar1IndianInstituteoftechnologyMadras,IndiaEffectofparentalageonmeioticrecombinationratesinArabidopsis.RamswaroopSaini,AmitKumarSinghandRamamurthyBaskarDepartmentofBiotechnology,IndianInstituteofTechnology–Madras,Chennai600036.Abstract:Weexaminedtheinfluenceofparentalreproductiveageonmeioticrecombination(MR)ratesusingasetofArabidopsisdetectorlines.ThesetransgeniclinescarrybothGFPandRFPmarkerslinkedincisthataredrivenbyaseedspecificpromoter.Segregationofthesemarkersbyarecombinationeventcanbeassayedbyexaminingtheseedsandfourphenotypescanbeseen:RFPfluorescent;GFPfluorescent;bothRFPandGFPfluorescentandwildtypeseeds.ToknowtheinfluenceofparentalageonMRratesintheprogeny,detectorlinesheterozygousforbothGFPandRFPwerereciprocallycrossedtowildtypeplantsonfourdifferentages-40,45,50and55daysaftersowing(DAS).Withtheincreaseinmaleaswellasfemaleparentalplantage,therewasnochangeinMRratesintheprogeny.Similartoearlierobservations,wealsoobservedsignificantlyhigherMRratesinmalescomparedtofemales.Plantsofdifferentageswhencrossedwiththeotherparentofaparticularage,hadnoinfluenceonMRratesintheprogeny.WearenowcomparingCHHmethylationinmalesandfemalestoknowifCHHmethylationdynamicscontributestohigher/lowerMRratesinmales/femalesrespectively.Keywords:Arabidopsis;meioticrecombination;parentalage;DAS(dayaftersowing).Keywords:Arabidopsis;meioticrecombination;parentalage;DAS(dayaftersowing)Abstract#74.TheRegulationofGAsBiosynthesisDuringthePhotoperiodicResponseinAspen.(Submission333)JoseAlfredoZambrano1,Shashank,Sane,SLU,Nilsson,Ove,SLU1SwedishUniversityofAgriculturalSciences,SwedenTheRegulationofGAsBiosynthesisDuringthePhotoperiodicResponseinAspen.JoséAlfredoZambrano1,ShashankSane1andOveNilsson11UmeåPlantScienceCentre,DepartmentofForestGeneticsandPlantPhysiology,SwedishUniversityofAgriculturalSciences,SE-90183Umeå,SwedenGibberellins(GAs)areoneofthemajorhormonesregulatingdifferentaspectsofplantgrowth,suchasstemelongation,germination,dormancy,floweringorfruitdevelopment.Intrees,GAsarekeyregulatorsofshootgrowthandhavebeensuggestedasimportantfactorscontrollingshortday(SD)-inducedgrowthcessation.Infact,Gibberellin20-oxidase(GA20ox)overexpressinghybridaspens(Populustremulaxtremuloides)donotsetbudswhengrowninSDconditions.Bycontrast,GA20oxantisensetransgenicaspentreesexhibitedearlierbudsetcomparedtowildtypeplants.TheaimofourworkistoinvestigatehowGAbiosynthesisisaffectedbythephotoperiodicsignalingpathwayintheregulationofgrowthcessation,budsetandbudbreak.InordertoelucidatetherelationbetweentheGAsandthephotoperiodpathwayweanalyzedtheexpressionlevelsoftheGA-metabolismgenes(GA2ox,GA3oxandGA20ox)inPopulusFLOWERINGLOCUST1(PtFT1),PtFT2andPtGIGANTEA(PtGI)RNAitransgenicplantsgrowninLongday(LD)andSDconditions,respectively.Wealsoassessedtheeffectofexogenousapplicationofgibberellinstothistransgeniclines

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comparedtothewildtype.OurresultsshowlowexpressionlevelsoftheGAbiosynthesisgenesinPtGIRNAiandPtFTRNAicomparedtoWT.Thismayberelatedtotheearlybudsetphenotypeinbothlines.ItisknownthatgrowthcessationinhybridaspenultimatelydependsonconcentrationsofbioactiveGA.OurdatasuggeststhatthisoccursthroughtheregulationofFT.Besidestheseapproaches,wehaveundertakentheabsolutequantificationofthedifferentGAmetabolitesinFTandGIRNAilines.Thisstudy,technicallychallenging,offerscomplementaryinformationthatsuggeststhatthephotoperiodpathwaycontributestotheregulationofGAmetabolismduringgrowthcessationinaspentrees.CellandDevelopmentalBiology:Abstract#75.CLAVATA1controlsdistinctsignalingoutputsthatbuffershootstemcellproliferationthroughatwo-steptranscriptionalcompensationloop.(Submission17)ZacharyNimchuk11UniversityofNorthCarolinaatChapelHill,UnitedStatesTheregulationofstemcellproliferationinplantsiscontrolledbyintercellularsignalingpathwaysdrivenbythediffusibleCLAVATA3(CLV3p)peptide.CLV3pperceptionisthoughttobemediatedbyanoverlappingarrayofreceptorsinthestemcellnicheincludingthetransmembranereceptorkinaseCLV1,Receptor-LikeProteinKinase2(RPK2),andadimerofthereceptor-likeproteinCLV2andtheCORYNE(CRN)pseudokinase.Mutationsinthesereceptorshavequalitativelysimilareffectsonstemcellfunctionbutitisunclearifthisrepresentscommonordivergentsignalingoutputs.PreviousworkinheterologoussystemshassuggestedthatCLV1,RPK2andCLV2/CRNcouldformhigherordercomplexesbutitisalsounclearwhatrelevancetheseputativecomplexeshavetoinvivoreceptorfunctions.HereIusetheinvivoregulationofaspecifictranscriptionaltargetofCLV1signalinginArabidopsistodemonstratethat,despitethephenotypicsimilaritiesbetweenthedifferentreceptormutants,CLV1controlsdistinctsignalingoutputsinlivingstemcellnichesindependentofotherreceptors.ThisregulationisseparablefromstemcellproliferationdrivenbyWUSCHEL,aproposedcommontranscriptionaltargetofCLV3psignaling.Inaddition,stemcellproliferationisbufferedbyCLV1throughatwo-steptranscriptionalcompensationloopthatregulatestheexpressionofrelatedreceptorkinasesinthemeristem.CollectivelythesedatarevealauniqueinvivoroleforCLV1separablefromotherstemcellreceptorsandprovidesaframeworkfordissectingthesignalingoutputsinstemcellregulation.Keywords:Development,stemcells,receptorsignaling,peptidesAbstract#76.RCBL:anovelphytochromesignalingcomponentinitiateschloroplastbiogenesis(Submission28)EmilyJie-NingYang1,Yoo,ChanYul,UCRiverside,Wang,He,DukeUniversity,Cao,Jun,MaxPlanckInstituteforDevelopmentalBiology,Weigel,Delef,MaxPlanckInstituteforDevelopmentalBiology,Liu,Jiangxin,DukeUniversity,Sun,Tai-Ping,DukeUniversity,Zhou,Pei,DukeUniversity,Chen,Meng,UCRiverside1DukeUniversity,UnitedStatesThebiogenesisofphotosyntheticallyactivechloroplastistriggeredbylightthroughthered/far-redphotoreceptors,thephytochromes(phys).However,themechanismofphysignalinginthenucleusregulatingchloroplastbiogenesisremainselusive.Ourpreviousstudiesofthephysignalingcomponent,Hemera(HMR),revealedthathmristhefoundingmemberofanewclassofphysignalingmutantswithlonghypocotylandalbinophenotypes.HMRisdual-targetedtothenucleusandplastids.WhilenuclearHMRisatranscriptionalcoactivatorrequiredforearlyphysignaling,includingphylocalizationtophotobodiesanddegradationofthemasterantagonistictranscriptionalfactors,Phy-InteractingFactors1and3(PIF1andPIF3),plastidialHMRisassociatedwithPlastid-EncodedRNAPolymerase(PEP).ThediscoveryofHMRledtothehypothesisthatotherphysignalingcomponentsrequiredforplastidbiogenesisareyettobediscovered.Here,weusedaforwardgeneticscreentoidentifyRCBL(RegulatorforChloroplastBiogenesisinLightsignaling)–anuncharacterizedphysignalingcomponentrequiredforchloroplastbiogenesis.RCBLisrequiredforbothphyA-andphyB-mediatedresponses,andparticipatesinearlyphysignaling,includingphotobodybiogenesis,degradationofPIF1andPIF3,andexpressionofPIF-dependentgenes.RCBLisalsodual-targetedtothenucleusandplastids.AlthoughRCBLisnotassociatedwithPEP,itisessentialforthePEPactivity.Knockingout4PIFs(pifq,pif1/pif3/pif4/pif5)inrcblrescuesthetallhypocotylbutnotthealbinophenotype,indicatingRCBLplaystwoseparateroles:aPIF-dependentroleinhypocotylgrowthandaPIF-independentroleinplastidbiogenesis.Together,thisstudyidentifiedanovelphysignalingcomponentrequiredforplastidbiogenesisanddemonstratesanintimatemechanisticlinkbetweenphysignalinginthenucleusandgeneregulationintheplastidstoinitiateplastidbiogenesisduringphotomorphogenesis.Keywords:Photomorphogenesis;Phytochromesignaling;Chloroplastbiogenesis;Nuclearandchloroplastsdual-targetedAbstract#77.DirectmetalsensingbytheIRT1transporter/receptororchestratesitsdegradationbyendocytosisandplantmetalnutrition(Submission35)GregVert11I2BC,Gif-sur-Yvette,FrancePlantrootsforagethesoilforiron,theconcentrationofwhichcanbedramaticallylowerthanthoseneededforgrowth.Indicotyledonousplants,suchasArabidopsis,ironuptakefromthesoilusesthebroadmetalspectrumIRT1transporterintheroot

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epidermis.ThetranscriptionofIRT1israpidlyandstronglyupregulatedbyironlimitationinroots,toincreaseironuptakelandtosustainplantgrowth.However,IRT1showslowselectivityforironandaspecificallytransportshighly-reactivenon-ironmetalssuchaszinc,manganese,cobaltandcadmium.IRT1isthereforeresponsiblefortheaccumulationofnoxiousheavymetalsiniron-deficientplantsandmoregenerallyinthefoodchain.Wepreviouslyshowedthatlowlevelsofnon-ironmetalstriggerIRT1multimonoubiquitination-dependentinternalizationfromthecellsurfaceanditsaccumulationinearlyendosomes.Here,weuncoverthatnon-ironmetalexcessmediatestheconversionofmultimonoubiquitinintolysine-63polyubiquitinchainstodriveIRT1towardsthevacuoleandpromoteIRT1degradation.Further,wedemonstratethatIRT1actsasatransporter/receptor(transceptor),directlysensingnon-ironmetalexcessinthecytoplasmtoregulateitsowndegradationbyendocytosis.Directbindingofnon-ironmetalstoahistidine-richstretchfoundinIRT1triggerstherecruitmentoftheCIPK22kinaseandIRT1phosphorylation.PhosphorylationofIRT1createsadockingsitefortheIDF1RINGE3ubiquitinligasethatelongatesmonoubiquitinmoietiesintolysine-63polyubiquitinchains.PolyubiquitinatedIRT1issubsequentlysortedintolateendosomesanddegradedinthevacuole.Thus,wehaveidentifiedthemolecularmechanismsallowingplantstoperceiveandrespondtonon-ironmetals,andshownthatIRT1integratesmultiplesubstrate-dependentregulationstooptimizeironuptakeandprotectplantsfromitshighly-reactivenon-ironmetalsubstrates.Keywords:Endocytosis;ubiquitination;plasmamembraneproteindegradation;metalsensing,phosphorylationAbstract#78.Rhamnose-containingcellwallpolymerssuppresshelicalplantgrowthindependentlyofmicrotubuleorientation(Submission40)AdamSaffer1,Carpita,Nicholas,PurdueUniversity,Irish,Vivian,YaleUniversity1YaleUniversity,UnitedStatesWhilespecificorgansinsomeplantspeciesexhibithelicalgrowthpatternsoffixedorvariablehandedness,mostplantsorgansarenothelical.Previousworkhasimplicatedtheorganizationofthecytoskeletonasabasisforhelicalgrowth.Wereportthatchangesincellwallcompositioncanalsocausehelicalgrowth.MutationsinArabidopsisRHAMNOSEBIOSYNTHESIS1(RHM1)resultedindramaticleft-handedhelicaltwistingofadaxialpetalepidermalcellsandwholepetals,andrhm1mutantrootsalsodisplayedleft-handedgrowth.Furthermore,rhm1mutantshaddecreasedexpansionofpetalepidermalcells,andthehelicaltwistingofthosecellswasdependentonexpansion,suggestingthatthehelicalgrowthofrhm1mutantsmightbelinkedtocellexpansion.RHM1encodesaUDP-L-rhamnosesynthase.Rhamnoseisamajorcomponentofpecticpolysaccharidesinthecellwall,andrhm1mutantsexhibitedsignificantlydecreasedlevelsofcellwallrhamnose.Linkageanalysisshowedthatrhm1mutationshaddecreasedlevelsofthepecticpolysacchariderhamnogalacturonan-I,aswellaspotentiallyotherrhamnose-containingcellwallpolymers.Furthermore,themutantmur8,thathasareductionincellwallrhamnose,alsoexhibitedleft-handedrootgrowth,confirmingaroleforrhamnose-containingcellwallpolymersinpreventinghelicalgrowth.Unlikeothermutantsthatexhibithelicalgrowthoffixedhandedness,theorientationofcorticalmicrotubulearrayswasunalteredinrhm1mutants,indicatingthatthehelicalgrowthofrhm1mutantswasindependentofmicrotubules.Ourfindingsrevealanovelsourceofleft-handedplantgrowthcausedbychangesincellwallcompositionthatisindependentofmicrotubuleorientation.Weproposethatanimportantfunctionofrhamnose-containingcellwallpolymersistosuppresshelicaltwistingofexpandingplantcells.Keywords:cellwall;pectin;rhamnose;petals;helicalgrowthAbstract#79.NovelSmallPeptidesinArabidopsisRootDevelopmentRevealedbySuper-ResolutionRibosomeProfiling(Submission41)PollyHsu1,LorenzoCalviello,LarryH.Wu,Fay-WeiLi,CarlRothfels,UweOhler,PhilipN.Benfey1DukeUniversity,UnitedStatesSmallpeptides,recognizedbyspecificreceptor-likekinases,regulatecell-cellcommunicationinplants,includingnumerousdevelopment,abioticandbioticresponses.Thereareover600receptor-likekinasesinArabidopsis,butmostoftheirligandpeptidesarestillunknown.Toidentifynovelsmallpeptides,wegeneratedsuper-resolutionribosomeprofiling(deepsequencingofribosomefootprints)tomonitorribosomeoccupancyintheArabidopsistranscriptome.Usingstringentstatisticstotestfeaturescorrespondingtoactivelytranslatingribosomes,weidentifiednoveltranslatedORFsthatareoutsideoftheannotatedcodingsequences,includingsmallORFs(sORFs)inannotatedncRNAs,upstreamORFsin5’UTRandnon-canonicalstartsites.AbigportionofthesORFsareevolutionarilyconserved,andsomeproducestableproteinsinplants,suggestingtheyarefunctionallyimportant.AmongthenovelsORFs,wefocusonthosedisplayingcelltypeortissue-specificityinrootand/orcontainingasignalpeptidesequence.WehaveidentifiedonesORFdramaticallychangesrootdevelopmentuponover-expressed.OurresultsdemonstratethefeasibilitytoidentifynovelORFsusingahigh-throughputexperimentalapproachandrevealnewfunctionsofsmallpeptidesinrootdevelopment.Keywords:peptide;ribosomeprofiling;rootdevelopment;translation;ncRNA

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Abstract#80.GeneticArchitectureandMolecularNetworksofLeafThicknessinDesert-AdaptedTomato(Solanumpennellii)(Submission44)ViktoriyaConeva1,Frank,Margaret,DDPSC,deLuisBalaguer,MariaA.,NCSU,Li,Mao,DDPSC,Sozzani,Rosangela,NCSU,Chitwood,Daniel,IndependentResearcher1DonaldDanforthPlantScienceCenter,UnitedStatesThethicknessofleaveshasbeenlinkedtotheabilityofplantstowithstandaridhabitats.However,understandingofthemolecularnetworks,whichpatternthishighlyfunctionalquantitativetraitislacking.Weusedacustom-builtconfocalprofilometertomeasureleafthicknessinanintrogressionline(IL)populationderivedfromthedeserttomatospeciesSolanumpennellii,andidentifiedquantitativetraitloci(QTL).Significantcorrelationsofleafthicknesswithasuiteoftraitssuggestthatthicknessispatternedinconcertwithotheraspectsofleafmorphology.Thickertomatoleaveshavedramaticallyelongatedpalisadeparenchymacells–acommonfeatureofmanythickleaves.TodissectthemolecularnetworksthatpatternthicknessweinferredDynamicBayesianNetworksofgeneexpressionacrossearlyleafontogeny(plastochronstagesP1-P4)intwoILswiththickerleaves.WeidentifiedregulatorsofS.pennellii-likeleafshapeandpresentmolecularevidenceforalterationsintherelativepaceofthecellulareventsunderlyingleafdevelopment,whichmayleadtothepatterningofthickerleaves.Collectively,thesedatasuggestgenetic,anatomical,andmolecularmechanismsthatpatternleafthicknessindesert-adaptedtomato.Keywords:leafthickness;desertadaptation;generegulatorynetworks;QTLAbstract#81.Identificationofnovelproteinsinvolvedincytoskeleton-endomembranecrosstalkthroughforwardgeneticscreensonactindisruptingcompounds(Submission50)ElisonBlancaflor1,Sparks,J.Alan,TheSamuelRobertsNobleFoundation,Kwon,Taegun,TheSamuelRobertsNobleFoundation,Khan,BibiRafeiza,TheSamuelRobertsNobleFoundation1TheSamuelRobertsNobleFoundation,UnitedStatesTodiscovernewproteinsthatfunctioninactin–dependentcellularprocesses,weisolatedArabidopsisthalianamutantsthatwerehypersensitiveorresistanttolatrunculinB(LatB),achemicalinhibitorofactinpolymerization.Weidentified3non-allelic,recessivehypersensitivetolatB(hlb)and3non-allelictoleranttoLatBmutants.Thedisruptedgenesinthemutantsencodedforpreviouslyuncharacterizedproteinsinvolvedinmembranetraffickingpathwaysinroots.Forexample,wefoundthatHLB1isatetratricopeptiderepeatdomain-containing,plant-specific565aminoacidproteinwhileHLB2isanewroothairtip-directedprotein.HLB1colocalizedwithtrans-GolgiNetwork(TGN)/earlyendosome(EE)markersthroughitsconservedC-terminaldomainwhileHLB2wastargetedtopost-Golgicompartmentsattheapicaldomeofroothairsviaitsphosphoinositidebinding,pleckstrinhomology(PH)domain.Co-immunoprecipitationidentifiedtheTGN/EE-localizedHOPMinteractor7/BrefeldinA(BFA)-visualizedendocytictraffickingdefective1(MIN7BEN1)asanHLB1interactingprotein.MIN7/BEN1belongstotheBIGclassofADP-ribosylationfactorguaninenucleotideexchangefactors(ARF-GEF),whichareactivatorsoftheARFclassofsmallGTPbindingproteins(smallGTPases).ConsistentwiththesubcellularlocalizationofHLB1,recyclingofproteinstotheplasmamembranewasdisruptedinhlb1rootsandmin7/ben1werehypersensitivetoLatBtothesameextentashlb1.Basedonthesedata,weproposethatHLB1togetherwithMIN7/BEN1formacomplexthatfunctionsattheintersectionoftheexocyticandendocyticpathways.Ourstudyalsodemonstratesthefeasibilityofforwardgeneticscreensonactin-disruptingcompoundstouncovernovelproteinregulatorsthatmediateinteractionsbetweenthecytoskeletonandendomembranetraffickingpathwaysinplants(ThisworkwassupportedbyNASAgrantNNX12AM94GandtheNobleFoundation).Keywords:Actincytoskeleton;Livecellmicroscopy;Endomembranetrafficking;Rootdevelopment;TipgrowthAbstract#82.AutocrineregulationofstomataldifferentiationpotentialbyEPF1andERECTA-LIKE1ligand-receptorsignaling(Submission58)XingyunQi1,Han,Soon-Ki,HHMI-UWSeattle,Dang,HJonathan,HHMI-UWSeattle,Garrick,MJacqueline,HHMI-UWSeattle,Ito,Masaki,NagoyaUniversity,Hofstetter,KAlex,HHMI-UWSeattle,Torii,UKeiko,HHMI-UWSeattle1UniversityofWashington,UnitedStatesDevelopmentofstomata,valvesontheplantepidermisforoptimalgasexchangeandwatercontrol,isfine-tunedbymultiplesignalingpeptideswithunique,overlapping,orantagonisticactivities.EPIDERMALPATTERNINGFACTOR1(EPF1)isafoundingmemberofthesecretedpeptideligandsenforcingstomatalpatterning.Yet,itsexactroleremainsunclear.Here,wereportthatEPF1anditsprimaryreceptorERECTA-LIKE1(ERL1)targetMUTE,atranscriptionfactorspecifyingtheproliferation-to-differentiationswitchwithinthestomatalcelllineages.Inturn,MUTEdirectlyinducesERL1.Theabsoluteco-expressionofERL1andMUTE,withtheco-presenceofEPF1,triggersautocrineinhibitionofstomatalfate.Duringnormalstomataldevelopment,thisautocrineinhibitionpreventsextrasymmetricdivisionsofstomatalprecursorslikelyowingtoexcessiveMUTEactivity.Ourstudyrevealstheunexpectedroleofself-inhibitionasamechanismforensuringproperstomataldevelopmentandsuggestsanintricatesignalbufferingmechanismunderlyingplanttissuepatterning.Keywords:stomata;autocrineinhibition;negativefeedbackloop;ligand-receptorsignaling;transcriptionfactor

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Abstract#83.SucroseistransportedfromleavestoseedsbySWEETs(Submission61)Li-QingChen1,Li,Jiankun,UniversityofIllinoisatUrbana-Champaign,Frommer,Wolf,CarnegieInstitutionforScience1UniversityofIllinoisatUrbana-Champaign,UnitedStatesThereisanurgentneedtoincreasecropyieldtomeetincreasingdemandsforfood,astheworldpopulationgrows.Engineeringsugarfluxtoseedsisoneofthepromisingstrategiestoachievethegoaloffoodincreasing.Sugartransportersarerequiredforintra-andextra-cellularsugarexchangeinthelivingorganism.Arecentlycharacterizedsugartransporterfamily,SWEET,playsimportantrolesinthedifferentbiologicaleffluxprocesses.AtSWEET11and12exportsucroseintotheapoplasmfromthephloemparenchymacellsinpreparationforphloemloading.Theatsweet11;12doublemutantimpairssucroseexportoutoftheleaf.SWEET13wasfoundup-regulatedinatsweet11;12doublemutantplant.Thetriplemutantatsweet11;12;13displayedmoreseverephenotypeonthesugar-freemediumthanatsweet11;12,indicatinganimportantroleofSWEET13inthesteppriortophloemloading.AtSWEET11,12and15arerequiredforseedfillingbysupplyingsucrosefromtheseedcoatandendospermtotheembryo.Triplemutantatsweet11;12;15severelydelaysembryodevelopmentandreducesseedyield.SWEETscompletetherouteofsucrosetransportfromphotosyntheticleaftoheterotrophicembryo.Unexpectedly,theconstitutiveexpressionofAtSWEET11orAtSWEET12leadstostuntedgrowthasatsweet11;12does,suggestingtheprecisemanipulationofsugartransporterisrequiredforsugarfluxengineeringtoincreasecropyield.Keywords:SWEET,sugartransporter,phloemloading,seedfilling,sugarallocationAbstract#84.RemodelingoftheFtsZRingduringChloroplastDivisioninArabidopsisRequiresActivationofARC3byPARC6attheDivisionSite(Submission63)ChengChen1,Yang,Yue,MSU,Porter,Katie,MSU,Osteryoung,KatherineW.,MSU1DepartmentofPlantBiology,MichiganStateUniversity,UnitedStatesChloroplastdivisioninplantsisdrivenbyconstrictionofthestromalFtsZring(Zring),composedofthefilament-formingcytoskeletalproteinFtsZ.RemodelingoftheZringatthemid-plastidisindispensableforZ-ringandchloroplastconstriction.Z-ringassemblyanddynamicsaregovernedinpartbythestromalFtsZassemblyinhibitorACCUMULATIONANDREPLICATIONOFCHLOROPLASTS3(ARC3).Here,wereporttherearetwopoolsofARC3thatfunctiondistinctlyduringchloroplastdivision.Oneisdistributedevenlyacrossthechloroplaststroma;previousworkindicatesthispoolpreventsZ-ringformationatnon-divisionsites.AsecondpoolcolocalizeswiththeZringatthedivisionsite,whereitsassembly-inhibitoryactivitylikelyacceleratesZ-ringremodelingduringchloroplastdivision.ARC3isrecruitedtothechloroplastdivisionsitebytheFtsZ-interactingmembraneproteinPARALOGOFARC6(PARC6).ARC3bearsaC-terminaldomaincalledtheMORNdomain,whichwepreviouslydemonstratedisrequiredforARC3-PARC6interactionbutpreventsARC3-FtsZinteraction.Here,weshowthatPARC6allowsfull-lengthARC3bearingtheMORNdomaintointeractwithFtsZproteinsinayeastthree-hybridsystem,suggestingthatPARC6sequesterstheMORNdomain,enablingARC3-FtsZinteraction.Wefurthershowthatfull-lengthARC3inhibitsassemblyofFtsZfilamentsinaheterologousyeastsystemonlyinthepresenceofPARC6.However,geneticdataindicatethatPARC6alsocontributestotheregulationofZ-ringassemblyindependentlyofARC3.Consistently,PARC6aloneenhancesremodelingofFtsZfilamentsinyeast.OurresultssuggestthatPARC6hasmultiplefunctionsatthedivisionsite:itactsasascaffoldtobringARC3andFtsZintocloseproximity,itactivatestheinhibitoryactivityofARC3onZ-ringassemblybysequesteringtheMORNdomaintoaccelerateZ-ringremodeling,anditmaydirectlypromoteZ-ringremodelingthroughanARC3-independentactivity.Keywords:chloroplast;division;FtsZ-ring;Remodeling;ARC3;PARC6Abstract#85.CELLULASE6andMANNANASE7affectcelldifferentiationandsiliquedehiscenceinArabidopsis(Submission64)MingYang1,He,Hanjun,SouthChinaAgriculturalUniversity,Bai,Mei,SouthChinaAgriculturalUniversity,Hu,Yanting,SouthChinaAgriculturalUniversity,Wu,Hong,SouthChinaAgriculturalUniversity1OklahomaStateUniversity,UnitedStatesCellulases,hemicellulasesandpectinasesplayimportantrolesinfruitdevelopmentandmaturation,butmutantswithdefectsinthefruithavenotbeenreportedforcellulaseorhemicellulasegenes.HerewereportthefunctionalcharacterizationofcellulasegeneCEL6andhemicellulasegeneMAN7insiliquedevelopmentanddehiscenceinArabidopsis.Thesegeneswerefoundtobeexpressedinvegetativeandreproductiveorgans,andtheirexpressioninthesiliquepartiallydependedontheINDandALCtranscriptionalfactors.Mutantallelesofcel6andman7exhibiteddelayedsecondarycellwallthickeningandalteredcellmorphologyinthevalvemarginandimpairedsiliquedehiscence.Cellsintheseparationlayerinnearlymaturesiliquesofthesinglemutantsandthecel6-1man7-3doublemutantremainedintactwhereastheydegeneratedinthewild-typecontrol.Phenotypicstudiesofsingle,double,tripleandquadruplemutantsrevealedthatthehigher-ordermutantcombinationsofthecel6-1,man7-3,andpectinaseadpg1-1andadpg2-1mutationsproducedmoreseveresiliqueindehiscentphenotypesthanthecorrespondinglower-ordermutantcombinations,exceptforsomecombinationsinvolvingcel6-1,man7-3,andadpg2-1.Ourresultsdemonstratethattheabilityofthesiliquetodehiscecanbemanipulatedtodifferentdegreesbyalteringtheactivitiesofproteinsofdifferenttypes.Keywords:Fruitdehiscence;cellulase;hemicellulase;pectinase;mutants

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Abstract#86.MechanismsofribosomalRNAturnoverandtheirroleincellularhomeostasisinArabidopsis(Submission67)GustavoMacIntosh1,Morriss,Stephanie,IowaStateUniversity,Floyd,Brice,IowaStateUniversity,Liu,Xiaoyi,IowaStateUniversity,Bassham,Diane,IowaStateUniversity1IowaStateUniversity,UnitedStatesRibosomesareessentialcellularcomponents,andalargeproportionofcellularresourcesarededicatedtotheirsynthesis.Yet,thepathwaysinvolvedinturnoverofnormalribosomesremainpoorlystudied.WehaveshownthattheArabidopsisribonucleaseRNS2functionsinthevacuolardegradationofrRNA.MutantslackingthisRNaseactivityhaverRNAwithalongerhalf-life,andwedeterminedthatrns2mutantsaccumulaterRNAinthevacuole.Thesemutantsalsohaveconstitutiveactivationoftheautophagypathway,possiblyasanattempttocompensateforthelossofrRNAdegradation.AfunctionalautophagypathwayisalsonecessarytomaintainnormalRNAlevelsinArabidopsis,suggestingthatplantsuseanautophagy-dependentmechanismtotransportribosomestothevacuoleforrecycling.However,differentialrRNAaccumulationinvacuolesofspecificatgmutantssuggestthatrRNAorribosometransporttotheorganellemaybenormallyoccurthroughaselectivemechanismthatutilizessome,butnotall,theautophagycorecomponents.InadditiontodissectingtherRNAdecaypathwayandthemechanismsofrRNAtransporttothevacuole,weareinterestedinunderstandingwhyrRNAisrecycled.Metabolomeandtranscriptomeanalysesofrns2mutantsthatcannotrecyclerRNAproperlyindicatedthatcarbonfluxthroughthepentosephosphatepathwaysisalteredinthemutants.OurresultssuggestthatrRNAturnoverisnecessarytomaintaincellularhomeostasis,likelyaspartofthenucleosidesalvagepathway.Whenthissalvagepathwayisblocked,thePPPisreroutedtoproduceribose-5-Pfordenovonucleosidesynthesis.Thischangeincarbonflux,inturn,causesgrowthphenotypesandtheproductionofreactiveoxygenspeciesthatareresponsibleforactivationofthegeneralautophagypathwayinrns2mutants.Keywords:rRNAturnover;selectiveautophagy;cellularhomeostasis;salvagepathwayAbstract#87.Identifyingregulatorsofasymmetricproteinlocalizationinthestomatallineage(Submission72)YanGong1,Alassimone,Julien,StanfordUniversity,Bergmann,Dominique,StanfordUniversity1StanfordUniversity,UnitedStatesGeneratingcellpolaritypriortoasymmetriccelldivisiondeterminesdiversedaughtercellfatesduringdevelopmentacrossdifferentspecieswithintheeukaryotickingdom.IntheArabidopsisstomatallineage,anumberofproteins(e.g.BASL)arepolarlylocalizedatthecellcortexbeforedivisionandcontributetothephysicalandfateasymmetriesofthesubsequentdivision.Howtheseproteinsachievetheirstrikingpolarlocalization,however,isunknown.Inageneticscreen,weidentifiedamutationintheRaf-likekinaseConstitutiveTripleResponse1(CTR1)thatresultsindepolarizationofpolarityproteinsinstomatallineagecells.CTR1isthenegativeregulatorofethylenesignalingpathwayandthectr1mutantexhibitsaconstitutiveethyleneresponse.Stomatallineagespecificknock-downofCTR1expressionandexogenoussupplyofethyleneonwildtypeArabidopsisseedlingsalsoleadtocorticalproteindepolarization,whichfurthersupportethylene’sfunctioninestablishingcellpolarityinstomatallineagecells.Wearecurrentlyapplyinggenetic,cellbiology,andbiochemicalapproachestodissecttherelationshipbetweenthestemcellpolarityandtheethylenesignalingpathwayinthecontextofstomataldevelopment.Keywords:stomatallineage;cellpolarity;ethylenesignalingAbstract#88.EfficientPlastidTransformationinACC2-DefectiveArabidopsis(Submission74)PalMaliga1,Yu,Qiguo,RutgersUniversity,Lutz,Kerry,FarmingdaleStateCollege1Rutrgers,TheStateUniversityofNewJersey,UnitedStatesPlastidtransformationisroutineintobacco,but100-foldlessfrequentinArabidopsis,preventingitsuseinplastidbiology.Arecentstudyrevealedthatnullmutationsinacc2,encodingaplastid-targetedacetyl-CoA-carboxylase,causeextremesensitivitytospectinomycin.Wehypothesizedthatplastidtransformationefficiencyshouldincreaseintheacc2background,becausewhenACC2isabsentitmakesfattyacidbiosynthesisdependentontranslationoftheplastid-encodedACCβ-Carboxylasesubunit.WebombardedACC2-deficientArabidopsisleaveswithavectorcarryingaselectablespectinomycinresistance(aadA)geneandgfp,encodingthegreenfluorescenceproteinGFP.Spectinomycinresistantcloneswereidentifiedasgreencellclustersonaspectinomycinmedium.PlastidtransformationwasconfirmedbyGFPaccumulationfromthesecondopenreadingframeofapolycistronicmRNA,thatwouldnotbetranslatedinthecytoplasm.WeobtainedonetotwoplastidtransformationeventsperbombardedsampleinthespectinomycinsensitiveSav-0andColumbiaacc2knockoutbackgrounds.TheColumbiaaccessionisrecalcitranttoplantregeneration.However,plantregenerationwasobtainedintheSav-0ecotype.TheSav0transplastomicshootsfloweredandproducedseedinsterileculture.TherecognitionthattheduplicatedACCaseinArabidopsisisanimpedimenttoplastidtransformationprovidesarationaltemplatetoimplementplastidtransformationinrelatedrecalcitrantcrops.Keywords:Sav-0;plastidtransformation;spectinomycinselection;aadAgene;transplastomic

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Abstract#89.PCH1isessentialforphyBnuclear-microdomainformationtoregulatephotomorphogenesisandlightinputintothecircadianclock(Submission88)HeHuang1,Sorkin,Maria,WashingtonUniversityinSt.Louis,Bindbeutel,Rebecca,DonaldDanforthPlantScienceCenter,Nusinow,Dmitri,DonaldDanforthPlantScienceCenter1DonaldDanforthPlantScienceCenter,UnitedStatesAfundamentalquestionincellbiologyishowthedenselypackedcellularcontentsareorganizedtocarryoutthespatiotemporalcontrolovervarioussignalingpathwaysefficiently.Onewaytoachievethisisthroughformingsubcellular,micron-sized,membrane-lessbiomolecularcondensatesconsistingofmultipleproteinsandnuclearacids.InArabidopsiscells,theprimaryred/far-redlightphotoreceptorsphytochromescanformsubnuclear,micron-sized,nuclearmicrodomainscalledphotobodies(PBs).AlthoughthecorrelationsbetweenPBandphytochrome-regulatedphysiologicalresponses,suchasphotomorphogenesis,havebeenestablished,thecompositionandfunctionsofPBrequirefurtherinvestigation.HerewepresentthataphytochromeB(phyB)-interactingproteincalledPCH1functionsasastructuralcomponentofthephyB-PB.PCH1isaplant-specific,evening-phasedproteinthatpreferentiallybindstotheactiveformofphyB.UsingaconstitutiveactivephyBalleleYHB(phyB-Y276H),wetestedgeneticinteractionsbetweenPCH1andphyBsignaling.Consistentwithpriordata,YHBissufficienttoinducephotomorphogenesisandformPBsevenindark-grownseedlings,andtophenocopyredlightinputintothecircadianclocktosustainrobustrhythmsofplantsgrownindark.However,pch1mutationdramaticallyrepressedtheconstitutivephotomorphogenesisphenotypescausedbyYHB.pch1mutationalsopreventsYHBfromformingPBsregardlessoflightordarkconditionswithoutaffectingthenuclearlocalizationofYHB,whileoverexpressingPCH1dramaticallyincreaseYHB-PBformation.ModulatingPCH1levelsalsoaffecttheYHB-mediatedlightinputtotheclock,asYHBpch1plantsexhibitedlossofcircadianrhythmsinconstantdark.Therefore,ourdataindicatedthatPCH1isrequiredforformingphyB-photobodiesandthatphotobodiesarecriticalforproperphyBfunctionsinphotomorphogenesisandinregulatingthecircadianclock.Keywords:phytochrome;photobodies;photomorphogenesis;thermomorphogenesis;circadianclockAbstract#90.TheelaboratedeliveryofUDP-arabinoseintotheGolgiofplants(Submission96)JoshuaHeazlewood1,CarstenRautengarten,ArielOrellana,MichaelG.Hahn,HenrikVibeScheller,BeritEbert1TheUniversityofMelbourne,AustraliaArabinose,specificallyinitsfuranoseform(Araf),isamajorconstituentofnon-cellulosiccellwallpolysaccharidesthataresynthesizedintheGolgiapparatusbyglycosyltransferasesusingactivatedsugars(nucleotidesugars)assubstrates.MostnucleotidesugarsaremadeinthecytosolandtheirtransportfromthecytosolintotheGolgilumenismediatedbynucleotidesugartransporters(NSTs).ThedenovosynthesisofUDP-arabinoseinitspyranoseconformation(UDP-Arap)takesplacewithintheGolgilumen.However,previousstudieshavedemonstratedthattheinterconversionUDP-AraptoUDP-Arafiscatalyzedbyreversiblyglycosylatedproteins(RGPs)localizedinthecytosol.ThisobservationsuggeststhatbothUDP-ArapandUDP-ArafmustbeactivelytransportedacrosstheGolgimembrane.UsinganapproachthatcombinesreconstitutionofNSTsintoliposomesandthesubsequentLC-MS/MSanalysisofnucleotidesugaruptakeweidentifiedsixuncharacterizedproteinsthatcanspecificallytransportUDP-Arafinvitro.Adetailedbiochemicalcharacterizationwillbepresentedanddiscussedincontextwithendogenousnucleotidesugarpoolsinplants.TransientexpressionoftheseNSTsintobaccohasshownthattheyarelocatedintheGolgiapparatus,whichconfirmstheirfunctionasGolgiNSTs.DataobtainedfrommutantandoverexpressionlinesindicatethattheimportofUDP-AraffromthecytosolicintotheGolgilumenisacriticalstepincellwallbiosynthesisandplantgrowth.Keywords:PlantGolgiUDP-arabinofuranosetransportersAbstract#91.Regulationofrootcellelongationbyatranscriptionfactor,whichactsundersignaloftheROS.(Submission97)HironakaTsukagoshi1,Mabuchi,Kaho,Nagoyauniversity.,Maki,Hiromasa,Nagoyauniversity.,Itaya,Tomotaka,Nagoyauniversity.,Suzuki,Takamasa,Chubuuniversity.,Nomoto,Mika,Nagoyauniversity.,Sakaoka,Satomi,MeijoUniversity.,Higashiyama,Tetsuya,Nagoyauniversity.,Morikami,Atsushi,MeijoUniversity.,Tada,Yasuomi,Nagoyauniversity.,Busch,Wolfgang,SALKinstitute.1Meijouniversity,JapanReactiveoxygenspecies(ROS)areimportantasthesignalmoleculeforrespondingtovariousstressesinplant,aswellasingrowthregulation.However,themolecularmechanismsbywhichROSactasgrowthregulator,aswellashowROSdependentgrowthregulationrelatestoitsrolesinstressresponsesarenotwellunderstood.Toaddressthisquestion,wegeneratedcomprehensivetranscriptomemap(ROS-map),whichcapturedROSresponseindifferentzonesofroottip.UsingtheROS-map,weidentifiedaMYBtranscriptionfactor,MYB30,whichshowedastrongresponsetoROStreatmentandisthekeyregulatorofagenenetworkthatleadstothehydrogenperoxidedependentinhibitionofrootcellelongation.Inaddition,weshowedthatMYB30isnecessaryforrootgrowthregulationupondefenseresponses,thusprovidingamolecularlinkbetweenthesetwoROSassociatedphenomena.Keywords:ReactiveOxygenSpecies;TranscriptionalNetwork;RootCellElongation;LipidTransfer

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Abstract#92.ElucidationoftheTOR(targetofrapamycin)networkbynewTORkinasealleles(Submission100)MyriamSchaufelberger1,John,Florian,UniversityofZurich,Ringli,Christoph,UniversityofZurich,Zeeman,SamuelC.,SwissFederalInstituteofTechnologyinZurich1UniversityofZurich,SwitzerlandThetargetofrapamycin(TOR)isahighlyconservedSer/ThrkinasecentraltotheTORnetwork.ManipulationoftheTORsignalingnetworkinArabidopsishashighlighteditscentralroleinregulatingtranslationandmetabolism,aswellascellproliferationandcellwallintegrity.ThelethalityoftheAtTORgenedisruptioncalledforalternativestrategiestocharacterizethefunctionsofthisgene.TheapplicationofchemicalinhibitorswithspecificitytotheTORkinase,aswellasTORsilencingintransgenicArabidopsisbasedonRNAinterferencehaveproventouncoverdiversebiologicalplantTORfunctions.However,prolongedchemicaltreatmentandvariableefficiencyofTORsilencingmightinducearangeofphenotypes,whichcouldhinderinterpretationsofTORsignalingfunctions.Inthisprojecttwonewlyidentifiedtoralleles,harboringamissensemutationintheTORkinasedomain,areinvestigated.Phenotypicanalysisofthetorallelesrevealsaconsistentalterationofrootgrowth.ThetorallelesdisplaydifferentsensitivitiestoTORkinaseinhibitorscomparedtothewildtype.Therefore,furtheranalysesofthetwotoralleleswillprovideinsightintheroleoftheTORpathwayincontrollingplantgrowth.Thiswillpotentiallyhelptoestablishmeanstomodifyplantdevelopmentincludingbiomassproductionandplantyield.Keywords:TORkinaseNewallelesAbstract#93.LRX1:AnextracellularchimericproteinimportantforcellwalldevelopmentinArabidopsisthaliana(Submission101)ShibuGupta1,Ringli,Christoph,UniversityofZurich1UniversityofZurich,SwitzerlandThecellwallthatsurroundseachplantcellisoneofthemajorfactorsforplantgrowthanddevelopmentandlargelydeterminescellularmorphogenesis.Manydevelopmentalprocessesinplantsdependonpropercellwalldevelopment.Afamilyofextracellularproteins,LRX(containingaLRRandanextensindomain),havebeenidentifiedthatareexpressedindifferentplanttissues.OneoftheseLRXgenes,LRX1,isinvolvedinroothairmorphogenesisbecausealrx1mutantdevelopsaberrantroothairswhichfrequentlyabort,swell,orbranch.InordertounderstandtheroleofLRX1incellwallformation,asuppressorscreenwasperformedonthelrx1mutant.Anumberofrolmutants(repressoroflrx1)wereidentifiedthatsuppressthelrx1mutantphenotype.Forexample,rol1androl5reverselrx1mutantphenotypeviamodifyingthepectinstructureandTORsignaling,respectively.Wehaveidentifiednewrolmutantsthatalsosuppressthelrx1mutantphenotype.Thegenesaffectedconferstresstoleranceinplants.Also,wehaveseenalterationsinROSlevelsinthelrx1mutantwhichisalleviatedbytherolmutants.Hence,thisgivesusastrongindicationtheROLgenesarefunctionallylinkedtotheLRX1.LRR(Leucine-rich-repeat)domainshavebeenshowntomediateprotein-proteininteractionsforsignalingincellsaswellasinthecellwall.IthasbeenestablishedbyconfocalimagingthattheLRRdomainofLRXproteinsisassociatedwiththeplasmamembrane,afindingthatwasverifiedbythepresenceofaLRR-citrinefusionproteininthemembranefractions.ThisledtoaconclusionthattheLRRdomaininteractswithabindingpartnerattheplasmamembranethatcausesanchoringofLRXforitscorrectfunction.Therefore,itwouldbeinterestingtofindthepotentialinteractionpartner(s)oftheLRXandhelpustoelucidatetheprocesstheseproteinsareinvolvedin.Keywords:LRX;cellwall;LRXinteractionpartnerAbstract#94.AMP1controlsSAMintegritybylimitingHD-ZIPIIItranscriptionfactoractivity(Submission110)SaiqiYang1,TobiasSieberer1PlantGrowthRegulation,TechnicalUniversityofMunich,Freising,GERMANY,GermanyTheplantshootapicalmeristem(SAM)bearsasmallpoolofstemcells,whichisresponsiblefortheformationofleaves,stemsandflowersthroughoutpostembryonicgrowth.InArabidopsis,mutationintheputativecarboxypeptidaseALTEREDMERISTEMPROGRAM1(AMP1)causesseveredisturbancesinSAMorganisation,includingtheformationofectopicorganizingcentres(OCs)inthemeristemperiphery.RecentlyithasbeenshownthatAMP1impactsonthetranslationalrepressionofmiRNAtargets.SuchtargetsincludeHD-ZIPIIItranscriptionfactors,whichdetermineSAMidentityandorganisation.Inthisstudyweaskedwhethertheamp1-relateddefectsinSAMorganisationaremediatedbyanenhancedtranslationofHD-ZIPIIIfamilymembers.WefoundthattheHD-ZIPIIIdirecttargetZPR3isupregulatedinamp1atthetranscriptandproteinlevelindicatingthatendogenousHD-ZIPIIIactivityisincreasedinamp1.Nextwecompared,towhichextentamp1SAMsresemblethoseofplantswithageneralincreaseinmeristematicHD-ZIPIIIactivitybyusingzpr3zpr4.Similartostrongamp1alleles,zpr3zpr4seedlingsestablishedring-likeexpansionsoftheOCaroundacentralradial,differentiateddomain.Moreover,zpr3zpr4andamp1geneticallyinteractedinastrongsynergisticmannerinrespecttoSAMmalformation,whereasZPR3overexpressioncouldpartiallysuppressthesedefectinamp1.Finally,monitoringthetissue-specificexpressionlevelsofYFP-taggedversionsofthetwoHD-ZIPIIITFsPHVandPHB,wefoundthatHDZIPIIIproteinabundanceisincreasedinamp1,howeversurprisinglywithoutasignificantalterationintheirspatialdistributioninleafprimordiaorroottissues,whichismainlydeterminedbymiRNAs165/166.OurdatasuggestthatAMP1controlsSAMorganisationbylimitingHD-ZIPIIIexpressioninaquantitativeratherthanaspatialmanner.Keywords:amp1;ZPR3;Shootapicalmeristem;HDZIPIII;plantdevelopment

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Abstract#95.IOJAPisNecessaryforPlantDevelopmentatLowTemperaturebyMediatingChloroplastDevelopmentinArabidopsisthaliana.(Submission111)ThomasPayne1,MattOdom,Dr.AndreasNebenführ1UniversityofTennessee,DepartmentofBiochemistryandCellular&MolecularBiology,UnitedStatesTranslationinplastidsisacrucialcomponentinplantdevelopment.Mostmutationsofthechloroplasttranslationmachineryarelethalorpresentaseverephenotype.Recently,wediscoveredthatmutantsintheIOJAPgene,encodingachloroplastribosomeassociatedprotein,appearsnormalatoptimalconditionsbutleadtogrowthdefectsatlowtemperatures(12˚Cand4˚C).Thesedefectsmanifestedasanoverallreductionofplantgrowthaswellaschlorosisandhyponastyinleaves.However,measurementofphotosyntheticcapacityrevealedadecreaseofphotosyntheticcapacityinyoungleavesofiojapmutantsatoptimalconditionsaswellaslowtemperatures.Chloroplastdevelopmentduringde-etiolationalsoshowedadelayintheestablishmentofphotosyntheticcapacitycomparedtoWT.WeconcludethatlossofIOJAPresultedinachloroplastdevelopmentdefect,whichisexacerbatedwhenexposedtolowtemperaturesthatsecondarilyaffectsphotosynthesisandplantgrowth.Keywords:ChloroplastBiogenesis;Chloroplasttranslation;ColdstressAbstract#96.Cross-speciesfunctionaldiversitywithinthePINauxineffluxproteinfamily(Submission113)DevinO'Connor1,Elton,Samuel,SainsburyLaboratoryCambridgeUniversity,Hsia,MonMandy,USDA-ARSWesternRegionalResearchCenter,Vogel,John,U.S.DepartmentofEnergyJointGenomeInstitute,Leyser,Ottoline,SainsburyLaboratoryCambridgeUniversity1SainsburyLaboratoryCambridgeUniversity,UnitedKingdomThedirectionaltransportofauxincreatesconcentrationmaximaandpathsoftransportthatprovidepositional,polarity,andgrowthregulatorycuesthroughoutdevelopment.InArabidopsis,thepolar-localizedauxintransportproteinPIN-FORMED1(AtPIN1)isrequiredtocoordinatedevelopmentduringflowering.However,ArabidopsishasaderivedPINfamilystructure;themajorityoffloweringplantshaveretainedacladeofPINproteinsphylogeneticallysistertoPIN1,theSister-of-PIN1clade(SoPIN1),whichhasbeenlostintheBrassicaceae,includingArabidopsis.BasedonPINlocalizationinBrachypodiumdistachyonandZeamays,whichhavebothSoPIN1andPIN1clades,wepreviouslyproposedthattheorganinitiationandveinpatterningrolesattributedtoAtPIN1weresharedbetweentheSoPIN1andPIN1cladesingrasses.Hereweshowthatsopin1andpin1bmutantshavedistinctphenotypesinBrachypodiumandthusthetwocladesarenotfunctionallyequivalent.sopin1mutantshavesevereorganinitiationdefectssimilartoArabidopsisatpin1mutants,whilepin1bmutantsinitiateorgansnormallybuthaveincreasedstemelongation.HeterologousexpressionofBrachypodiumSoPIN1andPIN1binArabidopsisatpin1mutantsprovidesfurtherevidenceforfunctionaldistinction.SoPIN1butnotPIN1bcancomplementnullatpin1mutants,whilebothSoPIN1andPIN1bcancomplementanatpin1missenseallelewithasingleaminoacidchange.ThedifferentlocalizationbehaviorsofSoPIN1andPIN1bwhenexpressedinArabidopsisprovideinsightintohowPINmembraneaccumulation,tissue-levelproteinaccumulation,transportactivity,andinteraction,allcontributetothepolarizationdynamicsthatdistinguishPINfamilymembers.Combined,theseresultssuggestthatthePINpolarizationandtraffickingbehaviorsrequiredfororganinitiationdifferfromthoserequiredforotherPINfunctionsintheshoot,andthatinmostfloweringplantsthesefunctionsaresplitbetweentwoPINclades.Keywords:evo-devo;auxin;organinitiation;Brachypodium;computationalmodelingAbstract#97.GeneregulatorynetworkscontrollingstemcellregulationintheArabidopsisthalianaroot(Submission114)NatalieClark1,Fisher,AdamP,NCSU,deLuisBalaguer,MariaA,NCSU,Butler-Smith,Tiara,NCSU,Nguyen,Thomas,NCSU,Sozzani,Ross,NCSU1NorthCarolinaStateUniversity,UnitedStatesDevelopmentinmulticellularorganismsrequiresnotonlytheproductionofspecializedcelltypesbutalsomechanismsofcoordinationamongthem.Stemcellsareultimatelythesourceofallcelltypes,andthebalancebetweenself-renewalanddifferentiationoftheirprogenyregulatesorgangrowth.Transcriptionfactorsandcell-to-cellsignalinghaveakeyroleincoordinatingtheseprocesses;however,howthesetranscriptionalnetworkscontrolplantdevelopmentisnotcompletelyunderstood.Thus,weaimtopredictGeneRegulatoryNetworks(GRNs)importantforstemcellregulationintheArabidopsisroot.WeobtainedatranscriptomicprofileofallofthestemcellpopulationsintherootusingFluorescenceActivatedCellSorting(FACS)coupledwithRNAsequencing(RNA-seq).Ofthe8200genesenrichedintheSCN,wefound6900genes(84%)areexpressedin1-2stemcellpopulations,whiletheremaining1300(16%)areexpressedin3ormorestemcells.Toinvestigatehowthesespecificandgeneralregulatorsinteract,wedevelopedacomputationalpipelinethatcaninferGRNsfromtranscriptomicdata.Thispipelinecombinesspatialclustering,regressiontreeinference,andadirectionalityalgorithmtopredicttherelationshipsbetweengenes.Wethenusedmotifanalysistoidentifythemostimportantgenesinthenetworkforbiologicalvalidation.Ourcomputationalpipelinepredicts550genes(7%)and150transcriptionfactors(2%)thatareimportantforstemcellregulationintheArabidopsisroot.Further,bothgenesexpressedin1-2stemcellsaswellasgenesexpressedin3ormorestemcelltypeshaveshownT-DNAmutantphenotypesintheroot.OurresultssuggestthatbothgenesthatregulatespecificstemcellsandgenesthatregulatetheentireSCNareimportantforproperArabidopsisrootdevelopment.Keywords:rootstemcellniche;fluorescenceactivatedcellsorting;cellspecificexpressionprofile;generegulatorynetworkinference

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Abstract#98.RoleofCarbonicAnhydrasesinAntherCellDifferentiationasDownstreamPlayersoftheEMS1ReceptorKinase(Submission115)JianHuang1,ZhiyongLi,GabrielBiener,ErhuiXiong,ShikhaMalik,NathanEaton,CatherineZ.Zhao,ValericaRaicu,DazhongZhao1UniversityofWisconsin-Milwaukee,UnitedStatesCarbonicanhydrases(CAs)catalyzetherapid,reversiblereactionCO2+H2O↔HCO3‾+H+.Inanimals,CAsareimportantforvariousprocessesinnormalandespeciallypathologicalstates,suchasgluconeogenesis,lipogenesis,ureagenesis,andtumorformation.Inplants,CAsinvolveinphotosynthesisandCO2-regulatedstomatalmovement;however,littleisknownabouttheCAfunctioninplantdevelopment.Infloweringplants,successfulsexualreproductiondependsonthenormaldevelopmentofanther.Withineachoffourlobes(microsporangia)inamatureanther,thecentralreproductivemicrosporocytesaresurroundedbyfourconcentricallyorganizedsomaticcelllayers:epidermis,endothecium,themiddlelayer,andtapetum.Inparticular,thetapetumisessentialforpollendevelopmentandrelease.OurpreviousstudiesshowthattheEMS1(EXCESSMICROSPOROCYTES1)LRR-RLKanditsligandTPD1(TAPETUMDETERMINANT1)arerequiredfordifferentiationofsomatictapetalcellsandreproductivemicrosporocytesduringearlyantherdevelopmentinArabidopsis.Here,wereportidentificationofβ-carbonicanhydrases(βCAs)asthedirectdownstreamtargetsofEMS1.EMS1biochemicallyinteractswithβCAproteins.Loss-of-functionofβCAgenescausesdefectivetapetalcelldifferentiation,whileoverexpressionofβCA1leadstotheformationofextratapetalcells.EMS1phosphorylatesβCA1atfoursites,resultingintheenhancementofβCA1activity.Furthermore,thephosphorylationblockingmutationimpairstheβCA1functiontorecovertapetalcelldifferentiationintheβCAloss-of-functionmutant,whilethephosphorylationmimicmutationpromotestheformationoftapetalcells.Moreover,βCAsareinvolvedintapetalcellpHregulation.OurfindingsnotonlyhighlightanovelroleofβCAincontrollingcelldifferentiationduringantherdevelopment,butalsoprovidenewinsightintothepost-translationalmodificationofcarbonicanhydrasesviathereceptorkinasemediatedphosphorylation.Keywords:carbonicanhydrases;anthercelldifferentiation;receptor-likekinase;phosphorylaltionAbstract#99.TheroleofreceptorkinaseERECTAinShootApicalMeristemdevelopment(Submission118)PawelKosentka1,Maradiaga,Richard,UniveristyofTennesseeKnoxville,Shpak,Elena,UniveristyofTennesseeKnoxville1UniversityofTennessee-Knoxville,UnitedStatesTheshootapicalmeristem(SAM)housesstemcellsandisasourceofallaerialplantorgans.DifferentregionsoftheSAMhavespecializedroles.Thecentralzonemaintainsstemcellpopulation.Cellsoftheperipheralzoneareincorporatedintoleaves,flowersandouterlayersofthestemwhilecellsoftheribzoneintothepith.AnaccuratebalancebetweencellproliferationandcelldifferentiationintheSAMrequirescell-to-cellcommunications.OneofthesignalingpathwaysregulatingSAMsize,leafinitiation,andphyllotaxyincludesERECTAfamilygenes(ERfs).TheERfsencodeleucine-richrepeatreceptor-likekinasesandinArabidopsisthisfamilyconsistofERECTA(ER),ERECTA-LIKE1(ERL1)andERL2.TheligandsofERfsbelongtoafamilyof11smallsecretedpeptidesknownastheEPIDERMALPATTERNINGFACTOR/EPIDERMALPATTERNINGFACTORLIKE(EPF/EPFL)proteins.Usingdifferentmeristematicpromoters,weuncoveredthatexpressionofERECTAinthecentralzoneoftheSAMissufficienttorescuemajorityofgrowthrelateddeficienciesoftheererl1erl2mutant.AnalysisofEPF/EPFLgeneexpressionandofselectedhigherordermutantsidentifiedligandsthatarelikelytobesensedbyERfsintheSAM.OurfindingsshedlightonhowERfsfunctionintheSAM,anduncoveranewroleforpreviouslycharacterizedanduncharacterizedEPF/EPFLgenes.Keywords:ERECTAfamily;Receptorkinases;Shootapicalmeristem;EPFLfamily;smallsecretedpeptidesAbstract#100.ProteindestinationsinArabidopsis,withinandbetweenorganelles(Submission136)HarrietParsons1,Stevens,Tim,MRCLaboratoryforMolecularBiology,McFarlane,Heather,MelbourneUniversity,Vidal-Melgosa,Silvia,MaxPlanckInstituteforMarineMicrobiology,Willats,William,NewcastleUniversity,Lilley,Kathryn,CambridgeUniversity1UniversityofCambridge,UnitedKingdomUnderstandingwhyandhowproteinsreachcellulardestinationsiscentraltounderstandinghowbiologicalsystemsareregulated.Aproteinmaytraffictomultiplefunctionallocations,adoptingindifferentfunctionineachlocation.Itmayreachthesedestinationsdirectlyorviathesecretorypathway,andshowrestrictedlocalizationwithinacompartment.TheLOPITtechnique(1)canrevealspatialclusteringofproteinswithinorganellesandidentifymulti-localizedproteins.TherecentadvanceswhichconstitutehyperLOPITareyettobeappliedtoArabidopsis,whosewhole-cellspatialproteomehasnotbeenupdatedsince2006(2).WearecurrentlyupdatingtheArabidopsisLOPITspatialproteomemapusingapartiallyphotosyntheticcellline,andcanreportresolutionofthechloroplastenvelopeandthylakoid,aswellasER,GolgiandTGN.Mappingcomplextraffickingpathwaysinthesecretorysystem,however,requiresevengreaterresolutionthanispossiblewithhyperLOPIT.Usingelectrophoresis,wehaveseparatedtheearly(ER,cis-Golgi)middle(medialGolgi)andlate(trans-Golgi)secretorypathway,alongwithpost-GolgiandPMvesicles.Thishasrevealeddiversetraffickingpathwaysforresidentproteins,distinctfromtraffickingpathwaysforcargoandchaperones.Wehavedefinedproteomesforthecis-,medialandtrans-Golgi,andtwoERcategories.Thedistributionofresiduecharge,size,hydrophobicityandpolaritywithinandaroundthetransmembraneregionisassociatedwithdifferenttraffickingpathways,andlikelydefinethefateofproteinsatthetrans-faceoftheGolgistack.Bycombiningsub-organellarandsub-cellularproteomes,weaimtoprovideacomprehensiveoverviewoftherelationshipbetweenproteinstructure,locationandmigrationwithinthecell.(1)Christoforouetal.NatureComm.2016PMID:26754106(2)Dunkleyetal.PNAS2006

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PMID:16618929Keywords:Spatialproteomics;subcellularlocalization;organelle;secretorypathway;transmembranedomainAbstract#101.Cis-andtrans-factorsinvolvedinthetargetingofKorrigan1(KOR1)tomultipleorganellesinArabidopsis(Submission139)YukihiroNagashima1,Hisashi,Koiwa,TexasA&MUniversity1TexasA&MUniversity,UnitedStatesKOR1,ahighlyN-glycosylatedplantbeta-1,4-glucanaseinvolvedincellulosesynthesispredominantlylocalizesinthetrans-Golginetwork(TGN)andattheplasmamembrane(PM)inrootcellsofArabidopsis.N-glycosylationdefectscausedbystt3a-2mutationaltersubcellulardistributionofKOR1andpromotesaccumulationofKOR1intheTonoplast(TP)aswellastheTGNandthePM.Similarly,slowgrowthandtemperature-sensitiversw2-1alleleproducesaKOR1variantthataccumulatesintheTP.AsthefirststeptounderstandfunctionalconnectionbetweensubcellularlocalizationprofileofKOR1andplantgrowth,inthisstudy,weanalyzedtheKOR1sequencemotifsandgeneticmutationsthataffectsubcellularlocalizationofKOR1.Wefoundaprolinerichregion(P-motif)intheC-terminusofKOR1andthepreviouslyreporteddi-leucine(LL)motifatcytoplasmicdomainhavemajorimpactsonsubcellularlocalizationofKOR1.DeletionofP-motif(∆P)promotedTPaccumulationwhereasaminoacidreplacementinLLmotifproducedexclusivelabelingofKOR1atthePM.Hierarchicalrelationshipbetweentwomotifsarecurrentlyanalyzedbycombiningtwomutations.ToidentifyfactorsthataffectKOR1localizationviaN-glycanmodificationsinsecretorypathway,weconductedforwardgeneticscreening.EMS-mutagenizedArabidopsisexpressingGFP-KOR1werescreenedforhypersensitivitytokifunensine,analfa-mannosidaseIinhibitor,andindividualswithalteredGFP-KOR1localizationprofileswereidentified.ThesemutantsareexpectedtorevealhowKOR1sequencemotifsarerecognizedbythecelltotargetKOR1toeachsubcellularcompartment.Keywords:subcellularlocalization;N-glycosylation;screeningAbstract#102.Thegeneticaloriginsofthefractalmorphologiesincauliflowercurds(Submission141)EugenioAzpeitia1,GabrielleTichtinsky,MarieLeMasson,EtienneFarcot,ChristopheGodin,FrancoisParcy1INRIA,FranceFractalsarefascinatingmathematicalobjectsthathavecomplexproperties,suchasanon-integerdimensionandself-similarityatinfinitescales,butthatcanbeproducedwithextremelysimplealgorithms.Interestingly,naturehascreatedmanyfractal-likestructures,includinglungs,certaincancermorphologies,fernleaves,amongmanymore.However,incontrasttomathematicalfractal,biologicalstructuresareproducedthroughextremelycomplicateddevelopmentalprocesses.Thisraisesthequestionofhowarethedevelopmentalprocessescapabletoproducefractalmorphologiesinbiologicalsystems?Itisalreadywellknownthatinbiologicalsystems,generegulationisfundamentalfordevelopmentalprocess.Cauliflowercurdsarefractal-likestructures,whichcanbeproducedinArabidopsisthalianabymutatingtwohomologousgenes,APETALA1(AP1)andCAULIFLOWER(CAL).AP1andCALparticipateinthedeterminationoftheflowermeristemduringthefloweringtransition.Thus,cauliflowercurdsprovideanexcellentopportunitytostudywhichandtounderstandthegeneticbasesoffractalsbystudyingthegeneticregulationofthefloweringtransition.Inthisworkweprovide,fortheveryfirsttime,anexplanationofhowabiologicalgeneticprocessregulatesdevelopmentoffractalmorphologiesatamacroscopicscale.Combiningmathematicalmodelingandexperimentalapproximationswestudy(1)theeffectoftheap1/calmutationoverthemolecularprocessregulatingthefloweringtransition,(2)howthismutationcantransformflowers,whichareaterminalstate,intoafractal-likestructure,(3)howdoesthespectacularfractalshapeoftheRomanescocurdsgenesregulatecouldappearduetochangesinthemodelparameters,and(4)experimentallystudytheeffectofmodifyingknowngeneticregulatorsoftheseparameters.Keywords:Generegulatorynetwork,systemsbiology,plantarchitecture,multi-levelmodelling,fractalsAbstract#103.RegulationofArabidopsisflowerdevelopmentbythetranscriptionfactorAINTEGUMENTA(Submission147)BethKrizek1,Blakley,Ivory,UniversityofNorthCarolinaatCharlotte,Loraine,Ann,UniversityofNorthCarolinaatCharlotte1Univ.ofSouthCarolina,UnitedStatesUnderstandinghowflowersformisanimportantprobleminplantbiology,asthehumanfoodsupplydependsonflowersandseedproduction.GeneticanalysisofArabidopsishasshownthatthetranscriptionfactorAINTEGUMENTA(ANT)playsakeyroleinfloralorgangrowth.InconcertwithpartiallyredundantAINTEGUMENTA-LIKE(AIL)proteins,ANTregulatesflowerorganinitiation,identityspecification,andpatterning.UsingRNA-Seqanalysisofmutantfloralbuds,weidentifiedthousandsofgenesthatdependonANTand/orAIL6forexpression.However,thedirecttargetsofANTbindingremainunknown.Toidentifythesetargets,wegeneratedlinescontainingasteroid-inducibleformofANT(35S:ANT-GR)andanalyzedthemusingRNA-Seq.Interestingly,onlyasmallnumberofgeneswerechangedaftertwohoursofANTinduction,butaftereighthours,manymoregeneswerechanged.Ofthese,122genesshowedoppositeregulationin35S:ANT-GRandantail6.FurtherexperimentsonasubsetofthesegenesfoundthatsomeofthemwerealsodifferentiallyexpressedinANT:ANT-GRantinflorescencesandthatthisdifferentialexpressionwasindependentofproteinsynthesis.ThusourstudyhaslikelyidentifiedseveraldirecttargetsofANTregulationinflowers.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Keywords:floralorgansizeflowerdevelopmentAINTEGUMENTA-LIKERNA-SeqtranscriptionalregulationAbstract#104.ATG14guidesPI3KcomplexItoregulateearlyautophagiceventsinArabidopsis(Submission149)FenLiu1,FaqiangLi,SouthChinaAgriculturalUniversity,Guangzhou,China,RichardD.Vierstra,WashingtonUniversityinSt.Louis,St.Louis,MO1WashingtonUniversityinSt.Louis,UnitedStatesAutophagyisaconservedpathwayineukaryotesthatengagesacomplexmachinerytodeliverandrecycleintracellularconstituentsinthevacuole.Asoneofcoreproteincomplexesneededforautophagy,thefour-subunitclassIIIphosphatidylinositol3-kinase(PI3K)complexisresponsiblefordecoratingtheenvelopingautophagicvesicleswithphosphatidylinositol3-phosphate(PI(3)P),whichisthenusedtorecruitdownstreamcomponents.TwotypesofPI3Kcomplexesarepresentinplants,yeast,andanimals;theysharethreesubunits:ATG6,VPS34,andVPS15,withthefourthsubunitdeterminingwhetherthekinaseparticipatesinautophagy(ATG14)orinvacuolarproteinsorting(VPS38/UVRAG).Consequently,thestudyofATG14versusVPS38providesanidealmethodtostudythespecificrole(s)ofPI3Pinplantautophagy.Aspredicted,ArabidopsisATG14a/binteractswithitsimmediatepartnerATG6bybothY2HandBiFC.ViaCRISPR/Cas9geneediting,wegeneratedalibraryoflikelynullmutantsaffectingthetwoArabidopsislociexpressingATG14.Whilethesinglemutantplantsappearwildtype,thedoubleatg14aatg14bplantsdisplayphenotypestypicalofautophagymutants,includingearlysenescenceandahypersensitivitytoNandfixed-Cstarvation.WhiletheplantscansynthesizenormallevelsoftheATG12-ATG5conjugateandthelipidatedformofATG8,theyareunabletoaccumulateATG8-decoratedautophagicbodiesasdeterminedbyconfocalfluorescencemicroscopyofaGFP-ATG8reporterandpoorlydeliverGFP-ATG8tothevacuole.Interestingly,theatg14aatg14bplantsarelesssensitivetofix-Cstarvationthanmutantsmissingcoreautophagycomponents,asarecomponentoftheATG2-ATG18complexthatdeliverslipidstotheexpandingvesicles.Takentogether,itappearsthatdistinctautophagicroutesregulatedbythePI3KcomplexmightbeactiveduringNandfixed-Cstarvationinplants.Abstract#105.Efficientselectionofantibodyfragmentsusingphagedisplayandexhaustiveyeasttwo-hybridscreening(Submission153)PetraTafelmeyer1,Moutel,Sandrine,TranslationalResearchDepartment,InstitutCurie,Paris,France,Djander,Selma,TranslationalResearchDepartment,InstitutCurie,Paris,France,Collura,Vincent,HybrigenicsServices,Paris,France,Arrial,AlexisArrial,HybrigenicsServices,Paris,France,Jupin,Isabelle,InstitutJacquesMonod,Paris,France,Olichon,Aurélien,INSERM,CRCT,Toulouse,France,Perez,Franck,CNRSUMR144,InstitutCurie,Paris,France,Rain,Jean-Christophe,HybrigenicsServices,Paris,France1HybrigenicsCorp.,UnitedStatesAntibodiesrepresentcentraltoolsinmostbiologicalstudiestoanalyzeproteinlocalizationandfunction.Oneoftheremaininglimitationsisthechallengetomakethemworkinsidealivingcell.Forthispurposeintrabodiescanbeselectedaspowerfultoolstoanswercomplexbiologicalquestions,ashasbeenshownforexamplewithaconformationalintrabodyrecognizingspecificallytheGTP-boundformofthesmallGTPaseRab6(1),GTP-tubulin(2),orfarnesylatedPSD95(3).Sofar,theaccesstointrabodieswaslimitedtohighlytrainedlabspecialistsinthisfield.WehavethereforesetupanewplatformforintrabodyscreeninganddesignedforthispurposeafullysynthetichumanizednaïveLlamaVHHlibrarycontaining3x10exp9antibodies,basedonauniquescaffoldwithrandomcomplementarydeterminingregions(CDRs).Weuseacombinationofphagedisplayandsubsequentyeasttwo-hybrid(Y2H)screeningtoidentifyantibodiesagainstnativeantigensandeventuallyintrabodies.TheVHHclonesaredirectlyaccessibleandtherecombinantantibodiescanbeproducedasfusionstoeitherahuman,mouseorrabbitFcdomain(4).WesuccessfullyselectedfromthislibraryVHHagainstavarietyofantigensincludinglargeproteins,haptensandreceptorsdirectlyselectedfromcellsurfaceexpression.TheaffinityofourVHHissimilartotheaffinityofantibodiesselectedafteranimalimmunization.UsingonlyasingleroundofphagedisplayfollowedbyoneroundofY2Hscreeningwewereabletosignificantlyenrichtheselectioninintrabodies.Inaddition,wetookadvantageofyeastgeneticstofurtherstudyandcharacterizetheselectedintrabodies(5).HerethistechniquewillbeexemplifiedwiththeselectionofintrabodiesagainstUSP7,HER2andaproteinfromaplantvirus.1)NizakC.etal.Science2003,300:9842)DimitrovA.etal.Science2008,322:13533)FukataYetal.J.CellBiol.2013,202:1454)MoutelS.etal.BMCBiotechnology2009,9:145)MoutelSetal.eLife2016,5:e16228Keywords:intrabody,nanobody,phagedisplay,yeasttwo-hybridAbstract#106.TheArabidopsisfloweringregulatorCONSTANSbindsDNAinaheterotrimericcomplexthatisanalogoustoNF-Ycomplexes(Submission158)BenHolt1,Gnesutta,Nerina,UniversitàdegliStudidiMilano,Kumimoto,Roderick,UCDavis,Swain,Swadhin,UniversityofOklahoma,Chiara,Matteo,UniversitàdegliStudidiMilano,Siriwardana,Chamindika,UniversityofOklahoma,Chiara,Matteo,UniversitàdegliStudidiMilano,Horner,David,UniversitàdegliStudidiMilano,Mantovani,Roberto,UniversitàdegliStudidiMilano1UniversityofOklahoma,UnitedStatesThetransitionbetweenvegetativeandreproductivegrowth(i.e.,flowering),aswellasmanycircadianclock-regulatedprocesses,reliesontheactionsofDNA-bindingCCT(CONSTANS(CO),CO-Like,TOC1)domainproteins.FormorethanadecadewehaveknownthatCCTproteinssharesignificantidentitywithNF-YAproteins.NF-YA,NF-YB,andNF-YCproteinsformtheheterotrimericNF-YtranscriptionfactorthatbindsDNAwithhighspecificityatCCAATelements.NF-YAmakesallthedirectcontactswithCCAAT,whilethehistonefolddomain(HFD)proteins(NF-YBandNF-YC)stabilizeDNAbinding,makinglessspecificcontactswithbasesflankingCCAAT.Hereweuseda

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combinationofserialmutagenicEMSA,RNA-Seq,ChIP,andtraditionalgeneticstodemonstratethataunifyingmolecularmechanismofCOfunctionrelatesittotheNF-YAparadigm,aspartofatrimericcompleximpartingsequence-specificitytoHFD/DNAinteractionsthatwetermNF-CO.NF-COpreferentiallybindstoCCACA,anelementthatiscloselyrelatedtoCCAATandidenticaltothepreviouslydescribedmorningelement.ExaminationofapreviouslydevelopedNF-Y/CCAATcrystalstructurehighlightsasingleaminoacidasresponsibleforthebindingspecificitydifferencesbetweenNF-YandNF-CO.HFDmutationsthatspecificallydisruptNF-YfunctionalsodisruptNF-COfunctioninbothinvitroDNAbindingandinvivofloweringassays.Further,apreviouslydescribedstrongmutantalleleofCOabolishesNF-CObindingatCCACA,andourdatasuggeststhatmostpublishedCCTmutationsimpactDNAbinding.ItislikelythatmostmembersoftheCCTfamilyparticipateinsimilarcomplexeswithNF-YBandNF-YC,vastlybroadeningHFDcombinatorialpossibilitiesintermsoftrimerization,DNA-bindingspecificities,andtranscriptionalregulation.Keywords:CONSTANS;CCT;NF-Y;Flowering;TranscriptionalRegulationAbstract#107.CompartmentationofPutrescinebiosynthesisinplants(Submission161)MenakaAriyaratne1,JigarPatel,SheazaAhmed,PaulMorris1BowlingGreenStateUniversity,UnitedStatesAdistinguishingfeatureofeukaryoticcellsisthepresenceofmembrane-boundorganellesandvesicles.Inplants,thesecellularroomshavemultiplefunctionsthatenablethespecializedcompartmentationofmetabolicprocessessuchascarbonfixation,respiration,energycaptureandbiosynthesisofprimarymetabolites.Anadditionalfeatureofplantmetabolismistheredundancyofcertainmetabolicpathways.Thisisalsothecaseforputrescinebiosynthesis.Putrescineisanessentialmetaboliteinplantsandtherearetwobiosyntheticpathwaystosynthesizeputrescine.Inthefirstpathway,Ornithinedecarboxylase(ODC)convertsornithinedirectlytoputrescineintheER.Asecondrouteutilizesargininedecarboxylase(ADC)toconvertargininetoagmatine,andtwoadditionalenzymes,agmatinedeiminase(AI)andN-carbamoylputrescineaminohydrolase(NLP1)tocompletethispathwayinthecytosol.HereweshowthatplantscanuseADCandarginase/agmatinase(ARGAH)toprovideathirdrouteforputrescinesynthesisinthechloroplast.TransformationofAtADC2andarginasesfromA.thalianaandsoybean(AtARGAH1,AtARGAH2orGmARGAH)intoayeaststraindeficientinODC,fullycomplementedtheWTphenotype.HPLCanalysisofinvitroassaysofAtADC1andAtARGAH2confirmedthattheseenzymesfunctioninconcerttoconvertargininetoagmatineandputrescine.ConfocalmicroscopyexperimentsshowthatbothsoybeansandA.thalianahaveaplastidlocalizedputrescinepathway.ExperimentalsupportforthispathwayalsocomesfromthefactthattheexpressionofAtARGAH,andnotAtAIHorAtNLP1,clusterswithAtADC2inresponsetodrought,oxidativestress,wounding,andmethyljasmonatetreatments.BasedonthehighaffinityofARGAH2foragmatine,itsco-localizationwithADC2,andtypicallevelsofarginineinplanttissues,weproposethatthesetwoenzymesarethemajorcontributorstoputrescinesynthesisinmanystressresponsesofA.thaliana.Keywords:PolyaminebiosynthesisAbstract#108.MolecularRequirementsforMLO-MediatedCommunicationDuringPollenTubeReception(Submission162)DanielJones1,Yuan,Jing,PurdueUniversity,Smith,Benjamin,UCBerkley,Kessler,Sharon,PurdueUniversity1UniversityofOklahoma,UnitedStatesIntercellularcommunicationregulatesessentialdevelopmentalprocessesandcomplexsignalingeventswithinmulticellularorganisms.Infloweringplants,cell-cellcommunicationiscrucialforsuccessfulreproductionasprocessesregulatingpollination(includingpollentube(PT)attraction/reception)andsubsequentfertilizationrequiresuchinteractions.InArabidopsisthaliana,theMildewresistancelocuso(MLO)familyproteinNORTIA(NTA)hasbeenidentifiedasacriticalcomponentregulatingcommunicationduringPTreception.Inthenortia(nta-1)mutant,PT-synergidcellcommunicationisdisruptedin~30%ofovules,resultinginreducedseedset.MLOproteinswerefirstdescribedassusceptibilityfactorsinvolvedinpowderymildewpathogenesis;however,themolecularfunctionofMLOproteinsremainsunresolved.Inthisstudy,therequirementsforMLOfunctionduringPTreceptionwereexploredthroughafunctionalanalysisofdivergentMLOproteinsandchimericMLOfusionsectopicallyexpressedinthesynergidcellsofnta-1.MLO8,closelyrelatedtoNTA,wasincapableofrescuingnta-1’sunfertilizedovulephenotype,whilethemoredistantlyrelatedMLO,MLO2,wasable.AFRET-basedinteractionassayrevealedthatNTAformshomo-oligomersinplantaandthatdisruptionofitsN-terminaldomainreducedtheseinteractions,suggestingfunctionalsignificance.Interestingly,theMLOproteinsthatcouldfunctioninPTreceptionallpartiallyco-localizedwithaGolgimarkerinthesynergidcellpriortoPTarrival.ApreviousstudyshowedthatNTApolarlyredistributestothesiteoffirstcontactbetweenthePTandsynergidcell.WhilethisredistributionwasnotconservedwitheveryMLOanalyzed,ourresultssuggestthatpolarmovementofMLOsduringPTreceptioncanbelinkedtocanonicalendomembranetrafficking.AsetofendomembranemarkersspecificallyexpressedwithinthesynergidcellwasgeneratedtoassessMLOsubcellularlocalization.Abstract#109.Theroleoftheshootapicalmeristeminvegetativephasechange(Submission164)JimFouracre1,Poethig,Scott,UniversityofPennsylvania1UniversityofPennsylvania,UnitedStatesWhilethemolecularmechanismthatregulatesvegetativephasechange(thetransitionfromjuveniletoadultvegetativegrowth)isincreasinglywelldescribed,howthismechanismoperatesspatiallywithintheshootapexispoorlyunderstood.Leafablationandapexculturestudieshavesuggestedaroleforpre-existingleafprimordiaindeterminingtheidentityoflaterleaves.However,theprecocious

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phenotypeofloss-of-functionwuschel(wus)plants,whichimmediatelyproduceadultleaves,suggestsanintrinsicrolefortheshootapicalmeristem(SAM)inthemaintenanceofjuvenility,andalsoimpliesthatleafprimordiaarenotrequiredtopromotevegetativephasechange.Ouridentificationofaloss-of-functionclavata1alleleinamutantscreenforjuvenilizedplantsprovidedfurthersupportforaroleforWUSintheregulationofleafdevelopmentalstate.Here,wepresentananalysisoftheroleofWUSand,morebroadly,theSAMindeterminingleafdevelopmentalage.GeneexpressionanalysesshowthatWUSislikelytoactinparalleltothemiR156-SPLpathway,themajorregulatorofvegetativephasechange.Analysesofadditionalmutantswithmeristematicdefects,aswellasablationoftheSAM,suggestthattheroleofWUSinthespecificationofleafidentityislikelytobeindirect.OurresultsindicatethattheSAMisrequiredfortherepressionofSPLfunctioninleavesproducedearlyinshootdevelopment,andthatlocalizedexpressionofmiR156withintheSAMcanpartiallycomplementlossofmiR156acrosstheshootapex.However,theSAMplaysarelativelysmallroleintheregulationofvegetativephasechange.Instead,thisprocessislargelydeterminedbyregulatoryfactorsthatoperatewithinandbetweenleaves.Keywords:vegetativephasechange;miR156;wuschel;leafdevelopment;shootapicalmeristemAbstract#110.CharacterizingnewArabidopsismicrotubuleplus-endtrackingproteins(Submission166)RachappaBalkunde1,Dixit,Ram,WashingtonUniversityinSaintLouis1WashingtonUniversityinSt.Louis,UnitedStatesMicrotubuleplus-endtrackingproteins(+TIPs)localizetogrowingmicrotubuleplus-endsandregulatemicrotubulepolymerizationdynamicsandinteractionswithothercellularstructures.TheEndBinding1(EB1)proteinsareanevolutionarilyandstructurallyconservedclassof+TIPsfoundinplants,animalsandfungi.EB1functioninanimalsandfungireliesonitsinteractionswithahostofotherproteins.However,mostoftheseproteinsareeithermissinginplantsorhavenotbeendemonstratedtointeractwithplantEB1.Giventhedistinctbehaviorandarchitectureofplantmicrotubulearrays,wehypothesizedthatplantsmighthaveuniqueEB1-interactingpartners.Asafirststeptowardscharacterizingtheplantmicrotubule+TIPcomplex,weemployedayeasttwo-hybridscreenusingtheC-terminaldomainofA.thalianaEB1b(amino-acids162-293)asbaitagainstapreylibraryfromArabidopsisseedlingcDNA.WeidentifiedseveralputativeEB1b-interactionpartners.Here,wepresentanovelfamilyof+TIPsinArabidopsisconsistingofthreemembers,whichwenamedMicrotubuleEndbindingProtein1(MEP1),MEP2andMEP3.LiveimagingusingvariableangleepifluorescencemicroscopyshowedthatMEP1andMAP3localizetothegrowingplus-endsofcorticalmicrotubules.FurtheranalysisofMEP1showedthatitinteractsdirectlywithallthreemembersoftheArabidopsisEB1familyindirectedyeasttwo-hybridandpull-downexperiments.Inaddition,MEP1itselfbindstotaxol-stabilizedmicrotubulein-vitro.WefoundthatthecentralregioninMEP1issufficientforbothEB1interactionandmicrotubulebinding.ReportergeneanalysisshowedthatMEP1ispreferentiallyexpressedinthevasculature,suggestingaroleinvasculardevelopmentand/orfunction.Ourongoingworkseekstounderstandthemechanismofplus-endtrackingbyMEP1anditsroleinplantdevelopmentandgrowth.Keywords:Microtubule,NovelPlusendbindingprotein,Abstract#111.Branchingoftherootsystemispromotedbyphotosynthesis(Submission178)LinaDuan1,Dinneny,José,CarnegieinstitutionforScience1CarnegieInstitutionforScience,UnitedStatesInataprootsystemsuchasArabidopsis,lateralroots(LRs)areimportantcomponentsinshapingthewholerootsystemarchitecture.HereweidentifiedanEMS-inducedmutantsnamedpresto(prematurelystressedlateralorgans),whichhasgreatlyreducedLRemergence,especiallyunderhighsalinity.Usingmappingbysequencing,PRESTOwasfoundtoencodeacyclophillin,whichisonlyexpressedinphotosynthetictissues.FluorescentproteintagginganalysisindicatesthatPRESTOisspecificallylocalizedinplastids,whichsupportspreviousworkshowingthatthisproteinservesasanimportantregulatoroflightdependentphotosystemassembly.Impairedphotosynthesismayleadtoanoverallreductioningrowth,includingprimaryrootelongationandlateralrootemergence.ThesedefectsarenotsimplyaconsequenceoflessfixedcarbonasaddingsucrosetothemediaisnotabletorescueLRemergence.Byperformingametabolomicsexperiment,wehavefounddramaticperturbationsinprimarymetabolism,includingchangesinthelevelsofsugars,aminoacidsandorganicacidsinprestomutant.Interestingly,wehavefoundthatinthemutant,therearesignificantdown-regulationsofvariouslateralrootdevelopmentrelatedmetabolites,likelinolenicacidandputrescine,whicharealsoinvolvedinstressanddefenseresponsesinplants.Ourfindingssuggestsystemicconnectionsamongphotosynthesis,rootdevelopment,andstressresponseprograms.Thisworkwillultimatelyleadtoabetterunderstandingofhowtheplantcoordinatesdevelopmentofthebelowgroundrootsystemwithlight-dependentproductivity.Keywords:photosynthesis;lateralrootdevelopment;metabolomics;lightsensingAbstract#112.ChloroplastproteolysisinArabidopsis;functionalcontributionsofClpP5andClpP3inClpproteaseactivity(Submission179)Jui-YunLiao1,Friso,Giulia,Cornell,vanWijk,KlaasJ.,Cornell1CornellUniversity,UnitedStatesTheArabidopsischloroplastClpproteasesystemisessentialforplantgrowthanddevelopmentandconsistsofClpC/DAAA+chaperones,

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substrateadaptorsClpS1andClpFandatetramericbarrel-likeserine-typeClpPRTprotease.ThisClpPRTiscomposedofnon-proteolyticClpRsubunits,proteolyticClpPsubunitsandtwoClpTproteinsinvolvedinactivationoftheClpPRcomplex.AlthoughthestoichiometryofthesesubunitsinClp(P1:P3:P4:P5:P6:R1:R2:R3:R4=3:1:2:3:1:1:1:1:1)isknown,thedetailedmechanismofhoweachsubunitcontributestoClpbarrelstructureandproteolysisremainsunclear.Usingsite-directedmutagenesisandcomplementationofclpmutants,weshowedthatwildtypeClpP3orthecatalyticallyinactiveClpP3S164Arecoveredthedevelopmentalarrestofclpp3-1.WildtypeClpP5,butnotthecatalyticallyinactiveClpP5S193A,rescuedtheembryolethalphenotypeofclpp5-1.Thesedatasuggestthata)ClpP5iscriticalforcatalyticfunctionandb)ClpP3isimportantforClpstructurebutthatitscatalyticroleisdispensable.Keywords:chloroplasts,caseinolyticprotease(Clp),ClpP3,ClpP5,proteinhomeostasisAbstract#113.SnRK1phosphorylationofFUSCA3regulatesembryogrowthrate,seedyieldandplantgrowthathightemperatureinArabidopsis(Submission181)SoniaGazzarrini1,Chan,Aaron,Carianopol,Carina,Tsai,AllenYi-Lun,Varathanajah,Kresanth,Chiu,RexShun1UniversityofToronto,CanadaThetranscriptionfactorFUSCA3(FUS3)actsasamajorregulatorofseedmaturationinArabidopsis.FUS3isphosphorylatedbytheSnRK1,aconservedeukaryotickinasecomplexinvolvedinenergyhomeostasis.HereweshowthatAKIN10andFUS3shareoverlappingexpressionpatternsduringembryogenesis,andthatFUS3isphosphorylatedbyAKIN10duringearlyembryogenesis.TounderstandtheroleofFUS3phosphorylation,wegeneratedfus3-3plantscarryingFUS3phosphorylation-null(FUS3S>A)and-mimic(FUS3S>D)variants.WhileFUS3S>AandFUS3S>Drescuedallfus3-3seedmaturationdefects,FUS3S>Ashowedreducedtranscriptionalactivationandenhancedfus3-3previouslyuncharacterizedphenotypes.FUS3S>Aembryosdisplayedincreasedseedabortionanddelayedembryodevelopmentandcorrelatedwitha50%decreaseinseedyield.Atelevatedtemperature,FUS3S>Aphenotypeswereexaggeratedandnextgenerationseedlingsgrewpoorly.Accordingly,theakin10andakin11mutantsdisplayedafrequencyofseedabortionsimilartofus3-3.Collectively,theseresultssuggestthatFUS3phosphorylationbySnRK1isrequiredforcorrectembryodevelopmentandintegrationofenvironmentalcuestoensurethesurvivalofthenextgeneration.Keywords:SnRK1;AKIN10;FUSCA3;embryodevelopment;seedabortion;hightemperatureAbstract#114.AninferenceapproachcombinesspatialandtemporalgeneexpressiondatatopredictgeneregulatorynetworksinArabidopsisstemcells(Submission192)RossSozzani1,M.AngelsDeLuisBalaguer,AdamFisher,NatalieClark,CranosWilliams,OscarLorenzoSanchez,DolfWeijers1NCSU,UnitedStatesIdentifyingthetranscriptionfactors(TFs)andassociatedregulatoryprocessesinvolvedinstemcellregulationiskeyforunderstandingtheinitiationandgrowthoftissuesandorgans.AlthoughmanyTFshavebeenshowntohavearoleintheArabidopsisrootstemcells,acomprehensiveviewofthetranscriptionalsignatureofthestemcellsislacking.Inthiswork,weusedspatialandtemporaltranscriptomicdatatopredictinteractionsamongthegenesinvolvedinstemcellidentity,function,andmaintenance.Forthis,wetranscriptionallyprofiledseveralstemcellpopulationsanddevelopedageneregulatorynetwork(GRN)inferencealgorithmthatcombinesclusteringwithDynamicBayesianNetwork(DBN)inference.Weleveragedthetopologyofournetworks,whichgrantsthemrobustnesstorandomdisruptionsandsusceptibilitytothelossofhubs,toinferpotentialkeyregulators.Weexperimentallyvalidatedandmathematicallymodelledsomeofourpredictions.Weusedgeneexpressionandchromatinimmunoprecipitationdatatoconfirmgenespredictedtobedownstreamofthemainnodeofthexylemnetwork.Moreover,amongthemainnodesinthequiescentcenter(QC)network,weidentifiedPERIANTHIA(PAN)playingaroleinQCfunctionandstemcellmaintenance.Theresultspresentedinthisworkshowthatourcombinationofmolecularbiologyapproaches,computationalbiologyandmathematicalmodelingwaskeytoidentifycandidatefactorsthatfunctioninthestemcells.Abstract#115.CharacterizationofthehypergravitropicArabidopsismutantgravitypersistentsignal5(gps5)(Submission227)DarronLuesse1,EricaBohmer,HaHuynh,DonaldVonKannon,MatthewEgan,JoshuaKinser1SouthernIllinoisUniversityEdwardsville,UnitedStatesTheabilitytosenseandrespondtogravityisacriticalcomponentofplantgrowthanddevelopmentfromseedtoflowering.Thegravitypersistentsignal(gps5)mutantofArabidopsisthalianawasdiscoveredinascreenformutantsthatshowedalteredgravitropismafteracoldgravitytreatment.Afterahorizontalcoldtreatment,inflorescencestemsplacedverticallyatroomtemperaturerespondwithafasterresponseofgreatermagnitude.Thismutantalsoshowsincreasedrootslanting,fastergrowth,andenhancedhypocotylandrootgravitropism.Microarrayanalysisofgps5indicatesthataglycosyltransferasegeneisseverelydownregulated.SubsequentPCRanalysisrevealedthepresenceofasmalldeletionwithinthisgene.Deepsequencingrevealedfouradditionalcandidatelociwhicharecurrentlybeinganalyzed.Inaddition,mutantsfromothergenesidentifiedinthemicroarrayhavebeenanalyzed.AnArabinogalactanproteinwasshowntobeupregulatedinthemutant,butdoesnotshowanalteredGPSresponse.However,aT-DNAinsertioninthecodingregionofafar-redhypocotyllikemutantdoesproduceareducedGPSresponse,whileaninsertioninthe3’UTRdoesnot.Keywords:Gravitropism;glycosyltransferase;Far-Red

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Abstract#116.ChemicalandphysicalsignalsinthecontrolofearlyphotomorphogenesisinArabidopsis(Submission229)AnkitWalia1,AnnalisaRizza,AlexanderJones1TheSainsburyLaboratory,UniversityofCambridge,UnitedKingdomAmajorchallengeinplantbiologyistounderstandhowmulticellularplantsintegratedynamicdevelopmentalandenvironmentalinputstodrivecellularresponses.Thesecellularresponsesarewellorchestratedacrossthespatialandtemporalscalestoenhancetissue-andorgan-levelfunctionality.Weareusingphotomorphogenichypocotylsasamodeltoelucidatehowchangesinhormonallevelsandmechanicalpropertiesofthecellwallarealteredtodrivecellulargrowthassociatedwithearlyphotomorphogenesis.Tothisend,wearemappingthespatiotemporalpatternsoftheplantgrowthregulatorgibberellin(GA)usingthenlsGPS1biosensoralongsidecellulargrowthratesandcellwallmechanicsusingAtomicforcemicroscopy(AFM).Usinglong-termco-imagingofsuchphotomorphogenichypocotylsexpressingnlsGPS1andafluorescentplasmamembranemarker,wehavefoundregionsofbothrapidGAaccumulationandacceleratedcellelongationafterexposuretolight.WeaimtosystematicallycharacterizetheregulatoryroleofspecificaccumulationsofGAinthedynamiccellulargrowthratesofphotomorphogenichypocotylsusingiterativemorphodynamicmodelingandhigh-resolutioninterventionsintoGAspatiotemporalpatterns.Keywords:Hormones,cellwall,cellbiology,cellulargrowth,photomorphogenesisAbstract#117.PLK1,areceptor-likekinase,isrequiredforrootpatterningand,indifferentcelltypes,localizestodistinctplasmamembranedomains(Submission238)JaimieVanNorman1,RoyaCampos,JasonGoff1UniversityofCalifornia,Riverside,UnitedStatesDuringplantdevelopment,intercellularcommunicationservesacriticalroleincoordinationofasymmetriccelldivisionsanddifferentialcellfatespecification.Intheplantroot,theconsequencesoftheseprocessesonorganmorphologyareelegantlydisplayed.Frequently,directionalsignalingisproposedtohaveakeyroleinasymmetriccelldivisionsandintissuepolarity;yet,proteinswithpolarlocalization,beyondthoseinvolvedinauxinornutrienttransport,arelargelymissinginaction.Furthermore,althoughroughlyhalfoftheasymmetriccelldivisionsinrootpatterningareorientedparalleltothegrowthaxis,proteinslocalizedtothelateralplasmamembranedomainsareexceedinglyrare.Wehaveidentifiedatransmembranereceptor-likekinase,POLARLYLOCALIZEDKINASE1(PLK1),thatisrequiredfornormalrootpatterning.plk1mutantshaverootpatterningdefectsthatappeartoarisefromdisorderedasymmetriccelldivisionsinthegroundtissue.PLK1:GFPfusionsarepolarlylocalizedinlateralplasmamembranedomainsinembryonicandroottissues.Unexpectedly,PLK1lateralpolarityappearstovarywithcelltypeandismaintainedunderavarietyofconditionsthatdisruptpolarlocalizationofothertransmembraneproteins.However,examinationofPLK1localizationinrootdevelopmentmutantssuggestsitspolarlocalizationdependsnotoncellidentity,butoncell-cellcommunication.WeproposethatPLK1perceivesdirectionalcuesthatinformthespatiotemporalregulationofkeyasymmetriccelldivisionsinrootpatterning.Keywords:rootpatterning;asymmetriccelldivisions;intercellularsignaling;cellpolarityAbstract#118.Sortingoftail-anchoredproteinstodifferentmembranesinchloroplasts(Submission292)DonnaFernandez1,Anderson,StacyA.,UW-Madison1UniversityofWisconsin-Madison,UnitedStatesMostbacteria,includingcyanobacteria,containoneSectranslocasethatmovessecretoryproteinsacrossmembranesorintegratesmembraneproteins.Incontrast,plantchloroplastscontaintwoSECtranslocases,whichlocalizetodifferentmembranes.ThechloroplastSECtranslocaseshavetwomembranecomponents:SCY,withtentransmembranedomains;andSECE,withonetransmembranedomainandashortC-terminaltail.TheSECEcomponentsbelongtotheclassofmembraneproteinsknownastail-anchoredproteins.WehavetransientlyexpressedandimagedGFP-SECEfusionproteinsinleafprotoplaststoinvestigatethetargetingprocess.Despitetheirsmallsize,wefindthatSECEproteinstargetexclusivelyeithertotheinnerenvelope(SECE2)orthylakoids(SECE1).WehaveuseddomainswappingtocreateSECE1-SEC2chimericmoleculesanddeterminedthattargetingdeterminantsarelargelyassociatedwiththetransmembranedomainandtail.Inoursearchforstroma-basedfactorsthatmaybeinvolved,weidentifiedthechloroplast-localizedhomologofGet3(GuidedEntryofTail-anchoredproteins3),theeukaryoticcytosolicchaperonethathandlestail-anchoredproteins,asatopcandidate.WearetestingthehypothesisthatGET3BcontributestotargetingofSECE1and/orSECE2throughacombinationofco-immunoprecipitationexperimentsandgeneticanalyses.Resultsfromtheseon-goingexperimentswillbepresented.SupportedbyNSFMCB-1158173(DF)andDGE-1256259(SA).Keywords:proteintargeting;chloroplastsAbstract#119.SynergisticregulationofshootapicalmeristembyERfandCLAVATAsignalingpathways(Submission309)LiangZhang1,Shpak,Elena,DepartmentofBiochemistry,CellularandMolecularBiology,UniversityofTennessee,Knoxville,TN1UniversityofTennessee,UnitedStatesTheshootapicalmeristem(SAM)isadynamicstructurethatenablestheformationofneworgansthroughoutthelifeofaplant.The

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abilityoftheSAMtomaintainitssizedependsonanegativefeedbackloopbetweentheCLAVATA1/CLAVATA3(CLV1/CLV3)signalingpathwayandthetranscriptionalfactorWUSCHEL(WUS).AnothersignalingpathwayregulatingSAMfunctioninvolvestheERECTAfamilygenes(ERfs).InArabidopsis,thisfamilyconsistsofERECTA(ER),ERECTA-LIKE1(ERL1),andERL2.ERfsareplasmamembranelocalizedreceptorsactivatedbysmallcysteine-richproteinstranscribedfromtheepidermalpatterningfactor/EPF-likegenefamily.WehavepreviouslydemonstratedthattheERfsignalingpathwayrestrictsmeristemsize,promotesleafinitiationandregulatesphyllotaxy.HereweinvestigategeneticinteractionsbetweenERfs,CLV3,andWUS.Remarkably,thesimultaneousknockoutofERfsandCLV3leadstoatremendouslyenlargedSAMandcompletelyabolishesleafinitiationandstemelongationemphasizingthesynergisticroleofthesetwosignalingpathwaysincontrollingproliferationanddifferentiationofmeristematiccells.Analysisofererl1erl2wusandererl1erl2clv3wusmutantsindicatesthatWUSisepistatictoERfsinrespecttomeristemsize.IndirectevidencesuggeststhatERfsmightregulateWUSpost-transcriptionally.Keywords:shootapicalmeristemAbstract#120.EvidenceofaSERK1-SOBIR1mediatedsignalingpathwayregulatingfloralabscissioninArabidopsis(Submission310)IsaiahTaylor1,Baer,John,WashingtonUniversity,Walker,JohnC.,UniversityofMissouri1UniversityofMissouri,UnitedStatesAbscissionisthesheddingofplantorgans.FloralabscissioninArabidopsisisregulatedbytworelatedreceptorlikeproteinkinases(RLKs)HAESAandHAESA-like2(HAE/HSL2).DoublemutantsofHAE/HSL2arecompletelydefectiveinabscissionandretainsepals,petals,andstamenindefinitely.Toidentifyothergenesthatregulateabscission,suppressorscreensofanabscissiondeficienthaehsl2mutantwereperformed.Fromthesescreens,5lineswereisolatedwithsemi-dominantpointmutationsintheSERK1RLK,eachexhibitingrestoredabscission.SERK1encodesamemberoftheSERKfamilyofreceptor-proteinkinases,andhasrecentlybeenshowntoregulateabscissionbyactingasaHAE/HSL2coreceptor.GeneticandtransgeneticanalysesindicatesthesignalingpathwayactivatedbytheSERK1suppressormutationsreliesonthepresenceandkinaseactivityoftheSOBIR1RLK,butnotonthekinaseactivityoftheSERK1proteinitself.TranscriptionalprofilingofastrongSERK1suppressormutantdemonstratesitexhibitshighlevelsofabscissionsignalingandstrongdefenseresponsesinthefloralreceptacle.Interestingly,thistranscriptionalprofilemimicstheprofileobservedinthefloralreceptacleofamutantintheNEVERSHED(NEV)gene.NEVencodesanARF-GAPwhichlocalizestothetrans-Golginetworkandearlyendosome.MutationsinNEVblockabscissionbyanunknownmechanism.Resultsofanevsuppressorscreenhaveshownthatloss-of-functionmutationsineitherSERK1orSOBIR1suppresstheabscissiondefectofnev.Thus,thereisevidencethatthenevmutantfailstoabsciseasaresultofdysregulatedsignaling,likelyleadingtogeneralcellulardysfunction.ThisdysregulatedsignalingpathwayappearstobethesameoneactivatedintheSERK1mutantsisolatedinourhaehsl2suppressorscreens.Theseresultssuggestabscissionrequiresbalancedfeedbackregulation,disruptionofwhichcanleadtoabscissiondefectsinmultipleways.Keywords:abscission;signaling;pathogenresponsesAbstract#121.IdentificationofAuxinCo-ReceptorsthatRegulateTransverseMicrotubulePatterninginEpidermalHypocotylCells(Submission319)JillianTrue1,SidneyShaw1IndianaUniversity,UnitedStatesAuxinleadstobothaxialcellgrowthandtransversemicrotubule(MT)patterninginepidermalhypocotylcells.ExogenousauxintreatmentpromotesanearlyimmediatelossofgrowingmicrotubuleplusendsfollowedbyMTco-alignmentthatistransversetothecell’sgrowthaxis.WehypothesizetheseMTresponsesarecontrolledandcoordinatedwithaxialcellgrowththroughtheauxintranscriptionalpathwaybeginningwiththeTIR1/Aux/IAAauxinreceptors.WeusedauxinreceptormutantstoaskifauxinactsthroughthistranscriptionalpathwaytocauselatertransverseMTco-alignment.OurdatashowsthatthelaterformationofthetransversepatternclearlyworksthroughtheTIR1pathway;however,weobservedthattheearlylossofgrowingMTsappearstobetriggeredindependentlyofnewgeneexpression,pointingtoanunknownnon-transcriptionalauxinreceptor.ToidentifywhichcomponentsoftheauxintranscriptionalpathwayspecificallyregulatetransverseMTpatterning,wenextstudiedauxinco-receptors(Aux/IAAs)tofindifoneormorerepresstranscriptionfactors(ARFs)thatregulategenesneededfortransverseMTpatterning.WefoundthatAXR2isanimportantregulatorofauxin-inducedtransverseMTpatterning.Finally,sinceweobservedthatbrassinosteroid(BR)inducestransverseMTpatterningtothesameextentasauxin,weaskedifthiseffectdependedonauxintranscriptionalpathway.Intheaxr2-1gain-of-functionmutant,BRinducedtransverseMTpatterning,suggestingBRactsindependentlyfromauxin.TheseresultsprovidenewinformationabouthowauxinregulatesMTpatterningandcanbeusedtonarrowthesearchforputativedownstreamtargetsofauxinneededfortransverseMTpatterning.Keywords:microtubulepatterning;auxin;brassinosteroid;hypocotylcells;cellgrowth

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Abstract#122.TheDiscreteReproductiveExpressionDomainsoftheArabidopsisMLOFamily(Submission325)ThomasDavis1,DanielJones,JingYuan,AndrewWilloughby,PatrickDay,NicCejda,SharonKessler1PurdueUniversity,UnitedStatesThemildewresistancelocus-o(MLO)proteinfamily,comprisedof15members,playsrolesindiversecellcommunicationprocessessuchaspowderymildewresistance,rootthigmomorphogenesis,andpollentubereception.TheNORTIA(NTA,AtMLO7)geneisexpressedinthesynergidcellsofthefemalegametophyteandfunctionsinintercellularcommunicationwiththepollentube.Discrepanciesbetweenpreviouslypublishedpromoter::GUSandpromoter::gene-GUSconstructsexpressionpatternsledustoexploretheregulationofNTAexpression.HerewefoundviapNTA::gNTA-GUStruncationsthatsequenceswithintheNTAgenenegativelyregulateitsexpressioninthestomataandcarpelwalls.ThisledtothehypothesisthatotherMLOfamilymembersmayalsohaveadditionalregulatorysequenceswithinthegene.pMLO::MLO-GUSconstructswereexaminedforeachfamilymemberfocusingspecificallyonflowersinordertodetermineifotherMLOscouldplayaroleinreproductivecellcommunication.Notably,severalMLOswereexpressedinthepollen,inthestigma,inthepollinatedstyle,andinthesynergidsandcentralcell.ThesefindingsindicatethatotherMLOsinadditiontoNTAcouldplayaroleinreproduction.PreviousstudiesontheMLOfamilyshowedthatphylogenicallyrelatedMLOshadredundantfunctionsinpowderymildewinfectionandrootthigmotropism.MLOexpressioninreproductivetissuesdidnotstrictlyfollowphylogeneticrelationships,indicatingthatMLOsfromdifferentevolutionaryoriginsmayhavebeenrecruitedforuseinsexualreproduction.Keywords:MLO;PlantSexualReproduction;CellcommunicationAbstract#123.InvestigatingthemechanisticroleofTHRUMIN1inbluelight-inducedchloroplastmovement(Submission327)MatthewDwyer1,Shaw,Sidney,IndianaUniversity,Hangarter,Roger,IndianaUniversity1IndianaUniversity,Bloomington,UnitedStatesRepositioningchloroplastswithinleafcellsinresponsetochangesinlightintensityisoneprocessplantsusetooptimizephotosyntheticpotential.Specifically,underlowlightconditions,chloroplastsaccumulatealongthepericlinalcellsurfacestoabsorbthemaximumamountoflight,whereashighlightconditionsinducetheavoidanceresponseinwhichthechloroplastsarerepositionedalongtheanticlinalcellsurfacesallowingmorelighttoreachothercelllayers.Mutantscreenshaveidentifiedoveradozengenesrequiredfornormalchloroplastmovements.OneofthosegenesencodesTHRUMIN1,whichlocalizesattheplasmamembraneofmesophyllcellsandbundlesactinfilamentsinresponsetobluelight.Usingconfocalmicroscopy,THRUMIN:YFPwasfoundtolocalizetoactinbundleswithinaminuteofexposuretobluelight.Withinaminuteofremovalofthebluelightstimulus,THRUMIN:YFPdisassociatesfromtheactinbundles.Bluelight-dependentphosphorylationofTHRUMIN1hasbeenhypothesizedtobenecessaryforchloroplastmovements.Additionally,sequenceanalysisrevealedaputativeWASP-Homology2(WH2)domainwithintheintrinsicallydisorderedregionofTHRUMIN1.TheWH2domainishypothesizedtobecriticalfortheactin-bindingactivityofTHRUMIN1inresponsetobluelight.TotesttheimportanceofthephosphorylationstateofTHRUMIN1andtheWH2domainforlight-dependentassociationwithactinbundles,fluorescenttaggedTHRUMIN1constructsweremutatedtohaveinactiveandconstitutivelyactivephosphorylationsitesandalteredaminoacidswithinthecoreoftheWH2domain.Thesemutantformsarebeingtestedbytime-lapseconfocalmicroscopyintransgenicthrumin1mutantplantstodetermineifanyofthepreviouslyidentifiedphosphorylationsitesandthepreviouslyuncharacterizedWH2domainarenecessaryforactinbundlingand/orchloroplastmovementsbyTHRUMIN1.Keywords:chloroplasts;actin;photoreceptors;confocalmicroscopyAbstract#124.TheRolesofNF-YandbZipTranscriptionFactorsinFloralDevelopment(Submission329)AndrewWilloughby1,BenFHoltIII1UniversityofOklahoma,UnitedStatesThevastmajorityofnon-animalfoodsweeatcomefromflowers.Flowersarenotjustthesitesofplantsexualreproduction;theyaredesignedtoattractpollinatorsorotherwisefacilitatepollendispersalandtoprotectthedevelopingreproductiveorgans.Inthesewaysandothers,themorphologyofflowersisvitaltotheirfunctions.ThisprojectdescribesanovelroleforNUCLEARFACTORY(NF-Y)infloraldevelopment.IconductedanexperimentwithplantsthatlackedthreeNF-Ygenes(NF-YC3,NF-YC4,andNF-YC9)aswellasabZipgene(HY5)andshowedthatthesemutationsinteractsynergisticallytocausedisruptioninArabidopsisflowerdevelopment.Arabidopsiswildtypeflowershave4sepals,4petals,and6stamens.Onaverage,nf-yctriplemutantsshowmoresepals,morepetals,andmorestamensthanwildtype.Onaverage,hy5mutantsshowslightlymoresepalsandpetalsthanwildtype,andsignificantlylessstamens;nf-yctriplehy5mutantshavemoresepalsandpetalsthanwildtypeoritsparentalgenotype,andwildtypenumbersofanthersonaverage.ThisprojectisanattempttoelucidatetherolesoftheNF-YandHY5infloraldevelopment.Keywords:NuclearFactorY;floraldevelopment;meristem;flower;lightsignaling

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Abstract#125.ANTI-SILENCINGFUNCTION1ProteinsarerequiredformitosisingametogenesisinArabidopsis.(Submission332)YunsookMin1,Yoo,Hyunjin,SeoulNationalUniversity1SeoulNationaluniversity,Korea,RepublicofANTI-SILENCINGFUNCTION1ProteinsarerequiredformitosisingametogenesisinArabidopsis.YunSookMin*(SeoulNationalUniversity,Korea),YooHyunJin*(SeoulNationalUniversity,Korea)andYeonheeChoi(SeoulNationalUniversity,Korea)min84@snu.ac.kr*TheseAuthorscontributedequallytothiswork.Inangiosperms,thediploidfemaleandmalesporophytesproducehaploidmegasporesandmicrospores,respectively.Thesegiverisetogametophytesaftermeiosisandasubsequentseveralroundsofmitosisthatarenotseeninanimalsorfungi.Themechanismsregulatinggametophytedevelopmentinplantsareincompletelyunderstood.Here,wereportthatAtASF1proteinsplayanimportantroleinArabidopsisgametogenesis.Inyeastandanimals,ASF1proteinsplayimportantrolesinchromatin-relatedprocesses,suchastranscriptionandDNAreplicationandrepair.Theyparticipatebothinthereplication-dependentandthereplication-independentchromatinassemblypathways,asASF1copurifieswiththereplication-specifichistoneH3.1andwiththetranscription-specifichistoneH3.3andHIRA,respectively.InArabidopsis,therearetwogenesencodingASF1homologs,AtASF1AandAtASF1B(At1g66740andAt5g38110,respectively).BothproteinsbindhistoneH3andarelocalizedinthecytoplasmandthenucleus.MutantsineitherAtASF1AorAtASF1Bshownoobviousdefects.However,theasf1a/asf1bdoublemutantsdisplayedanovuleabortionphenotypewithsiliquessignificantlyshorterthanthoseofthewildtype.UsingT-DNAinsertionmutants,weidentifyAtASF1playsacrucialroleinmitosisduringbothfemaleandmalegametophyteformationinArabidopsisthaliana.AtASF1AandAtASF1Bdoubleabsenceresultsinimpairedgametogenesis,failureofovuleandpollendevelopment.ThereisnoinformationonthephysiologicalroleofASF1duringthegametogenesisinhigherplants.asf1aasf1b/ASF1Bplantsshows50%ovuleabortionbutASF1A/asf1aasf1bplantsshowsweakphenotype.ThisphenotypeindicatesthatASF1bgeneisrelatedtoovuledevelopmentandthemutationofovuledevelopmentinASF1bcanberescuedbyASF1A.Reciprocalcrossestowild-typeplantswithasf1aasf1b/ASF1BorASF1A/asf1aasf1bplantsrevealedthattheovuleabortionphenotypeofasf1aasf1bdoublemutantsweremainlyduetogametophyticdefects.ThesefindingsindicatethatAtASF1AandAtASF1Bhaveredundancyinbothmaleandfemalegametogenesis.Keywords:gametogenesis,mitosis,plantreproductionAbstract#126.Molecularregulationofthecambium:fromArabidopsisresearchtotreeresearch(Submission334)MelisKucukoglu1,Sevilem,Iris,InstituteofBiotechnology/DepartmentofBiosciences,UniversityofHelsinki,00014Helsinki,Finland.,Wang,Xin,InstituteofBiotechnology/DepartmentofBiosciences,UniversityofHelsinki,00014Helsinki,Finland.,Ye,Lingling,InstituteofBiotechnology/DepartmentofBiosciences,UniversityofHelsinki,00014Helsinki,Finland.,Chaabouni,Salma,UmeåPlantScienceCentre,SwedishUniversityofAgriculturalSciences,DepartmentofForestGeneticsandPlantPhysiology,90183Umeå,Sweden.,Nieminen,Kaisa,GreenTechnology,NaturalResourcesInstituteFinland(Luke),01301Vantaa,Finland,Nilsson,Ove,UmeåPlantScienceCentre,SwedishUniversityofAgriculturalSciences,DepartmentofForestGeneticsandPlantPhysiology,90183Umeå,Sweden.,Mähönen,AriPekka,InstituteofBiotechnology/DepartmentofBiosciences,UniversityofHelsinki,00014Helsinki,Finland.,Helariutta,Ykä,InstituteofBiotechnology/DepartmentofBiosciences,UniversityofHelsinki,00014Helsinki,Finland,SainsburyLaboratory,UniversityofCambridge,CambridgeCB21LR,UnitedKingdom1UniversityofHelsinki,InstituteofBiotechnology,FinlandMolecularregulationofthecambium:fromArabidopsisresearchtotreeresearchMelisKucukoglu1,2,IrisSevilem1,2,XinWang1,2,LinglingYe1,2,SalmaChaabouni3,KaisaNieminen4,OveNilsson3,AriPekkaMähönen1,2andYkäHelariutta1,2,5InstituteofBiotechnology,UniversityofHelsinki,00014Helsinki,FinlandDepartmentofBiosciences,UniversityofHelsinki,00014Helsinki,FinlandUmeåPlantScienceCentre,SwedishUniversityofAgriculturalSciences,DepartmentofForestGeneticsandPlantPhysiology,90183Umeå,Sweden.GreenTechnology,NaturalResourcesInstituteFinland(Luke),01301Vantaa,FinlandSainsburyLaboratory,UniversityofCambridge,CambridgeCB21LR,UnitedKingdomRadialexpansionorsecondarygrowthofthestemsandrootsinplantsderivesfromtheactivityofthevascularcambium–ameristematictissue,whichcontainsthevascularstemcellsandgeneratexylem(wood)ontheinsideandphloemontheoutside.Maintenance,proliferationanddifferentiationofthislateralmeristemistightlyregulatedtoachieveanorganizeddevelopmentofsecondarytissues.StudiesusingmodelplantArabidopsisthalianasuggestedthatregulationofcelldivisionsinthecambiumismediatedbyWOX4andWOX14,downstreamtargetsofTDIF/CLE41-PXY/TDRpeptidesignalingpathway.RecentlyweshowedthatWOX4-likegenesregulatecambialcelldivisionactivityandsecondarygrowthalsoinPopulustrees.Furthermore,ourdataindicatedthatCLE41-likegenespositivelyregulateWOX4-likegenesinthetreestem.InterestinglyotherWOXgenesarealsodifferentiallyexpressedinthewoodformingzoneofPopulus.WearecurrentlyanalyzingthetransgenicRNAitreestargetingthesegenestogetabetterunderstandingoftheirfunctions.Moreover,throughtranscriptprofilingapproach,weidentifiedacollectionofPopulusCLEgenesthatarespecificallyexpressedoverthecambialzoneand/orthesecondaryxylem.RNAi-mediateddownregulationorectopicoverexpressionofthesecandidateCLEgenesintreesaffectedadiversityofcharacteristicssuchasplantheight,leafsize/shape,andstemwidth.Finally,weidentifiedanumberofcandidatetranscriptionfactorsthatpromotecambiumactivityandsecondarygrowthinArabidopsisthalianaroots.Byapplyingthisknowledgetoourtreeresearchwearetestingiftheseidentifiedcambiumregulatorscanstimulatetreetrunkgrowthandligno-cellulosicbiomassproductionintrees.Keywords:vascularcambium;secondarygrowth;Populus;WOX;CLE

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Abstract#127.InvivoanalysisofthereceptorkinaseERECTArevealsaspecificroleforitsdomain(Submission346)MichalMaes1,JulianAvilla,DepartmentofBiology,UniversityofWashington,Seattle,Washington98195,USA.,PaulDerbyshire,TheSainsburyLaboratory,Norwich,UK,JanSklenar,TheSainsburyLaboratory,Norwich,UK,FrankMenke,TheSainsburyLaboratory,Norwich,UK,KeikoU.Torii,DepartmentofBiology,UniversityofWashington,Seattle,Washington98195,USAandHowardHughesMedicalInstitute,UniversityofWashington,Seattle,Washington98195,USA1DepartementofBiology,UnitedStatesInplants,leucine-richreceptor-likekinases(LRR-RLK)areinvolvedinavarietyofsignalingpathways.ERECTAisaLRR-RLKinvolvedinmultipledevelopmentalandcellularprocesses,amongothersstomataldevelopment,elongationofabovegroundorgans,leafinitiationandinflorescence.Inaddition,thisreceptorkinaseisalsoinvolvedinresponsestobioticandabioticstress,mostlikelybyformingcomplexeswithotherLRR-RLKs.ERECTAanditshomologues,ERL1andERL2,perceivesmallcysteine-richpeptides,termedEPF/EPFLs,andtransducethesignalacrosstheplasmamembrane.SeveralEPF/EPFLpeptideshavebeenidentifiedasagonistsorantagonistsofERECTA,andlinkedtospecificphenotypiccharacteristicssuchasstomataldifferentiation,growth,leafserrationandothers.Themolecularmechanismbywhichthereceptoractivatesitsdownstreamsignalingisnotyetfullyunderstood.TounravelthebiochemicalmechanismoftheERECTAfunction,weperformedaninvivophosphorylationanalysisofERECTAundernon-stimulatedconditionsusingmass-spectrometry.WediscoveredaspecificdomaininERECTAthatisheavilyphosphorylated.Interestingly,whentheinvivophosphorylationanalysiswasperformedusingArabidopsiserecta-nullmutantseedlingsexpressingthekinase-deadversionofERECTA,nophosphorylationsweredetectedatthisdomain,suggestingthatthekinaseactivityofERECTAisrequiredforthephosphorylationofthisdomain.RemovalofthedomainconferredhyperactivityofERECTA.ComparedwithpreviousknowledgeofotherLRR-receptorkinaseactivationourfindingsemphasizedconservedanduniquefeaturesastothemolecularmechanismofERECTAactionandregulation.Keywords:LRR-RLKs;StomataldevelopmentAbstract#128.RoleoftheSCRMC-TerminalDomainintheStomataDifferentiationPathway(Submission347)AARTHIPUTARJUNAN1,LYNDSEYAGUIRRE,KEIKOTORII1UNIVERSITYOFWASHINGTON,UnitedStatesInplants,gasexchangeandtranspirationtakeplacethroughsmallporesontheleafsurfacecalledstomata.Stomatadifferentiatethroughaseriesofcell-statetransitioneventsmediatedbybHLHTFscalledSPEECHLESS(SPCH),MUTE,andFAMA.TwootherpartiallyredundantbHLHTFs,SCREAM(SCRM)andSCRM2,workinconcertwithSPCH,MUTEandFAMA,therebypromotingstomatalcell-fate.AsidefromthebHLHdomain,SCRMcontainsthehighly-conserved"KRAAM"motif,whichinfluencesthestabilityoftheprotein.AnR-to-Hmutationwithinthismotifresultsinthedominant,gain-of-functionmutant,scrm-D,conferringan"all-stomata"phenotype.TounderstandtheroleofthespecificdomainsspecifyingSCRMfunction,weperformedasuppressormutagenesisscreenonscrm-D.Wehavefoundthatthescrm-DphenotypecanlargelybesuppressedthroughintragenicsecondarymutationswithintheC-terminaldomain(CTD)ofthescrm-Dprotein.WehypothesizethattheCTDofSCRMisimportantforthestabilityoftheproteinasawholeandbyextensionforinteractionsbetweenSCRMandotherstomatalbHLHTFs.OurpreliminaryanalysessuggestthattheCTDofSCRMisnecessaryforinteractionsattheMUTEstep.OurfindingsrevealtheuniqueinteractionpropertiesamongthethreerelatedbHLHTFsthatsequentiallygovernthecell-fate,thereforeprovidingabroaderperspectiveonhowsimilarbHLHTFsperformspecificfunctionswhilesharingthesamepartnerbHLHprotein.Keywords:stomatadevelopment,cell-statetransition,bHLHtranscriptionfactorAbstract#129.PhloemsieveelementregulatespericlinalcelldivisionsinArabidopsisrootvasculatureviamobiletranscriptionfactors(Submission355)IrisSevilem1,Miyashima,Shunsuke,NaraInstituteofScienceandTechnology,Roszak,Pawel,UniversityofCambridge,Toyokura,Koichi,UniversityofCambridge,Helariutta,Ykä,UniversityofCambridge1UniversityofHelsinki,FinlandPlantgrowthanddevelopmentarecruciallydependentonpositionalinformationfromneighboringcells,mediatedbymobileregulatorymolecules,suchashormonesandtranscriptionfactors.InArabidopsis,theinteractionoftwoplanthormones,auxinandcytokininareessentialfortheradialorganizationoftherootvasculatureconsistingofcentralxylemaxis,twoperipheralphloempoles,andinterveningprocambialcells.Periclinalcelldivisionsincreasethenumberofcellfilesinprocambium/phloem,whereaspericlinaldivisionseldomoccursinxylemcells.Ithasbeenproposedthatxylemcontrolsnon-cell-autonomouslypericlinaldivisionsoccurringinthephloem/procambiumbyactivatingcytokininproduction.However,whetherphloemhasaregulatoryroleaswellhasremainedunclear.Plasmodesmata(PD)areplantspecificnanochannelsthattraversethecellwallsofneighboringcellsandenablethemovementofmoleculesdirectlyfromcelltocell.InArabidopsis,PDaperturescanberegulatedinaspatiallyandtemporallyspecificmannerwithamutatedCALLOSESYNTHETASE3(cals3m)thatenhancescallosedepositionatPDresultingininhibitionofsymplastictransport.Toinvestigatetherequirementofsymplasticconnectionduringvasculardevelopment,weinhibitedsymplasticconnectionsbyicals3m,andobservedareductionofcellfilesinphloem/procambiumafterexpressingicals3mintheearlyprotophloemsieveelement(SE).Subsequently,weidentifiedafamilyoftranscriptionfactorsthatmovefromtheSEtothesurroundingcells,andwhichpromotepericlinalcelldivisionsinphloem/procambium.Thus,ourresultsindicatethatnotonlyxylembutalsotheSEhasanessentialroleasanorganizing

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centerduringvasculardevelopment.Keywords:vasculardevelopment;periclinalcelldivisions;cell-to-cellcommunicationAbstract#130.Auxinresponsefactorsregulateflowerprimordiainitiationbyrepressingthepluripotencyprogram(Submission359)YuheeChung1,Miin-FengWu,SaraSimonini,DorisWagner1UniversityofPennsylvania,UnitedStatesFlowerprimordiainitiationismediatedbyalterationofgeneexpressionprogramsatthesitesofauxinmaximaattheflanksoftheshootapicalmeristem.AUXINRESPONSEFACTOR5(ARF5)/MONOPTEROS(MP)isamasterregulatorforflowerprimordiainitiationandupregulatesdiversetargetgenesinresponsetotheauxinhormone.Thepopulationofstemcellsisrestrictedtothecentralregionoftheshootapexbypluripotencygenes,mostofwhicharespecificallyexcludedfromtheperipheralzone,whichcontainstransitamplifyingcellsthatarecompetenttorespondtotheauxincuebyadoptingprimordiumfounderfate.OneprominentexceptionistheclassIKNOXgenes.Thesegenesareexpressionintheperipheryoftheshootapex,butdownregulatedintheprimordiumfoundercells.Howtheyarerepressedinthesecellsispoorlyunderstood.WeperformedgeneticenhancerteststoidentifyadditionalAuxinResponseFactors(ARFs)requiredforflowerprimordiuminitiationandidentifiedtwoauxinresponsefactors,ETTIN(ETT/ARF3)andAUXINRESPONSEFACTOR4(ARF4),repressorARFswithoverlappingfunctions,contributetoorganogenesisfromtheshootapex.ClassIKNOXgeneslikeSHOOTMERISTEMLESS(STM)aremisexpressedattheshootapexofmpettarf4loss-of-functionmutants.HerewediscusshowETTandARF4contributetorepressionofpluripotencyprogramforflowerprimordiainitiationinparallelpathwaytoMONOPTEROS,likelybyrecruitingotherrepressivefactorstotheregulatorylociofpluripotencygenestoturnofftheirtranscription.

Keywords:flowerprimordiainitiation,pluripotencyprogram,auxinAbstract#131.UnderstandingtheFunctionofMSL7andMSL8,TwoMechanosensitiveIonChannelsExpressedintheArabidopsisthalianaPollenTube(Submission370)YanbingWang1,EricHamilton,GregoryJensen,ElizabethHaswell*1WashingtonUniversityinSt.Louis,UnitedStatesIt’scriticaltounderstandthemolecularmechanismsforhowplantssenseandperceivemechanicalforce,includingosmoticpressure.WerecentlyfoundthatMSL8functionsasamechanosensitivechannelrequiredtoprotectArabidopsisthalianapollenfromosmoticchallengesduringinvitropollenrehydration,germinationandtubegrowth(Hamilton,2015).However,anullmutantmsl8allelehadonlyamodesteffectonpollenfertility(a40%transmissionratiocomparedto50%forthewildtypeMSL8gene).Futhermore,survivingpollentubesfromthenullmsl8-4mutantshowedthesametubemorphology,tubegrowthrate,growthoscillation,andchloridedistributioninthetipcomparedwithwildtype.MSL8hasaveryclosehomolog,MSL7,whichisexpressedinthesemi-invivopollentubeandislikelytoplayasimilarrole.TotestforredundantfunctionsbetweenMSL7andMSL8,wearegeneratingdoublemsl7msl8mutantsusinganumberofapproaches.MSL7andMSL8genesarelocatedintandemonthegenomeresultinginthedifficultyingeneratingdoublemutantsbyconventionalcrossing.WethereforeusedartificialmicroRNA(amiRNA)andCRISPR/Cas9technologiestocreatedoublemutants.Preliminarydataindicatethat,inanmsl7-1T-DNAinsertionlineexpressingamiRNAstargetedagainstMSL8,pollentubegrowthrateisslightlybutsignificantlyfasterthanthatinwildtype.MultipleCRISPR/Cas9-inducedmutationsinMSL8inanmsl7-1T-DNAinsertionbackgroundhavealsobeenproduced.FurtherinvestigationsontheroleofMSL7andMSL8inpollentubemorphology,growthrate,andionfluxdynamicsarecurrentlyinprogressandwillbereported.Keywords:MSL8,MSL7;pollentube;MechanosensitiveIonChannels;functionalredundantAbstract#132.IdentificationofchloroplastinteractionpartnersofMatrixAttachmentRegionBindingProtein1(MFP1)inArabidopsisthaliana(Submission375)SandiptyKayastha1,AlisonDeShields,RebeccaRzasa,AnnkatrinRose1AppalachianStateUniversity,UnitedStatesCoiled-coilproteinsareubiquitousproteinsfoundinmostorganisms,representingapproximately10%ofallproteinsineukaryotes.Theirstructureconsistsoftwoormorealphaheliceswrappedaroundeachothertoformasupercoilcomplexstructure.Plantspecificlongcoiled-coilproteinsarepredictedtobeinvolvedinspecificprocessessuchasphotosynthesis,cytokinesisorplantdefensemechanismsviaprotein-proteininteractions.Amongthe286longcoiled-coilproteinfoundinArabidopsis,oneisMatrixAttachmentRegionBindingFilamentlikeProtein1(MFP1).Thoughinitiallybelievedtobeassociatedwiththenuclearmatrix,itwaslaterfoundtolocalizetothechloroplastandembeditselfinthethylakoidmembrane.OurworkidentifiestheroleofMFP1proteininsidethechloroplast.AtransgenicplantlinewasconstructedbyinsertinganMFP1-TAP(TandemAffinityPurification)constructinamutant(MFP1knockout)Arabidopsisthaliana.ThesuccessofthetransformationwasconfirmedviaPCRandthetransformationefficiencywithandwithoutacetosyringonewas41.4%and1.6%respectively.SecondgenerationtransformedplantswillbegenotypedandusedforisolationofMFP1proteincomplexandidentificationofproteininteractionpartners.ForthesechloroplastswillbeisolatedfromthetransgenicplantsbygradientcentrifugationandMFP1proteincomplexpresentinsidethechloroplastwillbeisolatedandpurifiedusingTandemAffinityPurification.Proteininteractionpartnerswillbeidentifiedusingmassspectrometryandbioinformaticstools.Theresultsofthisstudywillallowusto

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elucidateMFP1functionwiththehelpofproteinpartnersinamodelplant,Arabidopsisthaliana.Keywords:MatrixAttachmentRegionBindingFilamentlikeProtein1(MFP1);TandemAffinityPurification(TAP);Chloroplast;Thylakoid;coiledcoil.Abstract#133.TelomeraseandCajalbodyRNPassemblyinArabidopsis(Submission389)MarioIzaguirreSierra1,Villalba,Alondra,NNMC,Romero,Andres,NNMC,Drysdale,Samantha,NNMC,Shippen,Dorothy,TexasA&M1NorthernNewMexicoCollege,UnitedStatesThecellnucleusiscomposedofanumberofdistinctnon-membranoussubcompartments(nuclearbodies),whichareformedbyauniquesetofproteinsthatcarryoutspecificfunctions.Cajalbodies(CBs)areevolutionaryconserved,dynamicnuclearstructurescentralinthemetabolismandassemblyofdifferenttypesofribonucleoproteins(RNPs)suchasthoseinvolvedintelomerehomeostasis,mRNAprocessingandgenesilencing.TodateCajalbody-likestructureshavebeenidentifiedinvertebrates,yeasts,insectsandplants.Sinceplantsexhibitresponsestotheirenvironmentintheformofchangesinnuclearorganizationandbehavior,plantsprovideuswiththemeanstoidentifyfactorsthatregulateandmaintainnuclearstructureduringnormaldevelopmentandinresponsetoenvironmentalstress.Thus,wewilltakeadvantageofthepowerfulgenetictoolsavailableinthemodelplantArabidopsisthalianatounderstandtherole(s)oftheCBinthebiogenesisofnon-codingRNAs,withaspecificfocusoninteraction(s)betweenCBsandthetelomeraseRNPattheorganismallevel.WeareusingacollectionofCajalbodymutantplantsthatexhibitmultiple,none,smallandlargeCajalbodiestogeneratedoubleandtriplemutantswithcomponentsofthetelomeraseandshelteringcomplex.ThemaingoaloftheprojectistoidentifythefunctionoftheTelomeraseCajalbodyprotein1(TCAB1)anditsrelationshipwithcoilin,anessentialcomponentoftheCBineukaryotes.Specifically,wearecharacterizingtwomutationsontheAtTCAB1locus:tcab1-1andtcab1-2.Additionally,weareexaminingthelocalizationoftelomeresandCBcomponentsinourcollectionofCBmutantsinvivo.Uniquely,ArabidopsiscontainsmultipletelomeraseRNAswithdifferentRNAandproteincomposition.Therefore,wearestudyingthecorrelationbetweenCBsandtelomerehealthusingimmunofluorescenceandinsituhybridizationtechniquesunderstress,andnormalconditions.Keywords:Telomere;rnabiogenesis;Cajalbody;Sumoylation;UlpproteasesEducationandOutreach:Abstract#134.PromotionofUrbanandSuburbanAgricultureThroughBasicResearch,Education,andCommunityOutreachPrograms(Submission342)MichaelSchläppi11MarquetteUniversity,UnitedStatesThelong-terminterestofmylaboratoryistoidentifythegeneticmechanismsforchillingtoleranceinrice(Oryzasativa)andfreezingtoleranceinmodelsystemssuchasArabidopsis(fundedbytheNIFA-AFRIFoundationalProgramoftheUnitedStatesDepartmentofAgriculture).Ourimmediategoalistoselectand/ordevelopfromseveralhundredricegermplasmsvarietiesthatcanbeefficientlycultivatedinacoldclimatesuchastheMidwestoftheU.S.A.Towardthisgoal,weareusingArabidopsisasa“tester”ofputativecoldtolerancegenesidentifiedinricebygenomewideassociationstudies(GWAS).Toeducatethegeneralpublic,wearegivinglecturesaturbanagricultureorganizations,publicmuseums,andlocaluniversities.Toanalyzefieldperformancesofpotentialcoldtolerantricevarieties,wecollaboratewithlocalnon-profitorganizationsthatpromoteminorityfarmers(e.g.ethnicHmong)toestablisharicefarmingbusinessatasuburbanlocationtoprovidelocallygrownfoodtourbanresidents(fundedbyaStrategicInnovationGrantfromMarquetteUniversity.Thus,throughurbanandsuburbanagricultureinitiatives,weeducatethegeneralpublicandprovideundergraduatestudentresearchopportunitiesandpotentialeconomicrevitalizationofunderprivilegedinnercityneighborhoods.Keywords:AbioticStress;ChillingTolerance;CommunityPartners;EconomicRevitalization;RiceCultivationBusinessModelEpigeneticsandChromatin:Abstract#135.POWERDRESSinteractswithHISTONEDEACETYLASE9topromoteaginginArabidopsis(Submission12)XiangsongChen1,LiLu,KevinS.Mayer,MarkScalf,ShuimingQian,AaronLomax,LloydM.Smith,XuehuaZhong1UniversityofWisconsin-Madison,UnitedStatesLeafsenescenceisanessentialpartoftheplantlifecycleduringwhichnutrientsarere-allocatedtoothertissues.Theregulationofleafsenescenceisacomplexprocess.However,theunderlyingmechanismispoorlyunderstood.Here,weuncoveredanovelandpivotalroleofArabidopsisHDA9(aRPD3-likehistonedeacetylase)inpromotingtheonsetofleafsenescence.WefoundthatHDA9actsincomplexwithaSANTdomain-containingproteinPOWERDRESS(PWR)andtranscriptionfactorWRKY53.Ourgenome-wideprofilingofHDA9occupancyrevealsthatHDA9directlybindstothepromotersofkeynegativeregulatorsandthisassociationrequiresPWR.Furthermore,wefoundthatPWRisimportantforHDA9nuclearaccumulation.Thisstudyrevealsanuncharacterizedepigeneticcomplexinvolvedinleafsenescenceandprovidesmechanisticinsightsintohowahistonedeacetylasealongwithachromatin-bindingproteincontributetoarobustregulatorynetworktomodulatetheonsetofplantaging.

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Keywords:Histonedeacetylase;Chromatinbindingprotein;Aging;ArabidopsisAbstract#136.Theplant-specifichistoneresiduePhe41isimportantforgenome-wideH3.1distribution(Submission24)LiLu1,Chen,Xiangsong,UWMadison.,Qian,Shuiming,UWMadison.,Zhong,Xuehua,UWMadison.1universityofwisconsin,UnitedStatesThedynamicincorporationofhistonevariantsinfluenceschromatinstructureandplaysimportantrolesintranscriptionandotherDNA-dependentprocessesineukaryotes.InArabidopsis,thecanonicalvariantH3.1isassociatedwithtranscriptionalsilentregionswhileH3.3isenrichedatactivelytranscribedregions.Despitedistinctdepositionpattern,plantH3.3andH3.1differinonlyfouraminoacids,threeofwhichareconservedinplantsandanimals.ArabidopsisH3.3differsfromH3.1withanadditionalresidueatposition41.However,theevolutionarysignificanceandfunctionofthisplantspecificH3.1Phe41hasyettobeinvestigated.Here,weshowedthatPhe41firstappearedinH3.1infernsandbecamestableduringlandplantevolution.Ourfluorescencemicroscopyandgenomicanalysesrevealedthat,unlikethespecificenrichmentofH3.1withsilentregions,H3.1F41Ylostthispreferenceandgainedectopicaccumulationatactivelytranscribedregionsmarkedwithactivehistonemodifications.Furthermore,ourreciprocaltailandcoredomainswapbetweenH3.1andH3.3showedthattheH3.1core,whilenecessary,isinsufficienttorestrictH3.1inthesilentregions.Collectively,ourdatashowthatPhe41iscriticalforH3.1genomicdistributionandmayactcoordinatelywithH3.1coretoregulatedepositionpatterns.ThisstudyrevealsapreviouslyunexploredroleofplantspecificPhe41inH3.1genome-widedistributionandprovidesanimportantinsightintoitsevolutionarysignificance.ThehighconservationofPhe41inplantsledtoaspeculationthatPhe41mayhaveevolvedtoprovideanotherlayerofhistonedepositionregulationinplants.Keywords:Histonevariants;Plantepigenetics;Genomicdistribution;Histoneevolution.Abstract#137.Cis-andtrans-determinantsofepigeneticsilencingbyPolycombRepressiveComplex2inArabidopsis(Submission30)JunXiao1,Jin,Run,UniversityofPennsylvania,Yu,Xiang,UniversityofPennsylvania,Helliwell,Chris,CSIROAgricultureandFood,Pruneda-Paz,Jose,UCSanDiego,Cui,Sujuan,HebeiNormalUniversity,Goodrich,Justin,UniversityofEdinburgh,Zhang,Xiaoyu,UniversityofGeorgia,Austin,Ryan,Agriculture&Agri-FoodsCanada,Bonasio,Roberto,UniversityofPennsylvania,Wagner,Doris,UniversityofPennsylvania1UniversityofPennsylvania,UnitedStatesDisruptionofgenesilencingbyPolycombComplexesleadstohomeotictransformationsandaltereddevelopmentalphaseidentityinplants.Herewedefineshortgenomicfragments,PolycombResponseElements(PREs),thatdirectPolycombRepressiveComplex2(PRC2)placementatdevelopmentalgenesregulatedbysilencinginArabidopsis.WeidentifytranscriptionfactorfamiliesthatbindtothesePREs,co-localizewithPRC2onchromatin,physicallyinteractwithandrecruitPRC2,andarerequiredforPolycombsilencinginvivo.TwoofthecissequencemotifsenrichedinthePREsarecognatebindingsitesfortheidentifiedtranscriptionfactorsandarenecessaryandsufficientforPREactivity.Thus,PRC2recruitmentinplantsreliesinlargepartonbindingoftrans-actingfactorstocis-localizedDNAsequencemotifs.Keywords:Polycombrepressivecomplex2;PRE;recruitment;cismotifs;transcriptionfactorsAbstract#138.GenomeEliminationinArabidopsis(Submission80)EkHanTan11UniversityofMaine,UnitedStatesInnature,genomeeliminationisaphenomenonthatcanoccurduringsexualreproductioninplantsandanimals.Whengenomeeliminationtakesplace,anembryolosesanentireparentalchromosomeset,resultinginhaploidoffspring.Themechanismbehindgenomeeliminationisunclearinmostcases,onlythatitisdependentona“haploidinducer”parent.Incontrast,thecentromere-mediatedgenomeeliminationsystemdiscoveredinArabidopsisisbasedonthealterationofthecentromere-specifichistoneH3variant,CENH3.AlteredCENH3iscapableofassemblingpropercentromericfunctionbutisepigeneticallylesseffectivethanwild-typeCENH3.Therefore,whenplantscarryingalteredCENH3(thehaploidinducerinthiscase)arecrossedtoplantswithwild-typeCENH3,massivechromosomemissegregationcanoccur,leadingtogenomeelimination.GenomicexaminationoftheoffspringfromCENH3-mediatedgenomeeliminationcrossesrevealthatawide-rangeofploidyvariantsisalsocreatedamonghaploidprogeny.Theseincludeindividualsthatexhibitchromothripsis,aphenomenonfirstdescribedincancerinwhichachromosomehasundergonehighlycomplexgenomicrearrangementsasaresultofasinglecatastrophicevent.UsingtheCENH3-mediatedgenomeeliminationinArabidopsisasamodelforchromosomemissegregation,wecannowdesignexperimentstotesthypothesesontheeffectsofrapidkaryotypicchangeinawholeorganismsettingtounderstandhowgenomesevolveundertheseconditions.Furthermore,therearealsosubstantialinterestsincreatinghaploidinducersincropplantsthatlackanaturalhaploidinducerbecausethistechnologyfacilitatesplantbreedingefforts.ThisisnowpossiblebasedonourunderstandingfortheroleofCENH3ingenomeelimination.Inshort,ourworkhighlightsthatbasicscienceresearchongenomemanipulationinArabidopsiscanleadtofindingsthatarerelevanttocancerresearchaswellastoeconomicallyimportantplants.

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Keywords:geneticsandgenomics;uniparentalgenomeelimination;chromosomeinstabilityAbstract#139.PolIV-dependentsiRNAsfrommaternalsomatictissuearerequiredforseeddevelopment(Submission81)RebeccaMosher1,JeffreyW.Grover,TimmyKendall,AbdulBaten,GrahamJ.King,RebeccaA.Mosher1TheUniversityofArizona,UnitedStatesPolIV-dependentsiRNAsfrommaternalsomatictissuearerequiredforseeddevelopmentJeffreyW.Grover1,TimmyKendall2,AbdulBaten3,GrahamJ.King3,andRebeccaA.Mosher1,21BiochemistryandMolecular&CellularBiologyDepartment,TheUniversityofArizona,Tucson,AZ85721-0036,USA2TheSchoolofPlantSciences,TheUniversityofArizona,Tucson,AZ85721-0036,USA3SouthernCrossPlantScience,SouthernCrossUniversity,Lismore,NSW2480,AustraliaHostgenomesdeploysmallRNAstosuppresstransposableelements,whichcandisruptthegenomeiftheyareallowedtomobilize.Inflies,smallRNAsareproducedfrommaternaltissuesandloadedintoeggcellstocontroltransposableelementsinthezygoteafterfertilization.SimilarsmallRNAtransportbetweenso-called“companion”cellsandreproductivecellshasbeenproposedinplants,howeveritisnotclearwhetherparentally-derivedsmallRNAsplayasignificantroleduringplantreproduction.HereweshowthatmaternalmutationsinthePolIV-dependentsmallinterferingRNApathwaycauseseedabortioninBrassicarapa.SmallRNAproductionisrequiredinmaternalsomatictissues,butnotinthematernalgametophyteorthedevelopingzygote.TheseobservationssupplythefirstevidencethatsomaticproductionofsmallRNAsisrequiredforzygoticdevelopmentinplants.WeproposethatparentalinfluenceoverzygoticgenomesisacommonstrategyineukaryotesandthathistoricallyoutbreedingspeciessuchasB.rapaarekeytounderstandingtheroleofsmallRNAsduringreproduction.Keywords:RNA-directedDNAmethylation;smallRNA;RNAPolIV/V;seeddevelopmentAbstract#140.EpiTEome:SimultaneousDetectionofTransposableElementInsertionSitesandtheirDNAMethylationLevels(Submission106)JosquinDaron1,R.KeithSlotkin1OhioStateUniversity,UnitedStatesTransposableelements(TEs)aremobilegeneticelementsubiquitouslypresentineukaryoticgenomes.TEscanamplifyandmovethemselvesfromonegenomiclocationtoanother,disruptinggenesandgeneratingDNArearrangements.Tocounteractthisinherentlymutagenicactivity,eukaryoticorganismshaveevolvedmultiplemolecularmechanismstoidentifyandsilenceTEs,oneofthemajorbeingDNAmethylation.TheroutineapproachusedtoinvestigateDNAmethylationlevelsatthegenome-widelevelisbybisulfitesequencing(MethylC-seq/Methylomeanalysis).However,thesegenome-wideanalysesarelimitedtoreferenceTEpositionswhileDNAmethylationofnon-referenceTEsremainsignored.Recently,themethylationanalysisofnon-reference/mobileTEshasbeenanalyzed,butrequiresbothcostlyandlaboriouswholegenomeresequencingcoupledwithMethylC-seq.HerewepresentEpiTEome,thefirstprogramthatdetectsbothnewTEinsertionsitesandtheirmethylationstatesfromasingleMethylC-seqdataset.EpiTEomeoutperformsothersplit-readTEinsertionsitedetectionprograms,evenwhilefunctioningonbisulfite-convertedreads.EpiTEomecharacterizesthepreviouslydiscardedfractionofDNAmethylationatnewornon-referenceTEinsertionsites,enablingfutureinvestigationintotheepigeneticregulationoftransposedTEs.EpiTEomeprovidestheabilitytodetectnewTEinsertioneventsfrompublicornewMethylC-seqdata,enablingnewunderstandingofhowthecellregulatesTEactivityfromexistingorlessextensivedatasets.Keywords:Methylome;transposableelements;insertionsite;bioinformatics;MethylC-seqAbstract#141.ACTIN-RELATEDPROTEIN6PROMOTESTHETRANSCRIPTIONOFMIR156AANDMIR156CBYMEDIATINGH3K4me3DEPOSITION(Submission109)MingliXu1,TieqiangHu,R.ScottPoethig1UniversityofPennsylvania,UnitedStatesVegetativephasechangeinArabidopsisthalianaismediatedbyadecreaseintheexpressionofMIR156AandMIR156C,andacorrespondingincreaseintheirdirecttargets,SQUAMOSAPROMOTERBINDINGPROTEIN-LIKE(SPL)transcriptionfactors.Loss-of-functionmutationsinAUXIN-RELATEDPROTEIN6(ARP6)andSERRATEDEARLYFLOWERING(SEF)acceleratevegetativephasechangeanddecreasethelevelofmiR156earlyinshootdevelopment,butdonotaffectthetimingofthedown-regulationofthismiRNA.ARP6andSEFencodecomponentsoftheSWR1complex(SWR1-C),whichexchangesH2A.ZforH2A.MIR156AandMIR156ChavehighlevelsofH2A.Z,andtheabundanceofH2A.Zatthesegenesremainsconstantduringvegetativephasechange.Thisresult,andtheobservationthatarp6andsefonlyreducethelevelofmiR156earlyinshootdevelopment,indicatesthatH2A.Zpromotestheearly,high-levelexpressionofmiR156,butdoesnotcontrolthetimingofvegetativephasechange.WeshowthatthatH2A.ZpromotestheexpressionofMIR156A/MIR156CbypromotingthedepositionofH3K4me3ratherthanbypreventingthedepositionofH3K27me3orreducingnucleosomeoccupancy,andthatthiseffectismediatedinpartbytheH3K4methyltransferase,ATXR7.Keywords:ARP6;H2A.Z;H3K4me3;H3K27me3;vegetativephasechange;

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Abstract#142.QuaQuineStarch:Insightsongeneevolution(Submission112)SethO'Conner11IowaStateUniversity,UnitedStatesQua-QuineStarch(QQS)isanorphangenefoundinArabidopsisthaliana,withnoknownsequencehomologyoutsideofthespecies.Thisyounggeneregulatesstarchmetabolismandrespondsactivelytochangingenvironments.QQSregulatesnitrogenandcarbonallocationviainteractionwithNF-YC4:atranscriptionfactorconservedacrosseukaryoticspecies.EctopicexpressionofQQSincrops—suchascorn,rice,andsoybean—decreasesstarchandincreasesprotein.However,thestudyofQQSisnotlimitedtocropenhancement,byunderstandingtheepigeneticcontroloftheQQSgenewecangainfurtherinsightintothemechanismswhichregulatetheexpressionlevelofthis"young"gene.VariousecotypesofA.thalianashowawiderangeofexpressionforQQS,indicatingthattheymayhavedevelopeddifferentstrategiestoregulateepigeneticcontrolofthisgene.ByusingtransgenicA.thalianaplantswhichcontainQQSpromotersfromdifferentecotypes,upstreamofthereportergeneGUS,thisresearchprojectattemptstofurtherunderstandtheepigeneticmechanismsthatregulateQQSviaitspromotersequence.Italsoprovidesinsightintohowyounggenessurviveandevolve.Keywords:OrphanGene;Geneevolution;EpigeneticsAbstract#143.HistoneH1mutationsaffectgenomicimprintingandDNAmethylationinArabidopsis(Submission124)QiangHan1,Bartels,Arthur,SaintLouisUniversity,Nair,Pooja,SaintLouisUniversity,Bhan,Aishwarya,SaintLouisUniversity,Hsieh,Tzung-Fu,NorthCarolinaStateUniversity,Xiao,Wenyan,SaintLouisUniversity1SaintLouisUniversity,UnitedStatesGenomicimprinting,differentialexpressionofparentalalleles,regulatesdevelopmentinmammalsandplants.DNAmethylationisregardedasamaincauseofimprintingbysilencingoneparentalallele.IthasbeenshownthatDEMETER(DME),aDNAglycosylase,demethylatesDNAandimpactsgenomicimprintinginArabidopsis.ItisalsoknownthathistoneH1variants(H1.1,H1.2,andH1.3)interactwithDMEinvitroandregulateexpressionofimprintedgenesintheArabidopsisendosperm.BasedonexpressionofthetransgeneH1promoter:GUS,threehistoneH1genesarewidelyexpressedindifferenttissues,especiallyinembryo,endosperm,roottipsandfloralorgans,andeachH1genehasitsownexpressionpattern.Yeasttwo-hybridassaysrevealthathistoneH1.2bindsstronglywiththeDMEN-terminalregioncomparedwiththeDMEC-terminalregion(A,Glycosylase,andBdomains).Inaddition,thehistoneh1triplemutanthasreducedMEDEA:GFPexpressioninthecentralcellandendosperm.Furthermore,theDNAmethylomedataofthehistoneh1triplemutantendospermrevealthatthematernalh1mutantalleleaffectsthemethylationlevelofmostDMEtargets.TheseresultssuggestthathistoneH1isinvolvedinDME-mediatedglobalDNAdemethylationinArabidopsis.Keywords:GenomicImprinting;DNAMethylation;Seeddevelopment;DEMETER;HistoneH1Abstract#144.Genome-wideanalysisofnon-canonicalRNA-directedDNAMethylationmechanisms(Submission142)KaushikPanda1,Ji,Lexiang,UniversityofGeorgia,Vejlupkova,Zuzana,OregonStateUniversity,Schmitz,RobertJ.,UniversityofGeorgia,Fowler,John,OregonStateUniversity,Slotkin,R.Keith,TheOhioStateUniversity1TheOhioStateUniversity,UnitedStatesTransposableelement(TE)insertionsand/orrearrangementscausemutationsandDNAdamage.Todefendtheirgenome,eukaryotesevolvedvarioussilencingmechanismstorepressTEactivity.SmallRNA-directedDNAmethylation(RdDM)isonesuchsilencingmechanismthatiswell-studiedinthereferenceplantArabidopsis.Canonically,RdDMfunctionsthroughtheRNAPolymeraseIV(PolIV)generationof24ntsmallRNAs(sRNAs)thatareincorporatedintoARGONAUTE4(AGO4)orAGO6proteins.Recently,non-canonicalRdDMpathwayshavebeendiscoveredwhereinsRNAsgeneratedfromPolIItranscripts(whichwerethoughttosilenceTEsonlypost-transcriptionally)canalsodirectDNAmethylation.Multiplenon-canonicalRdDMmechanismshavebeenreportedinsinglelocusstudies;however,onlyrecentlyhaveweinvestigatedtheroleofallknownRdDMpathwaystosilenceTEsonthegenome-widelevel(Pandaetal.,GenomeBiology,2016).Wedeterminedthatthenon-canonicalRDR6-RdDMpathway(whichutilizesPolIImRNAs,RDR6,AGO1,AGO6andPolV)preferentiallytargetsfull-lengthTEscapableofself-transposing.ThispreferenceofRDR6-RdDMtomethylatefull-lengthTEsisdrivenbythesRNA-inducedpreferentialcleavageoffull-lengthTEmRNAs,demonstratingthattargetingspecificityinitiatedonthemRNAcleavage-levelcandictateheritablechromatin-levelsilencing.Weadditionallydiscoveredanewnon-canonicalRdDMpathway(DCL3-RdDM)thatonlyfunctionswhenTEsaretranscriptionallyactive(needsPolIItranscripts),butuncharacteristicallyisRNA-dependent-RNA-polymerase(RDR)independent.OurmostrecentworksuggeststhatthispathwayisalsofunctioningonmanytranscribedTEsincropspeciesincludingmaize.IwilluseDCL3-RdDMasacasestudytodemonstratehowTEregulationincomplexTE-richgenomessuchasmaizecanbemodeledbystudyingtheregulationoftranscriptionallyreactivatedTEsinArabidopsis.Keywords:Transposableelement(TE);SmallinterferingRNA(siRNA);MethylC-seqanalysis;RNA-directedDNAmethylation(RdDM)

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Abstract#145.TheIdentificationandAnalysisofPutativeOriginRegionsintheArabidopsisgenome(Submission151)EmilyWheeler1,Concia,Lorenzo,NCSU,Brooks,Ashley,NCSU,Wear,Emily,NCSU,LeBlanc,Chantal,CSHL,Ramu,Umamaheswari,CSHL,Song,Jawon,TACC,Maritiessen,RobertCSHL,Vaughn,Matthew,TACC,Thompson,WilliamF.,NCSU,Hanley-Bowdoin,Linda,NCSU1NCSU,UnitedStatesLikeallorganisms,plantsmustaccuratelyduplicatetheirgenomesduringSphaseofthecellcycle.Theselectionandfiringoforiginsarethoughttoplaykeyrolesinensuringthatfungiandmetazoansaccuratelyreplicatetheirgenomes.MuchlessisknownabouthowplantsregulateDNAreplication,inpartduetoourlackofknowledgeoforiginsequencesinplantsystems.WehavedevelopedanovelmethodforcapturingtheearliestreplicatingregionsduringS-phaseinArabidopsisthalianaCol-0suspensioncells.Wefractionatednucleibasedontheirpositioninthecellcyclewith2D-FlourescenceActivatedNucleiSorting(2D-FANS).NascentDNAfromearlyS-phasenucleiwassequencedandmappedtotheArabidopsisreferencegenometoidentifyearlyreplicatingregionsthatarelikelytobenearorincludeorigins.Wearecharacterizingthegenomiccontextoftheseregionsbylookingatnucleosomeoccupancy,epigeneticmarkassociations,DNaseIhypersensitivesites,andtheirproximitytogenesanddifferentTEfamilies.Keywords:DNAreplication,replicationorigins,epigenetics,chromatin,Abstract#146.FromChromatintoRNA:SDG8regulatesH3K36me3andmRNAprocessingofgeneregulatorynetworksunderlyingnutrientresponses(Submission201)YingLi1,IndraniMukherjee,KarenEThum,JennyYeoh-Wang,MatthewBrooks,ManpreetSKatari,SandrineRuffel,MilosTanurdzic,W.RichardMcCombie,RobertAMartienssen,GloriaMCoruzzi1PurdueUniversity,UnitedStatesAuthors:YingLi,IndraniMukherjee,KarenEThum,JennyYeoh-Wang,MatthewBrooks,ManpreetSKatari,SandrineRuffel,MilosTanurdzic,W.RichardMcCombie,RobertAMartienssen,GloriaMCoruzziInstitutions:NewYorkUniversity;PurdueUniversity;Coldspringharborlab;UniversityofQueensland;INRA,FranceThemode-of-actionofhistonemethyltransferasesandtheroleofhistonemodificationinenvironmentalresponsesisabasicbiologicalquestionwithsignificantimpactinagriculturalimprovement.Recently,weprobedthisquestionwithacasestudyofahistonemethyltransferasenamedSDG8.Wehaveidentifiedadeletionmutantofsdg8,andcharacterizedthegenome-wideroleofSDG8inregulatinghistonemodificationandmRNAprocessinginenvironmentalresponses.WefoundthatSDG8depositsH3K36me3onspecificgenomictargets,preferentiallytowardsthe3'endofthegenebody(Lietal.,GenomeBiology2015).Thishistonemarkisassociatedwithelevatedgeneexpressionlevel.Specifically,SDG8isrequiredforaccuratemRNAprocessingsuchasexon/intronsplicing(Lietal.,unpublished).Onagenome-widelevel,weidentified728highconfidencedirecttargetsofSDG8.ThissetofSDG8targetsisenrichedinspecificbiologicalprocessesincludingdefense,photosynthesis,andnutrientandenergymetabolism.OurresultssuggestedthatthehistonemethyltransferaseSDG8achievesthistargetspecificitythroughtranscriptionfactorpartners(Lietal.,GenomeBiology2015).Importantly,SDG8regulateslightresponsivegenesandnitrogenassimilationgenenetworks,indicatingaroleofSDG8inenvironmentalresponses.Indeed,sdg8mutantisimpairedinenvironmentalresponsesattheepigenomiclevel,inadditiontothetranscriptionalandphysiologicallevels,revealinganewlayerofregulationinplantresponsestoenvironmentalsignals.Reference:YingLi,etal.ThehistonemethyltransferaseSDG8mediatestheepigeneticmodificationoflightandcarbonresponsivegenesinplants.GenomeBiology:16(79)(2015)Keywords:Histonemethyltransferase;epigeneticregulation;systemsbiology;epigenomics;environmentalresponseAbstract#147.TheroleofCytosolicIron-sulfurclusterAssemblypathwayinDNAdemethylationandgeneevolution.(Submission214)XiaokangWang1,Li,Qi,PekingUniversity,Qian,Weiqiang,PekingUniversity1PekingUniversity,ChinaDNAmethylationpatternsinplantsaredynamicallyregulatedbyDNAmethylationandactiveDNAdemethylationinresponsetobothenvironmentalchangesanddevelopmentofplant.BeginningwiththeremovalofmethylatedcytosinebyROS1/DMEfamilyof5-methylcytosineDNAglycosylases,activeDNAdemethylationinplantsoccursthroughbaseexcisionrepair.Sofar,manycomponentsinvolvedinactiveDNAdemethylationremainundiscovered.ThroughaforwardgeneticscreeningofArabidopsismutantsshowingDNAhypermethylationattheEPF2promoterregion,weidentifiedaconservediron-sulfurclusterassembly(CIA)proteinMET18.MET18dysfunctioncausedDNAhypermethylationatmorethan1000lociaswellasthesilencingofreportergenesandsomeendogenousgenes.AsacomponentofcytoplasmicFe-Sclusterassemblycomplex,MET18candirectlyinteractwithROS1invitroandinvivo.ROS1activitywasreducedinthemet18mutantplantsandpointmutationintheconservedFe-SclusterbindingmotifofROS1disrupteditsbiologicalfunction.Interestingly,morethan2000DNAhypomethylatedloci,especiallyintheCHHcontext,wereidentifiedfromthemet18mutantsandmostofthehypo-DMRswerefromTEregions.ThelossofCHHDNAmethylationcausedthereactivationofsometransposons.OurresultssuggestthatMET18mayregulatebothactiveDNAdemethylationandDNAmethylationpathwaysinArabidopsis.ThroughthepurificationofROS1complexandmassspectrometryidentification,weidentifiedanothercytosoliciron-sulfurclusterassemblypathwaycomponentDRE2.DRE2actsinanearlystepintheelectrontransferchainforthematurationofiron-sulfurclusteranddoesnotactinthelatersubstratetargetingstep.IthasbeenshownthatmutationofDRE2canaffectDME-mediatedimprintinggenesexpressionandthisfunctionisindependentofitsknownactioninthecytosoliciron-sulfurclusterassemblypathway（DianaMihaelaBuzasa,etal.,2014）.OurresultsshowedDRE2andROS1couldformacomplexinvivo,buttheydidn'thaveadirectinteraction.Sotheremaybeother

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componentsexsitingtolinkDER2andROS1.NearlyallgenesencodingCIApathwaymembershaveonlyonecopy.However,wefindthatDRE2doeshaveanothercopywhichshowshighsimilaritywithDRE2.Thus,wetermitasDRE2-like.WeusesdCRISPR-Cas9tocreatemutantsofDRE2andDRE2-like.DuetotheessentialroleofDRE2,wecouldnotgethomozygousmutant.Butthemosaicdre2mutantalreadyshowedseverephenotype,suchaswrinkledrosetteleaveswhichwerespreadwithwhitespotsandprematuresenility.Wesuccessfullycreatedahomozygousdre2-likemutant,whichshowedatotallydifferentphenotypecomparedtothatofthemosaicdre2mutant.MutationofDRE2-likeshowedthree-cotyledons,five-petals,abnormalsiliquesandseveresterility.ItseemsthatwhenDRE2-likewasgeneratedduetogeneduplicationandduringthelongperiodofevolution,itdidnotchoosetoactinthesamepathwayasthatofDRE2andchosetotakepartinanotherimportantpathway,eventhoughtheirproteinsequencewerequitesimilar.Butwhatcontributedtothedifferentchoicesremainedelusive.Ourworkprovidesagoodmodelontheinvestigationofgeneevolution.Keywords:CytosolicIron-sulfurclusterAssembly;DNAdemethylation;MET18;DRE2;geneevolutionAbstract#148.Changingcellidentityduringdevelopment;reversalofPolycombrepression(Submission317)Un-SaLee1,Yamaguchi,Ayako,GucciChemical,Wagner,Doris,UPenn1UniversityofPennsylvania,UnitedStatesDuringdevelopment,newcellidentityisspecifiedbyalteringtheexistingtranscriptionalprogram.Suchtranscriptionalreprogramminginturnrequireschangesoftheepigenome,asepigeneticregulatorymechanismscontrolaccessibilityofthegenomicinformationforgeneexpression.Inparticular,Polycombrepressionsilencesgeneexpressionprogramsnotneededordetrimentalatagivenstage,tissueorcondition.IaimtoidentifyepigeneticregulatorsthatcanovercomePolycombrepression,andthusenableactivationofnewgeneexpressionprogramswhenandwheretheyarerequired.Towardsthisend,IhaveemployedadualgeneticenhancerscreeninthemodelorganismArabidopsis,toidentifygenesthatcontributetoupregulationoffloralhomeoticgenesinnewlyformedflowers,thatarelikelytobechromatinregulators.FloralhomeoticgeneexpressionissilencedbyPolycombrepressionuptothisdevelopmentalstage.IhaveidentifiedmultipledifferentcomplementationgroupsofepigeneticregulatorspotentiallyinvolvedinantagonizingPolycombrepression.Iwillpresentworkononeofthesecomplementationgroups,whichcontributestoactivationoffloralhomeoticgenesandactsinoppositiontoPolycombatasubsetofPolycombtargets.Iamparticularlyinterestedinthemolecularmechanismbywhichthischromatinregulatormightcontributetoactivationofsilencedgenes.Keywords:flowerdevelopment;polycombgroup;trithoraxgroupAbstract#149.RegulatoryDNAinA.thalianacantoleratehighlevelsofsequencedivergence(Submission339)JoshCuperus1,CristinaAlexandre,JamesRUrton,KenJean-Baptiste,MichaelWDorrity,AlessandraMSullivan,JenniferLNemhauser,StanleyFields,DetlefWeigel,KerryLBubb,ChrisineQueitsch1UniversityofWashington,UnitedStatesVariationinregulatoryDNAisthoughttodriveevolution.Cross-speciescomparisonsofregulatoryDNAhaveprovidedevidenceforbothweakpurifyingselectionandsubstantialturnoverinregulatoryregions.However,disruptionoftranscriptionfactorbindingsitescanaffecttheexpressionofneighboringgenes.Thus,thebase-pairlevelfunctionalannotationofregulatoryDNAhasprovenchallenging.Here,weexploreregulatoryDNAvariationanditsfunctionalconsequencesingeneticallydiversestrainsoftheplantArabidopsisthaliana,whichlargelymaintainthepositionalhomologyofregulatoryDNA.UsingchromatinaccessibilitytodelineateregulatoryDNAgenome-wide,wefindthat15%ofapproximately50,000regulatorysitesvariedinaccessibilityamongstrains.Someoftheseaccessibilitydifferencesareassociatedwithextensiveunderlyingsequencevariation,encompassingmanydeletionsanddramaticallyhypervariablesequence.Forthemajorityofsuchregulatorysites,nearbygeneexpressionwassimilar,despitethislargegeneticvariation.However,amongallregulatorysites,thosewithbothhighlevelsofsequencevariationanddifferentialchromatinaccessibilityarethemostlikelytoresideneargeneswithdifferentialexpressionamongstrains.Unexpectedly,thevastmajorityofregulatorysitesthatdifferedinchromatinaccessibilityamongstrainsshowlittlevariationintheunderlyingDNAsequence,implicatingvariationinupstreamregulators.Keywords:ChromatinaccessibilityDnaseIhypersensitivityAbstract#150.RegulationofNucleosomeStabilityandGeneExpressionbyArabidopsisATPaseBrahmaandtheHistoneVariantH2A.Z(Submission362)ShannonTorres1,Deal,RogerB.,EmoryUniversity1EmoryUniversity,UnitedStatesDifferentiatingcellsacquireastabletranscriptionalprogramnecessaryforproperdevelopmentandhomeostasis,whichisfacilitatedbymanychromatincomponents,suchchromatinremodelersandhistonevariants.Thehistonevariant,H2A.Z,isinvolvedinmanygenomicprocesses,includingtranscriptionalregulation.However,themechanismsthroughwhichH2A.Zregulatestranscriptionarecurrentlyunclearanditsroleintranscriptionvariesdependingonthegeneticcontext.ChromatinremodelingbyanArabidopsisSWI/SNFATPase,Brahma(BRM),torepresstranscriptionmakestheroleofH2A.Znecessaryfortranscriptionalactivationatsomeloci.TheantagonisticrelationshipbetweenBRMandH2A.ZprovidesawaytostudyH2A.Zfunctioninthecontextofotherregulatorypressures.So,ifwecanunderstandhowBRMaffectschromatinorganizationandtranscriptionusinggeneticandgenomicassays,thenwecanbetterunderstand

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theroleofH2A.Zintranscriptionalregulationatthesameloci.Towardthisgoal,wehaveidentifiedgenesthatareeithercoordinatelyorantagonisticallyregulatedbyBRMandH2A.Z-containingnucleosomes,usingRNA-seqandChIP-seq.ToexplorethemechanismofhowBRMandH2A.Zregulatechromatin,weareusingMNase-sequencingtocharacterizehowdepletionofoneorbothaffectsnucleosomeoccupancyandstabilityatlociwherebothregulatetranscription.Ingeneral,BRMcontributestonucleosomesstabilizationatlociwhereitisenrichedandcontributestodestabilizationofflankingnucleosomes.FurtherworkwillcharacterizehowdepletionofH2A.Z-containingnucleosomesaffectsnucleosomestabilityandhowthesetwofactorsinteracttofacilitatetranscription.Ultimately,byunderstandingtheantagonisticrolesBRMandH2A.Zplayintranscriptionalregulation,wearetakingstridestountanglethecomplicatedinvivochromatinenvironmentthatcaneitherfacilitateorobstructtranscription.Keywords:ChromatinRemodeler;H2A.Z;Nucleosomestability;BRM;TranscriptionAbstract#151.Single-CellTypeProfilingofChromatinAccessibilitywithINTACT-ATAC-seqOffersInsightintoTranscriptionalRegulatoryNetworks(Submission363)KelseyMaher1,Deal,Roger,EmoryUniversity1EmoryUniversity,UnitedStatesEukaryoticgenomesarepackagedintoahierarchicalstructure,calledchromatin,whichplaysacriticalroleingeneexpression.Geneticregulatoryelementsfoundinlesscompactedchromatinaremoreaccessibletotranscriptionfactor(TF)binding,andcanmodulatethetranscriptionaloutputoftargetgenes.Therefore,beingabletodetecttherelative‘openness’ofchromatiniscrucialtobothidentifyingactiveregulatoryelementsandtounderstandingthecomplexnetworkoftranscriptionalregulatoryfactorsinagivencelltype,aspectsthatremainpoorlycharacterizedinplantspecies.AtechniqueusedtoassesschromatinopennessisAssayforTransposase-AccessibleChromatin-sequencing(ATAC-seq),whichreliesontheactivityofahyperactivetransposasetogeneratenext-gensequencinglibraries.Whilethismethodisrobust,ithasremainedchallengingtoapplyinplanttissuesasbothmitochondrialandchloroplasticDNAarevulnerabletotransposaseactivity,generatingnon-nuclearreadsthatcannotbeusedindownstreamanalyses.WeutilizedIsolationofNucleiTAggedinspecificCellTypes(INTACT)inArabidopsisthalianatoincreasetheefficiencyofATAC-seqby80%,generatingthefirstchromatinaccessibilitydatasetinanyplantspecieswithsinglecell-typespecificity.HereweexaminethechromatinlandscapeoftwodevelopmentallylinkedArabidopsiscelltypes,roothairandnon-haircells.Ourdatashowthatwhilethesecelltypesappearsimilaronaglobalscale,closerinspectionrevealsthousandsofcell-specificdifferencesatTFbindingsites.Thesedifferencesledtothediscoveryofatranscriptionalregulatorymoduleuniquetothehaircelltype,whichplaysaroleindrivingbothcell-fateregulatorsandinabioticstressresponses.INTACT-ATAC-seqallowsforthenovelexaminationofchromatinaccessibilityinplantspecieswithsingle-celltypespecificity,andrevealsnewlinesofinvestigationintoplanttranscriptionalregulation.Keywords:INTACT;ATAC-seq;chromatin;transcriptionfactor;rootcellAbstract#152.IdentificationofChromatinAccessibilityChangesinPlantsDuringCellDifferentiationandStressResponse(Submission371)MarkoBajic1,PajaSijacic,KelseyMaher,RogerDeal1EmoryUniversity,UnitedStatesPackagingofDNAintohighlyorderedstructuresknownaschromatinisimportantformaintainingpropergeneexpression.Chromatinpackagingchangesduringcelldifferentiationandstressresponsewhereactivegeneexpressioncorrelateswithregionsofmorelooselypackagedchromatin.TobetterunderstandtheregulationofcellfatedeterminationwecomparedchromatinaccessibilitybetweenArabidopsisthalianapluripotentstemcellsoftheshootapicalmeristemanddifferentiatedmesophyllcellsoftheleaf.Additionally,weuseddifferentiatedroothairandrootnon-haircellstocomparechromatinaccessibilitychangesbetweenrootandshoottissue.WeutilizedINTACT(IsolationofNucleiTAggedinspecificCellTypes)toisolatenucleifromthesecelltypesandthenperformedATAC-seqtoidentifyregionsofhighlyaccessiblechromatin.OurresultsshowthatthemajorityofATAC-seqaccessibleregions,termedTransposaseHypersensitiveSites(THSs),arecommonbetweenshootstemcellsandmesophyllcellsandbetweentheroothairandnon-haircells,butthatthereisagreaterdifferenceinchromatinaccessibilitybetweentheshootandrootcelltypes.UsingHTSeq-countandDESeq2weidentifiedwhichTHSsarespecificallyenrichedforeachcelltype,andbyidentifyinggenesnearesttotheseTHSswefoundthatthesegenesassociatewithGOtermsspecifictothesecelltypes,suchasorgandevelopmentinstemcellsandresponsetobioticstimuliinmesophyllcells.Additionally,weperformedfootprintingandmotifenrichmentanalysestoidentifypotentialtranscriptionfactorsthatregulategeneexpressioninthesecelltypes.Finally,thesesametechniquesandanalyseswereutilizedinMedicagotruncatulatoidentifyhowchromatinregulatesgeneexpressioninresponsetosubmergencestress.Keywords:ATAC-seq;chromatin;differentiation;stressresponse;footprints;

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Abstract#153.IdentificationofaccessiblechromatinregionsandtranscriptionalregulatorynetworksforArabidopsisstemcellsandmesophyllcellsusingATAC-seq(Submission372)PajaSijacic1,BajicMarko,EmoryUniversity,RogerDeal,EmoryUniversity1EmoryUniversity,UnitedStatesInhigherplants,allabovegroundtissuesarebeingcontinuouslyproducedduetoactivitiesofpluripotentstemcellslocatedinthecentralzone(CZ)oftheshootapicalmeristem(SAM).Differentiatingcellstightlyregulategeneexpressionastheyprogressfromundifferentiatedstemcellstofullydifferentiatedcellsthatmakeupthelateralorganssuchasleaves.TobetterunderstandtheregulationofcellfatedeterminationduringdifferentiationwecomparedtheaccessiblechromatinregionsbetweentwocelltypesinArabidopsis:pluripotentstemcellsfromtheSAManddifferentiatedmesophyllcellsoftheleaf.WefirstemployedINTACT(IsolationofNucleiTAggedinspecificCellTypes)toisolatenucleifromthesetwocelltypesandthenperformedATAC-seqtoidentifytheiropenchromatinregions.OurresultsshowthatthemajorityofATAC-seqaccessibleregions,whichwetermedTransposaseHypersensitiveSites(THS),arecommonbetweenthetwocelltypes,howeverthereareseveralthousandsTHSthatarecell-typespecific.Inaddition,genomicdistributionoftheTHSappearstobeverysimilarbetweentwocelltypes,withmorethan75%beingenrichedwithintheregionsinArabidopsisgenomewheremostofthecis-regulatoryelementsarefound.Furthermore,GOanalysisrevealedthatmanyofthegenesassociatedwiththestemcell-specificTHSareinvolvedinregulationoftranscriptionandorgandevelopmentwhilethegenesnearbythemesophyll-specificTHSwerepredominantlyinvolvedinresponsetobioticandabioticstimuli,whichcorrelateswellwiththeknownfunctionsofthesetwocelltypes.Finally,weperformedDNAfootprintingandmotifenrichmentanalysestogeneratealistofpotentialtranscriptionfactorsthatmayplayanimportantroleinregulatingthebasicbiologicalfunctionsofthesetwocelltypes.GeneRegulation:Abstract#154.PPD-KIX,aconservedproteinrepressorcomplexregulatingleafgrowthindicots(Submission21)AlexandraBaekelandt1,NathalieGonzalez,LaurensPauwels,GwenSwinnen,JanVanDoorsselaere,GeertDeJaeger,AlainGoossens,DirkInzé1PlantSystemsBiology/UGent,BelgiumLeafsizeisregulatedbyamultitudeofpathways,amongwhichcelldivisionplaysapivotalrole.Indicots,alargeportionofepidermalcellsisderivedfromthestomatallineage.Inthislineage,stemcell-likeprecursorcells,calledmeristemoids,undergoasymmetricdivisionsgeneratingpavementcellsadjacenttotwoguardcellsconstitutingastoma.PEAPOD2(PPD2)isatranscriptionalregulatornegativelyregulatingmeristemoiddivisioninArabidopsisthaliana(Arabidopsis).WefoundthatPPD2interactswithKIX8andKIX9,adaptorproteinsrecruitingtheco-repressorTOPLESS(TPL)(Gonzalezetal.,2015).Interestingly,thekix8-kix9mutantandatransgeniclineover-expressinganamiRNAtargetingPPD1andPPD2(ami-ppd)bothhaveenlargeddome-shapedleavesresultingfromincreasedmeristemoidamplifyingdivisions.DownstreamtargetsofthisPPD2-KIX8/9repressorcomplexwereidentified,includingtranscriptionfactorsandD3-typecyclins.GenesencodingmembersofthePPD-KIXrepressorcomplexareabsentfromPoaceae(grasses),butconservedindicots.Toshedlightonthefunctionalconservationofthiscomplexacrossdifferentdicotplantspecies,CRISPR/Cas9mediatedgenomeeditingwasusedtosimultaneouslyknock-outtheKIX8andKIX9orthologuesinSolanumlycopersicum(tomato).PrimarytransformantswereobtainedwheretheSlKIX8andSlKIX9allelescontainindelsleadingtoaframeshift.Theseplantsandtheirprogenyexhibitedenlargeddome-shapedleaves,reminiscentofArabidopsis.Consistently,SlKIX8andSlKIX9couldinteractwithtomatoorthologuesofPPDandTPL.TheidentifiedPPD-KIXcomplexisconservedindicotsonlyanddownregulationofKIXexpressionhassimilareffectsonleafmorphologyinArabidopsisasintomato,indicatingthatthisisakeycomplextoregulateleafgrowthindicots.Mostlikely,thiscomplexplaysaroleindeterminingleafgrowthintheseconddimension,adevelopmentalprogramabsentfrommonocotgrasses.Abstract#155.DynamicregulationofPHYTOCHROMEINTERACTINGFACTOR5(PIF5)byCONSTITUTIVEPHOTOMORPHOGENESIS1/SUPPRESSOROFPHYA(COP1/SPA)complexinArabidopsis(Submission27)VinhPham1,Huq,Enamul,UTAustin1TheUniversityofTexasatAustin,UnitedStatesLightisoneofthemostimportantfactorsthatnotonlyregulatesplantgrowthanddevelopmentbutalsoprovidesplantsthespatialandtemporalinformationforadaptationtotheprevailingconditions.Alterationinthelightenvironmentcantriggersignificantchangesinglobalgeneexpression.InArabidopsisthaliana,twogroupsofkeyfactorsregulatingthosechangesingeneexpressionareCONSTITUTIVEPHOTOMORPHOGENESIS/DET/FUSCA(COP/DET/FUS)andasubsetofbasichelix-loop-helixtranscriptionfactorscalledPhytochromeInteractingFactors(PIFs).COP1/SPA1complexwasshowntobeessentialfortherapidlight-induceddegradationofPIF1.However,itisnotclearifCOP1/SPA1complexalsopromotesdegradationofotherPIFs.Inaddition,thedynamicregulationofPIFstabilityunderprolongedlightconditionsisstillunknown.Here,weshowthatCOP1/SPA1complexisalsonecessaryforthelight-induceddegradationofPIF5underredlight.Furthermore,COP1/SPA1stabilizedPIF5indark-grownseedlings,butpromotesthepoly-ubiquitinationandsubsequentlydegradationofPIF5inresponsetoredlightthroughthe26Sproteasomepathway.ThegeneticanalysisillustratesthatoverexpressedPIF5canpartiallysuppressthecop1-4andspaQphenotypeinthedarkandredlightconditions.Inaddition,PIF5proteinabundancecyclesunderthediurnalandconstantlightconditionssuggestingPIF5asakeyfactorregulatingdiurnalgrowthrhythms.Takentogether,ourdataillustratethedynamicmechanismofregulatingPIF5polyubiquitination,degradationandthesuppressionofphotomorphogenesisviatheCOP1/SPA1E3ligase.

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Keywords:bHLHtranscriptionfactor,phytochromeinteractingfactors,E3Ubiquitinligase,photomorphogenesis,ProteasomedegradationAbstract#156.MediatorcomplexsubunitsMed25andMed16PromotePapillaeFormationonTrichomeCellWalls(Submission31)ChristyMoore1,Rickerd,Trevor,IllinoisStateUniversity,Suo,Bangxia,IllinoisStateUniversity,Zahde,Mais,IllinoisStateUniversity,Juveland,Katelyn,IllinoisStateUniversity,Kirik,Viktor,IllinoisStateUniversity1IllinoisStateUniversity,UnitedStatesTheplantcellwallplaysanimportantroleincommunication,defense,organizationandsupport.Theimportanceofeachofthesefunctionsvariesbycelltype,withspecializedcells,suchasArabidopsistrichomes,orleafhairs,exhibitingdistinctcellwallcharacteristics,includingpapillae.Tobetterunderstandthemolecularprocessesimportantforpapillaedepositiononthecellwallsurface,weidentifiedtheGLASSYHAIR1(GLH1)andGLASSYHAIR2(GLH2)genes,whicharenecessaryforpapillaeformation.Wefoundthatasplice-sitemutationinthecomponentofthetranscriptionalMediatorcomplexMED25geneisresponsibleforthepapillae-lessphenotypeoftheglh1mutant.Preliminaryelementalanalysisindicatesthatcalciumionaccumulationintrichomesisstronglyreducedinglh1mutants,suggestingthattheprocessesimportantforpapillaedepositionmayalsobeimportantforcalciumdepositionatthetrichomecellwallsurface.Fortuitously,theglh2mutationwasmappedtoageneencodingtheMediatorcomplexsubunitMED16.AGFP-MED16fusionwasshowntolocalizetothenucleus,consistentwitharoleintranscriptionalregulation.TheMED25andMED16genesareexpressedintrichomes.TheexpressionofthetrichomedevelopmentmarkergenesGLABRA2(GL2)andEthyleneReceptor2(ETR2)isnotaffectedintheglh1orglh2mutants.Collectively,thepresentedresultsshowthatMED25andMED16arenecessaryforpapillaeformationonthecellwallsurfaceofleaftrichomesandthattheArabidopsisMED25andMED16Mediatorcomponentsarelikelyinvolvedinthetranscriptionofasubsetofgenesthatpromotepapillaedepositionintrichomes.Keywords:trichomes;papillae;mediatorcomplex;cellwallAbstract#157.Regulatorynetworksduringseeddevelopment(Submission57)RanTian1,FangfangWang,QiaolinZheng,A.BruceDownie,SharynPerry1UniversityofKentucky,UnitedStatesRegulatorynetworksduringseeddevelopmentRanTian;FangfangWang;QiaolinZheng;A.BruceDownie;SharynPerryPlantembryodevelopmentisimportantbecauseseedsmakeuparound70%ofthehumandietdirectly.Understandingregulatorymechanismtogenerateaseedisfundamentallyimportant.TheLAFLgenesencodetranscriptionalregulatorsthatarecriticalforseeddevelopment.ThreemembersofLAFL,LEAFYCOTYLEDON2(LEC2),ABSCISICACID3(ABI3)andFUSCA3(FUS3),areB3domainfactorsthatbindDNAmotifscalledRYmotifsthathaveacoresequenceofCATG.WhileLEC2isexpressedearlierinembryodevelopment,ABI3andFUS3areexpressedduringlaterdevelopment.LEC2andFUS3,butnotABI3caninduceembryo-specificprogramsaftercompletionofgerminationinaprocesscalledsomaticembryogenesis.PriorworkdetermineddirectandindirecttargetsofFUS3.HerewereportondirectresponsivetargetsofABI3,andcomparetothedirecttargetswithFUS3.InterestinglywefoundthatABI3candirectlyup-regulatesomekeyregulatorygenesinvolvedinembryodevelopment,butalsorepressortargets.Somegenesencodingproteinsofunknownfunction,thataretargetsnotonlyofABI3andFUS3,butalsooftheembryoMADS-factorAGL15,arebeingstudied,tounderstandinteractionsbetweenthesefactorsandrolesofthesetargets.Keywords:Embryodevelopment;Generegulation;Transcriptionfactors;ChIP(Chromatinimmunoprecipitation);SeeddevelopmentAbstract#158.RoleofPCB1,aputativeCa2+-bindingprotein,inplantdefenseagainstthegreenpeachaphid(Submission71)DevasantoshMohanty1,JyotiShah,JoeLuis,HossainAliMondal,SujonSarowar,SumitaBehera1UniversityofNorthTexas,UnitedStatesPHYTOALEXIN-DEFICIENT4(PAD4),whichisanucleocytoplasmicproteinwithhomologytoacylhydrolases,isinvolvedinmodulatingplantdefenseagainstpathogens.OurstudieshaveshownthatPAD4alsohasaroleinArabidopsisdefenseagainstthegreenpeachaphid(GPA),Myzuspersicae.PAD4expressionisupregulatedatthesiteofaphidfeedingfromthevasculature,aswellasinadjacentcells.However,themechanismandcomponentsofthePAD4-regulatedpathwayindefenseagainsttheGPAarepoorlyunderstood.WehaveidentifiedaputativeCa2+-bindingEFhandprotein-encodinggenePCB1(PAD4-DEPENDENTCa2+-BINDINGPROTEIN),whichisexpressedatelevatedlevelsatthesiteofGPAfeedingfromthevasculature.PAD4functionisessentialfortheupregulationofthisgene.InsectbioassaysconfirmthatlikePAD4,PCB1hasanimportantroleincontrollingtheGPApopulationonArabidopsis.GPApopulationsizeissignificantlylargeronapcb1mutantplants,andsmalleronplantsoverexpressingPCB1fromtheCauliflowermosaicvirus35Spromoter.Further,PCB1overexpressionrestoredresistanceinthepad4mutantbackground,whileconstitutiveexpressionofPAD4fromthe35Spromoterwasunabletorestoreresistanceinthepcb1mutant,thussuggestingthatPCB1functionsdownstreamofPAD4indefenseagainsttheGPA.FutureeffortsaredirectedatunderstandingthemolecularfunctionofPCB1anditspotentialcontributiontodefenseagainsttheGPA,andotherpathogensandinsects,aswell.Keywords:Plantdefense,BioticStress,GreenPeachAphid

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Abstract#159.ComparativeandquantificationanalysesofRTFL/DEVILsuppressors(Submission195)PinGuo1,Yamaguchi,Takahiro,Acel,Inc.SIC1Japan.,Abe,Tomoko,RIKENNishinaCenter.,Tsukaya,Hirokazu,TheUniversityofTokyo,NationalInstitutesofNaturalSciences.1TheUniversityofTokyo,JapanThelandplant-specificRTFL/DEVILfamilyencodessmallpeptidesfunctioningintheregulationofpositionalcuesandpolarizedcellproliferationofmultipledevelopmentalprocessesinArabidopsisthaliana.Uptonow,ourunderstandingofabovebiologicalfunctionofRTFL/DEVILfamilyismainlybasedonthepleiotropicphenotypesofthelateralorgansamongtransgenicoverexpressorsinA.thaliana.Theloss-of-functionlines,however,providelittleinformationonthefunctionofRTFL/DEVILfamily,suggestiveofahighlevelofitsgeneticredundancyinA.thaliana.Inthisstudy,adouble-RTFL/DEVILoverexpressor(p35S::ROT4/OsRTFL3)inA.thaliana,whichwasconstructedwithtwoRTFL/DEVILmembersfromA.thalianaandOryzasativa,wasmutatedbyheavy-ionbeamirradiation.Uptonow,twosuppressors(sup-1andsup-2)whichshowedrescuedphenotypesonthelengthofrosetteleafwereobtainedafterscreeningof18,680M2populations.BoththeROT4andOsRTFL3wereconfirmedhighlyexpressedinabovetwosuppressorsbyRT-PCR,indicatingthatthecasualgenesforthesuppressionmightbepresentinthedownstreamofRTFL/DEVILsignalingpathway.Thebackcrossingofsup-1andsup-2andprogenysegregationratioshowedthatasinglemutationwasresponsibleforthesuppressioninsup-1,whileatleasttwomutationsinsup-2.Theleafphenotypesofthetwosuppressorswerecomparedandquantifiedviatheanalysesofleafbladeindex,cellnumberandsize,EdUstainingofleafprimordiaandsoon.RootphenotypesofbothRTFL/DEVILoverexpressorsandsuppressorswillalsobeanalyzedandreported.Keywords:RTFLpeptidefamily;leafmorphogenesis;suppressors;irradiationmutagenesisAbstract#160.Afamilyofputativeelongationfactorsthatcanpromoteorinhibittranscriptiondependingongenomiccontext(Submission199)PascalMartin1,Yu,Xuhong,IndianaUniversity,Thum,KarenE,IndianaUniversity,Michaels,ScottD,IndianaUniversity1IndianaUniversity,UnitedStatesTheregulationoftranscriptionandchromatinorganizationinplantspresentsbothsimilaritiesandspecificitiescomparedtothoseinanimalsandfungi.Comparatively,limitedinformationisavailableonhowtranscriptionelongationisregulatedinplantsandhowgeneexpressioniscompartmentalizedinthenucleus.Here,wefocusedonafamilyofthreeputativetranscriptionelongationfactors(TEFs)inArabidopsis.Inthiswork,weperformedgenome-widestudiestoinvestigatetheirfunction.RNAseqdefinedrepertoiresofhundredsofgenesthatwereeitherup-ordownregulatedfollowingthedisruptionofallthreeTEFgenes.Singletefmutantsexhibitedverylimitedeffectsongeneexpression,suggestingatleastpartialfunctionredundancy.Genome-wideTEFlocalizationbyChIP-seqcorrelatedgloballywithRNAPolymeraseII(PolII)occupancyandconsequentlywithgeneexpressionlevels.Foranumberofgenes,TEFsappeartoparticipateinacomplexenrichedatthe3'-endofgenes,likelyinvolvedinRNA3'processingandtranscriptiontermination.Consistently,ouranalysesrevealedthatintefmutantplants,alargefractionofgenesweredownregulated,mostlikelyasaresultoftranscriptionalinterference.Inthesemutants,defectivetranscriptionalterminationand/or3'PolIIpausinglikelygeneratescisinterferencewithtranscriptionalinitiationatthepromoterofdownregulateddownstreamgenes.Ontheotherhand,genesupregulatedintefmutantplantsexhibitaspecificpatternofchromatinmarks,PolIIdistributionandTEFlocalizationthatmaydeterminetheirsensitivitytoTEFdepletion.Theeffectsonboththeup-anddownregulatedgenesarethusconsistentwithafunctionofTEFsasnegativeelongationfactors.Theiroppositegeneexpressionoutcomesaredeterminedbythespecificchromatinandtranscriptioncontextsofthegeneitselfandofitsdirectneighbors.Keywords:transcriptionelongation;RNApolymeraseII;chromatin;transcriptionalinterferenceAbstract#161.AnalysisofBerberineBridgeEnzyme-likeFamilyGenesPotentiallyInvolvedinLeafDevelopment(Submission202)AllisonNewton1,WilliamSchryver,DarronLuesse1SouthernIllinoisUniversity-Edwardsville,UnitedStatesInplants,thesynthesisofisoprenoidsandisoprenoid-relatedcompoundssuchaschlorophyll,carotenoids,tocopherols,phytoalexins,andgibberellinsrequiretheGERANYLGERANYLDIPHOSPHATESYNTHASE(GGPPS)genefamily.InArabidopsisthaliana(At),apointmutationinonememberofthisfamily,ggpps11,resultsinrounded,variegatedrosetteandcaulineleaveswithirregularmargins.Thevariegationpatterningistypicallyreproducible,withthecenteroftheleavesbeingalbinoandtheperipheryphenotypicallywildtype.Wehavecomparedthetranscriptomeofwildtype,ggpps11whitesectors,andggpps11greensectors.ThisanalysisrevealedagroupoftwelveBerberineBridgeEnzyme-like(BBE-like)proteinswhicharedifferentiallyregulatedbetweenthetwomutanttissues.AlthoughAtdoesnotproduceendogenousberberine,exogenousapplicationofberberineleadstopointyleaves,likelyresultingfrominhibitionofadaxialcelldifferentiationbyberberine,causingtheleaf-polaritydefects.Toidentifyhowthesegenesareinvolvedinleafdevelopmentandpolarity,T-DNAlineswithindividualmutationsintheBBE-likegeneswereidentifiedandobtainedassegregatingpopulationsfromtheArabidopsisBiologicalResearchCenter.WehaveusedPCRanalysistoidentifyhomozygousmutantlinesforallfamilymembersexceptBBE-like23,whichappearstobeembryoniclethal.WehavedeterminedphylogeneticrelationshipsbetweenBBE-likefamilygenesandareusingtheinformationtocreatedoublemutantsbetweenthemostcloselyrelatedpairs.BecauseAtbbe28

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mutantsshowreducedsalttoleranceandbiomass,andBBEsinotherplantsareupregulatedinresponsetostressandpathogenicattack,leavesfrombbe-likemutantsgrowninnormalconditionsaswellassaltstressconditionswillbeexamined.Leaveswillbeexaminedfor1)overallleafarchitectureusingtheopenaccessLAMINAprogramand2)differentialRNAexpressionofknownleaf-polaritydetermininggenesusingqRT-PCR.Keywords:leafdevelopmentAbstract#162.RescuestudyofGGPPS(Submission203)ToriaTrost1,DarronLuesse1SouthernIllinoisUniversityEdwardsville,UnitedStatesAplant’sabilitytophotosynthesizeisdependentonthepresenceofisoprenoid-derivedcompoundssuchaschlorophyllandcarotenoids.Oneimportantprecursormolecule,synthesizedaspartoftheMEPpathway,isGGPP.ProductionofGGPPiscatalyzedbythesmallfamilyofGERANYLGERANYLDIPHOSPHATESYNTHASE(GGPPS)enzymes.InArabidopsisthalianatherearetwelvemembersintheGGPPSfamily.WhileGGPPS11isconsideredtobedominantmemberandknowntobeprimarilyresponsiblefortheproductionofmostphotosyntheticisoprenoids,theremainingfamilymembersstilldisplayenzymaticactivity.Apointmutationinggpps11(ggpps11-1)producesatemperaturesensitivevariegatedleafphenotypewithgreenontheedgesandawhiteoryellowcolorinthemiddleoftheleaf.Theleavesofthismutantarealsosmallerinsizethantheirwildtypecounterparts.Thisworkseekstodetermineiftheotherfamilymembers,whenconstitutivelyexpressedandtargetedtothechloroplast,canrescuethevariegatedphenotypeofggpps11-1.Agatewayconstructforeachgenewillbeproducedthatcontainsthecodingregionofthegene(minusanyN-terminustargetingsequence),thechloroplasttargetingsequencefromtobacco,andaC-terminusGFPtag.ThesearebeingassembledviaaGibsonreactionandthentransformedintoadestinationvectorpriortoAgrobacteriumtumefacienstransformationofwild-typeandggpps11-1plants.Byperformingthisrescuestudy,wehopetodetermineifanothermemberoftheGGPSfamilywillbeabletocompensateforthemutatedGGPS11enzyme.Keywords:GGPPS;rescuestudyAbstract#163.FunctionalAnalysisoftheWRKYTranscriptionFactorinGreenAlgae(Submission288)KevinCox1,PingHe,LiboShan1TexasA&MUniversity,UnitedStatesPlantsaresessileorganismsthatendurewithavarietyofabioticandbioticstresses.Tocopewiththesechallenges,plantsrelyondynamicandprofoundtranscriptionregulationinresponsetoexternalandinternalcuesinordertomaintaintheirgrowthanddevelopment.Transcriptionfactorsareknowntoplaykeyrolesinmaintainingthespecificityandrobustnessinvarioussignalingpathways.TheWRKYtranscriptionfactorsareplant-specificandamongoneofthelargestfamiliesoftranscriptionfactorsthatareknowntoplayaprevalentroleinabioticandbioticstresses.ItremainsunknownhowhigherplantshavedevelopedarelativelylargenumberofWRKYsintheirgenomesandtheevolutionarilyorigin.Interestingly,wehavefoundthatthereappearstobeonlyoneWRKYgeneinthegenomeofChlamydomonasreinhardtii,anancientplantspecies.FunctionalanalysishasrevealedthatCrWRKYfunctionsasatranscriptionalrepressorthatlocalizestothenucleus.Inaddition,CrWRKYappearstobeinducedbyabioticfactors,suchasheatandsalt,similartosomeoftheWRKYgenesinhigherplants.FutureworkinvolvessilencingCrWRKYingreenalgaeandoverexpressingthegeneinArabidopsistoperformfurtherfunctionalanalysis.Theworkwillprovideinsightsonhowoneofthekeyregulatorsofplantstressevolvedfromasinglegeneingreenalgaetoalargenumberinhigherplants.Keywords:WRKYTranscriptionFactor;FunctionalGenomics;Evolution;Chlamydomonasreinhardtii;AbioticandBioticStressAbstract#164.Regulationofgrowth-defensebalancebytheJAZ-MYCtranscriptionalmodule(Submission290)QiangGuo1,IanT.Major,YukiYoshida,MarceloL.Campos,GeorgeKapali,Xiu-FangXin,KoichiSugimoto,DaltondeOliveiraFerreira,ShengYangHe,GreggA.Howe1MichiganStateUniversity,UnitedStatesPlantresistancetoinsectherbivoresiscontrolledinlargepartbythestresshormonejasmonate(JA),whichalsoactsasapotentinhibitorofplantgrowth.JApromotesthedegradationofJASMONATEZIMDOMAIN(JAZ)proteins,liberatingdiversetranscriptionfactors(TF)toexecuteJAresponses.However,littleisknownabouthowcombinatorialcomplexityamongJAZ-TFinteractionsmaintainscontrolovermyriadaspectsofgrowth,development,reproduction,andimmunity.ToinvestigatethecontributionsofMYCTFstoJAresponsesinArabidopsisthaliana,weremovedMYC2/3/4inajazquintuplemutant(jazQ).ComparisonofjazQandajazQmyc2myc3myc4octuplemutantshowedthatMYCTFsareresponsibleforJA-dependentregulationofrootgrowth,chlorophylldegradation,andsusceptibilitytothepathogenPseudomonassyringae.WefoundthatMYCTFsalsocontrolboththeenhancedresistanceofjazQleavestoinsectherbivoryandrestrictedleafgrowthofjazQ.Genome-wideexpressionprofilingofthemutantshowedthattriterpenoidbiosyntheticandglucosinolatecatabolicgenesareupregulatedinjazQindependentlyofMYCTFs.OurstudyhighlightstheutilityofgeneticepistasistounravelthecomplexitiesofJAZ-TFinteractionsanddemonstratesthatMYCTFsexertmastercontroloveraJAZ-repressibletranscriptionalhierarchythatgovernsgrowth-defensebalance.

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Keywords:Jasmonates;JAZrepressors;MYCtranscriptionfactors;growth-defensetradeoffs;resistancetoinsectherbivoryAbstract#165.DifferentialspatiotemporalandepigeneticregulationoftypeIMADS-boxgeneexpressionbyPolycombRepressiveComplex2duringearlyendospermdevelopmentinArabidopsis(Submission297)ShanshanZhang1,DongfangWang,HuajianZhang,MeganI.Skaggs,AlanLloyd,DiRan,LinglingAn,KarenS.Schumaker,GaryN.Drews,RaminYadegari1UniversityofArizona,UnitedStatesEndospermisaproductofdoublefertilizationandfunctionsasanutritivetissueintheangiospermseedtosupportthegrowthoftheembryoand/orthegerminatingseedling.Inmostangiosperms,earlyendospermdevelopmentfollowsacoenocyticpattern;thatis,endospermnucleiproliferateinabsenceofcellularizationbeforeundergoingatransitiontocellulardevelopment.FunctionalanalyseshaveindicatedthatthiscoenocyticprogramisnormallyrepressedpriortofertilizationbytheFertilization-IndependentSeed(FIS)-PolycombRepressiveComplex2(PRC2),aputativeH3K27methyltransferase.Similarly,transitiontoendospermcellularizationisalsoregulatedbythesamecomplexasmutationsinFIS-PRC2componentsproduceabnormallyproliferating,non-cellularizedendospermuponfertilization.SomeofthemembersofthetypeIMADS-boxtranscription-factorgenefamilywerepreviouslyidentifiedastargetgenesoftheFIS-PRC2complex.Thesegeneshavebeenshowntoregulatecoenocyticdevelopment,beexpressedinthecoenocyticendosperm,and/orupregulatedincrosseswithexcesspaternalgenome.InordertounderstandtheroleoftheFIS-PRC2complexinregulationofthewholetypeIMADS-boxgenefamily,weundertookasystematicexpressionanalysisoftypeIMADS-boxgenesduringearlyseeddevelopment.UsingquantitativereversetranscriptasePCRandgene-fusionreporterlineanalyses,weshowthatasubclassoftypeIMADS-boxgenes(C2genes)thatarespecificallyupregulatedduringthecoenocyticphaseinwild-typeseedsaredysregulatedinthemutant.Furthermore,usingallele-specificexpressionanalysis,wehaveidentifiedasubsetofC2genesasbeingsubjecttoFIS-PRC2-dependentmaternalimprintingorFIS-PRC2-independentpaternalimprinting.WehavesynthesizedourdatawiththeavailablepublisheddatatoproposeamodelofhowFIS-PRC2regulatesC2typeIMADS-boxgeneexpressioninearlyendospermdevelopment.Keywords:Arabidopsisendosperm;fertilization-independentseed;PolycombRepressiveComplex2;typeIMADS-boxgenes;geneexpressionandsilencingAbstract#166.PosttranscriptionalregulationofmitochondrialgeneexpressioninArabidopsis(Submission301)Ming-HsiunHsieh1,Hsieh,Wei-Yu,AcademiaSinica,Sung,Tzu-Ying,AcademiaSinica,Tseng,Ching-Chih,AcademiaSinica,Liao,Jo-Chien,AcademiaSinica,Chang,Chiung-Yun,AcademiaSinica1AcademiaSinica,TaiwanMitochondriaplayanimportantroleinmaintainingmetabolicandenergyhomeostasisinthecell.Inplants,impairmentinmitochondrialfunctionsusuallyhasdetrimentaleffectsongrowthanddevelopment.Tostudygenesthatareimportantforplantgrowth,wehaveisolatedacollectionofslowgrowth(slo)mutantsinArabidopsis.Theslo1mutantisdefectiveinageneencodinganEmotif-containingpentatricopeptiderepeat(PPR)proteinthatisrequiredformitochondrialnad4-449andnad9-328RNAediting.TheSLO1PPRproteinislocalizedtothemitochondrion,mayindirectlyregulateplantgrowthanddevelopmentviaaffectingmitochondrialRNAediting.Bycontrast,theslo3mutantisimpairedinageneencodingaclassicP-typePPRprotein.TheSLO3-GFPislocalizedtothemitochondrion.FurtheranalysisofmitochondrialRNAmetabolismrevealedthattheslo3mutantwasdefectiveinsplicingofnad7intron2.ThisspecificsplicingdefectledtoadramaticreductionincomplexIactivityandthusdelayedthegrowthanddevelopmentinthemutant.Takentogether,ourstudiesontheslo1andslo3mutantssupportthenotionthatPPRproteinsplayanimportantroleinposttranscriptionalregulationofmitochondrialgeneexpressioninArabidopsis.Keywords:mitochondrion;RNAediting;RNAsplicing;PPRproteinAbstract#167.SmallRNAevolutionacrosstheBrassicaceae(Submission304)AleksandraBeric1,Mabry,Makenzie,DivisionofBiologicalSciencesUniversityofMissouri-Columbia,Brose,Julia,DepartmentofBiochemistryUniversityofMissouri-Columbia,Pires,J.Chris,DivisionofBiologicalSciencesUniversityofMissouri-Columbia,Meyers,BlakeC.,DonaldDanforthPlantScienceCenter,DivisionofPlantSciencesUniversityofMissouri-Columbia1DonaldDanforthPlantScienceCenter,UnitedStatesSmallRNAevolutionacrosstheBrassicaceaeAleksandraBeric1,2,MakenzieMabry3,JuliaBrose4,J.ChrisPires3,BlakeC.Meyers1,21DonaldDanforthPlantScienceCenter,St.Louis,Missouri2DivisionofPlantSciences,UniversityofMissouri,Columbia,Missouri3DivisionofBiologicalSciences,UniversityofMissouri,Columbia,Missouri4DepartmentofBiochemistry,UniversityofMissouri,Columbia,MissouriAbstractMicroRNAs(miRNAs)are~21nucleotidenon-codingRNAsthatplayanimportantroleintheproperregulationofgeneexpression.Theyareinvolvedinplantdevelopment,signaltransduction,responsetopathogensandabioticstress,andtriggerbiogenesisofothersmallRNAs,namelytasiRNAsorphasiRNAs.ThoughsomemiRNAsareconservedbetweenangiospermsandothernon-seedplants,themajorityofmiRNAfamiliesseemtohaveamorenarrowphylogeneticdistribution.HerewefocusspecificallyonthediversificationofmiRNAsinBrassicaceae,aphenotypicallydiverseandeconomicallysignificantfamilyofeudicotswhichincludesspeciesrangingfromfoodcropstoornamentalplantstoawell-knownmodelsystem,Arabidopsisthaliana.Rapiddiversificationpairedwithmultiplehybridizationandwholegenomeduplicationeventsmaketheelucidationofphylogeneticrelationshipsamongclades

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challenging.TounderstandtheimpactofspeciationandpolyploidyonmiRNAevolution,wesampledmiRNAsfrom21speciesspanningthefourmajor,knownBrassicaceaelineagestorepresentthediversityinthefamily,aswellasanoutgroupfromtheCleomaceaefamily.StudyingthevariationofmiRNAsinthesespeciescouldrevealpatternsofbothconservationandlineage-specificmiRNAandtasiRNAemergencethatreflectphylogeneticrelationshipswithinthefamily.Keywords:smallRNAs;evolution;Brassicaceae;miRNA;Abstract#168.StabilizationofAGO4bysingle-strandedsiRNAinArabidopsisthaliana(Submission306)WENCHEN1,Gohlke,Jochen,UA,Grover,JeffreyW.,UA,Mosher,RebeccaA.,UA1UniversityofArizona,UnitedStatesEukaryoticorganismsusechromatinmodifications,suchashistonemodificationandDNAcytosinemethylation,toregulategeneexpression.Inplants,RNAdirectedDNAmethylation(RdDM)triggersmethylationandsilencingofrepetitivesequencessuchastransposons.DuringRdDM,ARGONAUTE4(AGO4)binds24ntsiRNAinthecytoplasmanddirectsDNAmethylationtocomplementarysequencesinthenucleus.HerewereportthatAGO4accumulationispositivelycorrelatedwithsiRNAabundance,althoughAGO4transcriptlevelisunchangedintheabsenceofsiRNA.Furthermore,AGO4accumulationrequiressiRNAbindingandpassengerstrandcleavage.TherequirementforsiRNAloadingcannotbebypassedbynuclearlocalizationofAGO4,andnuclearlocalizationisnotrequiredforAGO4accumulation.Together,thisevidenceindicatesthatAGO4isunstableunlesscorrectlyloadedwithsingle-strandedsiRNA.Keywords:RdDM;AGO4;proteinaccumulationAbstract#169.ComprehensiveAnalysisofRDR-independentSmallRNAsinArabidopsisthaliana(Submission308)SethPolydore1,MichaelJ.Axtell1ThePennsylvaniaStateUniversity,UnitedStatesPlantsmallRNAs(sRNAs)are20-24nucleotideregulatorymoleculeswhosebiogenesisisdependentonDicer-Like(DCL)endonucleases,andwhichfunctionincomplexeswithArgonaute(AGO)proteins.ManyDCLsubstratesaredouble-strandedRNAmadebyRNADependentRNAPolymerases(RDR).ThreeArabidopsisthalianaRDRsareknowntocontributetosRNAbiogenesis,RDR1,RDR2,andRDR6.However,sometypesofsRNAsaregeneratedindependentofRDR1,RDR2,andRDR6.KnownRDR1/2/6-independentsRNAsincludemicroRNAs(miRNAs),invertedrepeatsshortinterferingRNAs(ir-siRNAs),andnaturalanti-sensesiRNAs(nat-siRNAs).Here,weusesRNA-seqfromanrdr1/rdr2/rdr6triplemutanttoidentifyacomprehensivelistofRDR-independentsRNAloci.AfterremovingknowntypesofRDR1/2/6-independentloci,wefound545locithatcouldnotbeclassifiedviapreviouslyidentifiedbiogenesismechanisms,manyofwhicharedouble-strandedandoverlapwithgenes.OurresultsindicatethattheremaybenovelRDR-independentsRNAbiogenesismechanisms.WealsoidentifymanyquestionableMIRNAsannotations.Keywords:RDR1/2/6-independent;RNADependentRNAPolymerases;miRBasemiRNAs;NaturalantisensesiRNAsAbstract#170.HistoneacetylationregulatorCD3mediatesseedgerminationbyenhancingABI5expression(Submission311)BoZhao1,LikaiWang1UniversityofTexasatAustin,UnitedStatesHistoneacetylationisdynamicallycontrolledbyhistoneacetyltransferases(HATs)andhistonedeacetylases(HDACs)whicharespecificforacetylationchangesofH3andH4N-terminal.Ingeneral,acelytatedhistonebyHATwillactivategeneexpressionandremovedacetylationbyHDACisassociatedwithtranscriptionalrepressionandgenesilencing.Histoneacetylationhasbeenreportedinvolvedinseedgerminationanddormancybycoordinatinghormonalregulationsuchasinductionandmaintenanceofseeddormancybyabscisicacid(ABA)anddormancyreleasebygibberellin(GA).ThehistoneacetylationregulatorCD3thathadbeenfoundtoenhanceH3K14acandH3K23aclevelinpromotersofmostethyleneresponsivegenesanditsover-expressionresultedin80%up-regulatedgenesinthetranscriptomeprofiling.HereweidentifiedthenewfunctionofCD3inseedgerminationregulation.Over-expressedCD3showedmuchmoresensitivitytoABAduringseedgerminationcomparedtowildtype,andCD3regulatedgenessharedmuchcorrelationwithABAresponsivegenes,indicatingitsroleinABA-mediatedseedgerminationpathway.FurtherinvestigationsuggestedABI5wasmoreaccumulatedattranscriptionalandproteinlevelinCD3OEthaninWT.Interestingly,CD3interactedwithABI5andbothboundtoABI5promotertoinitiateABI5autoregulation.WespeculatedthatCD3mediatedABI5feedbackloopbyalteringhistoneacetylationduringABAtreatmentwhichwasstillundergoing.Keywords:histoneacetylation,germination,ABA

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Abstract#171.NUCLEARFACTORY,subunitA(NF-YA)proteinspositivelyregulatefloweringandactthroughFLOWERINGLOCUST(Submission322)ChamindikaSiriwardana1,Gnesutta,Nerina,UniversitadegliStudidiMilano,Kumimoto,Roderick,UniversityofCalifornia,Jones,Daniel,UniversityofOklahoma,Myers,Zachary,UniversityofOklahoma,Mantovani,Roberto,UniversitadegliStudidiMilano,HoltIII,Ben,UniversityofOklahoma1UniversityofOklahoma,UnitedStatesPhotoperioddependentfloweringisoneofseveralmechanismsusedbyplantstoinitiatethedevelopmentaltransitionfromvegetativegrowthtoreproductivegrowth.NF-Ysareheterotrimerictranscriptionfactors,composedofthethreeindependentproteinfamiliescalledtheNF-YA,NF-YB,andNF-YC.WhileitisknownthatspecificNF-YBandNF-YCsubunitsinteractandfunctiontogetherwithCONSTANS(CO)toregulateflowering,theroleandspecificNF-YAsremainedinquestion.HerewetestedthehypothesisthattheNF-YAsactaspositiveregulatorsofphotoperioddependentflowering,usingthreeindependentapproaches.OurfirstapproachwastocreateamutantversionofNF-YBthatlosesinteractionwithNF-YA,butnotNF-YC.Themutantwasoverexpressedinthelatefloweringnf-yb2nf-yb3doublemutant,andwasfoundnottocomplementthelatefloweringphenotype,indicatingthatNF-YBrequiresinteractionwithNF-YAtoregulatefloweringresponses.OursecondapproachwastoexamineNF-YAoverexpression.HerewewereabletoidentifythattwoNF-YAoverexpressors,NF-YA2andNF-YA6,droveearlyfloweringandledtotheupregulationofakeyfloralintegratorFT.Finally,weprovidedexperimentalevidencethataNF-YA/NF-YB/NF-YCtrimercomplexformsonthepromoterofFT.Insummary,weprovidestrongsupport,intheformofgeneticandbiochemicalanalyses,thatNF-YA,incomplexwithNF-YB/NF-YCproteins,candirectlybindthedistalCCAATboxintheFTpromoterandarepositiveregulatorsoffloweringinanFT-dependentmanner.Keywords:NF-YA2,Photoperioddependentflowering,NF-Y,Abstract#172.ExpressionAnalysisofForked1andForked-LikeGenesDuringDevelopmentandinResponsetoHormones(Submission337)KurtisClarke1,Veenendaal,Janelle,UniversityofLethbridge,Prabhakaran-Mariyamma,Neema,UniversityofLethbridge,Schultz,Elizabeth,UniversityofLethbridge1UniversityofLethbridge,CanadaThepolardistributionofauxinbyPINproteinsiscriticalforrootandleafdevelopment.AuxinbaseddevelopmentalprocessesrelyonthePINFORMED(PIN)genestoexportauxininadirectionalmanner.TheproteinFORKED1(FKD1)isinvolvedinleafveinpatternformationandisrequiredforproperPIN1localizationinprovascularcells.Comparedtotheclosedloopsformedbywildtypeleafveins,mutationtoFKD1resultsinanopenleafveinpattern.FKD1isamemberofa9-membergenefamily(theFORKED-LIKE(FL)family).WhilesinglemutantsofotherFLgenefamilymembers(fl1,fl2,andfl3)resultinnophenotype,aquadruplemutantoffkd1withfl1,fl2,andfl3hasseverelydisconnectedveinsandsignificantlyreducedrootelongation.Thepleiotropiceffectsofmutatingmultiplemembersofthegenefamilypotentiallysuggeststheirredundantactioninseveralimportantdevelopmentalprocesses.Inordertoinvestigatetheroleofthesegenes,linesexpressingpromoterGUSfusionshavebeencreatedtovisualizespatio-temporalgeneexpression.Consistentwiththemutantphenotypes,expressionofFKD1,FL1,andFL2overlapinbothleafandroottissues,howeverallthreegeneshaveuniqueexpressioncharacteristics.insilicopromoteranalysisrevealedputativecis-regulatoryelementsthatregulategeneexpressioninresponsetoauxinandABA.TreatmentofbothFKD1:GUSandFL1:GUSexpressinglinessupportthehypothesisthatmembersoftheFLgenefamilyareregulatedbybothauxinandABA.TheregulationofmembersofthisgenefamilybyauxinandABAsupporttheirroleinvasculartissuedevelopment,andindicatethatthisfamilymay,inpart,beregulatedinresponsetoabioticstress.Keywords:Development;Leafvenation;cis-regulatoryelements;auxin;ABAAbstract#173.TranscriptionalregulationoftheArabidopsistricarboxylicacidcycle(Submission338)MichelleTang1,Li,Baohua,UCDavis,Zhou,Xue,UCDavis,Ngo,Richard,UCDavis,Cruz,Neiman,UCDavis,Clark-Wiest,Caitlin,UCDavis,Brady,Siobhan,UCDavis,Kliebenstein,Daniel,UCDavis1UCDavis,UnitedStatesThetricarboxylicacid(TCA)cycleisacentralprimarymetabolicpathwaythatgeneratescarbonprecursorsandenergy-richcarriermoleculesrequiredforcellularfunction.RegulationofTCAcyclegenesisofparticularinterestinplantssincemetabolismmustbefinelytunedandcoordinatedacrossthemulti-cellularplanttooptimizegrowthanddevelopmentundervariousenvironmentalconditions.Transcriptionalregulationislikelycriticaltothiscoordinationbutisvastlyunderstudied.TounderstandhowtheTCAcycleistranscriptionallyregulated,wemappedthetranscriptionfactorsthatbindtoandputativelyregulateenzyme-encodinggenesintheArabidopsisTCAcycleusinganenhancedyeastone-hybridsystem.Wehaveidentified3996interactionsbetween915transcriptionfactorsand55promotersofTCAcyclegenesintheyeastone-hybridassays.Combinedwithcorrelationanalysisusinggeneexpressiondatasets,wehaveselected18transcriptionfactorsforbiologicalvalidation.WepredictthattranscriptionfactorscanintegratespecificityofTCAcyclegeneexpressioninatissue-andcondition-dependentmannertomatchdevelopmentorstressresponseprograms.Wewillevaluatethegrowth,physiologicalandmolecularconsequencesofperturbingtranscriptionalregulationofTCAcyclegenesusinginsertionalmutantsoftranscriptionfactors.

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Keywords:transcriptionalregulatorynetworks;primarymetabolismAbstract#174.CellcycledependantregulationandfunctionofArgonaute1inplants(Submission351)AdrienTrolet1,Baldrich,Patricia,DonaldDanforthPlantsciencecenter,Criqui,Marie-Claire,IBMP-CNRS,Clavel,Marion,IBMP-CNRS,Meyers,BlakeC.,DonaldDanforthPlantsciencecenter,Genschik,Pascal,IBMP-CNRS1IBMP-CNRS,FranceTheRNAsilencing(RNAi)isabiologicalprocess,whichplaysakeyroleinawiderangeofeukaryotes,suchasgeneexpressionregulation,transposableelementscontrolandantiviraldefense.Inhuman,severalstudiesshowedthatmiRNAsandAGO2areinvolvedintheregulationofthecellcycle.Indeed,manycellcycleregulatorssuchascyclins,CDKs,CDKinhibitors,RBRproteinsorE2FtranscriptionfactorshavebeenidentifiedasmiRNAtargets.TranscriptionaldatasuggestthatthesecellcyclemiRNAsaredifferentiallyaccumulatedduringcellcycleprogressionandthatmisregulationofsomecouldleadtoproliferativediseases.However,inplants,almostnothingisknownaboutthecellcycleregulationthroughmiRNAs.UnpublisheddatasfromthelabsuggestthattheArabidopsisAGO1,whichisthemostimportantArgonauteformiRNA-mediatedgeneregulation,isessentialforcellproliferation.InordertoinvestigatetheroleofAGO1duringcellcycle,wesetupasystembasedoncellcyclesynchronizationoftobaccoBY-2cellsuspensionsexpressingaGFPfusedAGO1.First,wemonitoredtheregulationofAGO1atthetranscriptlevelandproteinlevel.PreliminaryresultsshowedthattheAGO1proteinaccumulatedduringG2/MbutbecomeslessabundantduringG1.ThispatternofAGO1proteinaccumulationcannotbeexplainedbyAGO1transcriptleveloritsregulatorymiRNA168,suggestingpost-translationalregulationofAGO1duringcellcycle.WealsoinvestigatedthelocalizationofGFP-AGO1duringthecellcycleandrevealedAGO1containingnuclearbodiesduringSphase.However,thenatureofthesesbodieswillneedfurtherinvestigations.Finally,wenowplantosequencesmallRNAsfromS,G2,MandG1phasesofsynchronizedcellsandinvestigatewhetherputativecellcyclespecificmiRNAscanbehighlighted.Keywords:cellcycle;RNAsilencing;miRNA;cellsuspensionHormoneSignaling:Abstract#175.RERJ1–awoundresponsiveJAdependentearlyinduciblebHLHtranscriptionfactorisinvolvedinthericeJA-signalingsystemtogetherwithOsMYC2andOsJAZ(Submission10)IoanaValea1,Miyamoto,Koji,TeikyoUniversity,Okada,Kazunori,TheUniversityofTokyo1TheUniversityofTokyo,JapanPathogenandherbivore-induceddamageinplantsisthemaincauseforyearlyyieldlossesandsubsequenteconomicones.(Oerke,2006)Thejasmonicacid(JA)pathwayisoneofthesignificantonesshapingthefitnessstrainingplantdefenseamongotherinfluencesonplantlifestages.(Staswicketal.,1992)RERJ1(riceearlyresponsivetojasmonates1)hasbeenpreviouslyshowntobeabasichelix-loop-helix(bHLH)transcriptionfactorinvolvedintheearlyJAsignalinginrice.Inresponsetowoundingitreachesitspeakwithin30minutesaftertreatment.(Kiribuchietal.,2004)ThemainfocusofourstudyistocharacterizethefunctionofRERJ1withintheJAsignalingsystemwithregardtoOsMYC2,actingasanactivator,andOsJAZ,themainknowninhibitorgroup(Ujietal.,2016).Ourapproachisontranscriptionallevel,trackingthetranscriptionalactivityofRERJ1inmutantssuchasrerj1-TOS17knock-downandOsMYC2RNAi;onproteinlevelidentifyingdirectinteractionsbetweenRERJ1withOsMYC2andOsJAZ;aswellasexaminingtheirpromotersandidentifyingRERJ1`sspecificcis-bindingelementsthroughChIP-qPCR.Adifferentialtemporalpatternofexpressionuntil4hafterJAtreatmentandwoundinginthererj1-TOS17mutantshowsthatRERJ1influencesawiderangeofthe15knownOsJAZ,severalofwhichareknowntobeinvolvedindefensemechanisms,lightresponseandotherJA-regulateddevelopmentalstagesofriceplants.OsMYC2transcriptaswellseemstobeslightlyaffectedbyRERJ1.Insupporttheprotein-proteininteractionwithinayeasttwo-hybridassayshowsRERJ1beingabletophysicallyinteractwithawiderangeofOsJAZ,leadingtothehypothesisthatRERJ1isdirectlyinvolvedandshapestheknownfeedbackloopbetweenOsMYC2andOsJAZ(KazanandManners,2013).Keywords:bHLHricetranscriptionfactors;jasmonicacidsignalinginrice;riceenvironmentalresponses;RERJ1,OsJAZandOsMYC2regulatoryloopAbstract#176.-WithdrawnAbstract#177.IdentificationandcharacterizationofmicroRNAsinvolvedinBrassinosteroidssignalinginplants(Submission32)GunjanSirohi1,KapoorMeenu,GuruGobindSinghIndraprasthaUniversity1GuruGobindSinghIndraprasthaUniversity,Dwarka,NewDelhi,India,IndiaPlanthormonesincludingabscisicacid(ABA),ethylene,gibberellins,auxin(IAA),cytokinins,andbrassinosteroids(BRs)arecontrollingmanyphysiologicalandbio-chemicalprocesses.Ithasaprofoundeffectonplantgrowthanddevelopment.Amongthese,Brassinosteroids(BRs)istheclassofsteroidhormonesregulatingawiderangeofdevelopmentalandphysiologicalprocessesduringthelifecycleofplants.BRsalsomodulateplantmetabolicresponsetobioticandabioticstresses,likesaltanddroughtstresstolerance,thermo-tolerance,oxidativestresstolerance,pathogenresistance,aswellasherbicideandpesticide.NowthequestionishowBRsmayimpactsuchdiversedevelopmentalandphysiologicalprocesseswhichremainedunanswered.Itisknownthatpropercellular

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differentiation,morphogenesis,versatilityandadaptabilityinorganismarebecauseofunambiguousregulationofgeneexpression.Thisregulatoryprocessisorganizedinahierarchicalandnetworkedmanner.Non-codingRNAslikesiRNA,snRNAandmiRNAarekeymembersofthisregulatorynetwork.EvidencessupportregulatoryactionofmiRNAsinplantsthathavedirectimplicationinnormalgrowth,developmentandadaptation.TheclearpictureofmicroRNAsmediatedBRsmechanismregulationisunknown.Giventheimportanceoftheabove,itbecomesimportanttoobservewhetherandtoatwhatextentmicroRNAsinvolveinregulationofthisimportanthormone(BR)signalingintheplantsystem.ThepresentstudyaimsatunbiasedprofilingofmicroRNAsandcomparingtheirroleinpresentandabsenceofBRinArabidopsisthaliana.Itwillalsoprovidethenewerperspectivestowardsourunderstandingoftheregulatorymechanismofhormoneinplantsystem.Keywords:microRNAs;hormone;brassinosteroids;epibrassinolidAbstract#178.Makingaspiral:theroleofauxinsignalinginshapingshootarchitecture(Submission43)MallorieTaylor-Teeples1,Nemhauser,Jennifer,UniversityofWashington1UniversityofWashington,UnitedStatesThepatternoforgansaroundtheshoot(phyllotaxy)affectslightharvestingcapacityanddeterminesthedensityofgrainorfruitalongastem.WehavefoundthatphyllotacticpatterninginArabidopsiscanbealteredbyre-programmingdegradationratesoftheauxinco-repressor/co-receptorIAA28.Wearecurrentlyperformingmorphometric,molecularandgeneticanalysestopinpointthemolecularmechanismunderlyingtheobservedphenotypesinplantsexpressingIAA28ratevariants.WearealsoextendingthesestudiestoincludeputativeIAA28orthologsinZeamaysandBrachypodiumdistachyon.Inayeastsyntheticsystem,wefoundthatthedegradationrateofIAA28issimilartothatofitsputativehomologsinbothmaizeandBrachypodium.Furthermore,themaizeorthologBARRENINFLORESCENCE4wasfoundtoplayaroleinphyllotaxy1,suggestingthatthatthediversityinnaturalphyllotacticpatternsacrossplantspeciesmaybeexplainedinpartbyvariationinauxinrepressors.Thebroadergoalofthisprojectistopilotconstructionofapipelineforrapidengineeringofdesirableagronomictraitsintodiverseplantspecies.1PMID:26464512Abstract#179.PLDα1derivedphosphatidicacidbindwithRGS1tomodulateheterotrimericG-proteinsignalinginArabidopsis(Submission60)SwarupRoyChoudhury1,SonaPandey1DonaldDanforthPlantScienceCenter,UnitedStatesHeterotrimericGproteinsinplantsareinvolvedintheregulationofmultiplebioticandabioticstressesaswellasmanydevelopmentalprocesses.OneGα,1Gβand3GγproteinsrepresenttheheterotrimericG-proteincomplexinArabidopsisandasingleregulatorofGproteinsignaling,RGS1,isoneofthefewknownbiochemicalregulatorsofthissignalingcomplex.Here,wehaveascertainedthatPhospholipaseD(PLDα1)interactswithRGS1proteinandbothcanacceleratetheGTPaseactivityofGproteinsubunitGαtoattenuateitsactiveform.WenowpresentevidencethatthephospholipaseDα1proteinisakeycomponentandmodulatoroftheG-proteincomplexduringregulationofasubsetofsignalingpathways.WealsoshowthatthesameG-proteinsubunitsandtheirregulatorsexhibitdistinctphysiologicalandgeneticinteractionsdependingonspecificsignalinganddevelopmentalpathways.Suchdevelopmentalplasticityandinteractionspecificitylikelycompensatesforthelackofmultiplicityofindividualsubunits,andhelpstofine-tuneplants’responsestoconstantlychangingenvironments.Furthermore,weshowthatPLDα1derivedphosphatidicacid(PA)isamoleculartargetofRGS1asitinhibitstheGAPactivityofRGS1.WeidentifyaconservedlysineresidueofRGS1(Lys259)whichisdirectlyinvolvedinRGS1-PAbinding.IntroductionofthisRGS1proteinvariantinthergs1mutantbackgroundmakesplantshypersensitivetoasubsetofABA-mediatedresponses.ThesedataprovidenewinsightsaboutABAresponseinplantsthroughdeactivationofRGS1proteinbyPAbinding.UnderstandingsuchcomplexregulatorymechanismsregulatedbyPLDα1andPAviaGproteinsignalingwillhelpustoevaluatetheiroverallcontributiontoplantgrowthanddevelopmentaswellasresponsestoabioticstress.Keywords:Abscisicacid,HeterotrimericG-proteins,PhospholipaseDalpha1,Phosphatidicacid,RegulatorofG-proteinsignaling.Abstract#180.RegulationoftheturnoverofACCsynthasesbyphytohormonesandheterodimerizationinArabidopsis(Submission62)GyeongMeeYoon1,Lee,HanYong,PurdueUniversity,WestLafayette,Chen,Yi-Chun,PurdueUniversity,WestLafayette,Kieber,Joseph,UniversityofNorthCarolina,ChapelHill1PurdueUniversity,UnitedStatesRegulationoftheturnoverofACCsynthasesbyphytohormonesandheterodimerizationinArabidopsisHanYongLee1,Yi-ChunChen1,JosephKieber2,andGyeongMeeYoon11DepartmentofBotanyandPlantPathology,PurdueUniversity,WestLafayette,IN,47907,USA2DepartmentofBiology,UniversityofNorthCarolina,ChapelHill,NC,27599,USAThegaseoushormoneethylenehasprofoundeffectsonmanyplantgrowthanddevelopmentalprocesses,includingfruitripening,abscission,senescenceandresponsestobioticandabioticstresses.Tofulfillthesediverserolesofethyleneinplants,ethylenebiosynthesismustbetightlyregulated.Theprimarytargetoftheregulationis1-aminocyclopropane-1-carboxylicacid(ACC)synthases(ACS),therate-limitingenzymesintheethylenebiosyntheticpathway,whichisregulatedbothtranscriptionallyandpost-transcriptionally.PriorresearchshowedthatcytokininandbrassinosteroidincreasetheproteinstabilityofasubsetofACSisoforms,thereforeenhancesethyleneproductioninplants.Recentlyweidentifiedadditionalphytohormones,includinggibberellicacid,salicylicacid,methyljasmonicacid,abscisicacid,andauxin,alsodifferentially

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influencethestabilityofACSproteins.Inaddition,wefoundthatheterodimerizationofACSisoformsisanovelmechanismtocontrolACSproteinstability,whichcontributestothemetabolicflexibilityinvariouscell/tissuesunderawiderangeofAdoMet,anACSsubstrate.Together,ourstudyprovidesacomprehensiveunderstandingoftherolesofvariousphytohormonesonACSproteinstabilityandshedsnewinsightsintocross-talkbetweenethyleneandotherphytohormones.Keywords:Ethylene;ethylenebiosynthesis;ACCsynthases;proteinstability;hormone;ArabidopsisthalianaAbstract#181.AnOptimizedRibo-seqLibraryPreparationMethodandAnalysisToolforPlants(Submission94)SerinaMazzoni-Putman1,Perkins,Patrick,NorthCarolinaStateUniversity,Heber,Steffen,NorthCarolinaStateUniversity,Stepanova,Anna,NorthCarolinaStateUniversity,Alonso,Jose,NorthCarolinaStateUniversity1NorthCarolinaStateUniversity,UnitedStatesItiswellestablishedthatchangesintranscriptionfrequentlydonotmatchchangesinthelevelofafunctionalproteinproduct.Thisdiscordancecanbeduetomanyfactorsincludingtranscriptstability,translationrate,etc.Ribosomefootprinting(alsocalledRibo-seq)seekstoquantifytheoccupancyofribosomesonatranscriptasameasureofitstranslationrates.OurgrouphasrecentlyusedRibo-seqtoshowthattranslationalregulationiskeytotheethyleneresponseinArabidopsis.Thisfindingbegsthequestionofhowpervasivethismechanismoftranslationalregulationis,particularlyduringtheresponsetootherphytohormones.Beforeaddressingthisquestion,wehavesoughttooptimizetheRibo-seqprocessforplants.OneofthegreatestissuesfacingscientistswhowanttocarryoutaRibo-seqexperimentistheefficiency(andthereforecost)ofsequencing.Upto90%ofsequencedreadscanberibosomalRNA(rRNA),meaningthatonly10%oftheseexperiments’timeandcostyieldsmeaningfuldata.WehavetestedseveralcommercialandhomemademethodsfortheremovalofrRNAfromRibo-seqsamples.Additionally,wehavefurtheroptimizedourpreviouslypublishedRibo-seqprotocoltoreducethetimingandnumberofsteps.OurmodifiedRibo-seqlibraryprepreducesthepercentageoftotalreadsmappingtorRNA(19-30%)andincreasesthosemappingtomRNA(25-38%).AsecondissuefacingpotentialusersofRibo-seqishowtoanalyze,andinterpretthequalityof,footprintingdata.WearedevelopingaRibo-seqanalysistool,riboStreamR,thatprovidesbiologist-friendlyanalysisofRibo-seqdata.riboStreamRenablesuserstocustomizedataanalyses,visualizedatafeatures,andcompareresultswithpreviouslypublisheddatasets,flaggingatypicalcharacteristics(ifany).OuroptimizedRibo-seqprotocol,togetherwiththestreamlinedriboStreamRplatform,provideauser-friendly,customizableandcost-efficientstrategyforRibo-seqstudiesinplants.Keywords:Ribosomefootprinting;assayoptimization;rRNAsubtraction;sequencinganalysispipelineAbstract#182.TheoctadecanoidpathwayisrequiredfornectarsecretionindependentofCOI1inArabidopsisthaliana(Submission132)AnthonySchmitt1,PeterKlinkenberg,MengyuanJia,RahulRoy,ClayCarter1UniversityofMinnesota,UnitedStatesOver75%ofcropspeciesproducenectarandaredependentonpollinatorsinordertoachievemaximumseedset,yetlittleisknownaboutthemechanismsregulatingnectarsecretion.Thephytohormonejasmonicacid(JA)isrecognizedtobeinvolvedinseveralplantprocessesincludingdevelopmentanddefense.JAwasrecentlyshowntopositivelyinfluencenectarsecretioninbothfloralandextrafloralnectaries.Forexample,endogenousJAlevelspeakinflowersjustpriortonectarsecretion,butthedetailsofhowJAregulatesnectarsecretionhaveyettobeelucidated.WehavefoundthattheoctadecanoidpathwaydoesindeedplayaroleintheproductionandregulationoffloralnectarinArabidopsis.NullallelesforseveralJAbiosynthesisandresponsegeneshadsignificantlyreducedamountsofnectar,aswellasalteredexpressionofgenesknowntobeinvolvedinnectarproduction.Surprisingly,aknockoutmutantfor12-oxophytodienoatereductase3[(anenzymefurtherdowntheJAbiosyntheticpathwaythatreduces12-oxophytodienoicacid(OPDA)],producednonectarinnewlyopenedflowers,butdidsecretenectarinolderflowers.Furthermore,asimilarphenotypewasobservedincoi1-1,aJAinsensitivemutant.TheseobservationsstronglysuggestaroleforaJA-andCOI1-independentpathwayinregulatingnectarproductioninArabidopsis.Additionally,wealsohaveidentifiedcrosstalkbetweentheJAandauxinresponsepathwaysinnectaries.Alleneoxidesynthase(AOS)isanenzymeearlyoninJAbiosynthesis.Interestingly,thenectar-lessmutantaos-2showednoauxinresponseinnectaries,butbothnectarproductionandtheauxinresponsewasrestoreduponexogenousJAtreatment.Conversely,coi1-1displayednoauxinresponseinnectariesunderanycircumstance,eveninolderflowersthatproducenectar.Cumulatively,ourfindingsindicateanessentialrolefortheoctadecanoidandauxinresponsepathwaysindependentofCOI1inregulatingnectarsecretion.Keywords:jasmonicacid;nectar,nectary,COI1Abstract#183.CytokininResponseFactorsareinvolvedinregulatingactive/inactivepoolsofcytokininunderstressconditions(Submission144)AaronRashotte1,Hallmark,H.Tucker,AuburnUniversity,Keshishian,ErikaA.,AuburnUniversity,Powell,RachelV.,AuburnUniversity,Dalis,Morgan,AuburnUniversity,Hughes,ArielM.,AuburnUniversity,Plačková,Lenka,FacultyofScienceofPalackýUniversity&InstituteofExperimentalBotany,Novák,Ondřej,FacultyofScienceofPalackýUniversity&InstituteofExperimentalBotany,Goertzen,LeslieR.,AuburnUniversity1AuburnUniversity,UnitedStates

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Cytokininisaplanthormoneknowntobeconnectedtoabioticstressresponse,yettherehasbeenlittleexaminationofhowcytokininlevelsarealteredinresponsetoenvironmentalstress.Wehaveexaminedchangesinbothcytokininlevels,viaLC/MS,andtranscriptomeprofiles,viaRNAseq,inthepresenceandabsenceofsaltandoxidativestresses.Thisallowedforcomparisonsbetweendifferentlevelsofcytokininconstituentforms(active,inactive,transportable)andtranscriptsconnectedtothecytokininbiosyntheticpathway.Wehaveidentifiedstressspecificchangesincytokininprofiles,withstrongalterationsinlevelsofN-andO-glucosideinactiveforms.Thesearemirroredbytranscriptchangesincytokininglucoslytransferasesgenes(UGT76C1,76C2,85A1)thatdirectlyregulatethemodulationfromactivecytokininformstoglucosideconjugatedinactiveforms.Importantly,wehavealsoexaminedthesecytokininlevelprofilechangesinArabidopsismutantsofthecytokininregulatedtranscriptionfactorsknownasCytokininResponseFactors(CRFs).OurfindingsrevealthatCRFshavespecificrolesinregulationofstressbasedchangesincytokininlevels.Undersalt(NaCl)stressconditionswefoundageneralincreaseinconjugatedcytokininlevels,whicharestronglyreducedunderthesameconditionsinacrf2mutant.Astherearenochangesincytokininprofileincrf2understandardconditionsthisindicatesthatCRF2isinvolvedinthesaltstressregulationofcytokinin.Incontrast,underoxidative(H2O2)stressconditionsthereweredecreasesincytokininlevels,whichareincreasedinthesameconditionsinbothcrf5andcrf6mutants.ThisindicatesthatCRF5andCRF6arelinkedtooxidativestressregulationofcytokininlevels.TogetherwithpreviousresultslinkingtheseCRFstoeachoftheiraboveexaminedstress,thissuggeststhatCRFsareinvolvedinregulationofstressbasedalterationsofcytokininlevels.Keywords:Cytokinin,CytokininResponseFactors,AbioticStress,CytokininGlucosyltransferasesAbstract#184.Delegatingdevelopment:specificityandredundancyofauxinreceptorsinmorphology(Submission170)MollyeZahler1,ClayWright,JenniferNemhauser1UniversityofWashington,UnitedStatesTheevolutionofcomplexbodyplansinlandplantshasbeenparalleledbygeneduplicationanddivergencewithinnuclearauxin-signalingnetworks.Adeepmechanisticunderstandingofauxinsignalingproteinsthereforemayallowrationalengineeringofnovelplantarchitectures.AuxinisperceivedbyacomplexconsistingofanF-boxprotein(TRANSPORTINHIBITORRESPONSE1/AUXINSIGNALINGF-BOXES,TIR1/AFBs),anauxinmoleculeandamemberofacoreceptor/transcriptionalcorepressorfamily(AUXIN/INDOLE-3-ACETICACIDPROTEINS,Aux/IAAs).InthemodelplantArabidopsisthaliana,theTIR1/AFBfamilyhassixmembers(TIR1andAFB1-AFB5).WhiletheAFBsarehighlysimilartooneanotherinsequenceandexpressionpattern,therearesomedifferencesinbiochemicalactivitiesmeasuredbyinvitroandinsyntheticaassays.Throughcloseanalysisofthemorphologyofmutants,wehaveuncoveredunevencontributionsofTIR1andAFB2intheregulationofleafdevelopment.WeareconductingamorethoroughexplorationoftherelationshipbetweenAFB2functionandleafphenotype,aswellasexaminingpotentialtunabilityofplantmorphologybyAFB2function.Wearealsoanalyzingtheleafphenotypesofmutantsinotherfamilymembers.Keywords:leafmorphology,development,auxin,F-box,paralogdivergenceAbstract#185.Network-BasedDiscoveryofBrassinosteroidRegulationofPlantGrowthandDroughtResponsesinArabidopsis(Submission173)YanhaiYin1,Nolan,Trevor,IowaStateUniversity,Chockalingam,Sriram,GeorgiaInstituteofTechnology,McNinch,Colton,IowaStateUniversity,Akintayo,Adedotun,IowaStateUniversity,Sarkar,Soumik,IowaStateUniversity,Aluru,Maneesha,GeorgiaInstituteofTechnology,Aluru,Srinivas,GeorgiaInstituteofTechnology,Schnable,Patrick,IowaStateUniversity1IowaStateUniversity,UnitedStatesUnderstandinggeneregulatorynetworksthatcontrolplantgrowthandstressresponsesisessentialtooptimizecropyieldinanever-changingenvironment.Brassinosteroids(BRs)regulateplantgrowthandstressresponses,includingthatofdrought.BRssignaltoregulatetheactivitiesoftheBES1/BZR1familytranscriptionfactors,whichinturnmediatetheexpressionofmorethan5,000BR-responsivegenes.RecentstudiesidentifiedseveralthousandBES1/BZR1targetgenesandabout500BR-relatedTranscriptionFactors(BR-TFs)thatlikelyfunctionalongwithBES1/BZR1toregulatethelargenumberofBRtargetgenes.AlthoughseveralfamiliesofBR-TFshavebeenfunctionallycharacterized,thenetworksthroughwhichBRs,BES1/BZR1andBR-TFsfunctionremaintobefullydefined.Toaddressthischallenge,webuiltacomprehensiveBRgeneregulatorynetwork(GRN)usingmorethan11,760publiclyavailablemicroarraydatasetsandprioritizedBR-TFsforfunctionalstudiesusingNEST(NetworkEssentialityScoringTool).TheANACfamilytranscriptionfactorswereamongthetoprankingBR-TFs,andourgeneticandgenomicstudiesdemonstratedthatANACfamilymembersinhibitBR-regulatedgrowthandpromotedroughtresponses,providinganimportantcrosstalkpointbetweenBRanddroughtresponsepathways(Yeetal2017,NatureCommunications).Further,weemployedphenomicsstudiesandidentifiedhundredsofBR-TFmutantsthatdisplayalteredBRresponses.ClusteringofBR-TFsbasedontheirpredictedtargetgenesshowedthatthe5toprankingTFswithstrongBRphenotypesaredistributedin3clustersthatareenrichedforBRanddroughttargetgenesandcontainthemajorityofBR-TFswithBRresponsephenotypes.GeneticandgenomicanalysisoftheseclustersisbeingusedrevealhowBR-TFsregulatespecificaspectsofgrowthandstressresponseprograms.ThisresearchissupportedbygrantsfromNSF(IOS1257631)andthePlantScienceInstituteatIowaStateUniversity.Keywords:brassinosteroid,generegulatorynetwork,genomics,drought,phenomics

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Abstract#186.TranslationRegulatorAtGCN2controlsABAHomeostasisandStomatalImmunityinArabidopsis(Submission185)XiaoyuLiu1,Pajerowska-Mukhtar,Karolina,UAB1UniversityofAlabamaatBirmingham,UnitedStatesInanimals,nutrientstarvationactivatestranslationalregulatorGCN2(GeneralControlNondepressible2),whichhasbeenimplicatedinestablishingadaptiveimmunityandmanipulatingdiseaseprogression.InArabidopsis,AtGCN2hasbeenidentifiedtophosphorylateeIF2αuponabioticstress,whiletheroleinplantimmunityremainsunclear.Here,wedemonstratethatpathogenchallengeactivatesAtGCN2,whichconsequentlyphosphorylateseIF2αtoreinitiatethetranslationofthetranscriptionfactorTBF1.Moreinterestingly,AtGCN2isessentialforTBF1-dependenttranscriptionalregulationofgenesthatareinvolvedinABAbiosynthesisandsignalingevents,whichcouldcontributetothediseaseresistancephenotypeoftheatgcn2mutant.SimilartoadditionaltranslationregulatorsAtGCN1andAtGCN20,AtGCN2positivelyregulatesMAMP-triggeredstomatalclosureandcoronatine-dependentstomatalreopening.Takentogether,bioticstressactivatesAtGCN2,whichexhibitsconservedfunctionbyregulatingtranslationalreinitiationandnovelfunctioninstomatalimmunity.Abstract#187.TowardstheDevelopmentofBiosensorsforidentificationofendogenousKAI2ligand(Submission189)AashimaKhosla1,Kapoor,Suraj,UniversityofGeorgia,Conn,Caitlin,UniversityofGeorgia,Nelson,David,UCRiverside1UniversityofCalifornia,Riverside,UnitedStatesTowardstheDevelopmentofBiosensorsforidentificationofendogenousKAI2ligandAashimaKhosla1,SurajKapoor2,CaitlinE.Conn2,DavidC.Nelson11DepartmentofBotany&PlantSciences,UniversityofCalifornia,Riverside2DepartmentofGenetics,UniversityofGeorgiaKarrikins(KARs)areafamilyofsmokederivedbutenolidecompoundsthatarerecognizedbythereceptorKAI2.Thereisnoevidencetodatethatkarrikinsarepresentinplants.Recently,workfromourlabandseveralothershasprovidedsubstantialevidencefortheexistenceofanunknown,endogenousligandofKAI2(KL).IdentificationoflowabundanceKLwillrequiresensitiveandhighlyspecificassays.PreliminaryexperimentfromourlabshowthatintobaccoSUPPRESSORofMAX21(SMAX1)proteinisrapidlydegradedfollowingKARtreatment.OurcurrentworkexaminestheutilityofkarrikintriggeredproteolysisofSMAX1asatooltoidentifyKL.ProgressinthedesignofquantitativeinvivobiosensorsforKAR/KLwillbepresented.Additionally,weareinterestedinidentifyinga“degron”domain(s)thatisnecessaryandsufficientforKAR-induceddegradationofSMAX1.Forthispurpose,variousSMAX1deletionvariantsweremadeandtestedforKARinduceddegradationintobacco.WewillpresentourresultssuggestingthattheC-terminalregionissufficientforligand-induceddegradation.SubsequentexperimentsaimedattestingitsinteractionwithArabidopsisKAI2andtrimmingdownthisregiontomakeamorerefineddegronareinprogress.IdentificationofdegronwillundoubtedlyaidindesigningbestsensorsthatareusefulforhighthroughputscreeningofcompoundlibrarytodetectKLandtostudyKLdistributionanddynamicsinvivo.Overall,weexpectthisworktoopennewresearchprospectsfortheplanthormonefieldandagriculturealike,asthediscoveryofKLmayrepresentanewphytohormone.Keywords:Karrikin,hormone,SMAXAbstract#188.UsingEthylmethanesulfonatemutagenesistoscreenforthesuppressorofBES1inArabidopsis(Submission193)HaoJiang1,Xie,Zhouli,IowaStateUniversity,Yin,Yanhai,IowaStateUniversity1IowaStateUniversity,UnitedStatesBrassinosteroids(BRs)regulateplantgrowthanddevelopmentinmanydifferentlevels,especiallytheseedlinghypocotylelongation.Brassinosteroidsareperceivedbythetrans-membranereceptorkinaseBRI1,andthenthroughseveralphosphatasesandkinasestoactivatetheBES1/BZR1familytranscriptionfactors.BES1gain-of-functionmutantbes1-Dshowedout-growthphenotypes,likelongerhypocotyl,curlyleafandelongatedleafpetiole.Theseedlingsofbes1-DareinsensitivetoBRbiosynthesisinhibitorBrassinazole(BRZ).Wefirstlytreatthebes1-DseedswithmutagenEthylmethanesulfonate(EMS),andthenscreenedforthesuppressorsofbes1-Dmutant,toidentifytheBRsignalingcomponentsdownstreamofBES1.Severalinterestingmutantswereidentified,andtheyallshowedincreasedsensitivitytoBRZinhypocotylelongationassayunderdarkcondition.TheyarealsomoresensitivetoBRbiosynthesisinhibitorPropiconazole(PCZ)whengrowninsoil.Thesuppressorswereback-crossedtobes1-D,andthenF1plantsself-crossedtogettheF2population.TheF2suppressorpopulationwillbepooledforthenextgenerationsequencingtodeterminethecasualmutationofthebes1-Dsuppressorphenotype.Keywords:EMSscreening,Brassinosteroids,

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Abstract#189.Semi-rationaldesignofabiosensorforthedirectvisualizationofauxin(Submission196)OleHerud1,Stiel,Andre,MaxPlanckInstituteforDevelopmentalBiology,Tübingen,Germany;HelmholtzZentrumMünchen,München,Germany,Höcker,Birte,MaxPlanckInstituteforDevelopmentalBiology,Tübingen,Germany;UniversitätBayreuth,Bayreuth,Germany,Jürgens,Gerd,CenterforPlantMolecularBiology,UniversityofTübingen,Tübingen,Germany;MaxPlanckInstituteforDevelopmentalBiology,Tübingen,Germany1MaxPlanckInstituteforDevelopmentalBiology,GermanyThesmallmoleculeauxinisamajormorphogeninplants.Itisindispensablefororganinitiation,tropicgrowthresponsesandcell-cyclecontrol.HerewereporttheengineeringofaFRET-basedbiosensorforauxinbyredesigningthebindingpocketoftheE.colitryptophanrepressor.Thissensorenablesustovisualizeauxindirectlyandwithhightemporalandspatialresolution.Traditionallyauxinlocalizationisinferredfromtheexpressionofreportergenesunderthecontroloftheauxin-induciblepromoterDR5.Thepresenceofreportersignalisusuallyreferredtoasanauxin-responsemaximum,anditisassumedthateachreporter-signalmaximumrepresentsalocalauxinmaximum.Quantitativemeasurementsindicatethatthisisnotnecessarilythecase.WeemployedthesimilaritiesbetweenauxinandtryptophantodevelopanauxinsensorbasedonFörsterresonanceenergytransfer(FRET)bysemi-rationalredesignofanestablishedtryptophansensor.WeimprovedtheIAAbinding,diminishedthebindingtoIAA-relatedmolecules,optimizedthefluorophorepair,andimprovedthelinkersbetweenthesensorydomainsandthefluorophores.Thefinalversionexhibitsa3-foldchangeoftheFRETratioupontreatmentwith50µMIAA,whichwasshowntobetheupperlimitoftheIAAconcentrationinrootsinferredfromrootprotoplasting.AsafirststeptoconfirmthefunctionalityoftheIAAsensorinplanta,weexpressedthesensortransientlyinArabidopsisprotoplastsandshowedthatthesensorisfunctionalinplanta.Withplantsstablyexpressingthesensorwemonitorthefastuptakeandclearanceofauxinbytheplantatanunprecedentedtimescale.Thesensorallowsthedynamicvisualizationofauxindistributionpatternspreviouslyinaccessibleforgeneticsandbiochemistrythusincreasingourunderstandingofamajordevelopmentalregulatorduringthelife-cycleoftheplant.Keywords:Auxin;Biosensor;Proteindesign;FRETAbstract#190.Theimpactofpromoterarchitectureonauxin-mediatedtranscription(Submission216)AmyLanctot1,Khakhar,Arjun,DepartmentofBioengineering,UniversityofWashington,Seelig,Georg,DepartmentsofElectricalEngineeringandComputerScience&Engineering,Nemhauser,Jennifer,DepartmentofBiology,UniversityofWashington1UniversityofWashington,UnitedStatesTheplantgrowthhormoneauxindrivesmanydistinctdevelopmentalprocesses.Howasinglehormoneleadstosuchdiversityindownstreamresponseshasbeenalong-standingquestion.Weproposethatonecriticalfactorinthisdiversityistheinteractionsbetweendifferentauxinresponsetranscriptionfactors(ARFs)andthepromotersofauxin-responsivegenes.WehaveportedtheauxinresponsepathwayintoyeastandcanmeasuretranscriptionalactivationonpromotervariantsbyARFsusingflowcytometry.Ourresultsshowthatchangingthenumber,sequence,spacing,ororientationofauxinresponseelementsinapromotersequenceaffectstranscriptioninpredictableways.WealsofoundthatdifferentARFsshowpreferencesfordistinctpromotersequences.Currently,wehavescaledupthisapproachtocharacterizeARFactivityonyeastlibrariesofrandomizedpromotervariants.ThedatacollectedfromthisapproachwillbeusedinacomputationalpipelinerelyingonneuralnetworkbasedmachinelearningtogeneratepredictivemodelsofARFaction.Keywords:transcriptionalregulation;auxinsignaling;syntheticbiologyAbstract#191.Brassinosteroidregulationofvasculardevelopment:acell-type-specifictranscriptomicapproach(Submission222)IsabelBetegon1,Lozano-Elena,Fidel,CRAG,Gonzalez-Garcia,MaryPaz,CNB,Benfey,Philip,DukeUniversity,Caño-Delgado,Ana,CRAG1CRAG,SpainBrassinosteroid(BR)hormonesareimportantregulatorsofplantgrowthanddevelopment.TheroleofBRsinvascularandstemcelldevelopmentinArabidopsisthalianaisanemergingtopicinhormonesignaling,whereasthespecificmolecularmechanismsthatcontrolthosebiologicalprocessesareonlystartedtobeelucidated(Fàbregasetal.,2013;González-Garcíaetal.,2011).Tounderstandthemolecularbasesofvasculardevelopment,weperformedcell-type-specifictranscriptomicstoidentifytheBR-regulatedgeneswithinthedifferentvasculartissuesintheArabidopsisroot.Genome-wiseexpressionanalyseswerespatiotemporallyevaluatedusingatime-courseexperimentinresponsetoBRs.Wegeneratedatranscriptionalnetworkthatcontrolvasculardevelopmentinthestele.Inaddition,theBR-responseswereanalysedseparatelyinfourdifferentvascularcelltypestofinelydeciphertheroleofBRsineachvascularlineage.ThestudyoftheBR-regulatedgenesinthestelesuggestsapredominantfunctionofBRsinprovascularcelldivisionandcellwalldifferentiation.BothtraitswereconfirmedphenotypicallybytheanalysisofsteleandxylemmorphologyinBR-relatedmutantsandindicatethatBRsignaling,throughBRI1receptor,controlpericlinalcelldivisionandxylemdifferentiationintheroot.Ourcell-type-specifictranscriptomicdatarevealeddifferentfunctionofBRsinprovascularandvasculartissues.Currently,wearecarryingoutthefunctionalcharacterizationofseveralvascularcell-specificBRcomponentsidentified.Fàbregasetal.,2013.Thebrassinosteroidinsensitive1-like3signalosomecomplexregulatesArabidopsisrootdevelopment.PlantCell.25(9):3377-88González-Garcíaetal.,2011.BrassinosteroidscontrolmeristemsizebypromotingcellcycleprogressioninArabidopsisroots.Development.138:849-59Keywords:Brassinosteroids,root,Arabidopsis,vasculartissue,transcriptomic

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Abstract#192.ArabidopsisWRKY46,WRKY54andWRKY70TranscriptionFactorsAreInvolvedinBrassinosteroid-RegulatedPlantGrowthandDroughtResponse(Submission232)JianiChen11IowaStateUniversity,UnitedStatesPlantsteroidhormones,Brassinosteroids(BRs),playimportantrolesingrowthanddevelopment.BRsignalingcontrolstheactivitiesofBES1/BZR1transcriptionfactors.Inadditiontotheroleinpromotinggrowth,BRsalsoplayaroleinresponsetodroughtstress.However,littleisknownaboutthemolecularmechanismthroughwhichBRsregulatedroughtresponse.Ontheotherhand,althoughtherolesofWRKYtranscriptionfactorsinstressresponsesarewelldocumented,theirfunctionsinBR-regulatedplantgrowthhavenotbeenestablished.Here,wefoundthreegroupIIIWRKYtranscriptionfactors,WRKY46,WRKY54andWRKY70,areinvolvedinbothBR-regulatedplantgrowthanddroughtresponseasthewrky46wrky54wrky70triplemutanthasdefectsinbothBRbiosynthesisandsignaling,andismoretoleranttodroughtstress.RNA-seqanalysisrevealedglobalrolesofWRKY46,WRKY54andWRKY70inpromotingBR-mediatedgeneexpressionwhileinhibitingdrought-responsivegenes.WRKY54directlyinteractswithBES1tocooperativelyregulatetheexpressionoftargetgenes.Also,WRKY54isphosphorylatedanddestabilizedbyGSK3-likekinaseBIN2,anegativeregulatorintheBRpathway.OurresultsthereforeestablishWRKY46/54/70asimportantsignalingcomponentsthatarepositivelyinvolvedinBR-regulatedgrowthandnegativelyinvolvedindroughtresponses.Keywords:crosstalkofhormonesignalinganddroughtstressAbstract#193.TheclathrinadaptorENTHregulatesplasmamembraneproteinabundanceforeffectivehormoneefflux(Submission236)EricaLaMontagne1,Collins,Carina,UniversityofMissouri,Anderson,Jeff,UniversityofMissouri,Peck,Scott,UniversityofMissouri,Strader,Lucia,WashingtonUniversityinSt.Louis,Heese,Antje,UniversityofMissouri1UniversityofMissouri,UnitedStatesPlantgrowthandproductivityhaveaprofoundimpactonourfoodsupply.Theplanthormoneauxindrivesgrowthbymediatingcelldivisionandexpansion.Forpropergrowthanddevelopment,internalcellularlevelsofauxin(indole-3-aceticacid;IAA)anditsstorageform,indole-3-butyricacid(IBA),mustbetightlyregulated.TomaintainappropriateintracellularlevelsofIBA,plantsrelyontransporterstobeattheircorrectsubcellularlocation,theplasmamembrane(PM),toeffectivelyeffluxIBA.ProperPMlocalizationandabundanceofIBAtransportersisdependentonafunctionalvesiculartraffickingnetwork;butfewvesiclecomponentsareknownthatregulatePMabundanceofIBAtransporters,whichappeartorequirevesiclecomponentsdistinctfromthosetraffickingthePINauxintransporters.Here,weusedlarge-scalequantitativeproteomicsofenrichedPMtoidentifyanovelrolefortheclathrinadaptorproteinENTHinregulatingPMabundanceoftheIBAtransporterPleiotropicDrugResistance9/ATPBINDINGCASSETTEG37(PDR9/ABCG37),previouslyshowntobepredominantlyexpressedintheoutermostsidesofrootcapandepidermalcells.LossofENTHresultedinreducedPMabundanceofPDR9inroots,whichcorrelatedwithIBAresponsedefectsreminiscentofthoseobservedinpdr9-2nullmutants.Thus,ourworkexpandsthelimitedknowledgeofvesiclecomponentsthathelpregulatecorrectaccumulationofIBAtransportersatthePMtoensureproperplantgrowthanddevelopment.Keywords:indole-3-butyricacid(IBA);transporters;vesicletrafficking;plasmamembrane;rootsAbstract#194.IdentificationofauxinpathwaycomponentsinrootsystemdevelopmentusingGWAS(Submission245)TakehikoOgura1,Goeschl,Christian,GMI-GregorMendelInstitute,Filiault,Daniele,GMI-GregorMendelInstitute,Busch,Wolfgang,GMI-GregorMendelInstitute1GMI-GregorMendelInstitute,AustriaTheplanthormoneauxinregulatesnumerousdevelopmentalprocessesofrootsthatconsequentlyshapethetotalstructureofrootsystem(RootSystemArchitecture:RSA).RSAdefinesthemaininterfaceofplantscopingwiththemanychallengesindifferentsoilenvironments.Itisthereforeoneofthemostimportantplanttraits.However,duetotheundergroundlocalizationofroots,thecomplexityandplasticityofRSA,studyingitisdifficult.Inaddition,whileauxinobviouslycontributestotheregulationofmanyaspectsofRSA,theinvolvementofauxininawide-rangeofdevelopmentalprocessesmakesitdifficulttostudyanddissectthemolecularbasisofitsrolesinRSAformation.Especially,fewstudieshavereportedgenesthatharmonizeauxinfunctionsinbasicrootgrowthprocessesincludingtheregulationofrootelongation,branchingandgravitropismtomakethemodificationofRSAavailable.Toidentifysuchgenes,weusednaturalvariationinArabidopsisthalianaandconductedaGenomeWideAssociationStudy(GWAS)upontheperturbationofauxintransportusinganinhibitorNPA.OurGWASidentifiedamemberofanexocytoticgenefamily,EXOCYST,tobeassociatedwitharootgravitropism-relatedtrait.WeshowedthatthisEXOCYSTgeneexclusivelyregulatesthedynamiclocalizationoftheauxineffluxcarrierPIN-FORMED4incolumellacells,andtherebycontrolsthequicknessofrootgravitropicresponses.Furthermore,naturalvariationoftheEXOCYSTgenewasassociatedwiththevariationinRSAanddroughtresistance,indicatinganadaptivevalueindroughtconditions.Alltogether,ourstudyusingGWASrevealedanauxinpathwaycomponentthatregulatesrootmorphologyandconfersvariationintherootgrowth.

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Keywords:Auxin;Rootgrowth;Rootgravitropism;naturalvariation;GenomewideassociationmappingAbstract#195.Auxin-activatediontransportbyABCB4andPIN2proteinsrequiredforpolarauxintransportinArabidopsis(Submission253)EdgarSpalding1,StephenDesLauriers1UniversityofWisconsin,UnitedStatesAuxinistransportedthroughplanttissuesbyamechanismthatstrictlydependsonATP-bindingcassetteB(ABCB)andPIN-FORMED(PIN)proteinsattheplasmamembrane.MostpeoplebelievethatABCBandPINproteinstransporttheauxinmoleculeacrosstheplasmamembrane,aviewthatislargelybasedonhowmuchradioactiveauxinisretainedincellsengineeredtoexpressoneorbothoftheproteinsandhowmuchescapesovertime.Theinabilitytocontrolforfundamentalthermodynamicparametersisaweaknessoftheseretentionassays.Electrophysiologicalmethodscanmoredirectlytesttransportactivitiesamembraneproteincatalyzesthanradioactivityretentionassays.WeusedthepatchclamptechniquetodemonstratethatArabidopsisABCB4andPIN2proteins,expressedseparatelyortogetherinhumanembryonickidneycells,conductedCl-preferentiallyoverCs+inthemannerofavoltage-independentchannel.AuxinonthecytoplasmicsideofthemembranesignificantlyactivatedABCB4channelactivity.Theactivitywascompletelyblockedbytheanionchannelblocker5-nitro-2-(3-phenylpropylamine)-benzoicacid(NPPB).NPPBblockedpolarauxintransportinArabidopsisrootsandagravitropismresponsethatdependsonpolarauxintransport.Promotionbyauxinofanactivityrequiredforauxintransportwouldcontributetothemacroscopicphenomenonofcanalization.Reversalpotentialanalysisdidnotdetecttransportoftheauxinanionbyeitherproteinortheircombination.Presumablyauxinistransportedataratethatcouldnotbedetected.TheonlyindicationsthatABCB4andPIN2interactwerealowdegreeofFörsterresonanceenergytransferbetweenthem,andinhibitionofABCB4byPIN2athighauxinconcentrations.Gravitropismphenotypesindicatedtherespectiveproteinsfunctionindependently.Aregulatorymechanismthatcontributestocanalizationandestablishestheauxinpatternresponsibleforgravitropismisproposed.Keywords:auxintransport;PIN2;ABCB4;electrophysiology;ionchannelsAbstract#196.ChemicalgeneticdissectionofsalicylicacidsignalinginArabidopsisthaliana(Submission303)VivekHalder1,Ninck,Sabrina,UniversityofDuisburg-Essen,Germany,Krahn,JanHenrik,UniversityofDuisburg-Essen,Germany,Bhandari,Deepak,MaxPlanckInstituteforPlantBreedingResearch,Germany,Kombrink,Erich,MaxPlanckInstituteforPlantBreedingResearch,Germany,Kaiser,Markus,UniversityofDuisburg-Essen,Germany1MaxPlanckInstituteforPlantbreedingResearch,GermanyByusingaforwardchemicalgeneticscreenwith1370well-annotatedchemicalsandanovelGUSassayonintactArabidopsisPR1p::GUSseedlings,wefoundtwofunctionalagonistsofsalicylicacid(SA)namelyPmE(rhizobacterialcycliclipopeptide)andKI1(proteinkinaseinhibitor).TheyunravelednovelmechanismsforPR1andSA-signalinginArabidopsis.PmEincreasedSAlevelsandshowedseveraluniquefeaturesasitworkedindependentofkeySA-signalingcomponentsICS1,EDS1andNPR1toinducePR1anddefenseagainstPseudomonassyringaepv.tomatoDC30000(PstDC3000).Surprisingly,thoughanantibioticPmEwasnon-cytotoxictoCol-0plantsandsuppressedthreeotherphysiologicalevents:primaryrootgrowth,jasmonate-signaling,andreactiveoxygenspecies(ROS)induction.Suchbioactivitywasdependentonitslipidchainandcationicpeptide-ring.FollowingstudiesshowedthatPmEworksviaphosphorylatingaunique46kDa(ap38-like)proteinkinase,pharmacologicalinhibitionofwhichsuppressesthebiologicaleffectsofPmE.Theseresultsthusshownovelrolesofap38-likekinaseindefensegeneregulation.ThesecondprobeKI1increasedtotalSA-levelsbutunlikePmE,KI1wasdependentofICS1andNPR1toupregulatePR1anddefenseagainstPstDC3000.Selectively,itdidnotinterferewithothermajorphytohormonalpathwaysandROSlevels.AsKI1wasknowntomakecovalentbondswithitsproteintargetinanimals,wemadeclick-taggedprobesofKI1foranaffinitybasedpulldowncoupledtoproteomics.Remarkably,wefoundanepoxidehydrolase(EH)isoformasKI1’sinvivotargetwhichshowedaninvitroepoxidehydrolaseactivity.LossofKI1bioactivityintheEHmutantfurtherconfirmedourfindings.AddedcharacterizationlaterputEHupstreamofSID2andindicateditsroleinICS1transcription.Thesefindingsreveal,forthefirsttime,adirectroleofanEHisoforminSA-signaling,whichwassofarunknownandongoingstudieswillushernovelinsights.Keywords:ForwardChemicalGenetics,Smallmolecules,Chemicalscreening,Salicylicacid,JasmonicacidAbstract#197.InvestigatingSMAX1DegradationintheKarrikinSignalingPathway(Submission323)NicholasMorffy1,LionelFaure,SurajKapoor,DavidNelson1UniversityofGeorgia,UnitedStatesThetimingofseedgerminationiscrucialtoaplant’ssuccess.Arecentlyidentifiedclassofsignalingmoleculesfoundinsmoke,karrikins(KAR),havebeenshowntobepotentgerminationstimulants.GeneticstudieshaveidentifiedsomeofthegenesresponsibleformediatingKARresponsesincludingMAX2,anF-boxprotein,KAI2,theputativeKARreceptor,andSMAX1,anegativeregulatorofKARresponsesthatinhibitsgermination.ItiscurrentlyunknownhowKARsregulateSMAX1andinducegermination.Interestingly,strigolactones(SL),endogenousplanthormonesthatregulateanumberofgrowthprocessesincludingshootbranching,sharesomecomponentswithKARsignaling.MAX2isrequiredforbothKARandSLsignaling,andtheSLreceptor,D14,isaparalogofKAI2.SMXL6,SMXL7,andSMXL8,paralogsofSMAX1,actasnegativeregulatorsofSLsignaling.InSLsignaling,thehormonestimulatesthedegradationofSMXL6andSMXL7inaMAX2andD14-dependentmanner,leadingtoSLresponses.RecentlyitwasalsoshownthatSMAX1isdegraded

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inresponsetoKARwhenexpressedundertheSMXL5promoter.WehypothesizethatKARsstimulatethedegradationofSMAX1inaMAX2andKAI2-dependentmanner.InordertotestthecontributionsofMAX2andKAI2toKARinducedSMAX1degradation,wehaveutilizedanumberofcomplementaryapproachesincludingtransientexpressioninNicotianabenthamianaleavesandinArabidopsisthalianamesophyllprotoplasts,invitrodegradationwithrecombinantSMAX1,andArabidopsistransgeniclinesexpressingGFP-taggedSMAX1inseveralgeneticbackgrounds.Keywords:Karrikins;hormonesignaling;strigolactones;germination;proteindegradationAbstract#198.QuantitativeanalysisofethyleneresponseinArabidopsisthalianamutantsusinginfraredimaging(Submission324)DavidBullock1,AnnaStepanova,JoseAlonso1NorthCarolinaStateUniversity,UnitedStatesEthyleneisagaseousphytohormoneinvolvedinmultipleaspectsofplantgrowth,development,senescence,andstressresponse.Seedlingsgerminatedinthedarkinthepresenceofethyleneundergocharacteristicphenotypicchangesknownasthetripleresponse.Thethreeelementsofthisresponsearetheradialexpansionandgrowthinhibitionofhypocotylsandrootsandanexaggerationoftheapicalhookcurvature.Atthemolecularlevel,thedevelopmentaleffectsofethyleneareaccompaniedbymajorchangesingeneexpressionatbothtranscriptionalandtranslationallevels.Whiletranscriptionalregulationiswellestablishedasakeyprocessinresponsetoethylene,littleisknownabouttheroleofethylene-triggeredgene-specificregulationoftranslation.Throughribosomalfootprinting,ourgroupuncoveredakeymolecularmechanismthatlinksethyleneperceptiontotheactivationofanovelgene-specifictranslationalcontrolmechanism.Characterizationofoneofthetargetsofthistranslationalregulation,EBF2,indicatedthatthesignalingmoleculeEIN2andthenonsense-mediateddecayproteinsUPFsplayacentralroleinthisethylene-inducedtranslationalresponse,settinganewparadigmofgene-specifictranslationalcontrol.Thegoalofmyprojectistotesttheroleofadditionalcandidategeneswhosetranslationalefficiencyisaffectedbyethylene.IamcharacterizingT-DNAknockoutscorrespondingtoethylene-responsivetranslationaltargetsandstudyingtheirrespectivegrowthkineticsthroughagrowthresponsekineticassay.Thisassayreliesonaninfraredliveimagingsystemtomonitorsubtlechangesintheratesofelongationinhypocotylsandrootsofdark-grownseedlingstransientlyexposedtotheethylenegas.Inparallel,Iamalsoexploringchangesinthehypocotylandrootelongationinpreviouslycharacterizedethylene-andauxin-insensitivemutants.Auxinisanothervitalplanthormonethatcontrolsnumerousprocessedinplant’slifecycle,fromembryodevelopmenttofruitripening.Remarkably,auxinbiosynthesis,transport,andsignalingareknowntobeinterconnectedwiththeethylenebiosynthesisandsignalingpathway.Thus,mutantplantswithdefectsinauxinalsoshowphenotypicdeviationsintheirresponsetoethylene.Myplanistotestasetofpreviouslycharacterizedauxinmutantsregardingtheirkineticresponsestoethylenetodeterminewhichstagesoftheethyleneresponseandrecoveryarecompromised.Thus,myprojectisexpectedtoexpandourlimitedknowledgeofethylene-triggeredtranslationalregulationandfurtherilluminatetheroleofauxininresponsetoethylene.Keywords:Liveinfraredimaging;Ethylene;Auxin;Planthormones;Abstract#199.InvestigatingIBAinflux(Submission335)ImaniMadison1,Powers,Samantha,WashingtonUniversityinSt.Louis,Strader,Lucia,WashingtonUniversityinSt.Louis1WashingtonUniversityinSt.Louis,UnitedStatesAuxinsregulatemanyaspectsofplantdevelopment,includingrootandstemelongationandleafepinasty,embryoandleafpatterning,roothaircellelongation,andlateralrootproduction.Tightly-regulatedauxinhomeostasisallowsplantstorelaygrowthsignalsinahighlyspecificandcoordinatedmannersothattheycanadjusttosubtleenvironmentalchanges.Indole-3-butyricacid(IBA),isanauxinprecursorthatcanbeshuttledbetweenplantcellsandbequicklyconvertedintoindole-3-aceticacid(IAA),anactiveauxin,andtriggercellgrowth.However,bothIBAandIAAinhibitgrowthiftheyhyperaccumulateinplantcells.Thus,understandingauxinhomeostasisnotonlyreliesonunderstandingIAAtransport,whichhasbeenwidelystudied,butalsoIBAtransport.SincesomeIBAeffluxcarriershavealreadybeenidentifiedasPLEIOTROPICDRUGRESISTANCE8/PEN3-4/ABCG36,wehaveundertakentounderstandIBAinfluxbywayofanabcg36mutantsuppressorscreeninArabidopsisthaliana.WechosetostudyEMS-mutagenizedabcg36(defectiveIBAefflux)individualsthatareIBA-resistant,quantifiedbymeasurablylongerroots,asindicatorsofIBAinfluxsincetheydonotappeartobehyperaccumulatinginhibitorylevelsofIBA,indicatingthatIBAinfluxhaslikelybeendisruptedalongsidetheoriginaldefectinIBAefflux.ThechosenlinesalsoexhibitedresistancesolelytoIBA,andIBA-resistancepersistedthroughthetwogenerationstestedafterbackcrossing.WewilldiscusstheresultsfromthesuppressorscreenandlinkgeneticinformationfromthelinesdiscoveredtoIBAinfluxandauxinhomeostasis,whichwillprovideaplatformfromwhichdefinitiveinformationaboutIBAinfluxtransportcandevelopinthefuture.Keywords:IBAinflux,Arabidopsisthaliana,suppressorscreen

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Abstract#200.IntegratorsofagronomicallyimportantsignalingpathwaysidentifiedinasystematicArabidopsisphytohormonenetworkmap(Submission343)PascalFalter-Braun1,Altmann,Melina,InstituteofNetworkBiology,HMGUMunich,Altmann,Stefan,InstituteofNetworkBiology,HMGUMunich,Panda,Gurudutta,InstituteofNetworkBiology,HMGUMunich,Palme,Julius,InstituteofNetworkBiology,HMGUMunich,Marin,Nora,InstituteofNetworkBiology,HMGUMunich1InstituteofNetworkBiology(INET)-HelmholtzZentrumMünchen,GermanyPhytohormonesplayacriticalroleinintegratingenvironmentalcueswithinternaldevelopmentalprogramstoensuresurvivalandreproductivesuccessandthusalsoagronomicproductivity.Understandinghowdifferenthormonesignalsareintegratedintoanoptimalphysiologicalresponseiscriticalforunderstandingthemolecularmechanismsregulatingagriculturalyieldandyieldstability.Protein-proteininteractionsplaycentralroleintransducingandintegratingdiversesignalingpathways.Whileprinciplesofplantsignaltransductionhavebeenrevealedoverthepastdecades,asystemsperspectiveisstillmissingandmanycomponentsmediatingsignaltransductionandcrosstalkremaintobediscovered.InthisprojectwemaptheArabidopsisphytohormonesignalingnetworkbysystematicyeasttwo-hybridprotein-proteininteractionanalysisof1.200proteinswithalikelyorgeneticallydemonstratedroleonphytohormonesignaling.Interactionsweremappedamongtheseandofthe1.200with13.000proteinsintheA.t.ORFeomecollection.Thenetworkisextensivelyvalidatedusingbiophysicalandfunctionalassays.GraphtheoreticanalysisoftheresultingPhyHormNet_v1revealshormone-specificnetworkcommunitiesthatshowamuchhigherinter-pathwayconnectivitythantheknownliteraturenetwork.Integrationofnovelhormone–dependentinteractionpartnersofphytohormone-receptorswithtranscriptionfactortargetsfortranscriptionalco-repressorsisusedtoidentifyhithertounknownstressresponsepathwaysandintegrationpoints.InteractioncontextualizationandnetworkdynamicshavebeenanalyzedbyintegratingthePhyHormNetreferencenetworkwithtranscriptionaldynamicsofitscomponentstofocusfunctionalassignmentandgeneticvalidationexperiments.FollowingintegrationwithLCItheresultingnetworkcoversthemajorityofinteractionsamongphytohormonesignalingproteinsandisamongthemostcompletenetworkmapsproducedtodate.Keywords:abioticstress,immunity;cross-talk;network,signalingAbstract#201.Cytokininsignalingandmisfoldedproteinaccumulationinthemodelplant,Arabidopsisthaliana(Submission348)SumuduKarunadasa1,Kurepa,Jasmina,UniversityofKentucky.,Smalle,Jan,UniversityofKentucky.1UniversityofKentucky,UnitedStatesAsinanimalcells,toxicmisfoldedproteinaggregationoccursinplantswhenexposedtostressconditions.Tosurviveinthesestressconditions,plantsmodulatedevelopmentalprocessesthroughacomplexhormonalinterplay.Recentdatahaveshownthatplantcytokininlevelsareimportantinmodulatingthedroughtrelatedphenotypesofplantsandotherresponsestovariousstressconditions.Althoughcytokininregulationandplantstressresponseshavebeenthefocusofmanystudies,therelationbetweencytokininsignalingandmisfoldedproteinaccumulationremainstobeuncovered.Theobjectivesofthisstudyaretodetermine1)thesensitivityofcytokinin-relatedmutantandtransgeniclinestodifferentantibioticsthatpromotemisfoldedproteinaccumulation.2)themisfoldedproteinlevelsincytokinin-relatedlinesinthepresenceofantibioticsthatcauseproteinmistranslation.3)theproteintranslationratesincytokinin-relatedplantlines.DifferenttransgenicplantlineswithincreasedactivityofthecytokininresponseactivatorARR1,wereassessedinthepresenceofdifferentaminoglycosideantibiotics,whichareknowntoaffectprokaryoticproteintranslation.Sinceplantorganellarproteintranslationisprokaryoticinnature,theseantibioticsaffectbothchloroplasticandmitochondrialproteintranslation.ARR1gainoffunctiontransgenicsshowedahighersensitivitytoantibioticslikekanamycinthatpromotestheformationofaberrantproteins.Ontheotherhand,ARR1gainoffunctionmutantsshowedatolerancetoaminoglycosideswhichinhibitproteinsynthesiswithoutcausingmistranslationandthusmisfoldedproteinaccumulation(eg:spectinomycin,lincomycin).Thissuggeststhatincreasedcytokininactionpromotesplantorganellarproteinsynthesisrateswhichinturnpromotesmisfoldedproteinaccumulationunderstressconditions.Keywords:Cytokininsignaling;ARR1;misfoldedproteins;antibioticsAbstract#202.TheRolesofAuxinandCytokininSignalingintheOnsetandMaintenanceofCambiumActivityinArabidopsisRoot(Submission352)TiinaBlomster1,Siligato,Riccardo,UniversityofHelsinki,Růžička,Kamil,CentralEuropeanInstituteofTechnology,MasarykUniversity,Mähönen,AriPekka,UniversityofHelsinki1UniversityofHelsinki,FinlandTheRolesofAuxinandCytokininSignalingintheOnsetandMaintenanceofCambiumActivityinArabidopsisRootTiinaBlomster1,2,RiccardoSiligato1,2,KamilRůžička3andAriPekkaMähönen1,2*1)InstituteofBiotechnology,UniversityofHelsinki,Helsinki,FI-00014,Finland.2)DivisionofPlantBiology,DepartmentofBiosciences,UniversityofHelsinki,Helsinki,FI-00014,Finland.3)DepartmentofFunctionalGenomicsandProteomics,CentralEuropeanInstituteofTechnology,MasarykUniversity,Brno,CZ-62500,CzechRepublic.*Correspondence:aripekka.mahonen@helsinki.fiAuxinandcytokininsignalingpathwaysgovernmanyaspectsofplantdevelopmentandphysiology,includingprimarypatterningofrootvasculatureandcambiumactivity.SeveralmechanismsofauxinandcytokininsignalinginteractionhavebeenidentifiedintheestablishmentoftheArabidopsisrootprimaryvascularpatternconsistingofacentralxylemaxisflankedbytwophloempoles,andtheinterveningprocambialcelllayers.However,thephysiologicalandmolecularmechanismsleading

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totheactivationofsecondarygrowthmarkedbypericlinal(pro)cambialcelldivisionsapproximatelyfivedaysaftergerminationarepoorlyknown.Ourdatashowthatprocambialcellsarecompetentfortheactivationofsecondarygrowthbyauxinandcytokininsincethefirstdaysaftergermination,andbothhormonesarerequiredforcambiumactivation.Duringcambiumactivation,auxinandcytokininresponsesoverlapincambialcells,andcytokininsignalingupregulatestheauxinresponse.Furthermore,inhibitionofcambiumactivationbytheestradiol-inducibleexpressionofauxinresistant3-1(axr3-1),adominantnegativeregulatorofauxinsignaling,canberelievedbycytokinintreatment.Consistentwiththephenotypesobtainedduringcambiumactivation,transcriptionalprofilingresultsshowthatexpressionofseveralcambialmarkergeneswasdecreasedbyaxr3-1induction,increasedbycytokininandintermediateexpressionwasobservedinthecombinedtreatment.Insummary,wefindbothauxinandcytokininactingaspositiveregulatorsofrootcambiumactivationinasynergisticmanner.Furtherdataanalysistogetherwithtime-coursestudieswillhelptounravelthemolecularmechanismsunderlyingthisphytohormonalregulationofsecondarygrowth.Keywords:Auxin;cytokinin;cambium;rootsecondarydevelopmentAbstract#203.InvestigatingtheRoleofProteinMultimerizationinARFTranscriptionFactorActivity(Submission358)SamanthaPowers1,Korasick,David,WashingtonUniversityinSt.Louis,Holehouse,Alex,WashingtonUniversityinSt.Louis,Schreiber,Katherine,WashingtonUniversityinSt.Louis,Pappu,Rohit,WashingtonUniversityinSt.Louis,Jez,Joseph,WashingtonUniversityinSt.Louis,Strader,Lucia,WashingtonUniversityinSt.Louis1WashingtonUniversityinSt.Louis,UnitedStatesThehormoneauxinplaysacrucialroleinnearlyeveryaspectofplantgrowthanddevelopmentbycontrollingcellexpansionanddivision.Inplants,theAUXINRESPONSEFACTOR(ARF)familyoftranscriptionfactorsregulatesauxin-responsivegeneexpressionandexhibitnuclearlocalizationinregionsofhighauxinresponsiveness;however,ourdatasuggestthatactivatingARFproteinsformbiomolecularcondensatesinthecytoplasmoftissueswithdecreasedauxinresponsiveness,suggestingamodelinwhichARFnucleo-cytoplasmicpartitioningplaysaroleinmediatingcellularcompetenceforauxinresponse.WehaveidentifiedrolesfortheintrinsicallydisorderedmiddleregionandelectrostaticPB1domainofARFproteinsindrivingtheformationofthesecondensates.MutationofasinglelysineresiduewithinthePB1domainissufficienttoallowARFlocalizationtothenucleusinalltissuetypes,resultinginmorphologicaldefectsandalteredtranscriptionalauxinresponsivenessintheplant.Incombination,thesedatasuggestamodelinwhichARFnuclear-cytoplasmicpartitioningissufficienttoregulateauxintranscriptionalresponsivenessindifferenttissuesoftheplant.Abstract#204.InvestigatingtheroleofoxidizedJAinplantgrowthanddefenseresponse(Submission373)AratiN.Poudel1,AbrahamJ.Koo1UniversityofMissouri,Columbia,UnitedStatesPlanthormonejasmonicacid(JA)controlsimmuneresponseagainstinsectsandregulatesplantdevelopment.Uponsynthesis,JAismetabolizedintoavarietyofderivativesincludingjasmonoyl-isoleucine(JA-Ile)whichistheknownendogenousbioactiveformofJAresponsibleforJAmediatedresponses.Incontrasttothewell-studiedfunctionsofJA-Ile,biologicalfunctionsofotherJAmetabolitesarelessclear.12-hydroxy-JA-Ile(12OH-JA-Ile)accumulatesinresponsetotissueinjuriesandisadownstreammetaboliteofJA-Ileinitsw-oxidativecatabolicpathway.Arabidopsisseedlingstreatedwith12OH-JA-IlestronglyaccumulatedanthocyaninandwerealsoincreasedinleaftrichomecellnumberstothelevelscomparabletothatinducedbyJA-Ile.Bothareanti-herbivoryfeaturesknowntoberegulatedbyJA-Ile.Inaddition,expressionofseveralJA-Ileresponsivemarkergeneswasupregulatedby12OH-JA-Ile.MutationinCORONATINEINSENSITIVE1(COI1)blocked12OH-JA-Ileeffectonanthocyaninandtrichomeinduction,indicatingthat12OH-JA-IlesignalsthroughthecommonreceptorandsignalingmechanismasJA-Ile.12OH-JA-IlewasabletotriggeranthocyaninaccumulationintomatoseedlingsinCOI1-dependentmannerindicatingthat12OH-JA-Ilesignalingsystemislikelytobeconservedintheeudicots.Theseresultsshowthat12OH-JA-IlelikelyplaysaroleintheJA-regulatedwoundresponse.Keywords:Hormonemetabolism;Jasmonicacid;defenseresponse;Abstract#205.CytokininregulationofapotassiumtransportmoduleoccursinanaCRF6-dependentmanner(Submission376)ArielHughes1,PaulZwack,PaulCobine,AaronRashotte1AuburnUniversity,UnitedStatesCytokininregulationofapotassiumtransportmoduleoccursinanaCRF6-dependentmannerHughesAM,ZwackPJ,CobinePA,RashotteAMCytokininisplanthormonethatplaysessentialrolesinplantgrowth,development,andresponse.CytokininResponseFactors(CRFs)areafamilyoftranscriptionfactorsinvolvedinregulatingthosecytokininresponses.CRF6,amemberoftheCRFfamily,anditsroleinmitigatingoxidativestresshasbeenrecentlyrevealed,however,itsroleincytokininsignalingatatranscriptomelevelhasnotbeeninvestigated.InordertoexaminetheCRF6cytokinin-dependenttargetswepreformedtranscriptomeanalyses(usingAffymetrixST1.0Arabidopsismicroarrays)inthepresenceandabsenceofcytokininonwildtypeandacrf6mutantline.Genesexhibitingnodifferentialexpression(DE)betweenthecrf6+and–cytokininsamples,butwithDEwhencomparedtothewildtypewereidentifiedaspotentialdownstreamtargetsofCRF6.MostpotentialCRF6targetgeneswerefoundtoberepressedinthepresenceofcytokinin,suggestingthatCRF6playsanegativeregulatoryroleincytokininsignaling.Oneunexpectedsetoftargetswerethreegeneswithasharedinvolvementinpotassium(K+)uptake/transport:SKOR,HAK5andNRT1.5.,TheseCRF6cytokinin-dependenttargetexpressionlevelswereverificationvia

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qPCR,andfurtheranalyzedphenotypicallyundervariouscytokininandpotassiumtreatments.WetestedconnectionsbetweenCRF6andinplantaionomiclevelsbyanalyzingtheionomiccontentusingInductively-CoupledPlasma:OpticalEmissionSpectrophotometry(ICP-OES)analysisonsamplesfromwildtype,crf6,CRF6OX(overexpressingline)andtheskor,hak5andnrt1.5mutantlinesgrowninthepresenceandabsenceofcytokininandintypicalK+andK+deficientenvironmentsinordertodeterminehowCRF6affectstheionomiccontentofArabidopsisthaliana.AdditionalexaminationoflinksbetweenCRF6,cytokinin,andpotassiumwereconductedwithproCRF6::GUSandpTCSn::GFPinK+deficient,richandtypicalconditions.Together,thesedatasuggestthatcytokininmayhaveamechanisticactionviapotassiumtransportinresponsetoabioticstressbeyondthefeedbacklooppreviouslyexplored.Keywords:transcriptionfactors;cytokininsignaling;generegulation;K+uptake/transportAbstract#206.EnhancerScreentoIdentifyIBAResponseMutantsRevealsInteractionBetweenPeroxisomalMetabolicPathways(Submission377)VanessicaJawahir1,Zolman,BethanyK.,UMSL1UniversityofMissouriSt.Louis,UnitedStatesPlantperoxisomesmediatenumerousprocessesinprimaryandsecondarymetabolismcrucialforgrowthanddevelopmentthroughouttheentiretyofaplant’slifecycle.Peroxisomefunctionsincludeinactivationofhydrogenperoxide,fattyacidβ-oxidation,photorespiration,andproductionofthephytohormonesindole-3-aceticacid(IAA)andjasmonicacid(JA).Indole-3-butyricacid(IBA)ismetabolizedintofreeIAAinastepwisefashionsimilartofattyacidβ-oxidation.AscreenidentifiedIBAresponsemutants(ibr)defectiveinIBAtoIAAconversionbutincludedperoxisomalbiogenesisandimportproteins.ibr3-1andibr1-1weremutagenizedandscreenedforenhancedIBAresistanceinhypocotyls.ThisenhancerscreenseekstoidentifyanddefineadditionalfactorsinvolvedinthefunctionofIBR3andIBR1,theconversionofIBAtoIAA,andgeneralperoxisomefunctioninArabidopsisthaliana.Herewedescribetheinitialcharacterizationoftwomutants.TheenhancingmutationinZ353ibr3-1wasidentifiedinACX3,afattyacidβ-oxidationenzyme.ACX3andIBR3arehypothesizedtofunctioninthesamestepoftheirrespectivepathways.Itisuncleariftheseenzymeshaveoverlappingcatalyticactivityorsimilarlyrelyonratelimitingcofactors.EnhancedIBAresistanceisalsoseenwhencombiningibr3withotheracxsandacx3withotheribrs.Thissuggeststhemechanismbywhichacx3enhancesibr3isindirect.WholegenomesequencinganduseofSALKlinesrevealedthecausativemutationofZ377ibr3-1liesinLACS4,amemberofthelong-chainacyl-CoAsynthetasefamily.LACS6andLACS7catalyzethefirststepinfattyacidβ-oxidation,therefore,allLACSfamilymembersweretestedforIBAresistance.Intriguingly,lacs6butnotlacs7wasfoundtobeIBAresistant.GeneticandbiochemicalanalysiswillbedonetodetermineifLACS4/LACS6cooperativelyfunctiontochargeIBAwithCoA.AsACX3andLACS6haveestablishedrolesinfattyacidβ-oxidation,bothprojectswillprovideinsightintotheextentofinteractionbetweenfattyacidβ-oxidationandIBAtoIAAconversionandtheoverallmetabolicnecessitiesofperoxisomes.Keywords:Peroxisome;IBA;fattyacidbeta-oxidationAbstract#207.ModulationofABAcoresignalingpathwaycomponentsexpressionrelyonmRNAstabilitycontrolandphosphorylationactivity(Submission382)JoãoGuilhermePortugalVieira1,Duarte,GustavoT,CenterforMolecularBiologyandGeneticEngineering(CBMEG),UNICAMP,Vincentz,Michel,CenterforMolecularBiologyandGeneticEngineering(CBMEG),UNICAMP1UniversityofCampinas,BrazilThehormoneabscisicacid(ABA)isessentialfordevelopmentandabioticstressresponses,suchasdrought,heat,coldandhighsalinity.TheseresponsesdependentonacoresignalingpathwaythatinvolvesPYR/PYL/RCARreceptors,PP2CphosphatasesandSnRK2kinases.WeshowthatABApromotesashutdown/attenuationofitscoresignalingpathwaythroughrepressionofPYR/PYL/RCAR(PYL1,PYL2,PYL4,PYL5,PYL6,PYL8andPYR1)andinductionofPP2C(ABI1,ABI2,HAI,HAI2,HAB1andPP2CA)genesexpression.Thisnegativefeedbackrelies,partially,onmRNAstabilitycontrol,sincePYL1,PYL4,PYL5andPYL6transcriptsweredestabilizedbyABA.Twodeadenilases(AHG2andCAF1-a)andoneexonuclease(XRN4)werefoundtobeinvolvedinthedestabilizationofABAreceptorstranscripts.OurdatashedlightontheimportanceofthefastcontrolofreceptorsmRNAslevelstoshutdown/attenuatetheABAsignalingpathway.Thiscontrol,possibly,contributestoestablishthehomeostasisofABAresponses.Inaddition,kineticsofABAtreatmentgavefurthersupporttotheimportanceofthePYR/PYL/RCARreceptorsaskey-elementsbothinthenegativefeedbackloopandintheresettingofABAcoresignalingpathway.Experiments,withthephosphorylationinhibitor(staurosporine),indicatethatkinasesactivitymaybeimportantnotonlytomaintenanceofbasalmRNAlevelofABAcoresignalingelements,butalsototriggertheshutdown/attenuationofthispathway.ThisresultpointstothepossibleinvolvementofABA-relatedSnRK2kinasesinthenegativefeedbackofABAcoresignalingpathwayinresponsetoitsownhormone.TogetherthedatasupportthehypothesisofanegativefeedbackcontroloftheABAcoresignaling,which,partially,dependsonthecontrolPYR/PYL/RCARreceptorsmRNAstability.Keywords:AbscisicAcid;GeneExpression,PYR/PYL/RCAR;Post-TranscriptionalControl;phosphorylationactivity

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Abstract#208.SRFR1,anegativeregulatorinplantimmunity,negativelyregulatesphosphatestarvationresponse(PSR)bymodulatingethylenebiosynthesis(Submission388)JianbinSu1,Garner,ChristopherM.,BenjaminSpears,Gassmann,Walter1UniversityofMissouri,UnitedStatesInnature,theconcentrationofphosphorusishigh,however,theabsorbableformofphosphorus,orthophosphate,(Pi)islimited,thus,plantsalwaysfacedwithlowPistress.UnderlowPicondition,primaryrootelongationwassuppressed,instead,lateralrootandroothairformationweregreatlyenhanced.Previously,weshowedthatSRFR1mutationcausedhigherbasallevelimmuneresponseandwasalsoinvolvedinSNC1-andEDS1-dependneteffector-triggeredimmunity.Inthisstudy,wefurthercharacterizedthreeallelesofsrfr1mutants.Surprisingly,underhighPi(1mM)condition,allofthethreesrfr1mutantsshowedshortprimaryrootwithmorelateralrootsandroothairs,typicallyofphosphatestarvationresponse(PSR).WedemonstratedthatthePSRmimicphenotypeofsrfr1mutantsunderhighphosphateconditionwasindependentofSNC1orEDS1,butwasdependentonethylenebiosynthesis.Accordingly,theACS2,ACS6,ACS7,ACS8andACS9weresignificantlyup-regulatedinsrfr1mutants.Theseresultssuggesthigherbasallevelimmunity,butnotETI,inducesPSRmimicphenotypeevenunderhighPicondition.Further,wefoundelf26treatment,couldalsoinducePSRmimicphenotypeunderhighPi(1mM)condition,whichispartiallydependentonethylenesignalingpathway.Mostinterestingly,thePSRmimicphenotypecanbepartiallyrescuedbyusingveryhighPi(5-10mM),indicatingahighPidemandduringimmuneresponse.TofurtherexploretheroleofSRFR1inconnectingimmunityandPSR,RNA-seqandidentificationofSRFR1interactingproteinsareinprogressandwillbediscussed.Keywords:Ethylenebiosynthesis;Phosphatestarvation;PlantimmunityMetabolismandBiochemistry:Abstract#209.Identificationandcharacterizationofcandidategenesinvolvedinflavonoidbiosynthesisandregulation(Submission135)NanJiang1,Abdollahzadeh,Azam,TheOhioStateUniversity.,Cruz,Mariel,TheOhioStateUniversity.,GómezCano,LinaAndrea,TheOhioStateUniversity.,Grotewold,Erich,TheOhioStateUniversity.1TheOhioStateUniversity,UnitedStatesFlavonoids,whichrepresentalargegroupofphenolicplantspecializedmetabolites,havediversefunctionsinplants,includingpigmentation,signalingandprotectionagainstUVradiationandoxidativestress.Althoughflavonoidbiosynthesisiswellcharacterized,severalaspectsremainunclear,includingtransport,storage,andregulationbypathwayintermediates.Here,wecombinetwoforward-geneticapproachestoidentifyandcharacterizecandidategenesinvolvedinflavonoidbiosynthesisandregulation.IncollaborationwiththeABRC,wescreenedthevariousinsertionlinecollectionsforabnormalseedcolorphenotypesthatwouldsuggestaperturbationinseedcoatproanthocyanidin(PA)accumulation.Weidentified18newlinesthatweregenotypedtoconfirmtheinsertion.Progresstowardsthecharacterizationoftheselinesandtherespectivegeneswillbepresented.Wecomplementedthisstudywiththeidentificationofflavonoidbiosynthesismutantsuppressors.WeEMS-mutagenized3gt(3-O-glycosyltransferase)andtt19(glutathioneS-transferase)mutantsandthenscreenedforM2seedlingsforwhichanthocyaninaccumulationwasrestoredinmediawithhighsucrose.Weidentified28M2linesinwhichanthocyaninwasaccumulated,andwearecurrentlycharacterizingtheanthocyaninprofilesandgeneexpressionpatternsinthesuppressedmutants.Keywords:flavonoidbiosynthesis;3-O-glycosyltransferase;glutathioneS-transferase;suppressorsAbstract#210.InterrogatingthebiochemicalactivitiesunderlyingcellularGAdistributiongradients(Submission215)AnnalisaRizza1,AnkitWalia,AlexanderJones1TheSainsburyLaboratory,UnitedKingdomTheanalysisofwhereandhowgibberellin(GA)isdistributedatcellularlevelisacrucialstepforunderstandinghowGAregulatesdifferentstagesoftheplantlife-cycle,suchasrootgrowth,hypocotylelongation,andtransitiontoflowering.InordertovisualizeandquantifyGAatthecellularlevel,weareusingGPS1(GibberellinPerceptionSensor1)thefirstFRETbiosensorwhichallowsforhigh-resolutionGAmeasurementinvivo.UsingGPS1,wehavediscoveredGAdistributiongradientsinrapidlyelongatingArabidopsisorgans.IngrowingArabidopsisroots,wehaveobservedalongitudinalGAgradientwhereGAislowintherootdivisionzoneandhighintheelongationzone.Sofar,thepatterningofGAbiosynthetic,catabolic,andtransportactivitiesresponsibleforthisgradientisnotclear.BecauseexogenousGAisalsoaccumulatedpreferentiallyintheelongationzone,wehypothesizethatGAimportand/orcatabolicactivitycouldbepatternedingrowingroots.WearenowinvestigatinghowanensembleofGAbiosynthetic,catabolic,andtransportactivitiestogetherdeterminethedifferentialGAdistributionamongthecellsoftheArabidopsisroottip.Keywords:Roots,Gibberellin,Biosensor,Physiology,CellBiology

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Abstract#211.SpectroscopicandPhotochemicalAnalysesofRecombinantly-ExpressedPhytochromesfromArabidopsis(Submission241)WeimingHu1,Burgie,Sethe,WashingtonUniversityinSt.Louis.,McLoughlin,Katrice,WashingtonUniversityinSt.Louis.,Lye,Shu-Hui,WashingtonUniversityinSt.Louis.,Vierstra,Richard,WashingtonUniversityinSt.Louis.1WashingtonUniversityinSt.Louis,UnitedStatesToadapttochanginglightenvironments,plantsemployasetofphotoreceptorsthatcollectivelymeasureabroadcolorspectrumandthenconvertthelightintosignalsthatdrivephotomorphogenesis.Themostdominantarephytochromes(Phys),afamilyofbilin-containingphotoreceptorsthatuselighttointerconvertbetweentwoconformers,aredlight-absorbingground-state-Pr,andafar-redabsorbingactive-state-Pfr.Inaddition,PfralsorevertsbacktoPrviaalight-independentreactioncalledthermalreversion.ThroughmeasurementsofPfrlevelsandthePfr/PrratiodrivenbylightandthedisappearanceofPfrthroughthermalreversionbacktoPr,Physprovidebothlightandtemperatureperception.MosthigherplantsexpressasuiteofPhyisoformswithoverlappingbutdistinctphysiologicalfunctions,thatcooperativelyrespondfromvery-lowtohighirradianceconditions.OurphotochemicalstudiesontheArabidopsisPhyA-PhyEfamilyexpressedrecombinantlyindicatethatthisbroadlightperceptionisdriven,atleastinpart,bydistinctphotochemicalpropertiesinherenttoeachisoform.IncludedaresubstantialdifferencesinPrtoPfrphotoconversionratesandPfrtoPrthermalreversionrates,andmoresubtledifferencesinabsorption.Wealsofoundthatthethermalreversionratecanbestronglyinfluencedbythenatureofthebilin.Theseinvitroresults,combinedwithproteinstructuralmodelingandinvivostudiesinArabidopsis,shouldhelpexplainthedistinctrolesofeachPhyisoformandidentifyhowtheymightcooperatetoregulateplantphotomorphogenesis.Abstract#212.RegulationofCellWallStrengthandSalttolerancebytheArabidopsisMUR4(Submission264)OmarZayed1,Zhao,Chunzhao1PurdueUniversity,UnitedStatesSalinityisoneofthewidely-studiedplantabioticstressesthatsubstantiallylimitscropyieldandproduction.Saltsreduceplantcellwallflexibilitybyincreasingcellwallcontentofcross-linkedstructures.Maintainingcellwallarchitectureandintegrityisanimportantcriterionforenhancingplantstresstolerance.Thepresenceofwallarabinose-containingpolymershadbeensuggestedtobethekeystructuralcomponentresponsibleoftheuniqueabioticstresstolerancecharacteristicofplants.Toidentifydifferentgeneticlocithatareinvolvedinsaltstressresponse,wescreenedforArabidopsismutantsthatshowedrelativelygrowthdefectinNaClmediumcomparedwithwildtype.mur4showedhypersensitivitytosalt,butbehavenormallyunderotherosmoticstresscondition.MUR4encodesaUDP-xylose4-epimerase,thekeypathwayofarabinosebiosynthesisinplant.Arabinoseaccountsfor5–10%ofcellwallsaccharidesinArabidopsisandismainlyfoundinarabinan,CLE,extensin,arabinoxylan,AGPandRGII.Fromthesedownstreamstructures,wefounddifferentcontributionfromeachofthesecomponentsincellwallintegrityandsalttolerance.Saltreducearabinan,AGPandextensincontentsinthecellwall.Reactiveoxygenspecies(ROS)andhydrogenperoxideH2O2werealsoover-accumulatedinmur4plantsundersaltstresscomparedtothewildtype.PLATareplant-stressproteinsthataresuggestedtopromotestresstolerance.Nevertheless,littleinformationareknownregardingtheirspecificfunctions.ItissuggestedthatPLATregulatesalttolerancebyaffectingthecatalyticactivityandsubstratespecificityofmembraneproteins.However,themechanismandthepartnerproteinsarestillunknown.BothMUR4andPLAT1,whichareinducedbysaltstress,positivelyregulatesalttolerance.Split-LUCandyeasttwohybridassayshowedthatMUR4directlyinteractswithPLAT1.Altogether,ourdatasuggestthatarabinosecontentisanimportantfactorinsalttoleranceandPLAT1isinvolvedintheregulationofMUR4activity.Keywords:Salt;MUR4;CellwallAbstract#213.ArabidopsisBaxinhibitor-1promoteVLCFAsynthesisthroughtheinteractionwithVLCFA-relatedenzymes(Submission285)MinoruNagano1,Kakuta,Chikako,theUniversityofTokyo,Fujiwara,Masayuki,KeioUniversity,Fukao,Yoichiro,RitsumeikanUniversity,Kawai-Yamada,Maki,SaitamaUniversity1SaitamaUniversity,JapanProgrammedcelldeath(PCD)iscrucialfordevelopmentsandstressresponsesinplants,andishighlyregulatedbyvariousfactors.BaxInhibitor-1(BI-1)isawidelyconservedcell-deathregulator.ArabidopsisBI-1(AtBI-1)isa7-timestransmembraneproteinlocalizedinendoplasmicreticulum(ER),andsuppressescelldeathinducedbyoxidativestress,whichgeneratesreactiveoxygenspecies(ROS)inplantcells.WepreviouslydemonstratedthatAtBI-1interactswithasphingolipidfattyacid2-hydroxylasethroughacytochromeb5(Cb5),andalsowithasphingolipidD8-desaturasepossessingaCb5-likedomainatitsN-terminus.TheseresultssuggestthatAtBI-1regulatesPCDthroughsphingolipidsynthesis,becausesphingolipidsparticipateinPCD.Inthisstudy,weidentifiedELOsasnovelproteinsthatarerelatedtoAtBI-1functionbythescreeningofsphingolipid-relatedyeastmutants.ELOisacondensingenzymeforvery-long-chainfattyacids(VLCFAs)inyeastsandanimals,andanumberofVLCFAsarecontainedinsphingolipids.InArabidopsis,thereare4ELOhomologues(AtELO1-AtELO4),andweshowedthatAtELO1andAtELO2interactwithCb5.TheyalsointeractedwithVLCFA-syntheticenzymessuchasKCR1,PAS2andCER10,suggestingthatAtELO1andAtELO2areinvolvedinVLCFAsynthesis.Inaddition,ourimmunoprecipitation-massspectrometryanalysisdemonstratedthatAtBI-1interactswithVLCFA-syntheticenzymesincludingAtELO2.Moreover,AtBI-1promotedrapidsynthesisof2-hydroxyVLCFAsafterthetreatmentofhydrogenperoxide.TheseresultsindicatethatAtBI-1regulateVLCFAsynthesisthroughtheinteractionwithVLCFA-syntheticenzymesduringstressresponses.

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Keywords:Sphinoglipids;VLCFA;programmedcelldeath;oxidativestressAbstract#214.Controlofplantgrowthbydifferentiallight/temperatureentrainmentoftheclock:phaseshiftsinclock-geneexpressionandcarbohydratemetabolism(Submission315)MarkvanHoogdalem1,Shapulatov,Umidjon,LaboratoryofPlantPhysiology-WageningenUniversity,Gebraegziabher,Habtamu,HorticultureandProductPhysiology-WageningenUniversity,Busscher-Lange,Jacqueline,LaboratoryofPlantPhysiology-WageningenUniversity,Schreuder,Marielle,LaboratoryofPlantPhysiology-WageningenUniversity,Wassenaar,Maarten,HorticultureandProductPhysiology-WageningenUniversity,VanIeperen,Wim,HorticultureandProductPhysiology-WageningenUniversity,VanderKrol,Sander,LaboratoryofPlantPhysiology-WageningenUniversity1WageningenUniversity,NetherlandsManagementofelongationgrowthisessentialfortheyearroundproductionofhigh-quality,compact-shapedplantsingreenhouses.Elongationisusuallysuppressedbysprayingchemicalplantgrowthregulators(PGRs),buttheuseofthesechemicalsneedstobereducedandreplacedbymoresustainablemethods.Anegativeday-nighttemperaturedifference(coldday-warmnight:-DIF)canbeusedtocontrolgrowthofplantsingreenhouseswithouttheuseofchemicalPGRs.However,thephysiologicalmechanismsunderlyingthisphenomenonarepoorlyunderstood.Previousstudiesshowedthat–DIFaffectsclockregulatedprocesses(e.g.leafmovement)andcauseslimitationsinauxinandethylenehormonalsignaling,whichultimatelylinkstogrowthsuppression.Hereweshowthat–DIFdirectlyaffectstheclockbyinducingdifferentialphaseshiftsinpromoteractivityofdifferentcoreclockgenes.Thealteredclockunder-DIFalsoaffectscarbohydratemetabolism:Under‘natural’conditions(coldnight-warmday:+DIF)starch,whichaccumulatedduringthephotoperiod,isbrokendowninaclock-controlledwaytoavoidcarbohydratestarvationattheendofthenight(EON).Under–DIFthealteredclockoutputresultsinearlierinitiationofstarchbreakdown.WedemonstratethatthisiscausedbychangesintranscriptionofBAM3,ISA3,andSEX1.Earlyinitiationofstarchbreakdown,combinedwithanincreasednight-timerespirationunder–DIF,resultsinlowerstarchlevelsattheEONandcausesinductionofthecarbohydratestarvationresponsestatus,whichinducesgrowthsuppression.Keywords:Circadianclock;abioticstress;growth;starchmetabolism;carbohydratestarvationAbstract#215-Abstractwithdrawn

Abstract#216.Understandingthecrosstalkbetweencarbohydratetransportandphosphateuseinplantswithenhancedphloempartitioningfromsourcetosink(Submission341)MearajShaikh1,UmeshYadav,BrianGAyre1UniversityofNorthtexas,UnitedStatesPlantyieldislargelydependentonphotosynthatepartitioningfromsitesofnetproduction(e.g.leaves)tositesofnetutilization(e.g.roots,fruitsandyoungleaves).Wepreviouslyshowedthatincreasedphloemtransportcouldbeachievedbyover-expressingSUCROSETRANSPORTERS(SUTs)inthephloemcompanioncellsofleaves;however,ratherthanimprovingproductivitytheplantswerestunted.Furtherinvestigationsuggestedthatstuntingwasduetotheperceptionofaphosphate(P)deficiencyintheSUTover-expression(OE)lines.OurstudiesrevealedthattheSUT-OElineshadup-regulationofphosphatestarvationgenes,andstuntingcouldbeovercomebyaddingPlantyieldislargelydependentonphotosynthatepartitioningfromsitesofnetproduction(e.g.leaves)tositesofnetutilization(e.g.roots,fruitsandyoungleaves).Wepreviouslyshowedthatincreasedphloemtransportcouldbeachievedbyover-expressingSUCROSETRANSPORTERS(SUTs)inthephloemcompanioncellsofleaves;however,ratherthanimprovingproductivitytheplantswerestunted.Furtherinvestigationsuggestedthatstuntingwasduetotheperceptionofaphosphate(P)deficiencyintheSUTover-expression(OE)lines.OurstudiesrevealedthattheSUT-OElineshadup-regulationofphosphatestarvationgenes,andstuntingcouldbeovercomebyaddingphosphatesupplementstothegrowthmedia.TheseresultsshowthateffortstoenhancecarbontransportviathephloemmaybeimperiledbygreaterPneeds.TheaimsofthisprojectaretoexploreCarbon(C):Phomeostasisandpossiblyuncoupleitforthebenefitofplantproductivity.FreeinorganicP(Pi)andtotalPlevelsinSUT-OEweresignificantlygreaterthanWT.MiR399-OElinesareknowntoover-accumulatephosphatebyinhibitionofphosphatesignalingpathway.WehypothesizedthatifSUT-OElinesareunderPdeficiency(perceivedortrue)thencrossingthemwithphosphateover-accumulatinglines,wouldalleviatestuntingofSUT-OEplants.HomozygouscrossedF3(MiR399-OExAtSUT2)linesshowedrescueofSUT-OEphenotype,metaboliteanalysisisinprogresstocharacterizechangesinmajorP–containingpoolsofcompounds.Phloemtransportstudieswithradiolabeled14CO2areunderwaytoassesschangesinphotosynthatepartitioning.PreliminaryfindingssupportourmodelfortightcouplinginC:Phomeostasis.Uncouplingtheseinteractionsmayleadtoimprovedproductivitywithouttheneedforincreasedfertilizeruse.phosphatesupplementstothegrowthmedia.TheseresultsshowthateffortstoenhancecarbontransportviathephloemmaybeimperiledbygreaterPneeds.TheaimsofthisprojectaretoexploreCarbon(C):Phomeostasisandpossiblyuncoupleitforthebenefitofplantproductivity.FreeinorganicP(Pi)andtotalPlevelsinSUT-OEweresignificantlygreaterthanWT.MiR399-OElinesareknowntoover-accumulatephosphatebyinhibitionofphosphatesignalingpathway.WehypothesizedthatifSUT-OElinesareunderPdeficiency(perceivedortrue)thencrossingthemwithphosphateover-accumulatinglines,wouldalleviatestuntingofSUT-OEplants.HomozygouscrossedF3(MiR399-OExAtSUT2)linesshowedrescueofSUT-OEphenotype,metaboliteanalysisisinprogresstocharacterizechangesinmajorP–containingpoolsofcompounds.Phloem

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transportstudieswithradiolabeled14CO2areunderwaytoassesschangesinphotosynthatepartitioning.PreliminaryfindingssupportourmodelfortightcouplinginC:Phomeostasis.Uncouplingtheseinteractionsmayleadtoimprovedproductivitywithouttheneedforincreasedfertilizeruse.Abstract#217.FunctionalCharacterizationofaNewCytochromeP450ReductaseGeneRelevanttoArtemisininBiosynthesis(Submission368)RikaJudd1,DeyuXie1NorthCarolinaStateUniversity,UnitedStatesIn2015,theWorldHealthOrganization(WHO)reportedthatmalariacaused212millioninfectiousdiseasecasesandcaused429,000deaths.Artemisinin,auniqueendoperoxidesesquiterpenelactonemoleculeproducedbyArtemisiaannua,isaneffectiveantimalarialdrug.Thismedicinalplantformstheonlynaturalsourceofthedrugforartemisinin-basedcombinationtherapy(ACT),whichisrequestedbyWHOtobethefirstclinicallineformalariatreatment.Apartfromanti-malarialactivity,artemisininhasbeenshowntobeapotentialtherapeuticforcancerandmalaria.Duetolowproduction,manyeffortshavebeenundertakentounderstandartemisininbiosynthesistoovercomethisproblem.NewgeneshavebeenclonedfromA.annuatoshowtheirpotentialinvolvementintheearlybiosyntheticstepstoartemisininprecursors.Inadditiontothis,newcandidategeneshavebeencontinuouslyminedfromtranscriptomesofA.annua.OurgoalistobiochemicallycharacterizeanewcytochromeP450reductasegenefromA.annua,andexploititsinvolvementinartemisininbiosynthesis.Abstract#218.ThetranscriptionfactorbZIP63modulatesstarchdegradation(Submission379)AméricoJoséCarvalhoViana1,Matiolli,CleversonC,CenterofMolecularBiologyandGeneticEngineering(CBMEG),UNICAMP,Vincentz,Michel,CenterofMolecularBiologyandGeneticEngineering(CBMEG),UNICAMP1StateUniversityosCampinas-Unicamp,BrazilTheArabidopsistranscriptionfactorbZIP63,amemberoftheCgroupofthebasicLEUCINEZIPPER(bZIP)family,underenergydeficitconditions,heterodimerizeswithS1groupbZIPs,bZIP1,bZIP11andbZIP53inaSnRK1.1dependentmannerandthereforemediatestranscriptionalchangesinducedbyenergydeficit.TwoT-DNAinsertionalmutants,bzip63-2and-3andthetransgeniclineRNAi-L9silencedforbZIP63expressionbyRNAiapproach,displayedimpairedgrowthunderdielconditions.AimingtoidentifybZIP63targetgenesthatcouldexplaintheobservedgrowthimpairment,acomparativetranscriptomicanalysisofbzip63-2,RNAi-L9andwildtypeWswasrealized.Theanalysisrevealed348and1844deregulatedgenesinbzip63-2andRNAi-L9,respectively.ThreegenesinvolvedinstarchdegradationGWD1/SEX1,PWDandDPE2werefoundtobeinducedinbzip63-2andbzip63-3.Inaddition,thepromoterregionofSEX1wasshowntobeboundbybZIP63.However,intheRNAi-L9,thissetofstarchdegradationgeneswerenotderegulated,butinsteadBAM1,3and4,knowntobeinvolvedinstarchdegradation,weredownregulated.Thedivergenceinamountandsetofderegulatedgenes,includingthoserelatedtostarchdegradationbetweenbzip63-2and-3andRNAi-L9mostlikelyreflectstheofftargetsilencingofbZIP63heterodimericpartnersbZIP1andbZIP53observedonlyinRNAi-L9.Thedataraisedthehypothesisthatstarchbreakdowninbzip63-2/bzip63-3andinRNAi-L9shouldbefasterandslower,respectively,comparedtoWs.Measurementsofstarchcontentthroughoutthedielcycleconfirmedthatthesepredictionswerecorrect.Inaddition,inRNAi-L7transgenicline,inwhichbZIP63silencingwasweakerthaninRNAi-L9,andbZIP1/bZIP53werenotderegulated,therewasnodifferenceinstarchcontentcomparedtoWs.Together,theseresultssupportthenotionthatbZIP63anditsdimerizationpartners,bZIP1andbZIP53areimportanttomodulatethestarchbreakdownatnight.Keywords:bZIPtranscriptionfactor;bZIP63heterodimerizationpartners;starchdegradation

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NaturalVariation,Evolution,Ecology:Abstract#219.TheevolutionofgeneregulatorynetworksconfersstresstolerancewithintheBrassicaceae(Submission38)YingSun1,Dong-HaOh,MaheshiDassanayake,JoséDinneny1Stanford,UnitedStatesSoilsalinityposesamajorthreattofoodsecurityandcoststheworldmorethan11billiondollarsperyear.UsingArabidopsis,severalkeycomponentsofthesalt-responsepathwayhavebeenidentifiedinrecentyears.However,littleisknownaboutthedegreeinwhichsalt-responsepathwaysareconservedacrossplantrelatives.Identifyinggeneticnetworksthataffectplantgrowthundersaltstresswillprovidenovelinsightintohowsalt-tolerancecanbeengineeredincropspecies.Themajorityofaplant’stranscriptionalresponsetosaltstressismediatedbytheplantstresshormone,abscisicacid(ABA),anditsdownstreamABA-responsivetranscriptionfactors(ABFs).Onepossibilityisthatsalt-tolerant(halophyte)relativesofArabidopsissuchasE.salsugineumandS.parvulautilizeABAsignalingpathwaystoacclimatetosalinizedsoil.Totestthis,IaimtodefinethecontributionsoftheABFtranscriptionfactorfamilyinregulatingsalinity-modulatedgrowthinhalophytespecieswithinBrassicaceae.UsingDNAaffinitypurificationandsequencing(DAP-Seq)IamidentifyinghowvariationinthefunctionofDNAregulatoryelements(cis-elements)determinesdifferencesinsalt-regulatedgeneexpressionbetweensalttolerantandsaltsensitiveBrassicaspecies.IdentifyingandcharacterizingthefunctionaleffectsofsequencevariationonABF-mediatedgeneexpressionwillelucidatethetranscriptionalnetworksthatcontributetosalttoleranceinplants.Keywords:Halophyte;regulatorykinetics;gene-regulatorynetworks;salinity-modulatedgrowth;DAP-SeqAbstract#220.ComparativeanalysisofdistinctresponsesofArabidopsisnaturalvariationstoNdeficiency(Submission53)AtsushiMabuchi1,Monda,Keina,KyushuUniv.,Takahashi,Sho,KyushuUniv.,Sakuraba,Yasuhito,Univ.Tokyo,Negi,Juntaro,KyushuUniv.,Yanagisawa,Shuichi,Univ.Tokyo,Iba,Koh,KyushuUniv.1KyushuUniversity,JapanNitrogen(N)andcarbon(C)areessentialelementsrequiredforplantgrowthandmetabolism.Nismainlytakenupasnitrateorammoniumbyroots,whileCistakenupasatmosphericCO2throughstomatalpores.ToclarifythemutualregulationbetweenNassimilationandCO2uptake,growthofnumerousArabidopsisecotypesundertheN-limitingconditionwasinvestigated.WemeasureddryweightsofshootsandrootsoftheseedlingsgrownundertheN-limitingconditionandfoundthatsomeecotypesshowedsignificantlylargerorsmallerbiomassunderthiscondition,comparedwithotherecotypes.WeselectedthreeecotypesexhibitinglargerbiomassandperformedfurtheranalysestoinvestigatethedifferencebetweenNnutrientresponsesoftheseecotypesandthereferenceaccessionCol-0.Wemeasuredtheirprimaryrootlengths,lateralrootnumbers,andlateralrootlengthsundertheN-deficientandN-sufficientconditions.OneoftheselectedecotypesshowedsignificantlyenhancedelongationoftheprimaryrootandincreasedthelateralrootnumberundertheN-deficientconditions,comparedwithCol-0.Inaddition,increasesofthelateralrootnumberofthisecotypeplantsundertheN-deficientconditiondependedonthelightcondition.WearecurrentlyanalyzingtheN-responsivegeneexpressionintheselectedecotype.Wewillpresentdetailedinformationandnewinsightsobtainedbyourcomparativeanalysiswithvariousecotypes.Keywords:Naturalvariation,NitrogenAbstract#221.TheStructuralConsequencesofPolyploidyinArabidopsisthaliana(Submission59)EvanPacey1,Maherali,Hafiz,UniversityofGuelph,Husband,Brian,UniversityofGuelph1UniversityofGuelph,CanadaPolyploidy,havingmorethantwosetsofchromosomespernucleus,canhavedramaticeffectsonthestructuralbiologyoforganisms.Themostcommoneffectisthatpolyploidcellsarelargerandhavehighervolume:surfacearearatiosthansmaller,diploidcells.Ihypothesizethatthesedifferencesmayleadtoagreaternetintracellularstoragecapacityandweakercellstructureinpolyploidtissuescomparedtodiploidtissues.Totestthesehypotheses,tetraploidandoctoploidindividualsofnaturallyoccurringdiploidaccessionsofArabidopsisthalianawereartificiallygenerated.Thisploidyserieswasthensubjectedtoanumberofteststhatquantifiedthestorageandstructuraldifferencesamongcytotypes.Tetraploidsandoctoploidshadsignificantlyhigherrelativewatercontentsperunittissuedrymassandsurvivedlongerunderwaterlimitationthandiploids.However,octoploidsweresignificantlysmallerthandiploidsandtetraploidsandoftenexperiencedstructuralcollapseduringfruiting.Theseresultsaswellasadditionalresultsforchlorophyllandstarchcontent,stemheight,fitnessinsalineenvironmentsandcellsizemeasurementswithconfocalimagingwillbediscussed.Keywords:Genomesize;Cellsize;Tissuestorage;Structuralstrength;StructuralcollapseAbstract#222.Multi-traitgenome-wideassociationmappingrevealsthegeneticarchitectureofplantstressresistance(Submission87)ManusThoen1,DavilaOlivas,Nelson,BayercropScience,Kloth,Karen,UmeåPlantScienceCentre,Coolen,Silva,UtrechtUniversity,Huang,Ping-Ping,WageningenUniversity,vanHeerwaarden,Joost,WageningenUniversity,Kruijer,Willem,WageningenUniversity,vanEeuwijk,Fred,WageningenUniversity,Dicke,Marcel,WageningenUniversity1UChicago,UnitedStatesInnature,plantsareexposedtocombinationsofvariousbioticandabioticstresses,butstressresponsesareusuallyinvestigatedforsinglestressesinasinglehostspecies.Multi-phenotypeanalyseshavedrawnincreasingattentioningenomicstudies.Weinvestigated

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thegeneticarchitectureunderlyingplantresponsesto11singlestressesandseveraloftheircombinationsbyphenotyping350Arabidopsisthalianaaccessions.Asetof214000singlenucleotidepolymorphisms(SNPs)wasscreenedformarker-traitassociationsingenome-wideassociationanalysesusingtailoredmulti-traitmixedmodels.Stressresponsesthatsharehormonalsignalingpathwaysalsosharegeneticarchitectureunderlyingtheseresponses.Forthe30candidateSNPswiththelowestPvalue,averagequantitativetraitlocus(QTL)effectsizeswerelargerfordualstressesthanforsinglestresses.Plantsappeartodeploybroad-spectrumdefensivemechanismsinfluencingmultipletraitsinresponsetocombinedstresses.Onepromisingcandidategenebelongstothenucleotide-bindingsiteleucine-richrepeat(NB-LRR)familyofresistance(R)proteins.Theknock-outlineshowedenhancedresistancetocaterpillars,osmoticstressandsaltstress.Thisbegsthequestionwhyweobservefunctionalpolymorphismforthisgene.AncientbalancedpolymorphismshavebeendescribedinArabidopsisforseveralRgenes.ThenextstepinourresearchisreconstructingtheevolutionofRgenepolymorphisminA.thalianaandcloserelatives.Diffuseecologicalinteractionsoftwoco-occurringBrassicaceaeweeds(CardaminehirsutaandDrabaverna)thatsharethesamegeneralistpathobiomeinnatureareagreatmodelforcomparativegenomics.Bystudyingnaturalvariationoftheseplantsandtheirenvironmentascomplexassembliesofinteractingcommunitymemberswecanstarttounderstandtheevolutionofhost-plantresistanceinthefaceofcommunitycomplexity.Keywords:Multi-traitGWAS;Combinedplantstress;R-genes;Host-plantresistance;EvolutionaryEcologyAbstract#223.TheeffectofstructuralvariationoncrossoverpositioninginArabiopsisthaliana(Submission92)BethRowan1,Feuerborn,Tatiana,UniversityofTuebingen**nowUniversityofCopenhagen,Henderson,IanR.,UniversityofCambridge,Weigel,Detlef,MaxPlanckInstituteforDevelopmentalBiology1UniversityofCalifornia,Davis,UnitedStatesOneoftheadvantagesofsexualreproductionisthepossibilityofformingnewcombinationsofallelesthroughcrossovers(COs)thatswapportionsofthematernalandpaternalhomologouschromosomesduringmeiosis,makingnewtraitcombinationsavailablefornaturalselection.TherateofCOformationandthelocationsofCOeventscanthereforeaffecttheco-inheritanceoftraits.AlthoughseveralfactorsthatinfluenceCOratesanddistributionshavebeenidentified,detailedknowledgeofhowtheCOlandscapeisestablishedremainssuperficial.ThisislargelybecausecharacterizingtheCOlandscapehastraditionallybeenlaboriousandimprecise.Inthisstudy,weengineeredcost-effectivemethodsforperforminghigh-throughputsequencingonlargepopulationsofrecombinantindividualstogeneratepreciseCOmaps.Usingthisapproach,weexaminedtheinfluenceoflarge-andsmall-scalegenomicstructuralvariationsonCOfrequencyandpositioningbygeneratingaCOmapfromover2000individualsofanF2populationderivedfromtwoArabidopsisthalianaaccessionswithhigh-qualityreferencegenomes:ColandLer.Withthesedata,wewereabletocharacterizealandscapeofover15,000COeventswithinasingleF2cross,representingthedensestCOmapavailableforahighereukaryote.WeexaminedthefrequencyofCOswithinandaroundinversions,insertions,deletions,translocations,andtandemcopynumbervariations.COsoccurredrarelywithinthesestructuralvariants,butCOrateswereoftenslightlyelevatedintheflankingregions.Otherhypervariableregionsofthegenome,suchasdiseaseresistancegeneclusters,exhibitedbothhighandlowCOrates.COswerestronglyassociatedwithregionsofopenchromatin.WeconcludethatCOsaregenerallysuppressedwithinregionscontainingstructuralvariation,butthatthiseffectdoesnotdependonthesizeofthevariantregionandisonlymarginallyaffectedbythevarianttype.Keywords:meiosis,recombination,structuralvariation,wholegenomesequencing,chromatinAbstract#224.UnderstandingmolecularvariationintheRNApolymeraseVAgo-bindingplatform(Submission117)JoshuaTrujillo1,Beilstein,MarkA.,UniversityofArizona,Mosher,RebeccaA.,UniversityofArizona1UniversityofArizona,UnitedStatesRNAPolymerase(Pol)VplaysacentralroleinsmallRNA-directedDNAmethylationbyrecruitingArgonaute(AGO)proteinstochromatin.ThelargestsubunitofRNAPolV(NRPE1)interactswithAGOproteinsthroughaseriesofGW/WGpeptidemotifs,knownasAgohooks,whichcreateanAgo-bindingplatformwithinthecarboxylterminaldomain(CTD).NRPE1orthologsshareextensivesequenceconservationwithinthecatalyticdomains,butAgo-bindingplatformsintheCTDarehighlyvariableamonglandplants.TobetterunderstandtheNRPE1-AGOinteraction,weinvestigatedtheevolutionarydynamicsoftheAgo-bindingplatformfrommorethan50species,includingdetailedanalysisoftwowell-studiedplantgroups,thefamilyBrassicaceaeandgenusOryza.WedemonstratethatwhiletheAgo-bindingplatformofNRPE1ishighlyvariableatthesequencelevel,orthologssharethepresenceofAgohooks,tandemrepeatarrays,andintrinsicdisorder.RapidevolutionoftheAgo-bindingplatformoccursthroughrelaxedselectioncoupledwithexpansionandcontractionofthetandemrepeatarray,allowingforrestructuringoftheAgo-bindingplatforminaslittleas50-60millionyears.WearecurrentlyassessingthefunctionalconsequencesofhypervariabilityintheNRPE1CTD,includingpotentialco-evolutionwithAGOproteins.Keywords:Proteinevolution;RNAPolymeraseV;Agohooks

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Abstract#225.High-andlow-affinityammoniumtransportersinMarchantiapolymorpha(Submission131)NuWang1,HanqingGuo,AnkeReinders,TamiR.McDonald,JohnM.Ward1UniversityofMinnesota,UnitedStatesAmmoniumuptakeviaAMTsisimportantfornitrogennutritioninplants.Plantsencodebothelectrogenic(AMT1)andelectroneutral(AMT2)ammoniumtransporters.Bothtypeshavebeenstudiedextensivelybutonlyinangiosperms.GenomesequenceforthebryophyteMarchantiapolymorphawasrecentlyobtainedandshowedthatMarchantiacontains9AMT1and10AMT2genes.Westudiedtransportactivity,geneexpressionandmembranelocalizationofMpAMT1;2andMpAMT1;5.ByexpressioninXenopusoocytesandtwo-electrodevoltageclamping,wedeterminedthatMpAMT1;2andMpAMT1;5arebothelectrogenicammoniumtransporters.MpAMT1;5hasalowaffinityforammonium(K0.5=0.38mMatpH5.6)whileMpAMT1;2isahighaffinityammoniumtransporter(K0.5=0.007mMatpH5.6).MarchantiapolymorphagametophytesweretransformedwithC-terminalcitrinefusionsforbothtransportersandbothclearlylocalizetotheplasmamembrane.Expressionofbothtransporterswasregulatedbynitrogensupply.Usingpromoter-GUSanalysis,MpAMT1;2showedhighexpressionwhentheplantsweregrownonhalf-strengthB5medium(12mMKNO3,0.5mM(NH4)2SO4)butlowexpressionwhengrownunderN-deficiencyconditionsorwithsufficientNsuppliedastheaminoacidalanine.ExpressionofMpAMT1;5showedlowerexpressionbutwasinducedunderNdeficiency.InArabidopsisAMT1transportersaredown-regulatedbyphosphorylationbyCPK23.SequencealignmentrevealedaconservedphosphorylationsiteinallMarchantiaAMT1homologsandnoneoftheAMT2homologssuggestingsimilarregulationinMarchantia.Overall,theresultsindicatethatMarchantiaisagoodmodeltostudyammoniumtransporteractivity.Keywords:Marchantiapolymorpha;Ammoniumtransporters;Geneexpression;ProteinlocalizationAbstract#226.AsymmetricevolutionoftranscriptionfactorexpressionandregulationinArabidopsisthaliana(Submission175)NicholasPanchy1,ChristinaAzodi,EamonWinship,RonanO'Malley,Shin-HanShiu1MichiganStateUniversity,UnitedStatesTranscriptionfactors(TFs)controlboththedevelopmentandenvironmentalresponseoforganismsbymodulatingtheexpressionofgenes.TheevolutionofTFfunctionshascontributedtotheemergenceofnewspeciesanddomesticationofcrops.Inplants,newTFsariseprimarilyasaresultofwholegenomeduplication(WGD)andwhileduplicatesarelostfollowingaWGDevent,transcriptionfactorsareretainedatasignificantlyhigherratethanothergenes.BymodelingtheretentionrateofduplicatesinArabidopsisthaliana,wefoundthattheexceptionalretentionofTFsfollowingWGDisstronglyassociatedwiththeirhigherthanaveragemaximumexpressionandlowerthanaveragemeanexpression.Furthermore,theevolutionofretainedTFduplicatesisbiasedsuchthatonecopyretainsthemajorityofancestralexpressionstatesandcis-regulatorysites,whiletheothercopylosesancestralexpressionbutgainsnovelcis-regulatorysites.ThispatternofpartitioningwasinvestigatedbymodelingtheevolutionofTFduplicatepairsusingasystemofordinarydifferentialequations.OurresultsrevealedabiastowardsTFduplicatepairsevolvingtoandremaininginapartitionedstate,whichsuggeststheseduplicateTFsmayhavebeenkeptbecauseonecopypreservedtheancestralfunctionwhiletheotherhasevolvednewfunctions.Keywords:Geneduplication;Geneevolution;Regulationofexpression;TranscriptionFactors;AncestralinferenceAbstract#227.ExploringthevariationofecophysiologicaltraitswithinabiparentalandgeneticallydiversepopulationofnaturalaccessionsofSetaria(Submission225)MaxFeldman1,PatrickEllsworth,GregZiegler,BriannaHaining,MelissaJurkowski,AsaphCousins,IvanBaxter1DonaldDanforthPlantScienceCenter,UnitedStatesSetariaviridisisprovingtobeanidealexperimentalmodeltostudythegeneticbasisofecophysiologicaltraitsincontrolledenvironments.Inadditiontomanyfavorableexperimentalandlifehistoryattributes,S.viridisexhibitshighgeneticdiversityandhasevolvedtheabilitytocolonizehabitatsthroughouttheglobe.Understandinghowthedevelopmentalprocessesthatinfluenceplantforminteractwithphysiologicalcharacteristicssuchaswateruseandnutrientassimilationisanimportantareaofresearch.Toachievethisobjectivewehaveperformedthreewaterlimitationexperimentsusingtwoindependentgeneticallystructuredpopulations(S.viridisnaturaldiversitypanelandaninterspecificS.italicaxS.viridisrecombinantinbredlinepopulation)intheBellweatherPhenotypingFacilityattheDonaldDanforthPlantScienceCenter.Thecapabilitiesaffordedbystableisotoperatioanalysis,broadspectrumelementalprofiling,high-frequencytemporaltraitmeasurementandstringentcontrolofenvironmentalvariablesenableustorapidlyidentifygermplasmwithuniquepropertiesandgaindetailedinsightintohowgeneticlociinteractwithabioticfactorstodetermineplantphenotype.Keywords:QuantitativegeneticsEcophysiologyNaturalvariationHigh-throughputphenotypingWateruseefficiency

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NovelTools,TechniquesandResources:Abstract#228.ApplicationsofCRIPSR/Cas9breedingusingfloweringstimulationandprecisionlighting(Submission33)JuanMatte1,R.Siqueira,F.Aquea,C.Santibañez,B.Jones,P.Arce-Johnson1PontificiaUniversidadCatolicadeChile,ChileCRISPR/Cas9hasbeenshowntobeanexcellenttoolforgenomeediting.Inplants,itisstartingtobeusedinbreedingtocreateimprovedvarietiesthataregeneticallymodifiedbuttransgene-free.Thispossibilityisparticularlyinterestingintheforestryindustry.Becausetheyrepresentarenewableresource,thedemandforwoodproductsisexpectedtocontinuetoincreaseintothefuture.Breedingisonewayofincreasingtheproductivityoftreesandforests.Geneticimprovementoflong-livedspeciesliketreesisproblematicbecausethelonggenerationtimesmakeincorporationofnewcharacteristicsprohibitivelylong-term.Inmostcountries,tightregulationsopposingtransgenicuseinthefieldmakedirectintegrationofnovelgeneticmaterialundesirable.CRISPR/Cas9hasseveralmajoradvantagesoverprevioustransgenic-basedapproachesandcanworkalongsideconventionalbreedingprogramsbydirectlyimprovingknownyield-relatedlociorgenes.Inthiswork,wetargetreportergenesinArabidopsisthalianabyusingamodifiedCRISPR/Cas9systemandhaveaddedastrongubiquitousCaMV35Spromoter,drivingtheFLOWERINGLOCUST(FT)gene.EctopicexpressionofFTacceleratessexualdevelopment.Toregulatetheaccelerationoffloweringtimetogetviableflowers,weuseprecisionlightingwithdifferentratiosofBlue,RedandFarRedlight.TheCRISPR/Cas9mutatedplantsflowerearlierthannormalasaresultoftheectopicFTexpression,resultinginfastrecoveryofthesecondgeneration(F2)inArabidopsis.Wewillusethistechnologytoacceleratebreedinginarborealspecies.Keywords:CRISPR/Cas9,PRECISIONLIGHTINGFORPLANTS

Abstract#229.Usingphylogenyofproteinstopredictsignalingpartnersinplantimmunity(Submission265)DmitryLapin1,Kovakova,Viera,Beyer,Andreas,Parker,Jane1Max-PlanckInstituteforPlantBreeding,GermanyUsingphylogenyofproteinstopredictsignalingpartnersinplantimmunityD.Lapin1*,V.Kovakova2*,A.Beyer2,J.Parker1*theauthorscontributedequally1-Max-PlanckInstituteforPlantBreeding,Cologne,Germany2-CECAD,UniversityofCologne,GermanyTheworkissupportedbyDFGSFB680Immunesystemsrelyontherecognitionofmicrobesbysurfaceorintracellularreceptors.Informationfromactivatedintracellularreceptors,representedbyNod-likeproteins(NLRs)inplants,istransmittedtothegeneexpressionregulatorysystemviatheEDS1proteinfamilybyanunknownmolecularfunction.Thisstructurallydefinedgroupofproteinsresembleslipases.Whilethepredictedcatalytictriadisdispensableforimmunity,thelipase-likedomainsupportsaflexibleandessentialC-terminalportioninsignalrelay.Here,wepresentresultsofinsilicopredictionsofsignalingpartners.Thismethodcomparesphylogenetictreesforplantproteinsandisbasedontheassumptionthatfunctionally-relatedproteinssharesimilarevolutionarypaths.WeusedthisideatoidentifycandidatesignalingpartnersoftheEDS1-family.ThemethodutilizestheimprovedMirrorTreealgorithmandasignificantefforthasbeenmadetobuildphylotreesfrom>11Khigh-qualityorthogroupsrepresenting>50plantgenomes.Thisworkrevealedseveralknownplantimmunityregulators(suchasNPR1,FMO1)asstronglycoevolvingwiththeEDS1-family.Inaddition,oneG-groupproteinphosphatase(PP2C)hadastrongcoevolutionsignal.Inpreliminaryexperiments,ArabidopsismutantsforseveralG-groupPP2CsdisplayedsomelossofpathogenresistanceconferredbytheEDS1-depenentNLR,RPP4.WeareinvestigatingwhetherG-groupphosphatasesfunctionwithotherNLRsand/ormolecularlyinteractwiththeEDS1-family.Furthermore,tomakethecoevolutiondataaccessibleforthescientificcommunity,wearedevelopingaweb-basedR-shinyapplication.Weinviteotherstodiscussthepotentialaswellaspitfallsofthemethodandphysiologicalrelevanceofthefindings.Keywords:coevolution;NLRimmunity;proteinphosphatase;RShiny;EDS1Abstract#230.IdentifyingArgonaute-RNAtargetinteractionsinvivothroughAGO-mediatedtargetcovalentmodifications(Submission296)PedroCosta-Nunes1,Teng,Chong,DonaldDanforthPlantScienceCenter,Baldrich,Patricia,DonaldDanforthPlantScienceCenter,Meyers,BlakeC.,DonaldDanforthPlantScienceCenter,UniversityofMissouri–Columbia,Carrington,JamesC.,DonaldDanforthPlantScienceCenter1DonaldDanforthPlantScienceCenter,UnitedStatesArgonaute(AGO)proteinsplayacentralroleinpost-transcriptionalandtranscriptionalgenesilencingpathwaysineukariots,impactingdevelopment,bioticandabioticstressresponse,genomeintegrityandepigeneticmodifications.LoadingofAGOproteinswithsmRNAs(21-24nt)conferssequencehomologybasedtargetrecognitiontotheeffectorcomplex.A.thalianaencodestenAGOproteins,withpredictionalgorithmsbasedonsmRNA/targethomology,reversegeneticsanddeepsequencingapproachesleadingtoourcurrentunderstandingofitsmodeofactionandfunctionaldiversification.WehavedevelopedanewapproachtostudyAGOfunctionbygeneratingN-terminalfusionproteinscontainingtheC.eleganspoly(U)polymerasePUP-2.PUP-2fusionshavebeenpreviouslydemonstratedtoselectivelytagRNAsboundtoaRNAbindingproteinofinterestinvivobyadditionofapoly(U)tailtoits3’-end.PUP-2N-terminalfusiontoAthAGO7doesnotinterferewithproteinfunctionasassessedbytransientassaysconductedinN.benthamiana,withthechimericproteindisplayingslicingactivityatthepredictedmiR390/TAS3aguidedcleavagesiteandpromotingbiogenesisofsecondaryta-siRNAs,henceretainingabilityforSGS3recruitment.TAS3apoly-uridylatedtranscriptswereidentifiedinmRNAenrichedsamplesofbothWTandslicerdeficientAGO7chimericproteinsdemonstratingtheN-terminalfusedPUP-2retainsitspolymeraseactivity

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andthatpoly-uridylationofTAS3atranscriptscanbeachievedwithfullyfunctionalAGOproteins.Thelaterobservationisofparticularimportance,aspreviouscharacterizationofinvivoAGOtargetsrequiresuseofslicerdeficientmutantsfoundtoactasdominantsuppressorsinaWTbackground.Furthermore,asPUP-2covalentlymodifiedRNAscanbeidentifiedfollowingtotalRNAisolation,thedescribedstrategyholdsthepotentialtofurtheradvanceourknowledgeofAGOfunctionandtomovefromtissuetocelltypespecificapproaches.Keywords:post-transcriptionalsilencing;ARGONAUTEproteins;RNAtagging;invivoanalysis;transcriptomicsAbstract#231.PlaMoM:acomprehensivedatabasecompilesplantmobilemacromolecules(Submission321)ShoudongZhang1,Guan,Daogang,HongKongBaptistUniversity,Yan,Bin,HongKongUniversity,Thieme,Christoph,MaxPlanckInstituteofMolecularPlantPhysiology,Hua,Jingmin,HongKongBaptistUniversity,Zhu,Hailong,HongKongBaptistUniversity,Boheler,Kenneth,HongKongUniversity,Zhao,Zhongying,HongKongBaptistUniversity,Kragler,Friedrich,MaxPlanckInstituteofMolecularPlantPhysiology,Xia,Yiji,HongKongBaptistUniversity1HongKongBaptistUniversity,HongKongInplants,variousphloem-mobilemacromoleculesincludingnoncodingRNAs,mRNAsandproteinsaresuggestedtoactasimportantlong-distancesignalsinregulatingcrucialphysiologicalandmorphologicaltransitionprocessessuchasflowering,plantgrowthandstressresponses.Givenrecentadvancesinhigh-throughputsequencingtechnologies,numerousmobilemacromoleculeshavebeenidentifiedindiverseplantspeciesfromdifferentplantfamilies.However,mostoftheidentifiedmobilemacromoleculesarenotannotatedincurrentversionsofspecies-specificdatabasesandareonlyavailableasnon-searchabledatasheets.Tofacilitatestudyofthemobilesignalingmacromolecules,wecompiledthePlaMoM(PlantMobileMacromolecules)database,aresourcethatprovidesconvenientandinteractivesearchtoolsallowinguserstoretrieve,toanalyzeandalsotopredictmobileRNAs/proteins.EachentryinthePlaMoMcontainsdetailedinformationsuchasnucleotide/aminoacidsequences,orthologpartners,relatedexperiments,genefunctionsandliterature.ForthemodelplantArabidopsisthaliana,protein–proteininteractionsofmobiletranscriptsarepresentedasinteractivemolecularnetworks.Furthermore,PlaMoMprovidesabuilt-intooltoidentifypotentialRNAmobilitysignalssuchastRNA-likestructures.ThecurrentversionofPlaMoMcompilesatotalof17991mobilemacromoleculesfrom14plantspecies/ecotypesfrompublisheddataandliterature.PlaMoMisavailableathttp://www.systembioinfo.org/plamom/.Keywords:PLAMOM,DATABASE,MOBILEMACROMOLECULES,tRNA-likemotif,orthologpartnersAbstract#232.Developmentofthedatabaseforthebio-resourcesofArabidopsisatRIKENBRC(Submission330)SatoshiIuchi1,Kobayashi,Masatomo,RIKENBRCExperimentalPlantDivision1RIKEN,JapanRIKENBRC(BioResourceCenter)hasjoinedtheNationalBioresourceProject(NBRP)inJapanandtheExperimentalPlantDivisionofRIKENBRChasdistributedtheDNAclonesofArabidopsisthalianatotheresearcheraroundtheworld.Toestablisheasieraccesstothecloneinformation,wearetryingtoconstructthenoveldatabaseandwebsite.Initially,ournewdatabaseincludedtheTFclone,whichcontainstheORFsequence(withoutSTOPcodon)ofArabidopsistranscriptionalfactorsinthegatewayentryvectorsystem,andtheTACclone,whichcontainsArabidopsisgenomefragment(78kb,onaverage)inTACvector.HerewepresenttheadditionofnewdatasetfromRAFLcDNAclones,thefull-lengthcDNAcloneofArabidopsisthaliana.Atfirst,wemappedtheDNAsequencesoftheseclones(eitherwholeregionorbordersequence)toArabidopsisgenomesequenceusingCLCworkbench.ThenweconstructedthedatabasethatincludesbothofthemappedpositiondataandArabidopsisgeneannotationsfromAraport11andTAIR10.Inordertoimprovethedataaccessibilityfromuserscientists,wetriedtovisualizethedatabydrawingaschematicviewoftheinsertregiononthewebpage.Furtherimprovementofthewebpagedesignisunderway.(Webaccess:https://plant.rtc.riken.jp/resource/)Keywords:database;bioresources;RAFLclone;TACclone;TFcloneAbstract#233.AComprehensiveIonomicsScreenofArabidopsisthalianaT-DNAInsertionLines(Submission386)JenniferBarrett1,Baxter,Ivan,USDA-ARS,Green,Kim,DonaldDanforthPlantScienceCenter,Jurkowski,Melissa,DonaldDanforthPlantScienceCenter,Ziegler,Greg,USDA-ARS1DonaldDanforthPlantScienceCenter,UnitedStatesArabidopsisthalianaisawell-studiedmodelorganism-theentiregenomeofwhichhasbeensequenced,althoughthefunctionofthose25,000+geneshavenotbeenfullyexplored.Here,wedescribeaprotocolforscreeningalargeselectionofArabidopsisthalianaT-DNAinsertionlines,withtheintenttofindgenesrelatedtoelementaluptake.Approximately32,500SALKInsertionlineswereobtainedfromtheABRCStockCenter.Overthecourseof5years,thelineswillbeplantedatasamplesizeofn=1,grownupfor5weeks,leaftissueharvested,andthenrunthroughanICP-MS.Theresultingionomicdatawillbescannedforstrikingelementaldifferencesbetweenthesamplesandthecontrols.Lineswithsignificantphenotypicdifferenceswillbereplantedatn=6.Preliminarytestsofthemethodhaveresultedinfurtheroptimizationoftheprotocol.Keywords:ICP-MS;ionomics;T-DNA

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PlantDefenseandBioticinteractions:Abstract#234.AphenotypeandgenotypestudyinArabidopsisthalianainresponsetoTurnipmosaicvirusinanaturalenvironment.Aremetabolictraitsmarkersoftheplantresponsetoviralinfection?(Submission42)BernadetteRubio1,Cosson,Patrick,UMR1332BFP-INRAUniversitédeBordeaux,Caballero,Mélodie,UMR1332BFP-INRAUniversitédeBordeaux,Revers,Frédéric,UMRBIOGECO-INRAUniversitédeBordeaux,Gibon,Yves,UMR1332BFP-INRAUniversitédeBordeaux,Roux,Fabrice,LIPM-CNRSINRA,Schurdi-Levraud,Valérie,UMR1332BFP-INRAUniversitédeBordeaux1INRA,FrancePlantresponsetovirusesisoftendescribedthroughalimitednumberofdiseasetraits.Mostoftheexperimentsareconductedincontrolledconditionsusingmodelpathosystems.Inordertodecipherthegeneticbasisfornaturalresistance/susceptibilitytoviruses,itisnownecessarytoexperimentnaturalpathosystemsinanaturalenvironmentwithawidephenotyping.Inthisstudy,thegeneticbasisofplant/virusinteractionswasanalyzedusingthenaturalpathosystemArabidopsisthalianaandTurnipmosaicvirus(TuMV).AmongthegenusPotyvirus,TuMVisprobablythemostwidespreadanddamagingvirusofthefamilyBrassicaceae.Tobeascloseaspossibletonaturalconditions,threeyearsofcommongardenexperimentswereleadwithworldwideandFrenchA.thalianaaccessions.Viralchargeandtraitsrelatedtodiseasewereusedinagenomewidemappinganalysis.Abroadphenotypingwasrealizedthroughtheanalysisoftwelveprimarymetabolicprofiles.Therefore,thepresentprojectaimsat(1)integratingdiseaseandmetabolomicstraitstoidentifythegeneticbasisofresponsetovirusinfectioninanaturalenvironment(2)analyzingifprimarymetabolitescouldbediagnosticmarkersorpredictorsofresistance/susceptibilityinA.thaliana/TuMVinteraction.GenomewidemappingusingdiseasetraitsallowedustoidentifysomegeneticdeterminantsinvolvedinA.thalianaresponsetoTuMVinfectioninourcommongardenexperiments.Somemappedlociwerepreviouslyknowntobeinvolvedinplant/Potyvirusinteractionsbutwealsohighlighteddenovocandidateloci.Somewerecommonbetweenthedifferentexperimentsandsomewereyeardependent.Metabolicphenotypingshowssignificantdifferencesinprimarymetaboliccontentbetweenresistantandsusceptiblegenotypeswithaglobalincreaseinsusceptibleones.FirstresultsonOPLS-discriminantanalysissuggestthatprimarymetabolictraitscouldbeusedtodiagnosetheresponseofA.thalianatoTuMVinfection.Abstract#235.TheEDR1ProteinKinaseInhibitsEDS1andPAD4Signaling(Submission47)MatthewNeubauer1,IreneSerrano,RogerInnes1IndianaUniversity,UnitedStatesTheplanthormonesalicylicacidhasbeendemonstratedtoplayanintegralroleinbioticstressresponses.However,welackafullunderstandingofhowsalicylicacidsignalingisregulated.EDS1andPAD4aretwomajorregulatorsofsalicylicacidsignaling.Together,theyareresponsibleforpositivelyregulatingtheproductionofsalicylicacidinresponsetopathogeninfection.AnessentialaspectofEDS1andPAD4signalingistheformationofanEDS1/PAD4complex.Theformationofthiscomplexisassociatedwithtranscriptionalchangesthatoccurduringinfection.PriorworkinourlabhasuncoveredarolefortheEDR1proteinkinaseintheregulationofdefensesignaling.Geneticevidencesuggeststhat,unlikeEDS1andPAD4,EDR1isanegativeregulatorofsalicylicacidandplantdefensesignaling.However,thereisalackofmolecularevidencedemonstratingtheroleofEDR1inregulatingplantstressresponses.RecentworkinourlabhasdemonstratedthatEDR1mayfunctionasanegativeregulatorofEDS1andPAD4.Wehaveidentifiedandcharacterizedauniquegain-of-functionmutationinPAD4(pad4S135F).pad4S135Fwasfoundtoenhanceasubsetofedr1phenotypes,indicatingthatsomeedr1phenotypesmayresultfrommisregulationofPAD4.ThispromptedustoinvestigatewhetherEDR1mayplayadirectroleinPAD4signaling.IhavefoundthatEDR1iscapableofinteractingdirectlywithbothPAD4andEDS1.Furthermore,myresultsindicatethatEDR1iscapableofinhibitingtheformationoftheEDS1/PAD4complex.ThesefindingsdemonstratethatEDR1isanegativeregulatorofEDS1/PAD4signaling,andprovidemolecularevidencetoexplaintheroleofEDR1indefensesignaling.Keywords:Defensesignaling;defensehormones;cellbiology;celldeathpathwaysAbstract#236.DiversemechanismsofresistancetoPseudomonassyringaeinathousandnaturalaccessionsofArabidopsisthaliana(Submission48)AndreVelasquez1,Oney,Matthew,MSU-DOEPlantResearchLaboratory,Huot,Bethany,MSU-DOEPlantResearchLaboratory,andCellandMolecularBiologyProgram,MichiganStateUniversity,Xu,Shu,MSU-DOEPlantResearchLaboratory,andInstituteofBotany,JiangsuProvinceandChineseAcademyofSciences,He,ShengYang,MSU-DOEPlantResearchLaboratory,DepartmentofPlantBiology,MichiganStateUniversity,PlantResilienceInstitute,MichiganStateUniversity,andHowardHughesMedicalInstitute,GordonandBettyMooreFoundation1MichiganStateUniversity,UnitedStatesPlantsarecontinuouslythreatenedbypathogenattack,andassuch,theyhaveevolvedmechanismstoevade,escape,anddefendthemselvesagainstpathogens.However,itisnotknownwhattypesofdefensemechanismsaplantwouldalreadypossesstodefendagainstapotentialpathogenthathasnotco-evolvedwiththeplant.Weaddressedthisimportantquestioninacomprehensivemannerbystudyingtheresponsesof1,041accessionsofArabidopsisthalianatothefoliarpathogenPseudomonassyringaepv.tomato(Pst)DC3000.FourteenaccessionsshowedresistancetoinfectionbyPstDC3000.Ofthese,twoaccessionshadasurface-basedmechanismofresistance,sixaccessionsshowedahypersensitive-likeresponseassociatedwitheffector-triggeredimmunity,whilethreehadelevatedsalicylicacidlevels.Interestingly,A.thalianawasdiscoveredtohavearecognitionsystemfortheeffectorAvrPto,andHopAM1wasfoundtomodulatePstDC3000resistanceintwoaccessions.Ourcomprehensivestudyhighlightsthediversemechanismsofresistancealready

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inplaceinindividualsofapopulationevenbeforeexposuretoaparticularpathogenstrainoccursand,likeintomato,AvrPtorecognitionappearstoplayaprominentroleinmediatingeffector-triggeredimmunityinA.thalianaagainstPstDC3000.Keywords:Arabidopsisthaliana;Pseudomonassyringaepv.tomatoDC3000;resistancemechanisms;plantimmunity;AvrPto.Abstract#237.AnRNAbindingproteinalteredinphosphorylationstateinresponsetoPlantElicitorPeptidesisanegativeregulatorofplantinnateimmunity(Submission49)KeiniDressano1,Weckwerth,Philipp,UCSD,Shen,Zhouxin,UCSD,Briggs,Steven,UCSD,Huffaker,Alisa,UCSD1UCSD,UnitedStatesAnRNAbindingproteinalteredinphosphorylationstateinresponsetoPlantElicitorPeptidesisanegativeregulatorofplantinnateimmunityPlantscanperceivemoleculesfromforeignorganismstodetectattack,andproduceendogenouspeptideelicitorstoamplifytheimmuneresponse.ThePlantElicitorPeptides(Peps)werefirstdiscoveredinArabidopsisandregulatedefenseagainstpathogens.OrthologousPROPEPgeneshavebeendiscoveredinover100plantspeciesandallmajorcrops.Inmaizeandotherplants,Pepsalsoregulateanti-herbivoredefenseresponses.TheidentificationofPepsignalingpathwaycomponentswillcontributetoourunderstandingofhowPepsmediateresistanceresponsestopathogensandherbivores,enablingthedevelopmentofstrategiestoimproveplantimmunity.ToidentifyPepsignalingcomponents,theprofilingofrapidchangesinthephosphoproteomewasinvestigatedinsuspensioncellsofArabidopsisandmaizetreatedwithAtPep1andZmPep3,respectively.OneoftheproteinsalteredinphosphorylationstateinbothplantspecieswasanRNArecognitionmotif(RRM)-containingprotein.OurresultsshowedthatArabidopsismutantscontainingT-DNAinsertionsinthegeneencodingRRM-containingproteinarehypersensitivetoAtPep1andmoreresistanttopathogens,indicatingthepotentialactivityofRRMasanegativeregulatorofPep-inducedresponses.WearecharacterizingthemolecularmechanismsbywhichthisRRM-containingproteinaffectsPepsignalingandimmunitythroughstudiesofearlysignalingresponses,transcriptionalprofilingandimmunopurificationofribonucleoproteincomplexestodetecttheRNAtargets.Keywords:Plantelicitorpeptide;plantinnateimmunity;phosphoproteomicanalysis;RNArecognitionmotif(RRM)-containingprotein;negativeregulator.Abstract#238.Structure-functionanalysisofArabidopsisEDS1immunesignallingcomplexes(Submission65)DeepakBhandari1,Lapin,Dmitry,MPIPZ,Huet,Gaelle,INRA-CNRS,Deslandes,Laurent,INRA-CNRS,Niefind,Karsten,UniversityofKöln,Parker,Jane,MPIPZ1MaxPlanckInstituteforplantbreedingresearch,GermanyActivationofplantinnateimmuneresponsesbyintracellularreceptorsinvolvesdynamicchangesinthesubcellularlocalisations,assembliesandactivitiesofsignallingcomplexes.A.thaliananucleocytoplasmicproteinEDS1,withitssignallingpartnersPAD4andSAG101,coordinatesbasalandreceptor-triggereddefencereprogramming.EDS1,PAD4andSAG101existinallseedplantsandformaplant-specificfamilywithacatalyticallyinactiveN-terminallipase-likedomainandauniqueC-terminal‘EP’domain.FunctionalanalysisofthecrystalstructureofEDS1-SAG101heterodimerandaderivedEDS1-PAD4modelshowedthatEDS1heterodimerswitheachpartnerareessentialforresistancesignalling.EDS1heterodimerizationcreatesacavitylinedwithconservedresiduesintheEPdomain.Structure-guidedanalysisrevealedaconservedArginine(R493)inEDS1,whichwhenmutatedtoAlanine(R493A)delaysimmunesignallingwithoutalteringnucleocytoplasmiclocalizationandinteractionwithitspartners.WefindthatincreaseddiseasesusceptibilityofR493Aineffector-triggeredimmunity(ETI)tobacterialstrainsisduetoafailuretocounteractvirulenceactivityofthephytotoxincoronatine(COR).CORdoesnotaffectdelayedSAaccumulationofR493A,althoughitsuppressesSAaccumulationinwild-typeplants.FurtherR493mutations,coupledwithRNA-seqanalysis,showthatapositivelychargedresidueatR493(R493K)isvitalforEDS1immunityandcorrelateswithanabilityofEDS1tobindtonucleicacidinsitu.AnegativelychargedR493EvariantissusceptibleirrespectiveofbacterialCORstatus,suggestingthatR493ArepresentsaweaklossoffunctionvariantofEDS1.OurstructuralanalysisofEDS1revealstwointertwinedfunctionsofEPdomainR493-(i)toantagonizeCOR-mediatedvirulenceand(ii)toorchestratetimelyimmunityreprogramming.Italsoprovidestoolstoprobethemolecularfunctionandinteractionsofthispivotalimmuneregulatorynode.Keywords:Effectortriggeredimmunity;EDS1;Structure-function;NLR;Salicylicacid;CoronatineAbstract#239.PathogenInfectionandMORCproteinsAffectChromatinAccessibilityofTransposableElementsandExpressionofTheirProximalGenesinArabidopsis(Submission66)YogendraBordiya1,YiZheng,Ji-ChulNam,AprilCBonnard,HyongWooChoi,BumKyuLee,JonghwanKim,DanielFKlessig,ZhangjunFei,HongGuKang1TexasStateUniversity,UnitedStatesToassessMORC1’sroleinepigeneticsinrelationtoplantimmunity,genome-widechromatinaccessibilitywascomparedbetweenmock-orPseudomonassyringaepv.tomato(Pst)-inoculatedwildtype(WT)Arabidopsisand/orthemorc1/2doublemutant.Mostchangesinchromatinaccessibility,scoredbyDNaseIhypersensitivesites(DHSs),werelocatedinthepromotersofgenesandtransposableelements(TEs).Comparisonsbetweenmorc1/2andWTreceivingthesametreatmentrevealeddifferentialDHSs(dDHSs)predominantlyassociatedwithheterochromaticTEs.Bycontrast,comparisonsbetweenmock-andPst-inoculatedplantsfromthesamegenotypeshoweddDHSs

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associatedwithbiotic/abioticstress-relatedgenes;asmallerbutsignificantpopulationwasinTEs.Interestingly,manydefensegenes,includingPR-1,PR-2andPR-5,wereproximaltoPst-induced,TE-associateddDHSs.Arandomsubsetofthesedefensegenesshowedmoderatelydelayed/reducedexpressioninPst-infectedmorc1/2ascomparedwithWT.MORC1wasphysicallyboundtochromatininaPstinfection-responsivemanneratsitesdispersedthroughoutthegenome.Notably,silencingofTE-associateddDHSsproximaltotheseinfection-induced,MORC1-interactingsitesledtosignificantsuppressionofPst-inducedtranscriptionofadjacentdefensegenes,includingPR-1.TheseresultsprovideevidencethatMORC1isassociatedwithTEsandsuggestthatasubsetoftheseTEsmayhelpregulatetheirproximaldefensegenes.Keywords:Plantdefensekinetics,TransposableelementsAbstract#240.RoleofaWRKYTranscriptionFactorinArabidopsisthalianaInteractionwiththeGreenPeachAphid,Myzuspersicae(Submission70)MonikaPatel1,Dr.SujonSarowar,Dr.JyotiShah1UniversityofNorthTexas,UnitedStatesInsectinfestationlimitsagriculturalproductivity.Insectsthatfeedonplantscanbebroadlyclassifiedaschewinginsectsandthosethatusestylets,whicharespecializedpiercingmouthparts,toconsumecell,xylemorphloemcontent.Aphidsarealargegroupofphloemsap-consuminginsectsthatlimitplantproductivityduetoremovalofphloemsap.Inaddition,someaphidsvectorviraldiseases.Thegreenpeachaphid(GPA;Myzuspersicae)isanimportantpestofmorethanfiftyplantfamiliesthatincludeimportantagriculturalandhorticulturalcrops,andfruittrees.Furthermore,GPAvectorsmorethan100viraldiseases.TheinteractionofGPAwiththecruciferArabidopsisthalianahasbeenutilizedtoidentifyplantgenesandmechanismsthatcontributetodefenseandsusceptibilitytotheGPA.WehaveidentifiedanArabidopsisWRKYgenethatisexpressedatelevatedlevelsinGPA-infestedleavescomparedtocontrol,uninfestedleaves.PlantscontainingaT-DNAinsertionwithinthisWRKYgeneexhibitedenhancedresistancetoGPA.GPApopulationsizewashigheronwild-typecomparedtomutantplants.Althoughtheweightofinsectsfeedingonwildtypeandthewrkymutantplantswascomparable,GPAfecunditywassignificantlyloweronthewrkymutantcomparedtowildtypeplants.Further,whenprovidedachoice,insectspreferredthewild-typeoverthewrkymutantplant.ExpressionofthisWRKYgeneisupregulatedinthevasculatureofGPA-infestedplantsthussuggestingthattheGPAtargetsexpressionofthisgenetofacilitateinfestation.EffortsareunderwaytocharacterizethemolecularfunctionofthisWRKYgeneandthemechanismunderlyingitsroleinfacilitatingGPAinfestationonArabidopsis.Keywords:PlantDefense;GreenPeachAphid;NoChoiceBioassay;TransgenicsAbstract#241.GeneticDissectionofArabidopsisMAPKinasePhosphatase1(AtMKP1)-dependentPAMP-inducedtranscriptionalresponses(Submission78)LingyanJiang1,Wan,Ying,UniversityofKansas,Anderson,Jeffrey,OregonStateUniversity,Hou,Jie,UniversityofMissouri-Columbia,Islam,Soliman,UniversityofMissouri-Columbia,Cheng,Jianlin,UniversityofMissouri-Columbia,Peck,Scott,UniversityofMissouri-Columbia1UniversityofMissouri-Columba,UnitedStatesPlantimmunitytopathogenscanbeinitiatedbyextracellulardetectionofpathogen-associatedmolecularpatterns(PAMPs)throughsurface-localizedpatternrecognitionreceptors(PRRs).DetectionofPAMPsbyPRRsinducesmanyintra-andextracellularresponsesincludingtheactivationofmitogen-activatedproteinkinases(MAPK)thatultimatelylimitbacterialgrowth.MAPkinasephosphatases(MKPs)areimportantnegativeregulatorsofdefense-associatedMAPKsinplants.PreviousworkidentifiedArabidopsisMAPkinasePhosphatase1(MKP1)asanegativeregulatorofsignalingpathwaysrequiredforsome,butnotall,ofPAMP-initiatedresponses.Specifically,lossofMAPKMPK6inanmkp1backgroundsignificantlysuppressedasubsetofthemkp1-dependentbiologicalphenotypes,indicatingtherequirementforMPK6inMKP1-dependentsignaling.TofurthergeneticallyseparatetheoutputsofPAMP-responsivesignalingpathways,weperformedatranscriptomeanalysisinArabidopsiswild-type,mkp1andmkp1mpk6seedlingstreatedwiththebacteria-derivedPAMPelf26andharvestedtissueat0,30,and90minpost-elicitation.Usingdifferentialgeneticandtemporalclusteringanalysesbetweenandwithingenotypes,wehaveidentifiedandseparated6963elf26-responsivetranscriptsbasedonbothgeneticrequirementsofMKP1(withorwithoutarequirementforMPK6)aswellastemporaltranscriptionalaccumulationpatterns.AnovelsetofgenemarkersforMKP1-andMKP1/MPK6-dependentand–independentpathwayswasfurthervalidatedbyqRT-PCRoveramoreextendedtimecourse,andthisfine-scaleanalysisrevealedadditionaltemporalseparationofaccumulationpatterns.Takentogether,ourtranscriptomeanalysisprovidesnovelinformationfordelineatingPAMPsignalingpathways.Keywords:mitogen-activatedproteinkinase;MKP1;pathogen-associatedmolecularpattern(PAMP);phosphatase;transcriptomeanalysis

Abstract#242.RKS1,anatypicalkinaseinvolvedinquantitativediseaseresistanceagainstXanthomonascampestris(Submission84)UllrichDubiella1,Huard-Chauveau,Carine,CNRS-LIPM,Delplace,Florent,CNRS-LIPM,Roux,Fabrice,CNRS-LIPM,Roby,Dominique,CNRS-LIPM1CNRS-LIPM,FranceIncontrasttoeffectortriggeredimmunity(ETI)whichdependsonlyonthepresence/absenceofonepathogenderivedeffectorandone

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plantderivedresistance-protein,andwhichconfersnearly100%resistanceagainstthepathogen,quantitativediseaseresistance(QDR)dependsontheinterplayofmultiplequantitativetraitloci(QTLs)withpartialeffectsonplantimmunity.IncontrasttoETI,QDRisconsideredamoredurabletypeofresistancewhichishardertobreakbypathogens(Frenchetal.,2016).Therefore,theidentificationofgenesunderlyingQDRvariationmighthaveenormouspracticalimplicationstoincreasecropyieldandquality.However,thereisstillverylimitedinformationaboutthemolecularmechanismscontrollingvariationinquantitativediseaseresistance.Oneofthemostimportantdiseaseofcrucifers(includingCabbage,BroccoliandRapeseed),istheblackrot,causedbythebacterialplantpathogenXanthomonascampestrispv.campestris(Xcc).Byadoptinggenomewideassociating(GWA)mappingapproach,wewereabletoidentifyResistancerelatedKinaSe1(RKS1)astheresponsiblegeneunderlyingamajorQTLconferringapprox.50%resistanceinArabidopsisthalianaagainstXcc568(Huard-Chauveauetal.,2013).OurstudyaimstoidentifydirectandindirectRKS1-dependentsignallingpathwaysinvolvedinQDR.Weusedtwocomplementaryapproaches:(i)comparativetranscriptomeanalysisofmis-expressingRKS1lines,and(ii)identificationofproteinsinteractingwithRKS1byYeast-two-Hybridassays.ResultsonseveralputativedirectorindirecttargetsofRKS1willbepresented.French,E.,Kim,B.S.andIyer-Pascuzzi,A.S.(2016)Mechanismsofquantitativediseaseresistanceinplants.Semin.CellDev.Biol.,56,201–208.Huard-Chauveau,C.,Perchepied,L.,Debieu,M.,Rivas,S.,Kroj,T.,Kars,I.,Bergelson,J.,Roux,F.andRoby,D.(2013)AnAtypicalKinaseunderBalancingSelectionConfersBroad-SpectrumDiseaseResistanceinArabidopsis.PLoSGenet.,9.Keywords:QDR;atypicalkinase;XanthomonasAbstract#243.ExtracellularvesiclesisolatedfromtheapoplastofArabidopsisleavescarrystress-responseproteinsandmicroRNAs(Submission86)BrianRutter1,Innes,RogerW.,IndianaUniversity1IndianaUniversity,UnitedStatesExtracellularvesicles(EVs)mediatethelong-distancetransportofproteinsandRNA.MammalianEVsplayakeyroleinintercellularsignalingandcanmodulateseveralimmuneresponses.PlantsalsosecreteEVs,particularlyinresponsetopathogens,butthecontentandfunctionofthesevesiclesremainsunknown.InordertobetterunderstandtheroleofplantEVsinimmunityandsignaling,wedevelopedamethodforpurifyingEVsfromtheapoplasticwashofArabidopsisthalianaleaves.ProteomicanalysisrevealedthatArabidopsisEVsareenrichedforproteinsinvolvedinstressanddefense,includingthesyntaxinPEN1andtheABCtransporterPEN3.Consistentwiththesefindings,EVsecretionwasenhancedinresponsetoinfectionwithPseudomonassyringaeortreatmentwithsalicylicacid.WealsodetectedmicroRNAsassociatedwiththeEVs,mostnotablymiR159andmiR166,whicharebothsecretedbycottonplantsduringfungalinfection.Toourknowledge,wearethefirsttosuccessfullyisolateEVsfromleaves.OurfindingssuggestthatplantEVsmayrepresentanimportantcomponentoftheplantimmuneresponse.Keywords:extracellularvesicles;exosomes;vesicles;PEN1;PEN3Abstract#244.Canplantssensemechanicalstimuliandactivatemechanicallytriggeredimmunity?(Submission89)debaratibasu1,KiraVeley,EricSchultz,ElizabethHaswell1WashingtonUniversityinSt.Louis,UnitedStatesWhilemuchisknownabouttheperceptionofmolecularelicitors,therolemechanicalstimuliplayinplantdefenseisstillunclear.Tenhomologsofthewell-characterizedbacterialmechanosensitive(MS)channelofsmallconductance(MscS)havebeenidentifiedinArabidopsisandarenamedMscS-Like(MSL)1-10.OurpreviousstudieshaveshownthatMSL10,aconfirmedstretch-activatedionchannel,actsamodularchannelwithtwoseparateoutputs,i)releaseofosmolytesii)promotionofcelldeath.ThesolubleN-terminaldomainissufficienttoinducecelldeathandisnegativelyregulatedbyphosphorylation.IaimtousetheregulationandfunctionofMSL10asamodelsysteminwhichtoinvestigatewhetherplantscansensemechanicalstimuliexertedbypathogens.Also,IwilldetermineifMSL10cantriggersignalingeventsculminatingintheactivationofknownplantdefensemechanisms.SeveralindependentlinesofpreliminaryevidencesupportaroleforMSL10indefenseresponse:1)MSL10-mediatedcelldeathrequiresSGT1,RAR1andHSP90,essentialcomponentsofplantinnateimmunity;2)InMSL10-overexpressingArabidopsis,thecelldeathphenotypeissuppressedbygrowthathightemperatures;3)RNA-seqanalysisrevealedthatMSL10-overexpressingplantsresembleplantswithconstitutivepathogenresponse;4)MSL10directlyinteractswithseveralstress-responsivekinasesinaphosphorylationstate-specificmanner;5)ConstitutiveoverexpressionofMSL10oraphosphodeadversionofgenomicMSL10promotesresistancetovirulentstrainofPseudomonassyringae.ResultsobtainedfromthisstudywillshedlightonthemodulararchitectureandfunctionaldiversityofMSLchannelsinplants.Inthefuture,itispossiblethatgenetictoolscanbedevisedtoboostplantimmunity,utilizing‘patho-sensors’likeMSL10incropplants.Keywords:Mechanosensitiveionchannel,Arabidopsis,plantdefense,PseudomonassyringaeAbstract#245.APlantImmuneReceptorDetectsPathogenEffectorsthatTargetWRKYTranscriptionFactors(Submission90)ZaneDuxbury1,Ma,Yan,TheSainsburyLaboratory,Huh,SungUn,TheSainsburyLaboratory,Sarris,PanagiotisF,TheSainsburyLaboratory,Segonzac,Cecile,TheSainsburyLaboratory,Sklenar,Jan,TheSainsburyLaboratory,Derbyshire,Paul,TheSainsburyLaboratory,Menke,FrankLH,TheSainsburyLaboratory,Sohn,KeeHoon,TheSainsburyLaboratory,Jones,JonathanDG,TheSainsburyLaboratory

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1TheSainsburyLaboratory,UnitedKingdomNucleotide-bindingdomainandLeucine-richRepeat-containing(NLR)proteinsarethemajorclassofintracellularreceptorsthatconferresistancetopathogensinplants.TheabilityofNLRstorecogniseandrespondtopathogen-secretedvirulencemolecules(“effectors”)isdependentontheformationofproteincomplexes.ThereisrelativelylittleknownaboutthemolecularmechanismsthattransducetheimmunesignalfromanactiveNLRtothenucleustoinitiatethetranscriptionalreprogrammingrequiredforaneffectiveimmuneresponse.TheNLRRRS1containsaWRKYDNA-bindingdomainandhasbeenhypothesisedtodirectlyreprogramthetranscriptionalmachineryduringanimmuneresponse.OurlabandothershavedemonstratedthatthisWRKYDNA-bindingdomainisactingasbaitforpathogeneffectorsandmaynotberesponsiblefordirecttranscriptionalregulation.RRS1requiresbothintramolecularandintermolecularinteractionstoestablishanimmunesignalincooperationwithapartnerNLR,calledRPS4.Inordertofullycharacteriseimmunesignallinginplants,weareundertakingproteomicandbiochemicalanalysesofimmunereceptoractivation.Iwilldiscussinter-andintra-molecularinteractionsrequiredforsignalling-competentRRS1andRPS4complexes.UnderstandingNLRreceptorcomplexeswillprovideinsightintopositiveandnegativeregulationofimmuneresponsesandallowustomoreeffectivelyengineerdiseaseimmunityintodisease-susceptibleplants.Keywords:Immunereceptors;mechanismsofintracellularsignalling.Abstract#246.RegulationofexpressionofplantimmunereceptorgeneSNC1inArabidopsis(Submission91)LeiyunYang1,JianHua,CornellUniversity1CornellUniversity,UnitedStatesPlantshaveevolvedelaborateinnateimmunitysystemagainstmicrobialpathogens.IntracellularplantimmunereceptorNB-LRRgenesaretightlyregulatedforbalancingimmunityandgrowth.RecentevidenceindicatesthattheexpressionofSNC1,aNB-LRRgene,isregulatedbyhistonemodificationssuchasH2Bub1andH3K4me3.MOS1(MODIFIERofSNC1)isalsoimplicatedinSNC1regulationatthechromatinlevel,anditisrequiredfortheupregulationofSNC1intheautoimmunemutantbon1.TofurtherrevealtheregulatorymechanismofSNC1,Iisolatedsuppressormutantsofbon1mos1namedsmobasedontheautoimmunedwarfphenotype.SNC1geneexpressionisindeedincreasedinbon1mos1smocomparedtobon1mos1,indicatingtheseSMOsplayaroleinregulatingSNC1geneexpression.Using‘MappingbySequencing’,IhaveisolatedcandidatesforseveralSMOgenes.Amongthem,halfareinvolvedinhistonemodificationandchromatinremodeling,suggestinganextensiveregulationofSNC1attheepigeneticlevel.TheseepigeneticchangeswillbeinvestigatedattheSNC1locusinvariousmutantcombinationsofbon1,mos1,andsmo.Knowledgegainedfromthisstudycouldshedlightonthecontrolledexpressionofplantimmunereceptorgenesinplantimmunity.Keywords:plantimmunity;Rgene;transcriptionalregulation;histonemodificationsAbstract#247.DirectandindirectEpigeneticRegulationonplantNLRsexpressionthroughachromatinremodelingprotein(Submission95)ChienYuHuang1,DianaSanchezRangel,XiaoboQin,HailingJin1UCRPlantPathologyandMicrobiology,UnitedStatesIntracellularNod-likereceptors(NLRs)regulateinnateimmuneresponsesagainstpathogeninfectioninbothplantsandanimals.Inplants,NLR-mediatedrecognitionofpathogeneffectorsinduceseffector-triggeredimmunity.ExpressionofNLRsaretightlyregulatedtoavoidautoimmuneresponsesordiseases.NLRgenesareregulatedbymiRNAsandsiRNAsatthepost-transcriptionlevel,whethertheyarealsoregulatedepigeneticallyatthechromatinlevelisstilllargelyunknown.Here,wereportthatanSWIBdomaincontainingchromatinremodelingcomplexsubunitsuppressesexpressionofNLRseitherdirectlybybindingtotheirpromoters,orindirectlybybindingtothepromoterofCDC5gene,whichregulatesalternativesplicingofNLRs.Uponinfection,twosmallRNAsareinducedtosilencetheSWIBgene,whichleadstotheactivationofNLRsforplantdefenses.ApanelofNLRsgeneswassuppressedinSWIBoverexpressionlines,andwasinducedintheSWIBmutant.Moreover,SWIBproteinfunctionsviapotentiatingthesuppressioneffectofhistonemarkerH3K9me2.Keywords:NLRs;smallRNA;autoimmuneresponses;epigeneticregulation;chromatinremodeling

Abstract#248.ALipid-AssociatedProteinMOR1isaNovelTemperature-dependentRegulatorofPlantImmuneResponses(Submission103)JiapeiYan1,ZhanLi,ShuWang,JianHua1CornellUniversity,UnitedStatesTemperatureisoneofthemostcriticalenvironmentalfactorsthathasgreatimpactonplantgrowth,development,aswellasdefenseresponses.Althoughmultipleevidenceshaveshownthemodulationroleoftemperatureonplantimmunity,however,theunderlyingmolecularmechanismisstilllargelyunknownandneedsfurtherinvestigation.NaturalvariantsofA.thalianathatadapttolocalenvironmentaresuitableresourcesfordissectingthemolecularcomponentsinvolvedinthermo-sensitivityofdefenseresponse.HereweperformedGWASanalysisofahundredArabidopsisnaturalaccessionsandidentifiedanovelgene,MOR1,mutantsofwhichexhibitedenhancedsusceptibilitytovirulentPseudomonassyringaepv.tomatoDC3000(PstDC3000)andavirulentpathogenwithAvrRPM1,but

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notthenon-virulentDC3000ΔhrcUat16°Cthanat22°C.ThetranscriptabundanceofMOR1wasupregulatedsignificantlyuponpathogeninfection,andtheexpressionlevelofSNC1,RPP4andPR1wereimpairedinmor1mutants.TheseresultssuggestthatMOR1isinvolvedintheRgene-mediateddefenseinatemperature-dependentmanner.SubcellularlocalizationassayrevealedMOR1anditshomologMOR2resideinlipidbodies.Thelipidaccumulationinmor1mutantswasdramaticallyreducedatboth16and22°CwhichcanbecomplementedbythenativegenomicfragmentofMOR1.Yeast-two-hybridscreenidentifiedtwoputativeinteractorsofMOR1:acysteinepalmitoyltransferaseandatransmembranemagnesiumtransporter.Interestingly,magnesiumtransportershowedduallocalizationatplasmamembraneandcytosolicorganellesat16°C.Theseresultsuncoveredanewfundamentalaspectoftheintegrationbetweenlipidmetabolism,thermo-sensitivityandimmunity.Thecharacterizationofmor2andmor1mor2mutants,theinteractionbetweenMORproteinsandtheputativeinteractors,andhowtheycoordinatelipidmetabolismandtemperature-dependentdefensewillbediscussed.Keywords:immunity;temperature;lipidbody

Abstract#249.StomatalimmunityiscellautonomousanduncoupledfromguardcellABAsignalling(Submission104)JaninaTamborski1,MichaelaKopischke,SilkeRobatzek1TheSainsburyLaboratory,UnitedKingdomStomataareformedbyapairofguardcellsthatactivelycontrolthesizeoftheporeaperture.Bydynamicallyincreasingordecreasingtheirvolume,thesecellsactasgatewaystotheleafinteriorforbacterialpathogens.Recognitionofinvadingpathogensbyplasmamembrane-localizedimmunereceptorsi.e.FLAGELLINSENSING2(FLS2)andEF-TuRECEPTOR(EFR)inducestheclosureofstomata.Yet,itremainscontroversialtowhatextentimmunesignallinginguardcellsconvergeswithguardcellsignallingcuesforABA-inducedstomatalclosure.Toaddressthis,wefirstexaminedthestomatalclosureinresponsetobacterialflagellin(flg22)inanumberofABAbiosynthesismutants.Wefoundthatallmutantsexhibitedwildtype-likeflg22-inducedstomatalclosureshowingthatstomatalimmunityisindependentofABAbiosynthesis.WenextfocussedonthethreecloselyrelatedSnRKkinases,ofwhichOST1(SnRK2.6)isrequiredforABA-inducedstomatalclosure.Analysisofsingleknock-outmutantsrevealedthatflg22-inducedstomatalclosurerequiredSnRK2.3butnotOST1.Thesedatasuggestthatflg22-inducedstomatalclosureisuncoupledfromABAguardcellsignalling.Wetheninvestigatedwhetherstomatalimmunityoccursinacell-autonomousmannerasknownforABA.Usingvirus-inducedgenesilencingandguardcell-specificpromoterstorestrictFLS2signallingtoguardcellsweobservedclosureofstomatauponflg22stimulation.Thus,flg22-inducedstomatalclosureiscell-autonomous.Inacomplementaryapproach,weexcludedtheexpressionofthereactiveoxygenspecies(ROS)producingNADPHoxidaseandEFRfromguardcells.Interestingly,thesestomataclosednormallyinresponsetobacterialEF-TusuggestingsignallingeventsfromthesurroundingROS-producingandEFR-expressingcells.Takentogether,ourdatasuggestthatstomatalimmunityisuncoupledfromABAguardcellsignallingandcanbeinducedbycell-to-cellsignals,butalsooccursincell-autonomousmanner.Keywords:StomatalImmunity;PathogenDefence;Guardcellautonomy;Guardcellsignalling;Abstract#250.ASystemsBiology-aidedInvestigationofPathogen-mediatedManipulationofSugarMetabolisminArabidopsis(Submission105)YaliSun1,Mukhtar,Shahid,UAB1UniversityofAlabamaatBirmingham,UnitedStatesTheplant–microbepathosystemconstitutesaverycomplexbiologicalnetworkinwhichthemolecularplayersfromboththepathogenandthehostengageinabattlefordominance.Toinitiateinfection,phytopathogenicbacteriaenterplanttissuethroughnaturalopeningsincludingstomataandresideintheextracellularspaceknownastheapoplast.Plantsdetectmolecularcomponentsoftheinvadingpathogens,rewiretheflowofbiologicalinformation,andoftenrespondwitheffectiveimmuneresponsessuchasmicrobial-associatedmolecularpatterns(MAMPs)-orEffector-TriggeredImmunity(MTIandETI,respectively).Stimulationofthesedefensesinvolvesdynamictemporaltranscriptionalreprogramming,aswellascomplexsignaltransductionnetworksincorporatingfeedbackandcross-talkcontrolledbylargelyunknownmechanisms.Meanwhile,specializedpathogenshaveevolvedsuitesofeffectorsthatmodulatehostcellphysiologyandsupportparasitismbyinducingeffector-triggeredsusceptibility(ETS).Effectorsaredeployedtobreachhostimmunityandmanipulatehostcellmetabolismtoacquirenutrients.Gainingaccesstohostnutrientsisessentialforpathogengrowthandreproductionandisofprimaryimportanceasavirulencestrategy.Keywords:Sugartransporters;transcriptionalregulations;Abstract#251.DualimpactofelevatedtemperatureonplantdefenseandbacterialvirulenceinArabidopsis(Submission107)BethanyHuot1,Castroverde,ChristianDanveM.,MSU,YoussefBelkhadir,AndréC.,MSU,Montgomery,BerondaL.,MSU,He,ShengYang,MSU1MichiganStateUniversity,UnitedStatesClimateconditionshaveprofoundeffectsonplantdiseasedevelopment;however,theunderlyingmolecularbasesarenotwellunderstood.WeusedtheArabidopsis-Pseudomonassyringaepv.tomatoDC3000(PstDC3000)modelpathosystemtoinvestigatewhetherenhanceddiseaseatelevatedtemperature(30°C)isduetocompromisedhostresistance,enhancedpathogenvirulenceorboth.

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WefoundenhanceddiseasefollowingPstDC3000infiltrationat30°Ctobecorrelatedwithlossofsalicylicacid(SA)biosynthesisandsignaling.Inoursystem,enhanceddiseasewasindependentofPHYTOCHROMEINTERACTINGFACTORS(PIFs)andpersistedintemperature-stablePhytochromeB(PhyB)plants,indicatingthatthePhyB/PIFthermo-sensingpathwayisnotinvolvedinimmunesuppressionatelevatedtemperature.Instead,wefoundthatbacterialtranslocationofvirulenceproteinsintoplantcellswasmoreeffectiveat30°Cthanat23°C.ThisincreasealsooccurredinmutantArabidopsisplantsdefectiveinSAbiosynthesis,pointingtoadirectpositiveeffectofelevatedtemperatureonthefunctionofacentralbacterialvirulencemechanism.However,bacterialgrowthinSAdeficientplantswasequivalentatboth23°Cand30°C,indicatinglossofSAisprimarilyresponsibleforenhanceddiseaseat30°C.GlobaltranscriptomeanalysisidentifiedadirectnegativeeffectoftemperatureonSAsignaling,impactingapproximately70%ofgenesregulatedbytheSAsyntheticanalog,benzothiadiazole(BTH).Thismajortemperature-sensitivenodeincludedISOCHORISMATESYNTHASE1(ICS1)andthecanonicalSAmarkergene,PATHOGENESISRELATED1(PR1).Remarkably,BTHcaneffectivelyprotectArabidopsisagainstPstDC3000infectionatelevatedtemperaturedespitethelackofICS1andPR1induction.Ourresultshighlightthebroadimpactofamajorclimateconditionontheenigmaticmolecularinterplaybetweentemperature,SAdefense,andfunctionofacentralbacterialvirulencesystem.Keywords:salicylicacid,environment,elevatedtemperature,pathogenvirulence,plant-pathogeninteractionsAbstract#252.PlasmodesmataattheIntersectionofBacterialPathogenesisandPlantImmunity(Submission119)KyawAung11MSU,UnitedStatesArabidopsishasbeenwidelyusedasamodelplanttouncoverbasicprinciplesunderlyingplant-microbeinteractions.Althoughintensivestudiesduringthepasttwodecadeshaveyieldedinsightintotheplant-pathogenarmsracesatthemolecularandcellularlevels,itremainsunknownwhethersuchbattlesalsooccurinhostcellsthatareadjacenttotheinfectedcellsand,iftheydo,whichpathogenandhostmoleculesareinvolved.Recentstudieshavedemonstratedthatplantscloseplasmodesmata(PD),whicharemembrane-linedchannelsinvolvedincell-to-cellcommunications,aspartofthedefenseresponseagainstbacterialinfection.ThisstudyfurtherexplorestheArabidopsis-Pseudomonassyringaepv.tomato(Pst)DC3000pathosystemtoinvestigatePDatthehost-microbeinterfaces.PstDC3000injects36virulence“effector”proteins,throughthebacterialtypeIIIsecretionsystem,intohostcellstosuppressplantimmunity.Usinglivecellimaging,wediscoveredthatPstDC3000effectorproteinHopO1-1istargetedtoPDinArabidopsis.ExpressionofHopO1-1inArabidopsisleadstoanincreaseinPD-dependentmolecularfluxbetweenplantcells.HopO1-1isphysicallyassociatedwithArabidopsisPD-locatedproteins(PDLP5andPDLP7);bothPDLPsareinvolvedinplantimmunityagainstbacterialinfection.Inaddition,HopO1-1destabilizesPDLP5andPDLP7proteinsinArabidopsis.ConsistentwithitsputativeADP-ribosyltransferaseactivity,weshowedthatHopO1-1isanactiveenzyme.Moreover,deletionofhopO1-1fromPstDC3000genomeleadstoasignificantdefectinbacterialproliferationuponinfectionandgreatlyreducesdistalspreadingwhenthebacteriaareinoculatedlocally.ThefindingraisestheexcitingpossibilitythatbacterialpathogensdelivereffectorssuchasHopO1-1tomodulatehostPDtofacilitateinitialinfectionanddistalspreadingofbacteria.Keywords:plasmodesmata;host-microbeinteractionsAbstract#253.AChloroplast/Peroxisome-localizedLipase-likeProteinRegulatesArabidopsisImmuneGeneExpressionandDefenseResponses(Submission120)ChenglongLiu1,Tao,Kai,OregonStateUniversity.,Cui,Fuhao,TexasA&MUniversity.,Fei,Zhangjun,CornellUniversity.,Tyler,Brett,OregonStateUniversity.,He,Ping,TexasA&MUniversity.,Shan,Libo,TexasA&MUniversity.1TexasA&MUniversity,UnitedStatesPerceptionofpathogen-associatedmolecularpatterns(PAMPs)bypatternrecognitionreceptors(PRRs)elicitsPAMP-triggeredimmunity(PTI)andcontributestoplantresistancetopathogeninfection.TounderstandthemechanismsunderlyingPTIresponses,wehaveperformedageneticscreenfortheArabidopsisgenesgoverningimmunegeneexpression(aggie)usingtransgenicplantscarryingaluciferasereporterunderthecontrolofthepromoterofaPTImarkergeneFRK1(pFRK1::LUC).Thedominantmutantaggie5showedthereducedexpressionofpFRK1::LUCreporterandendogenousPTImarkergenesinresponsetothetreatmentsbymultiplePAMPs.TheactivationofMAPkinasecascadesconstitutesaconvergentstepdownstreamofmultiplePRRsignaling.However,PAMP-inducedMAPKactivationremainedunalteredinaggie5.Inaddition,PAMP-inducedreactiveoxygenspecies(ROS)productionwasreducedinaggie5.Further,theaggie5mutantshowedincreasedsusceptibilityagainstavirulentbacterialpathogenPseudomonassyringae.Map-basedcloningcoupledwithbulkpopulationsequencingrevealedthataggie5carriesamutationinaputativelipasegene(LIP),whichencodesamembraneproteinassociatedwithbothchloroplastsandperoxisomes.OverexpressionofthemutantformofLIP(LIPaggie5)inwild-typeplantsreducedmultiplePTIresponses,mimickingtheaggie5mutant.Twoknockoutalleleslip-1andlip-2alsoshowedcompromisedPTImarkergeneinductionandpartiallylostflg22-triggeredresistance.Preliminaryanalysisonthetranscriptionreprogramming,metabolomicprofilingandintegrationwiththePTIsignalingnetworksuggestthatLIPpositivelyregulatesPTIresponsesinArabidopsislikelyviaorchestrationofthelipidsignaling.Keywords:PTI;Defense;ForwardGenetics;ChloroplastsandPeroxisomes

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Abstract#254.LeafsheddingasabacterialdefenseinArabidopsiscaulineleaves(Submission121)RahulPatharkar1,WalterGassmann,JohnC.Walker1UniversityofMissouri,UnitedStatesPlantsutilizeaninnateimmunesystemtoprotectthemselvesfromdisease.Whilemanymolecularcomponentsofplantinnateimmunityresembletheinnateimmunityofanimals,plantsalsohaveevolvedanumberoftrulyuniquedefensemechanisms,particularlyatthephysiologicallevel.Plant’sflexibledevelopmentalprogramallowsthemtheuniqueabilitytosimplyproduceneworgansasneeded,affordingthemtheabilitytoreplacedamagedorgans.Herewedevelopasystemtostudypathogen-triggeredleafabscissioninArabidopsis.CaulineleavesinfectedwiththebacterialpathogenPseudomonassyringaeabsciseaspartofthedefensemechanism.PseudomonassyringaelackingafunctionaltypeIIIsecretionsystemfailtoelicitanabscissionresponse,suggestingthattheabscissionresponseisanovelformofimmunitytriggeredbyeffectors.HAESA/HAESA-like2,INFLORESCENCEDEFICIENTINABSCISSION,andNEVERSHEDareallrequiredforpathogen-triggeredabscissiontooccur.Additionallyphytoalexindeficient4,enhanceddiseasesusceptibility1,salicylicacidinductiondeficient2,andsenescence-associatedgene101plantswithmutationsingenesnecessaryforbacterialdefenseandsalicylicacidsignaling,andNahGtransgenicplantswithlowlevelsofsalicylicacidfailtoabscisecaulineleavesnormally.Bacteriathatphysicallycontactabscissionzonestriggerastrongabscissionresponse;however,longdistancesignalsarealsosentfromdistalinfectedtissuetotheabscissionzone,alertingtheabscissionzoneofloomingdanger.Weproposeathresholdmodelregulatingcaulineleafdefensewhereminorinfectionsarehandledbylimitingbacterialgrowth,butwhenaninfectionisdeemedoutofcontrol,caulineleavesareshed.Togetherwithpreviousresultsourfindingssuggestthatsalicylicacidmayregulatebothpathogen-anddrought-triggeredleafabscission.Keywords:leafabscission;bacterialdefense;salicylicacid;signaltransduction;abscissiongeneticsAbstract#255.ElongatorisakeyregulatorofplantimmunityinArabidopsis(Submission123)ZhonglinMou1,ChristopherT.DeFraia,XudongZhang,YongshengWang,ChenggangWang1UniversityofFlorida,UnitedStatesPlantsareconstantlyexposedtopotentialmicrobialpathogensandsolelyrelyoninnateimmunitytobattleagainstmicrobialinvasion.Theefficacyofplantimmunityistightlycorrelatedwiththekineticsandmagnitudeofthetranscriptionalchangesinducedbytheinvadingpathogen.Numerousproteinshavebeenshowntoregulateplantimmunity-associatedtranscriptionalreprogramming,amongwhichisthemultitaskingproteincomplexnamedElongator.ElongatorwasfirstpurifiedasaninteractorofhyperphosphorylatedRNApolymeraseIIinyeast,andwaslateridentifiedinanimalandplantcells.TheElongatorcomplexiscomposedoftwocopiesofeachofitssixsubunits(ELP1toELP6),withELP1andELP2servingasscaffoldsforcomplexassembly,ELP3beingthecatalyticsubunit,andELP4-ELP6forminganaccessorycomplex.TheArabidopsisElongatorprotein(AtELP)complexplaysavitalroleinplantimmunity.Forinstance,theAtelp2mutantisassusceptibleasnpr1toPseudomonassyringae,andisassusceptibleascoi1andein2toBotrytiscinereaandAlternariabrassicicola.Additionally,AtelpmutantsarehypersusceptibletothenonhostbacterialpathogensXanthomonascitrisubsp.citriandP.syringaepv.phaseolicolaNPS3121.Incontrast,overexpressionofAtELP3and/orAtELP4inArabidopsis,tomato,andstrawberryenhancesresistancetoP.syringae,X.fragariae,Podosphaeraaphanis,andColletotrichumgloeosporioides.MechanisticallywehaveshownthatAtELP2andAtELP3regulatethekineticsofpathogen-inducedtranscriptomereprogramming.Recentin-depthinvestigationfurtherrevealedthatAtELP2regulatespathogen-inducedtranscriptomechangeslikelythroughmaintaininghistoneacetylationlevels,modulatingthegenomicDNAmethylationlandscape,andinfluencingpathogen-induceddynamicDNAmethylationchanges.ThispresentationwilldiscussrecentadvancesinunderstandingthecriticalepigeneticroleofElongatorinplantimmuneresponses.Keywords:Arabidopsisthaliana;theElongatorcomplex;plantimmunity;nonhostresistance;epigeneticregulationAbstract#256.TranscriptionalregulationoftheplantimmunetranscriptioncoactivatorNPR1(Submission125)MatthewDommel1,YezhangDing,XudongZhang,ZhonglinMou1UniversityofFlorida,UnitedStatesTheplantimmunesystemiscomposedofdifferentlayersthatworktoeliminateinvadingpathogensbeforepathogencolonizationhasbegun.Thefirstlayeroftheplantimmunesystemiscalledpathogen-associatedmolecularpattern(PAMP)-triggeredimmunity(PTI).OncePAMPsarerecognizedbypathogenrecognitionreceptors,theplantinitiatesPTI.SuccessfulpathogenscandeployeffectorproteinsthatdisruptordelayPTIsignaling,enablingeffector-triggeredsusceptibilityandplanttissuecolonization.Plantsinturnhavedevelopedspecializedresistanceproteinsthatcanrecognize,directlyorindirectly,pathogeneffectors.Onceapathogen’seffectorhasbeenrecognized,theplantwillactivateeffector-triggeredimmunity(ETI).Localinfectionalsotriggerssystemicacquiredresistance(SAR)throughouttheplant,whichservestoprotecttheplantfromfutureinfections.TheimmunetranscriptioncoactivatorNPR1isvitaltobothlocalresistanceandSAR.ItinteractswithagroupofTGAtranscriptionfactorstoinitiatetranscriptionalreprogramminguponpathogeninfectionorsalicylicacidtreatment.NPR1isregulatedheavilyatboththetranscriptionalandpost-translationallevel,yethowthetranscriptionoftheNPR1geneisregulatedhasnotbeenfullyunderstood.WefoundthatNPR1canautoregulatesitsowngenetranscriptionandproteinaccumulationthroughapositive-feedbackmechanism.Inthenpr1andtga2tga3tga5tga6mutants,bothNPR1geneinductionandNPR1proteinaccumulationarecompromised.However,theTGA-bindingsequenceTGACGintheNPR1

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promoter/5’UTRisnotrequiredforNPR1geneinduction.SinceithasbeenshownthattwocanonicalW-boxes(WRKY-bindingsites)inthe5’UTRandWRKY6areessentialforNPR1geneexpression/induction,NPR1mayautoregulateitsowngeneexpressionthroughWRKYtranscriptionfactors.TheserecentdiscoveriesonthemechanismsregulatingtheNPR1genetranscriptionwillbediscussed.Keywords:systemicacquiredresistance;salicylicacid;NPR1;transcriptionregulation;TGAfactorsAbstract#257.ACoinwithTwoSides:ProbingNon-PathogenicversusPathogenicinteractionsusingtheFusariumoxysporum-Arabidopsisthalianapathosystem(Submission130)KathrynVescio1,Guo,Li,UniversityofMassachusetts,Ma,Li-Jun,UniversityofMassachusetts1UniversityofMassachusetts,UnitedStatesFusariumoxysporum(Fo)isasoil-dwellingfungalpathogenthatresultsinvascularwiltdiseasesofabroadrangeofplants,includingagriculturalcropsaswellasthemodelplantArabidopsisthaliana1.TherearealsomembersoftheF.oxysporumspeciescomplexthatarenon-pathogenic,andconfervariousdefensebenefitsagainstotherpathogenstothehostplant2.ThroughRNA-seqanalysisofArabidopsisthalianainfectedbytwoFostrainsFo5176(pathogenic)andFo47(nonpathogenic),wehaveidentifiedshiftsinplantgeneexpressionspecifictotreatmentwithFo5176andFo47,respectively.Annotatingprotein-proteininteractionnetworkshighlightedanenrichmentofgenesrelatedtonutrientacquisitionandassimilation,andSalicylicacidmediateddefenseresponsesinFo47infectedA.thalianaroots.Pathogeninfectedroottissuecontainsmodulesrelatedtosecondarymetabolitebiosynthesis,proteinhomeostasis,andsignalingcascadesthattriggerJasmonicacidandsystemicdefenseresponses.PhenotypiccharacterizationhasalsoleadtodefiningprimingbenefitsthatFo47infectionconferstoA.thalianawhenitexposedtoFo5176simultaneouslyand4dayspostinoculationwithFo47.WeproposethatinfectionwithFo47primesSalicylicaciddefenseresponses,andthisisamechanismthatreducesdiseaseseverityofpathogenicF.oxysporuminfectioninA.thaliana.Keywords:RNA-seq;confocalmicroscopy;rootresponsestofungiAbstract#258.TheTIRproteinRBA1functionsasanovel"truncated"NLR-likeimmunereceptor(Submission152)MarcNishimura1,Anderson,Ryan,UniversityofNorthCarolina,Cherkis,Karen,UniversityofNorthCarolina,Dangl,Jeff,UniversityofNorthCarolina1ColoradoStateUniversity,UnitedStatesDetectionofpathogensbyplantsismediatedbyintracellularnucleotide-bindingsiteleucine-richrepeat(NLR)receptorproteins.NLRproteinsaredefinedbytheirstereotypicalmultidomainstructure:anN-terminalToll–interleukinreceptor(TIR)orcoiled-coil(CC)domain,acentralnucleotide-binding(NB)domain,andaC-terminalleucine-richrepeat(LRR).TheplantinnateimmunesystemcontainsalimitedNLRrepertoirethatfunctionstorecognizeallpotentialpathogens.WeisolatedResponsetothebacterialtypeIIIeffectorproteinHopBA1(RBA1),agenethatencodesaTIR-onlyproteinlackingallothercanonicalNLRdomains.RBA1issufficienttotriggercelldeathinresponsetoHopBA1.WegeneratedacrystalstructureforHopBA1andfoundthatithassimilaritytoaclassofproteinsthatincludesesterases,theheme-bindingproteinChaN,andanuncharacterizeddomainofPasteurellamultocidatoxin.Self-association,coimmunoprecipitationwithHopBA1,andfunctionofRBA1requiretwopreviouslyidentifiedTIR–TIRdimerizationinterfaces.AlthoughpreviouslydescribedasdistinctinotherTIRproteins,inRBA1neitheroftheseinterfacesissufficientwhentheotherisdisrupted.ThesedatasuggestthatoligomerizationofRBA1isrequiredforfunction.OuridentificationofRBA1demonstratesthat“truncated”NLRscanfunctionaspathogensensors,expandingourunderstandingofbothreceptorarchitectureandthemechanismofactivationintheplantimmunesystem.Keywords:atypicalTIRdomainproteins;NLRimmunereceptorfunction;TypeIIIeffectorsofPseudomonassyringae;Naturalvariation;structure/function

Abstract#259.DualnegativemodulationsofPTIsignalingbytwotypesofcalciumsignalingcomponents(Submission154)YouLu1,Liu,Xiaotong,UniversityofMinnesota,Truman,William,UniversityofMinnesota,Bethke,Gerit,UniversityofMinnesota,Zhou,Man,UniversityofMinnesota,Katagiri,Fumiaki,UniversityofMinnesota,Glazebrook,Jane,UniversityofMinnesota1UniversityofMinnesota,TwinCities,UnitedStatesPlantimmuneresponsesactivatedthroughperceptionofmicrobe-associatedmolecularpatterns(MAMPs),whichleadstopattern-triggeredimmunity(PTI),aretightlyregulated,reducingtheirnegativeimpactsonplantgrowthandreproduction.Thisregulationincludeskeepingimmuneresponseslowintheabsenceofpathogensandshuttingoffimmunesignalingrapidlywhenitisnolongerneeded.MembersoftheCALMODULIN-BINDINGPROTEIN60(CBP60)family,CBP60gandSARD1,arecrucialsignalingcomponentsforactivatingsalicylicacid(SA)productionandhavebroadrolesinregulatinggeneexpressionduringPTI,whileanotherCBP60familymember,CBP60a,negativelyregulatesSAaccumulationandimmunity.PreviouslytwoCALMODULIN-LIKEgenes,CML46andCML47,werefoundtoclustertogetherwithCBP60g,SARD1andSID2inaco-expressionanalysis.Inthisstudy,wedemonstratethatCML46andCML47arenegativeregulatorsofimmunityandSAaccumulation.Mutationsineithergeneconferenhanceddiseaseresistance(edr)toPseudomonassyringaepv.maculicola(Pma),andthiseffectisgeneticallyadditivetocbp60a.Transcriptomeprofilingofcbp60aandcml46cml47revealedeffectsonbothacommonsetofgenes,includingCBP60g,andseparatesetsofgenes.Themajoritiesofthese

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differentially-expressedgenesarePma-responsive,withmanyofthembeingCBP60g/SARD1-orSID2-dependent.MathematicalmodelingoftheexpressionpatternsofCBP60gincbp60aandcml46cml47overatimecoursefollowingflg22treatmentsrevealedthatmutationsincml46cml47leadtofasterandstrongerPTIsignalinput,whilecbp60ahasamuchslowersignalingdecayrate.Themodelpredictsthatflg22-PTIwouldbeextendedincbp60aandtheedrphenotypeofcbp60acouldonlybeobservedinthelaterstageofPmainfection.Wetestedthesehypothesesandfoundbotharecorrect.Keywords:Pattern-TriggeredImmunity;NegativeRegulator;CalciumSignaling;MathematicalModeling

Abstract#260.ThemutantincreasedsuppressionofTBF1-8(ist8)offersnewinsightintoposttranscriptionalregulationofimmuneresponseinArabidopsis.(Submission156)PaulZwack1,Xu,Guoyong,DukeUniversity,Zebell,Sophia,DukeUniversity,Greene,George,DukeUniversity,Dong,Xinnian,HowardHughesMedicalInstitute,DukeUniversity1DukeUniversity,UnitedStatesTranslationalregulationisemergingasacrucialaspectofplantimmuneresponsesbutthemechanismislargelyunclear.WehavepreviouslydemonstratedthattranslationofthekeyimmunityregulatingtranscriptionfactorTBF1israpidlyandtransientlyinducedinresponsetoimmunestimuli.Tounderstandthemechanismsofthisregulation,weperformedageneticscreenformutantsimpairedinimmune-inducedtranslationofaTBF1-luciferasereporter.ThroughthisscreenweidentifiedthemutantincreasedsuppressionofTBF1-8(ist8),whichhasconstitutivelylowlevelsofTBF1-luciferaseactivitythatcannotbeinducedbyimmune-inducingstimulisuchasthemicrobe-associatedmolecularpatternmoleculeelf18.Similartotheloss-of-functiontbf1mutant,ist8seedlinggrowthhasdecreasedsensitivitytoelf18.Consistentwitharoleinimmunity,ist8ishyper-susceptibletotheoomycetepathogenHyaloperonosporaarabidopsidis.Wehavemappedtheist8mutation,andfoundthatitisamissensemutationinthecodingsequenceofaDEA(D/H)-boxproteinwithsimilaritytoDHH1pandDDX6fromyeastandhumans,respectively.Thisproteinco-localizeswithmRNA-decappingcomponentsincytoplasmicpuncta(p-bodies)andmayplayaroleintheregulationofmRNAdecay.Futureworkonthisist8willgiveimportantinsightintowhetherTBF1aswellasothergenesdifferentiallytranslatedduringimmuneresponses,couldberegulatedinpartthroughmRNAdecayorsequestrationinp-bodies.Keywords:posttranscriptionalregulation;geneticscreen;Hyaloperonosperaarabisopsidis;p-bodiesAbstract#261.Differentialeffectsofpectindefectsoncellwallcomposition,growth,andimmunity(Submission159)GeritBethke1,Glazebrook,Jane,UniversityofMinnesota1UniversityofMinnesota,UnitedStatesPlantcellwallsarebothearlybarrierstopathogenentryandasourceforsignalingmoleculesthatinduceimmunesignaling.Wehavepreviouslyreportedthatpectincontentandmethylesterificationstatusaffectplantimmunity.PlantswithmutationsinUDP-Glucuronate-4-Epimerase1(GAE1)andGAE6havestronglyreducedhomogalacturonancontentandshowincreasedsusceptibilitytothefungusBotrytiscinereaisolateGallo1.Thegae1-1gae6-1mutantwepreviouslydescribedhadnoapparentgrowthdefects(Bethkeetal.,2016).Werecentlyidentifiedaseconddoublemutant,gae1-2gae6-2,withevenstrongerreductioninpectincontentthatexhibitedseveregrowthdefects.Othergroupshavedescribedplantswithmutationsinaputativeglycosyltransferase(QUA1,Boutonetal.,2002),aputativemethyltransferase(QUA2,Mouilleetal.,2007)orCGR2andCGR3thataffectpectinmethylesterification(Kimetal.,2015)thatshowreducedpectincontentandgrowthdefects.Tofurtherstudytheeffectsofpectinonplantgrowthandimmunitywecomparedallmutantsinparallel.Pectin,measuredasuronicacidcontentandbindingofthehomogalacturon-specificLM20antibody,wasstronglyreducedingae1-1gae6-1,gae1-2gae6-2andcgr2cgr3andsomewhatreducedinqua2.Incontrasttotheobservedincreasedsusceptibilityofgae1gae6toB.cinereaGallo1,cgr2cgr3andqua2plantsshowedincreasedresistancetothispathogen.Incgr2cgr3thiscoincidedwithconstitutivelyincreasedexpressionoftheimmunemarkergenesPR1,PAD3andJAZ10andreducedexpressionofPDF1.2whereasexpressionofthesegeneswasunalteredinqua2.Additionally,qua2,cgr2cgr3andgae1-2gae6-2plantsshowedincreaseddehydrationofrosetteleaves.Itappearsthatdifferentdefectsinpectinbiosynthesisdifferentiallyaffectplantgrowth,cellwallcompositionandplantimmunity.Theseresultsarepreliminary.Updatedresultswillbepresented.Keywords:plantimmunity;cellwall;pectin;BotrytiscinereaAbstract#262.Anovelfunctionforanorphangeneinmediatingpathogenandpestresistance(Submission165)LingLi1,MingshengQi,WenguangZheng,XuefengZhao,JessicaD.Hohenstein,DanNettleton,GustavoC.MacIntosh,GregoryL.Tylka,EveSyrkinWurtele,StevenA.Whitham1MississippiStateUniversity,UnitedStatesCropplantsmustintegratesignalsfromtheenvironmentandprioritizeresponsestostressesthatmayoccurindividuallyorsimultaneouslythroughoutthegrowingseason.Stressresponsescanadverselyaffectplantgrowthandqualitytraitssuchasprotein.Enhancingthenutritionalqualityanddiseaseresistanceofcropspecieswithoutsacrificingproductivityisakeyissuefordevelopingvarietiesthatarevaluabletofarmersandforsimultaneouslyimprovingfoodsecurityandsustainability.Higherproteinisadesirableagronomictrait,andisparticularlyimportantinstaplecropsthatprovidefoodforlargepopulations.ExpressionoftheArabidopsis

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thalianaspecies-specificAtQQS(Qua-QuineStarch)orphangeneoritsinteractor,NF-YC4(NuclearFactorY,subunitC4),hasbeenshowntoincreaselevelsofleaf/seedproteinwithoutaffectingthegrowthandyieldofagronomicspecies(1-6).WefurtherdemonstratethatoverexpressionofgenesrelatedtoQQSnetworkinArabidopsisandsoybeanenhancesresistance/reducessusceptibilitytoviruses,bacteria,soybeancystnematodes,andaphids.OurfindingspointthatthegenesinvolvedinQQS-relatednetworkcanbemanipulatedtoimproveproteinanddefensivetraitsincropplants,overcomingthenormaltradeoffsbetweengrowthanddefense.OurresultsopendoorstopotentialapplicationsofgenesrelatedtoQQSnetworkincrops.1.Li,L.etal.IdentificationofthenovelproteinQQSasacomponentofthestarchmetabolicnetworkinArabidopsisleaves.PJ(2009).2.Li,L.&Wurtele,E.S.U.S.Patent(2012).3.Li,L.&Wurtele,E.S.TheQQSorphangeneofArabidopsismodulatescarbonandnitrogenallocationinsoybean.PBJ(2015).4.Li,L.etal.QQSorphangeneregulatescarbonandnitrogenpartitioningacrossspeciesviaNF-YCinteractions.PNAS(2015).5.Arendsee,Z.W.,Li,L.&Wurtele,E.S.Comingofage:orphangenesinplants.TIPS(2014).6.Li,L.&Wurtele,E.S.,U.S.PatentOffice(2015).Keywords:carbonandnitrogenpartitioning,pathogen,pest,orphangene,susceptibilityAbstract#263.Acytokinin-regulatedtranscriptionalswitchbetweengrowthanddefense(Submission180)CrisArgueso1,Albrecht,Tessa,ColoradoStateUniversity,Salvador,Felipe,ColoradoStateUniversity,Hadju,Dawn,ColoradoStateUniversity,Berry,Hannah,ColoradoStateUniversity,Watson,Ruthie,ColoradoStateUniversity1coloradostateuniversity,UnitedStatesDuringactivatedstatesofimmunityplantsoftendisplayatradeoffbetweendefenseandgrowth.Highlevelsofdefenseactivationleadstoreducedshootgrowthandalsoreducedseedset.Hormonesignalingnetworksareresponsibleforregulatinggrowthanddevelopment,aswellasplant-pathogeninteractions.Toidentifypossiblemolecularmechanismsmodulatingthegrowthdefensetrade-offinplantswefocusedontheplantgrowthhormonecytokinin,widelyknownforaroleinplantgrowthanddevelopmentandforwhicharoleindefenseresponsestobiotrophicpathogenshasbeenrecentlydemonstrated.Weusedacomputationalbiologyapproachtoanalyzetranscriptionaldataforregulatorsofplantgrowth-defensetradeoffs.Withthisapproachweidentifiedaclassoftranscriptionfactorsthatareimportantforcytokinin-promotedplantgrowth,andwhoseexpressionisrapidlyreducedduringdefenseactivation.Geneticanalysesshowedthatmutationsinthesegenesleadstoincreasedresistancetobacterialandoomycetepathogens,aswellasincreaseddefensegeneexpression.Overexpressionofthesegenespositivelyaffectsplantgrowth.Weproposethatthesetranscriptionfactorsmayfunctionasaswitchbetweengrowthanddefense,throughtheregulationofcytokinin-regulatedtranscriptionaltargetsthatprioritizeplantgrowthoverdefenseactivation.Keywords:phytohormone;cytokinin;salicylicacid;defense;growthAbstract#264.BOTRYTIS-INDUCEDKINASE1regulatesArabidopsisresistanceagainstaphidsthroughsuppressingcelldeath(Submission186)JIAXINLEI1,LiboShan,KeyanZhu-Salzman1TexasA&Muniversity,UnitedStatesBOTRYTIS-INDUCEDKINASE1(BIK1)playsimportantrolesininduceddefenseagainstfungalandbacterialpathogensinArabidopsis.Itstomatohomologenhanceshostplantresistancetoachewinginsectherbivore.However,itremainsunknownwhetherBIK1functionsinplantdefenseagainstaphids,agroupofinsectswithaspecializedphloem-feedingstyle.Inthisstudy,thepotentialroleofBIK1wasinvestigatedinArabidopsisinfestedwiththegreenpeachaphid,Myzuspersicae.IncontrasttothepreviouslyreportedpositiveroleofintactBIK1indefenseresponse,lossofBIK1functionadverselyimpactedaphidsettling,feedingandreproduction.Relativetowild-typeplants,bik1displayedhigheraphid-inducedH2O2accumulationandmoreseverelesions,resemblingahypersensitiveresponse(HR)againstpathogens.Thesesymptomswerelimitedtotheinfestedleaves.Thebik1mutantshowedelevatedbasalaswellasinducedsalicylicacidandethyleneaccumulation.Intriguingly,elevatedsalicylicacidlevelsdidnotcontributetotheHR-likesymptomsortotheheightenedaphidresistanceassociatedwiththebik1mutant.Elevatedethylenelevelsinbik1accountedforaninitial,short-termantixenoticactivity.Introducingalossoffunctionmutationintheaphidresistanceandsenescence-promotinggenePHYTOALEXINDEFICIENT4(PAD4)intothebik1backgroundblockedbothaphidresistanceandHR-likesymptoms,indicatingbik1-mediatedresistancetoaphidsisPAD4-dependent.Takentogether,ArabidopsisBIK1conferssusceptibilitytoaphidinfestationthroughitssuppressionofPAD4function.Furthermore,theresultsunderscoretheroleofreactiveoxygenspeciesandcelldeathinplantdefenseagainstphloem-feedinginsects.Keywords:Greenpeachaphid;celldeath;plant-insectinteraction;reactiveoxygenspecies;hypersensitiveresponseAbstract#265.RolesandProgrammingofARGONAUTEProteinsduringTurnipCrinkleVirusInfectioninArabidopsis(Submission187)XingguoZheng1,KerriganB.Gilbert,JamesC.Carrington1DonaldDanforthPlantScienceCenter,UnitedStatesInplants,RNAsilencingfunctionsasanimportantantiviraldefensemechanismthroughtheactionofDICER-like(DCL)andARGONAUTE(AGO)proteins.ToevadeRNAsilencing,plantviruseshaveevolvedavarietyofstrategiestocounterstrikethisdefensemechanism,includingexpressingtheviralsuppressorsofRNAsilencing(VSRs).ArabidopsisthalianagenomeexpressestenAGOproteins,whichare

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classifiedintothreemajorclads,AGO1/5/10,AGO2/3/7andAGO4/6/8/9.AstheeffectorproteinsintheRNAsilencingpathways,AGOproteinsarepreferredtargetsofVSRs,suchasthecoatprotein(P38)encodedbytheTurnipCrinkleVirus(TCV)genome.ByusingaVSR-deficientTCVline,ageneticanalysiswasperformedtoidentifyantiviralAGOproteinsinthedefenseagainstTCVinArabidopsis.DuringTCVinfection,AGO1,AGO2,AGO3,AGO7andAGO10playedantiviralrolesindifferenttissuesinamodularway.Inleaves,AGO2andAGO7functionedastwoprominentnon-additiveanti-TCVeffectors,whileAGO3playedminorrolesinleaves.AGO1,AGO2andAGO10hadoverlappingantiviralfunctionsininflorescencetissues.Furtherco-immunoprecipitationresultsshowedthatTCVcoatproteinP38couldfunctionasitsVSRtohijacktheantiviralRNAsilencingpathwaysbyphysicallyinteractingwithAGO1,AGO2andAGO10effectorproteins.Introducinganaminoacidsubstitutionatspecificsite(R130T)inP38proteincouldabolishitsabilitytointeractwithAGO2protein,withoutaffectingitsinteractionswithAGO1andAGO10.FurtheraminoacidsubstitutiondatashowedthattheGWrepetitivemotifsinP38proteinareindispensableforitsphysicalinteractionwithAGO1andAGO10,butnotthatwithAGO2.Together,thesefindingsindicatethatdistinctAGOproteinshavemodularantiviralfunctionsindifferenttissues,andprovideevidenceabouttheVSRactivityofP38ofTCV.Keywords:AntiviralRNASilencing;ARGONAUTE;TurnipCrinkleVirus,ViralSuppressorofSilencingAbstract#266.Anovelfunctionalgenomicsapproachrevealspreviouslyunrecognizedregulatorsofplantdefenses(Submission188)JosePruneda-Paz1,KatiaBonaldi,ZhengLi,FranciscoUribe-Romeo,JosePruneda-Paz1UCSD,UnitedStatesIncreasedsalicylicacid(SA)levelsuponbacterialpathogeninfectionsleadtoanextensivetranscriptionalreprogrammingthatultimatelyinduceplantdefensemechanisms.InArabidopsisthistranscriptionalresponseismainlydependentonthefunctionofthetranscriptioncofactorNPR1.TheexpressionofNPR1increasesafterSAtreatmentorbacterialinfections,andNPR1levelspositivelycorrelatewiththeactivationofdefenseresponses.However,despiteitscriticalroleforplantdefenses,thetranscriptionalmechanismsthatcontrolNPR1expressionarestillelusive.Wedevelopedanovelluciferase-basedY1Hsystemandusedagenome-wideArabidopsistranscriptionfactor(TF)librarytoidentify,inanunbiasedandcomprehensivemanner,TFsthatbindtotheNPR1promoter.Thisfunctionalapproachuncovered54TFsthatconsistentlybindtotheNPR1promoter.Invivovalidationoftheregulatoryroleforthetop23candidates,identifiedpreviouslyunrecognizedTFsthatpositivelyandnegativelycontrolNPR1expression.TranscriptprofilingrevealedthattheexpressionofpositiveNPR1regulatorsisinducedfollowingPseudomonassyringaeinfection.Interestingly,theexpressionofNPR1negativeregulatorsisrepresseduponinfection,suggestingthatthetranscriptionalreprogramminginducedbythepathogeninteractionleadstoapermissiveconditionfortheupregulationofNPR1.Importantly,byusinganinduciblesystem,wefoundthatoverexpressionofpositiveandnegativeNPR1regulatorsonedaybeforeP.syringaeinoculationresultsinincreaseddiseaseresistanceorsusceptibility,respectively.Altogether,ourresultsindicatethatthecoordinatedfunctionofTFsthatactivateandrepresstheNPR1promoteractivityultimatelyshapeNPR1expressionpattern,influencingpathogencontrolafterinfection.Furthermore,theseresultsprovidevalidationofanovelscreeningapproachanduncoverpreviouslyunrecognizedregulatorsofdefenseresponsesinArabidopsis.Keywords:novelgene-centeredY1Hscreens;NPR1expression;plantdefenseagainstP.syringe;transcriptionalregulationAbstract#267.ExaminingmobilesmallRNAsexchangedbetweentheparasiticplantdodderanditshost(Submission235)NathanJohnson1,Shahid,Saima,PennStateUniversity,Kim,Gunjune,VirginiaTech,Wang,Feng,PennStateUniversity,Wafula,EricK.,PennStateUniversity,Coruh,Ceyda,PennStateUniversity,dePamphilis,ClaudeW.,PennStateUniversity,Westwood,JamesH.,VirginiaTech,Axtell,MichaelJ.,PennStateUniversity1PennStateUniversity,UnitedStatesTheobligatestemparasiticplantdodder(Cuscutapentagona)invadesadiverserangeofdicotyledonoushostplantsusingspecializedfeedingstructurescalledhaustoria.Besidesnutrientandwateruptake,haustoriaalsoallowexchangeofmacromoleculesandvirusesbetweendodderanditshosts.Alarge-scaletranscriptomicstudyrevealedthatmRNAexchangethroughhaustorialconnectionsisbidirectionalandinvolvesthousandsofdifferenttranscripts.Additionally,previousstudieshaveshownthathost-derivedtransgenicsmallRNAscanmoveacrosshaustoriaandsilencedodder-specificgenes.TheseresultsindicatethatendogenoussmallRNAssuchasmicroRNAs(miRNAs)maybealsomobilebetweendodderanditshost.Toaddressthispossibility,wegeneratedsmallRNA-seqdatafromdodder-Arabidopsisassociations.Ourresultsshowastrikingpredominanceof22ntparasitemiRNAsatthedodder-Arabidopsisinterface.MostofthesemiRNAswerealsodetectedinhosttissueawayfromthepointofhaustorialconnections.Additionally,severalofthesemiRNAstriggeredsecondarysmallRNAproductionfromatleastsixArabidopsismRNAtargets.ExamplesofsuchtargetsincludeBIK1(BotrytisInducedKinase1),animportantplayerinplantimmunity.Anothertarget,SEOR1(Sieve-Element-Occlusion-Related1)encodesaproteinthoughttobeinvolvedinsealingphloemsieveelementsafterwounding.Furthermore,mRNAsencodingthreeauxinreceptors,TIR1,AFB2,andAFB3aretargetedbyadoddermiRNAandshowedauniquepatternofsecondarysiRNAproductionindodder-hostinterface.Thesedatademonstratethatdodder-derivedmiRNAstargethostmRNAsduringparasitism,suggestingtheymayactasfactorstoenhanceparasitefitness.Keywords:miRNAs;ParasiticPlants;Inter-speciesregulation

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Abstract#268.Novelrolesofdynamin-relatedproteinnetworkinflg22-signalingandinnateimmunityagainstbacteria(Submission237)AntjeHeese1,Ekanayake,Gayani,UniversityofMissouri-Columbia(IPG),Smith,JohnM.,UniversityofMissouri-Columbia(IPG)1UniversityofMissouri-Columbia,UnitedStatesTheproteincompositionoftheplasmamembrane(PM)hasimportantimplicationsforhowacellperceivesandrespondstoitsenvironment.ControllingchangesinthePMproteomeisimportantforregulatingthestrengthanddurationofcellularresponsestoextracellularstimuli.ThePMimmunereceptorFlagellinSensing2(FLS2)detectsbacterialflagellin(orflg22)toinitiateimmuneresponses.Uponflg22-binding,FLS2undergoesligand-inducedendocytosisanddegradationasameanstodesensitizecellstoflg22andtoremoveactivatedreceptorsfromthePMforsignalattenuation.Sofar,theunderlyingcellularmechanismsandthemolecularmachineryfunctioninginflg22-inducedFLS2removalfromthePMremainlargelyundefined.Ineukaryotes,dynaminsanddynamin-relatedproteins(DRPs)actasmolecularscissorsduringendocytosis.Recently,weidentifiedtheArabidopsisDRP2Bwithnovel,non-canonicalrolesinflg22-signalingandimmunityagainstPseudomonassyringaepvtomato(Pto)DC3000.LossofDRP2Bresultsina20%reductioninflg22-inducedendocytosisofFLS2,correlatingwithheightenedearlyflg22-responses[PLOSPathogens(2014)10:e1004578].OurgoalistoidentifyvesicleproteinsthatfunctiontogetherwithDRP2Binimmunesignalingandendocytosis.Inlarge-scaleimmunoprecipitation,wedetectedseveralproteins,includingVesicularTrafficking3(VES3),thatformedcomplex(es)withDRP2B.ConsistentwithDRP2BandVES3regulatingimmunesignalinginasimilarmanner,lossofVES3resultedinthesamenon-canonicalcombinationofflg22-signalingdefectsobservedfordrp2b.Interestingly,drp2bves3doublemutantshowedsynergisticgeneticinteractionsinplantimmunesignalingandgrowth;butimportantly,wewereabletoseparategrowth&developmentaldefectsfromthoseinimmunesignaling.Currently,weareinvestigatingrole(s)ofVES3andDRP2Binconstitutiveandligand-inducedendocytosisofPMproteinsinvolvedinimmunity.Keywords:dynamin-relatedprotein;endocytosis,plantimmunity;proteintraffickingAbstract#269.RoleofVolatileOrganicCompoundsinPlantSymbioticandDefenseSignalingPathways(Submission243)MuthusubramanianVenkateshwaran1,Rubeck,Sara,UniversityofWisconsin-Platteville,Ackerman,Arlyn,UniversityofWisconsin-Platteville,Theisen,Nickolas,UniversityofWisconsin-Platteville,Brimeyer,Nathaniel,UniversityofWisconsin-Platteville,Welch,Kendell,UniversityofWisconsin-Platteville,Arida,Emily,UniversityofWisconsin-Platteville,Annamalai,Raja,UniversityofWisconsin-Platteville,Ane,Jean-Michel,UniversityofWisconsin-Madison1UniversityofWisconsin-Platteville,UnitedStatesVolatileorganiccompounds(VOCs)isolatedfromplantgrowthpromotingrhizobacteria(PGPR)havebeenshowntoconferresistanceinplantstopathogenicfungiandbacterialeadingtoreduceddiseaseincidenceandseverity.However,ourcurrentunderstandingofthemolecularmechanismsofthebacterialVOC-mediatedplantdefenseresponsesarestillrudimentary.WehypothesizedthattheVOCsactaselicitorsofdefensesignalingbytriggeringtheexpressionofanarrayofdefense-relatedgenesinplantsthatplayaroleineithersalicylicacid(SA)-orjasmonicacid(JA)-mediateddefensesignalingpathways.Throughgeneexpressionstudiesandpathogenicityassays,wehaveidentifiedthecandidateVOCsisolatedfromsoil-bornePGPRthattriggertheSAand/orJA-mediateddefense-signalingpathwayinbothdicots(ArabidopsisthalianaandMedicagotruncatula)andmonocot(rice).Similarly,themavalonicacidbiosyntheticpathwaygivesrisetovolatilesesquiterpenes,whichareshowntoplayanarrayofrolesincludingresistancetoherbivores.Recently,anewroleformevalonateassignalingmoleculesinlegume-rhizobiasymbiosishasbeendemonstrated.However,theroleofmevalonatepathwayinarbuscularmycorrhizal(AM)symbiosis,anotherimportantsymbiosisiscurrentlyunknown.Withthehelpofpharmacologicalandgeneticanalyses,weshowthatmevalonateactivatestheAMsignalingpathwayinrice.ApplicationofmevalonatetriggersnuclearcalciumspikinginricerootssimilartochitinoligomersandthegerminatingsporeexudatesofAMfungi.Similarly,themevalonate-inducedexpressionofAMgenes(AM1,AM3andAM11)aredependentonsymbioticsignalingpathwayinrice.WealsodemonstratethatmevalonatepromotesplantgrowthandlateralrootdevelopmentinricethataredependentonAMsignalingpathway.Keywords:volatileorganiccompounds;defensesignaling;symbioticsignaling;Abstract#270.TheArabidopsisalf3-1mutationcausesautoimmunityintherootandidentifiesaTIRdomainprotein(Submission318)SandaZolj1,Stefanini,Kristina,BostonUniversity,Darrow,Paige,BostonUniversity,RodriguezSastre,Nahomie,BostonUniversity,Hobson,Eric,JacksonStateUniversity,Celenza,JohnL,BostonUniversity1BostonUniversity,UnitedStatesPlantdefenseresponsesvarydependingonthepathogenandintensityoftheattackandaremediatedprimarilythroughtwolevelsofdefense.PAMP-triggeredimmunity(PTI)istriggeredinresponsetohostrecognitionofpathogen-associatedmolecularpatterns(PAMPs).However,pathogenscanevadePTIbysecretingeffectormoleculesintothehostcellthatblockPTI.Inturn,effectormoleculescanbeinhibitedbyasecondlineofplantdefensecalledeffector-triggeredimmunity(ETI).InETItheplantuseseffector-specificresistanceproteinstoblocktheeffector.ETIresultsingeneexpressionchangesthatleadtothehypersensitiveresponse(HR),aformofcelldeath,andtotheplant-widesystemicacquiredresistance.PreviouslyweidentifiedadominantArabidopsisthalianamutant,alf3-1(aberrantlateralrootformation3),whoseprimaryandlateralrootsdieunlessthegrowthmediumissupplementedwithauxinortheplantsaregrownathightemperature.Basedongeneexpressionprofiling,wefoundthatmanyimmuneanddefenseresponsegeneswereexpressedmorehighlyinalf3-1comparedtoWT.Thesegenesincludesalicylicacid(SA)-responsivegenessuchasPR1andPBS3aswellas

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severalWRKYtranscriptionfactors,agenefamilyimplicatedinplantdefense.Consistentwiththesefindings,alf3-1mutantshavegreatlyincreasedsensitivitytoSAaswellasincreasedproductionofdefensecompounds.Inadditionwefoundthatthevastmajorityofdefense-relatedphenotypesdysregulatedinalf3-1returnedtoWTlevelswhenthemutantwasrescuedbyauxinorgrowthathightemperature.UsingwholegenomesequencingwefoundthattheALF3geneencodesanuncharacterizedTIRdomainprotein.BecausecharacterizedplantTIRdomainproteinshavebeenshowntofunctioninplantinnateimmunity,wehypothesizethatalf3-1isagain-of-functionmutationthatcausesanHRinrootsevenintheabsenceofapathogenictrigger.Keywords:autoimmunity;TIRdomain;rootdevelopmentAbstract#271.TSA1isacceleratorofERbodyformationuponwound-relatedstress(Submission320)KyoungRokGeem1,DaeHeonKim,(DepartmentofLifeScience,SCNU)1POSTECH,Korea,RepublicofBrassicaceaeplantsincludingArabidopsiscontainanorganelle,ERbody,whichisderivedfromtheER.RecentstudiesshedsomelighttobiogenesisoftheERbodyandalsoitsphysiologicalroleinplants.However,howtheERbodyisproducedandwhatisthephysiologicalrolearenotfullyunderstood.Inthisstudy,weinvestigatedthephysiologicalroleofTSA1,aclosehomologyofNAI2involvedinERbodyformation,andprovideevidencethatitisinvolvedinERbodybiogenesisunderthewound-relatedstressconditions.TSA1localizestotheERbodyasamembraneproteinusingtheN-terminalhydrophobicstretchasaTMD,therebytheC-terminalregionbeingexposedtothecytosol.TSA1washighlyinducedbyaplanthormone,methyljasmonicacid(MeJA).EctopicexpressionofTSA1:GFPinducedtheERbodyformationinroottissuesoftransgenicArabidopsisandinleaftissuesofNicotianabenthamiana.TSA1andNAI2formedaheterocomplexandshowedanadditiveeffectonERbodyformationinN.benthamiana.However,tsa1mutantplantsdidnotshowanydefectintheconstitutiveERbodyformationinyoungseedlings.Basedontheseresults,weproposethatTSA1playsacriticalroleinMeJA-inducedERbodyformationinplants.Keywords:ERbodyformationAbstract#272.GhWAK1interactswithGhLYK5andpromoteschitininducedGhLYK5-GhLYK1associationincottondefenseresponse(Submission328)PingWang1,LizhuWu,TexasA&MUniversity.,PingHe,TexasA&MUniversity.,LiboShan,TexasA&MUniversity.1TexasA&Muniversity,UnitedStatesFusariumandVerticilliumwlitaretwodevastatingfungaldiseasesincottonandseverelyaffectglobalcottonproduction.Nocommerciallyviablewayisabletoeradicatethesediseasesfromcottoninfielduntilnow.Asafungalmicrobe-associatedmolecularpattern,chitinisrecognizedbylysinmotifreceptorkinases(LYKs)andactivesdefenseresponseagainstfungaldiseasesinplant.Here,byaloss-of-functionscreenusingvirus-inducedgenesilencing(VIGS),wefoundthatGhWAK1,anepidermalgrowthfactor(EGF)-typereceptor-likekinase,regulatesfungaldiseasesresponseandalsoplaysaroleinchitin-induceddefenseincotton.ThetranscriptionofGhWAK1canbehighlyinducedbyFusariumoxysporumandVerticilliumdahliae.SilencingofGhWAK1showedreducedsusceptibilitytotheinfectionsbythesetwofungiandcompromisedMAPKactivityafterchitinelicitation.ThesimilarresultswerefoundinGhLYK1(GhCERK1)andGhLYK5-silencedcottonasexpected,indicatingtheinvolvementofGhWAK1inchitinresponseincotton.FurtherresultsshowedthatGhWAK1interactswithGhLYK5constitutivelyandchitin-inducedGhLYK1-GhLYK5dimerizationisenhancedwhenco-expressionwithGhWAK1invivo.ThedatasuggestGhWAK1isinvolvedinchitin-inducedimmunityandpromotescottondefenseresponsetofungaldiseases.Keywords:CERK1；WAK1；LYK5；Fungaldisease；defense

Abstract#273.PlantParalysis:Localpathogeninfectionsuppressessystemicplantgrowthandleafmovements(Submission345)AdamSeroka1,JinChen,Sheng-YangHe1MichiganStateUniversity,UnitedStatesPlantsarehighlyattunedtotheirlocalenvironmentsandmustbecapableofrespondingtoadverseenvironmentalconditionstomaximizetheirsurvival.Oneofthemechanismsthatplantsemployisenvironment-inducedarchitecturalchangesthatmanifestthemselvesasuniquemovementsthataidinavoidingadverseenvironmentalstressorsandmaximizelightcapture.Arabidopsisthaliana,forexample,respondstoshadedorwarmenvironmentsbyinducingpetioleelongation,resultinginultradianverticalleafmovementsknownasnutations.UsingtimelapseimagingofArabidopsisthalianaduringPseudomonassyringaepvtomatoDC3000(PstDC3000)infection,weobservedsuppressionofpetioleelongationandleafnutationsinbothlocallyinfectedandsystemicallyuninfectedtissues,aphenomenonwecall“Pathogen-inducedPlantParalysis”.Byutilizingacollectionofmutantplantsandpathogens,wediscoveredthatPstDC3000-inducedplantparalysisisdependentonjasmonatesignalinginthehost.PstDC3000producesthephytotoxincoronatinewhichservesmultiplerolesinthevirulenceofPstDC3000andisastructuralmimicoftheactiveformofjasmonate.Bacterialmutantslackingcoronatinebiosynthesislostanabilitytosuppressleafoscillationsandpetioleelongationinsystemictissue.Previousworkestablishedthatshadeandwarmtemperature-inducedarchitecturalchangesrequirethegrowth-promotingtranscriptionalregulatorsphytochrome-interactingfactors(PIFs)andthatactivationofjasmonatesignalinginhibitsplantgrowthbyinterferingwithregulatorystepsupstreamofPIFs.However,weobservedphyBmutantsandPIF-overexpressinglinesareunabletoovercomePstDC3000-inducedplantparalysis,

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suggestingthatfurthercharacterizationofpathogen-inducedplantparalysisisnecessarytogaininsightsintoapreviouslyundescribedaspectofplantinteractionwiththeexternalenvironment.Keywords:Jasmonate,Pathogenesis,Phenomics,Growth-DefenseTradeoff

Abstract#274.ThemastertranscriptioncofactorNPR1repressestranscriptionfactorstoup-anddownregulatetwoimmunesignalsdependentontranscriptionalcontext(Submission353)MikaNomoto1,Itaya,Tomotaka,NagoyaUniversity,Tsukagoshi,Hironaka,MeijoUniversity,Suzuki,Takamasa,ChubuUniversity,Skelly,Michael,UniversityofEdinburgh,Matsushita,Tomonao,KyushuUniversity,Yamamoto,Yoshiharu,GifuUniversity,Higashiyama,Tetsuya,NagoyaUniversity,Spoel,Steven,UniversityofEdinburgh,Tada,Yasuomi,NagoyaUniversity1NagoyaUniversity,JapanExpressionofimmunegenesreliesonsequence-specifictranscriptionregulatorsthatfunctionasactivatorsorrepressorsdependingonthecofactorstheyrecruit.Ifandhowcofactorsalsoshiftbetweenactivatingandrepressingstatesduringinnateimmuneresponsesisfarlessclear.Herewereportthatdependentonthecontextoftranscriptionalnetworks,NPR1,anindispensablecofactorthatregulatestheantagonisticplantimmunesignalssalicylate(SA)andjasmonate(JA),switchesbetweencoactivatorandcorepressorbehavior.WhileNPR1coactivatorphysicallyremovedrepressorWRKYtranscriptionfactorsfromacognatecis-regulatoryelementtoactivateSA-responsivegenes,ithasnoeffectonactivatorWRKYs.TranscriptomeanalysisonSA-repressedJA-inducedgenesinwildtypeandnpr1mutantidentifiedtheG-boxmotifasanNPR1-regulatedcis-element,indicatingthedirectregulationofMYCfamilyproteinsbyNPR1.Indeed,wehaveconfirmedthatNPR1interactedwithMYC2,MYC3,andMYC4invitroandinvivo.Chromatinimmunoprecipitation(ChIP)assayrevealedthatSAsignificantlysuppressedthebindingofMYC2totheG-boxofJA-responsiveLOX2geneinanNPR1-dependentmanner.ThesefindingsdemonstratethatNPR1exertsrepressiveeffectonitstargettranscriptionfactorstoup-anddownregulatekeyimmunesignalsdependentontranscriptionalcontext.Keywords:transcriptionfactor;salicylicacid;jasmonicacidAbstract#275.DefenseCompoundProductionintheOilseedCropCamelinasativa(Submission361)JohnCelenza1,Rengarajan,Shruthi,BostonUniversity,BabaeiAmameh,Mohammad,BostonUniversity,Diallo,Aissata,BostonUniversity,RodriguezSastre,Nahomie,BostonUniversity,Bender,Judith,BrownUniversity,Zolj,Sanda,BostonUniversity1BostonUniversity,UnitedStatesClimatechangecanimpactdefenseagainstherbivoresandpathogensinmultipleways.Forexample,geographicalrangesofplants,insectpests,andplantpathogensmaychangeinwaysindependentofeachother.Thusaparticularplantspeciesmaybeexposedtodifferentand/orgreaternumbersofinsectpestsandpathogensthanithadevolvedtodeter.Identificationofwhichdefensepathwaysareavailabletoaparticularspeciesandunderstandingtheinteractionsbetweenprimaryandsecondarymetabolismisanimportantfocusofcropimprovementandsustainableagriculture.Thusuncoveringmechanismsthatmodulatedefensecompoundsynthesiswillelucidatekeytargetsforenhancingsynthesisandpotentiallyprotectingplantsfromrapidlychangingenvironmentsduetoclimatechange.Camelinasativaisanemergingsustainableoilseedcropadaptedtonorthernclimates.EnhancingCamelina’schemicaldefenseswillincreaseitsvalueasabioenergycropespeciallyinthefaceofchangingenvironmentsduetoclimatechange.Asmemberofthemustardfamily,Camelinaproducesanti-herbivoreglucosinolatesandthephytoalexin,camalexin.However,comparedtomostothermustardsincludingArabidopsis,Camelina’sglucosinolateproductionisreportedtobelessrobustintermsoftissuedistributionandchemicaldiversity.ThesedifferencesindicatethatCamelinamayhavedevelopeddefensestrategiesdistinctfromArabidopsisandsuggestwaystoimproveCamelina’sdefensestoexpanditsgrowthrange.Twoareasarebeingstudiedinthisproject.First,weareusinggenomicandtranscriptomicmethodstoidentifysimilaritiesanddifferencesindefensepathwaysbetweenCamelinaandArabidopsis.Second,weareusingourknowledgeoftryptophanprimaryandsecondarymetabolisminArabidopsistomodifytheprofileofCamelina’stryptophan-deriveddefensecompoundssuchascamalexinandindolicglucosinolates.Keywords:Camelinasativa;glucosinolates;anti-herbivory;defensepathwayevolutionAbstract#276.Bacteriaestablishanaqueouslivingspaceasacrucialpathogenesismechanism(Submission364)XiufangXin1,Nomura,Kinya,MichiganStateUniversity,Aung,Kyaw,MichiganStateUniversity,Velásquez,André,MichiganStateUniversity,Yao,Jian,WesternMichiganUniversity,Boutrot,Freddy,TheSainsburyLaboratory,Norwich,Chang,Jeff,OregonStateUniversity,Zipfel,Cyril,TheSainsburyLaboratory,Norwich,He,ShengYang,MichiganStateUniversity1MichiganStateUniversity,UnitedStatesTheArabidopsis-Pseudomonassyringaepathosystemhasbeenwidelyusedforunderstandingbacterialpathogenesisanddiseasesusceptibilityinplants,leadingtoinfluentialmodelsthatdepictimmunesuppressionmediatedbytypeIIIeffectorsasakeystepofbacterialpathogenesis.Here,ourexperimentsshowedthatimmunesuppressionisinsufficientforP.syringaepathogenesisinArabidopsis.Instead,humidity-dependent,pathogen-drivenformationofaqueousapoplastwasfoundtobeanothercriticalstep.TwoconservedeffectorsfromP.syringae,HopM1andAvrE,aresufficientandnecessarytoproduceaqueousapoplastinthecontextofbacterialinfection.Remarkably,HopM1isalsosufficienttotransformnon-pathogenicP.syringaestrainsintovirulentpathogensin

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Arabidopsisthatisdeficientinpattern-triggeredimmunity(PTI),butnotinplantsdefectiveinsalicylicacidsignaling.Likewise,ArabidopsisquadruplemutantsthataresimultaneouslydefectiveinPTIandahosttargetofHopM1couldsubstantiallyrescuethebasicfeaturesofthismodeldiseaseand,interestingly,losecontroloftheendogenousleaf“bacteriome”.Thus,wehavedefinedtheminimalhostprocessesunderlyingfoliarbacterialpathogenesisandbacteriomehomeostasisinamodelplant.Resultsprovideanewframeworkforpathogenesisandmicrobiomestudiesinplants.Keywords:bacterialpathogenesis;plantimmunity;typeIIIeffectorsAbstract#277.AnoveldimericMedicagodefensinMtDef5confersstrongresistancetoobligateoomycetebiotrophicpathogenHyaloperonosporaarabidopsidisintransgenicArabidopsis(Submission365)KaziIslam1,Islam,Kazi,DonaldDanforthPlantScienceCenter,Sonawala,Unnati,VirginiaTech,McDowell,John,VirginiaTech,Shah,Dilip,DonaldDanforthPlantScienceCenter1DonaldDanforthCenter,UnitedStatesCropdiseasescausedbyfungalandoomycetepathogensareamajorthreattofoodsecurity.Plantspossesssophisticatedinnateimmunesystemtocounteractpathogeninfection.Defensinsareoneoftheearlyeffectorsofplantinnateimmunityandmanyofthesecysteine-richantimicrobialeffectorproteinsprovideeffectivehostdefenseresponseagainstinvadingpathogens.Becauseoftheirbroad-spectrumantifungalactivity,defensinshavestrongpotentialtobeusedforgeneratingcropswithenhanceddiseaseresistance.Plantdefensinsaresmallcysteine-richcationicpeptidesof45-54aminoacids.ThegenomeofMedicagotruncatulacontainsalargefamilyof63genesencodingdefensin.Ofthisgenefamily,onememberencodesauniquehighlycationicdimericdefensin,designatedMtDef5,whichcontains107aminoacidsandconsistsoftwomonomericdefensinsof50aminoacidseachconnectedbya7-aminoacidlinkersequence.Thisdefensinispredictedtobetargetedtotheapoplast.MtDef5inhibitsthegrowthofseveralfilamentousfungiatnanomolarconcentrations.Ourmode-of-actionstudieshaverevealedauniquemechanismfortheantifungalactionofthisdefensinwhichinvolvesitsinteractionwithphosphatidylinositolmonophosphates,abilitytoformoligomericcomplexesandgainentryintofungalcells.Further,overexpressionofapoplast-targeteddimericMtDef5inArabidopsisthalianaconfersstrongresistancetoobligateoomycetebiotrophicpathogenHyaloperonosporaarabidopsidisindicatingthepotentialofthisdimericdefensintoconferresistancetoobligateoomycetepathogensincrops.Keywords:Defensins,antimicrobialpeptides,plantimmunity,oomycetes,ArabidopsisAbstract#278.Re-LocatingRPS5BasedResistance(Submission369)SarahPottinger1,Helm,Matthew,IndianaUniversity,Innes,Roger,IndianaUniversity1IndianaUniversity,UnitedStatesTheArabidopsisthalianadiseaseresistanceproteinRPS5anditspartnerPBS1,conferimmunitytoPseudomonassyringaethroughactivatingtheHypersensitiveResponse(HR),acontrolleddeathofinfectedcells.RPS5sensesP.syringaeindirectlythroughthecleavageofPBS1byaneffector.Therefore,anyeffectorcapableofcleavingPBS1willcauseHRandconferimmunity.PBS1wasmodifiedtocontainacleavagesiterecognisedbytheTurnipMosaicVirus(TuMV)NIaprotease.However,resistanceconferredbythemodifiedPBS1istooslowtostopthespreadofinfection.WetheorisedthiscouldbeduetoapositionalmismatchbetweenthePBS1/RPS5complexandtheTuMVNIaprotein.InanattempttoproducemoreefficientcleavageandtoinvestigatethelimitationsofPBS1/RPS5signallingthePBS1/RPS5complexwasrelocatedawayfromtheplasmamembranetothecellularsitesofTuMVreplication.ItwasfoundthatRPS5requiresaPMlocalisationtosignal.

Abstract#279.Cell-wall-basedregulationofstomataldefenseinArabidopsis(Submission380)yanjuanjiang1,LiZhang,WeiqingZeng,JinChen,ShengYangHe1MSU,UnitedStatesPlantsconstantlyexposetovariousabioticandbioticstressesthroughouttheirlifecycles,which,accordingly,haveevolvedsophisticateddefensestrategiestocopewithstresses.Recentstudieshaveshownthatplantsreducestomatalapertureasaninnateimmuneresponsetorestrictpathogeninfection,whereashighlyevolvedpathogensproducevirulencefactors,suchascoronatine(COR)inthecaseofbacterialpathogenPseudomonassyringaepv.tomato(Pst)DC3000,tocounteractstomataldefense.PreviouslyourlabhasisolatedeightArabidopsismutantsthatexhibitincreasedsusceptibilitytoaCOR-deficientmutantofPstDC3000(scord).Amongthem,sixofthescordmutantsaredefectiveinbacterium-triggeredstomatalclosure.SecondgenerationsequencingandmappingwereemployedfortheidentificationoftheSCORDgenes,twoofwhich,SCORD6andSCORD7genes,wereconfirmed.SCORD6isinvolvedinthedonovosynthesisofGDP-L-fucoseandSCORD7belongstotheTrichomeBirefringence-Likeproteinfamily,ofwhichseveralmembersexhibitrolesinsynthesisand/ormodificationofpectin,xyloglucanandxylan.TheidentificationofSCORD6andSCORD7geneshighlightsplantcell-wall-basedregulationofstomataldefenseandtheeffortstoidentifymoreSCORDgeneswouldcontributetothegeneralunderstandingofthemultifacetedhostdefensemechanismsagainstpathogeninfectioninplants.Keywords:ArabidopsisstomataldefensePseudomonassyringaepv.tomato(Pst)DC3000COR-deficientmutantofPstDC3000(scord)

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Abstract#280.InteractionsofArabidopsisSRFR1,anegativeregulatorofeffector-triggeredimmunity,withtranscriptionfactorsandtranscriptionalco-repressors(Submission381)ChristopherGarner1,Rogan,Conner,UniversityofMissouri,Gassmann,Walter,UniversityofMissouri1UniversityofMissouri,UnitedStatesRegulationoftheplantimmunesystemisimportantforcontrollingspecificityandamplitudeofresponsestopathogens,andinpreventingautoimmunity.Failuretocontroltheseprocessescanresultinareductioninfitness.Inpreviouswork,wereportedthatSRFR1,anegativeregulatorofeffector-triggeredimmunity,interactedwithseveralmembersoftheTCPfamilyoftranscriptionfactors.Wealsoshowedthatatcp8tcp14tcp15triplemutantwascompromisedineffector-triggeredimmunity.GivenSRFR1’sroleasanegativeregulator,andthesusceptiblephenotypeoftheSRFR1-interactingtcpmutants,wehypothesizedthatthefunctionoftheSRFR1-TCPinteractionistorepressTCPmediateddefensegeneexpressionuntiltheproperimmunestimulushasbeenreceived.TotestthishypothesisfurtherwehavebeenexploringinteractionsbetweenSRFR1andTCPswithmembersoftheTOPLESSfamilyofco-repressors.DataindicatethatintheCol-0backgroundageneticinteractionexistsbetweenSRFR1andtwomembersoftheTOPLESSfamily,TPR2andTPR3,asdemonstratedbyanincreaseinstuntingandPR2expressioninsrfr1tpr2andsrfr1tpr2tpr3mutants.Furthermore,thetpr2mutationalsointensifiesautoimmunityintheauto-activesnc1-1mutant,indicatinganovelroleoftheseTOPLESSfamilymembersinnegativelyregulatingSNC1-dependentphenotypes.WealsoshowthatbyoverexpressingTPR2inthesrfr1tpr2backgroundwecansuppressSNC1expression.Inaddition,wehavedetectedprotein-proteininteractionsbetweenSRFR1andTPR2usingco-immunoprecipitation,andbetweenTPR2andseveralTCPsusingbimolecularfluorescencecomplementation.ProgresstowardsestablishinganuclearSRFR1proteininteractionnetworkwillbepresented.Keywords:Transcriptionalregulation;Resistancegenes;histonedeacetylation;autoimmunity;constitutivePRAbstract#281.FormationandPathogenManipulationofReceptor-LikeKinaseComplexes(Submission383)TimothyHowton1,ElwiraSmakowska,HadiaMohamedRaafatAhmed,YaliSun,YoussefBelkhadir,M.ShahidMukhtar1UniversityofAlabamaatBirmingham,UnitedStatesFormationandPathogenManipulationofReceptor-LikeKinaseComplexesTCHowton1,ElwiraSmakowska2,HadiaMohamedRaafatAhmed1,YaliSun1,YoussefBelkhadir2,M.ShahidMukhtar11DepartmentofBiology,UniversityofAlabamaatBirmingham,Birmingham,Alabama2GregorMendelInstitute(GMI),AustrianAcademyofSciences,ViennaBiocenter(VBC),DrBohrGasse3,Vienna,1030,Austria.Plantsandphytopathogensarefixedinanever-evolvingarmsrace.Plantshaveevolvedcell-surfacereceptorsknownasleucine-richrepeatreceptor-likeproteinkinases(LRR-RLKs)torecognizepotentialpathogensthroughconservedpathogen-associatedmolecularpatterns(PAMPs)suchaschitin,flagellin,elongationfactorTu,etc.UponrecognitionofaPAMP,RLKactivatesPAMP-triggeredimmunity(PTI),wheretheplantimploresdefensivestrategiesincludingROSburst,callosedeposition,anddefensehormone(salicylicacidandjasmonicacid)productiontopreventbacterialcolonization.RLKsconsistofaligand-bindingextracellulardomain,atransmembranedomain,andanintracellularkinasedomain,whichisresponsibleforactivatingthedownstreamsignalingcascade.ThekinasedomainsofRLKsfrequentlyinteractwithadditionalRLKsduringthesignaltransductionprocess.InanefforttobetterunderstandRLKfunction,Iconductedabidirectional,pair-wiseyeasttwohybridinteractionstudy.Itested312pairsandfound24interactingpairs.UnderstandinghowtheseRLKsinteraction,canleadtonoveldiscoveriesoftheirrolesinplantimmunity.Additionally,hemibiotrophicbacteriahaveevolvedatactictosuppressthePTIresponse.BacteriacandeliversmalleffectorproteinsintothehostcelltosuppressPTI,therebygivingthepathogenanadvantageousenvironmenttothrive.BecauseRLKsarecrucialintheinitialrecognitionofabacterialinfection,theyarepotentialtargetsofeffectormanipulation.Therefore,IconductedanadditionalscreeningwhereIpair-wisetestedthekinasedomainof20RLKswith31knowneffectorsfromPseudomonassyringaepv.tomatoDC3000inayeasttwohybridsystem.Fromthisscreening,10RLKswereidentifiedaspotentialtargetsofpathogeneffectors.Thisdiscoveryopensthedoortoexploringthedownstreamramificationsofeffectormanipulationofthesekinases.Keywords:Receptor-likekinases;Effectors;Pseudomonassyringae;YeasttwohybridAbstract#282.ExploringanovelroleforTCPtranscriptionfactorsinplantinnateimmunity(Submission384)BenjaminSpears1,Nam,JiChul,UniversityofMissouri,Gao,Fei,UniversityofMissouri,Kim,SangHee,UniversityofMissouri,Gassmann,Walter,UniversityofMissouri1UniversityofMissouri,Columbia,UnitedStatesPlantsareregularlychallengedbymicrobialpathogens,translatingtoenormouseconomiclossannually.Acomplexinnateimmunesystemallowsplantstorecognizepathogen-specificmolecularsignatures,triggeringasystem-widedefenseresponseknownasPAMP-triggeredimmunity(PTI).AsecondlayerofdefenseistriggeredinresponsetotheactivityofspecializedeffectorproteinswhichtargethostcomponentstosuppressPTIandotherwisepromotepathogenfitness.Thestrongphysiologicalresponseandcelldeathassociatedwithhostdetectionofeffectorsisknownaseffector-triggeredimmunity(ETI).Anactiveimmuneresponse,however,ismetabolicallyexpensiveandcomesatthecostofplantgrowthanddevelopment;accordingly,tightregulationiscriticaltoplantfitness.TheTCPtranscriptionfactorfamilyconsistsofwell-characterizedtranscriptionalregulatorsofplantdevelopmentandmorphogenesis.Recently,weidentifiedaroleforthreeclosely-relatedClassITCPsaspositiveregulatorsofETI,andcharacterizednuclearinteractionsinplantawiththenegativeimmuneregulatorSUPPRESSOROFrps4-RLD1(SRFR1).WeproposedamodelbywhichSRFR1inhibitsdefensegene

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transcriptionthroughinteractionswithTCPproteinsandadditionaltranscriptionalcorepressors.NewworkhasrevealedthatactivityoftheseTCPsisnotlimitedtoETIsignaling,butalsoinvolvescomponentsofPTI,likelythroughdirectregulationatthepromotersofkeydefensegenes.AnanalysisofpreliminaryresultswillbepresentedtofurthercharacterizepotentialregulatorymechanismsbywhichTCPs,andbyextension,SRFR1acttomodulateinnateimmunityonmultiplelevels.Keywords:transcriptionalregulation;plantinnateimmunity;PTI;ChIPPost-translationalRegulation:Abstract#283.Disentanglingproteindegradationmechanismsofplantcircadianclocks(Submission29)JoshuaGendron1,Lee,Chin-Mei,YaleUniversity,Feke,Ann,YaleUniversity,Liu,Wei,YaleUniversity,Adamchek,Christopher,YaleUniversity,Li,Man-Wah,YaleUniversity1YaleUniversity,UnitedStatesThecircadianclockinplantsiscriticaltopropertimingofdailyandseasonaldevelopmentalprocesses.Dailyrhythmsinbiomoleculelevelsarecriticaltoclockfunction,andalotisknownabouttherhythmsofmRNAexpressionandthetranscriptionalmechanismsthatcontroltheserhythms.Farlessisknownaboutmechanismsthatdrivecyclingofclockproteins,althoughproteindegradationthroughtheubiquitinproteasomesystemiscriticaltoalleukaryoticclocks.Multiplechallengeshinderstudiesoftheubiquitinproteasomesysteminplants,andwehaveutilizedasimpleproteinengineeringstrategytoovercomethesechallenges.ThishasallowedustostudythegeneticandbiochemicalfunctionsofE3ubiquitinligasesthatcontrolclockfunctionandthattethertheclocktodownstreambiologicalpathways.WehavecompletedastudyofthesmallandpartiallyredundantF-boxfamily(ZTL,FKF1,andLKP2),knowntoregulateclockfunctionandhaveshownthatZTLisamasterregulatorofdiversenighttimeclocktranscriptionfactors.Followingthisweexploredtherolesof30additionalclock-regulatedF-boxproteinsrevealingnewclockregulatorsandnewpost-translationalcouplingmechanismsbetweentheclockandbiologicalprocesses.Finally,wehavecreatedatransgeniclibraryandscreenednearlyhalfofthe~700ArabidopsisF-boxgenesfordefectsinclockfunction.Hopefully,thiswillserveasavaluablecommunityresourceforothersinterestedinstudyingproteindegradationmechanismsinvariousbiologicalprocesses.Keywords:Ubiquitinproteasomesystem;E3ubiquitinligases;Circadianclock;Floweringtime;DevelopmentAbstract#284.TheF-BoxProtein-MediatedProteolyticRegulationofPhenylpropanoidMetabolism(Submission39)Chang-JunLiu1,XuebinZhang,MingyueGou1BrookhavenNationalLabortory,UnitedStatesPhenylpropanoidsrepresentalargefamilyofaromaticmetabolitesthatpossessavarietyofbiologicalfunctionsinplantgrowth,development,andplant-environmentalinteractions.Thebiosynthesisofphenylpropanoidsentailsasequenceofcentralenzyme-regulatedreactions,fromwhichbranchpathwaysemanatetowarddifferentclassesofendproductsincludingthesolublephenolicflavonoidsandthecellwallstructuralcomponentlignin.Thesynthesesarepreciselycontrolledviaamultitudeofregulatorymechanismsinresponsetothedevelopmentalcuesandenvironmentalstimuli.Adoptingconventionalyeast-two-hybridassayandimmunoprecipitation-massspectrometryapproach,werecognizedagroupofArabidopsisKelch(repeat)domain-containingF-box(KFB)proteinsincludingKFBPALs(i.e.,KFB01,KFB20,KFB39andKFB50)andKFBCHS(KFB07)thatphysicallyinteractwithphenylalanineammoniumlyases(PALs),theentrypointenzymeofgeneralphenylpropanoidpathway,andchalconesynthase(CHS),thebranchpointenzymeforflavonoidproduction,respectively,andmediatetheirturnoverviaUbiquitin/26Sproteasomepathway.BothKFBPALsandKFBCHSstronglyrespondtodifferentwavelengthoflight,sugarandstresssignals.DisturbingtheirexpressionreciprocallyaffectsthecellularconcentrationofPALandCHSenzymesand,consequently,alterstheproductionofasetofphenylpropanoidsorflavonoids.OurdatasuggestthattheidentifiedKFBsserveasproteolyticregulators,byintegratingtranscriptionalandpost-translationalregulationmechanisms,tocoordinatelytunephenylpropanoid-flavonoidproductioninArabidopsisphotomorphogenesisandstressresponses.Keywords:Ubiquitination;F-boxprotein;Phenylpropanoidmetabolism;Phenylalanineammonia-lyase;ChalconesynthaseAbstract#285.Cysteine-richreceptor-likekinasescontrolROSproductionandsignaling(Submission45)MichaelWrzaczek1,SachieKimura,KerriHunter,NghiaLeTri,AnneRokka1UniversityofHelsinki,FinlandBioticandabioticstressesinducereactiveoxygenspecies(ROS)productioninplantsasasignallingstrategy.Thereceptor-likeproteinkinases(RLKs)arelargelyresponsibleforcommunicationbetweencellsandtheextracellularenvironment,andROSproductionisafrequentresultofRLKsignallinginamultitudeofcellularprocesses(Kimuraetal.,2017).However,manyofthecomponentsforextracellularROSperception,signaltransmission,andspecificityofdownstreamresponsesremainunknown.Cysteine-richreceptor-likekinases(CRKs)representalargesubgroupofRLKs,definedbyaconservedpatternofcysteinesintheirextracellulardomain.Basedontheirexpressionprofile,loss-of-functionphenotypes,andthepotentialforredoxregulationintheirextracellulardomain,CRKsarepromisingcandidatestobeinvolvedinROSsignalling,potentiallyasextracellularROSsensors(Bourdaisetal.,2015).WehaveidentifiedseveralCRKsincludingCRK2,anevolutionarilyancientmemberofthisproteinfamily,asessentialcomponentswhichcandirectlyphosphorylateandtherebyactivateplasmamembrane-localizedNADPHoxidases(respiratoryburstoxidasehomologs;RBOH)ina

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calcium-independentmanner.Intriguingly,thetransmembraneproteinCRK2localizesuniformlytotheplasmamembraneofepidermalcellsundernormalgrowthconditions.However,uponexposuretovariousstimuliCRK2localizationconcentratesinapatternofconcentratedspotsattheplasmamembrane,potentiallyatplasmodesmata.PlasmodesmatalocalizationisalsosupportedbyproteomicdataasCRK2interactswithanumberofknownplasmodesmalproteins.Together,thissuggestsapotentialroleforCRK2incell-to-cellcommunicationviaplasmodesmatatherebylinkingplasmodesmalcontroltoROSsignaltransduction.References:Bourdais,etal.2015.PLoSGenetics7(11):e1005373.Kimura,etal.2017.AcceptedinThePlantCell.Keywords:reactiveoxygenspecies;receptor-likeproteinkinase;cysteine-richreceptor-likekinases;pathogendefense;systemicsignaltransductionAbstract#286.MultipleGeneDuplicationMechanismsContributedDifferentiallytotheExpansionoftheUbiquitinandUbiquitin-LikeProteinModifierSuperfamilyinPlants(Submission54)ZhihuaHua1,Vu,William,OhioUniversity1OhioUniversity,UnitedStatesUbiquitin(Ub)andUb-likeproteins,collectivelyformingtheubiquitonfamily,regulatesnearlyallaspectsofcellularprocessesviaposttranslationalmodifications.Studiesdevotedtospecificmemberssuggestedthattheubiquitonfamilyhadbeendramaticallyexpandedinplants.However,theglobalpictureofthisfamilyandthecoevolutionaryhistoryofindividualsubfamiliesremainunclear.Inthiswork,wefirstretrievedintotal5,856membersof17knownubiquitonsubfamiliesin50plantgenomesbysearchingbothpriorannotationsandmissinglociineachgenome.Wethenappliedthisfulllisttoanalyzetheduplicationhistoryof4majorubiquitonsubfamiliesinplants.WeshowedthatAuTophaGy-relatedprotein8(ATG8),Membrane-anchoredUB-fold(MUB),SmallUb-LikeModifier(SUMO),andUblociencode95%oftheplantubiquitonfamily.Whilewholegenomeduplications(WGDs)significantlyexpandedthefamily,eachgenomehasutilizeddifferentWGDevents.Inthefamily,theATG8andMUBmemberswereprimarilyduplicatedthroughWGDswhereasasignificantnumberofUbandSUMOlociweregeneratedthroughretropostionandtandemduplications,respectively.ThenewlydiscoveredretropostionduplicationmechanismintheexpansionofpolyUbgenescanbetterexplainthehead-to-tailamplificationprocessofmultiintronlessUbmoietiesinapolyUbgeneandtheextremelargesizeoftheUbsubfamilyinplants.Takingtogether,ourstudydemonstratedthattheplantubiquitonmembersweredifferentiallyexpandedthroughmultipleWGDeventsandotherduplicationmechanismsandthattheprolongedretentionofmulticopiesofATG8,MUB,SUMO,andtheUbmembersinplantsisconsistentwiththeirimportantregulatoryfunctions.Keywords:Ubiquitin(Ub)andUb-likeproteins;superfamily;wholegenomeduplications;novelevolutionarymechanism;functionAbstract#287.Post-translationalregulationofcarotenogenicrate-limitingenzymephytoenesynthasecomprisesproteolysisbyClpproteaseandstabilizationbyORANGEprotein(Submission79)LiLi1,Welsch,Ralf,UniversityofFreiburg,Zhou,Xiangjun,CornellUniversity,Yuan,HuiYuan,CornellUniversity1USDA-ARS/CornellUniversity,UnitedStatesCarotenoidsareindispensabletoplantsandhumans.Phytoenesynthase(PSY)istherate-limitingenzymeinthecarotenoidbiosynthesispathway.However,itspost-translationalregulationremainselusive.TheClpproteasesystemconstitutesacentralpartoftheplastidproteasenetworks,butitstargetsfordegradationarenotwellknown.HerewereportthattheClpproteasealongwiththecarotenogenicenhancerORdirectlymediatestheproteostasisofPSYandanumberofcarotenogenicenzymescotranslationallyinArabidopsis.PSYwasfoundtophysicallyinteractwithseveralkeycomponentsoftheClpproteasesystem,includingthesubstrateadaptorClpS1,chaperonesClpCandClpD,andcoreproteasesubunitsClpP4andClpP6.HighlevelsofPSYandseveralothercarotenogenicpathwayenzymesaccumulateintheClpactivitydefectmutantsclpc1,clpp4andclpr1-2.TheaccumulatedPSYwasfoundtobemostlyenzymaticallyinactive,whichwasconfirmedbymetabolicfluxanalysis.PSYproteinturnoverrateisgreatlyreducedinclpc1andclpr1-2,demonstratingPSYasasubstrateofClpproteaseandsupportingtheroleofClpproteaseindegradingunwantedPSYprotein.Ontheotherhand,theORANGE(OR)proteinpositivelyregulatesPSYproteinlevel,enzymeactivity,andcarotenoidcontent.ORenhancesPSYproteinstabilityandpreventsitsturnoverbyClpprotease.Moreover,significantlyhigherPSYenzymeactivitywasobservedintheclpc1xAtORcrossingline,illustratingthatORpromotesthefoldingofinactiveformsofPSYinclpc1tobecomeactive.Takentogether,ourresultsshowthatPSYproteinhomeostasisisgovernedbyClpproteasefordegradationandORforstabilizationandfolding.Thesefindingscollectivelyprovidenewinsightsintothequalitycontrolofplastid-localizedproteinsandestablishahithertounidentifiedpost-translationalregulatorymechanismtomediatecarotenogenesisinplants.Keywords:phytoenesynthase;Clpprotease;ORANGEprotein;carotenoids;proteostasis

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Abstract#288.F-boxdecoysrevealthegeneticandbiochemicalrolesofplantE3ubiquitinligasesinplantcircadianclock(Submission82)Chin-MeiLee1,AnnFeke,ChristopherAdamchek,WeiLiu,Man-WahLi,KristoforWebb,JosePruneda-Paz,EricJ.Bennett,SteveKay,JoshuaM.Gendron1YaleUniversity,UnitedStatesTheubiquitinproteasomesystem(UPS)isamajorproteindegradationpathwaythatregulatesaboardrangeofphysiologicalprocessesinalleukaryotes.Inplants,SCF(skp,cullin,F-box)complexisthelargestfamilyofmulti-subunitE3ligasesthattargetproteinsforpolyubiquitinationanddegradationby26Sproteasome.TheF-boxproteinswhichspecifytargetproteinsfordegradationarethekeystodissectthepathwaysregulatedbyUPS.However,functionalstudiesofF-boxproteinsarehamperedby(1)geneticredundancycausedbyextensiveexpansionofF-boxproteinsinplants,and(2)intrinsicshorthalf-livesoftheirtargets.Here,wehavedevelopedF-box“decoys”toovercometheseobstacles.Insteadoftargetingsubstratestodegradation,F-boxdecoysstabilizesubstratesandleadtodominantnegativephenotypes.WehaveperformedapilotstudywiththedecoysofthreepartiallyredundantF-boxproteins-ZTL,FKF1andLKP2,andsuccessfullyseparatedtheiroverlapfunctionsinregulationofcircadianclockandseasonalfloweringtime.Inaddition,usingimmunoprecipitationfollowedbymassspectrometrywithZTL,FKF1,andLKP2decoys,wehaveidentifiedsomeknownandnewinteractingpartners.WehavedemonstratedthatCHE,acentralclockregulator,isanewZTLtarget.Tofurtherovercomethetime-consumingvalidationofE3ligase-targetpairsinplants,herewepresentashowcaseonreconstitutionofZTLdirectlyinteractingwithandpolyubiquitinatingCHEinthemammaliancellculture.WehaveexpandedthisstrategytogenerateArabidopsisF-boxdecoylibrarytoidentifynovelF-boxproteinsinregulationofcircadianclock.ThisdecoystrategyandvalidationmethodscanbefurtherappliedtostudyotherbiologicalpathwaysandE3ligasesinplantsandothersystems.Keywords:E3ligases;F-boxproteins;Circadianclock;Novelgeneticandbiochemicalstrategy;ProteindegradationAbstract#289.DefiningtheO2/NOresponsiveN-endruledegradomeinArabidopsis(Submission85)GunjanSharma1,Boeckx,Tinne,DivisionofPlantandCropSciences,UniversityofNottingham,SuttonBoningtonCampus,Loughborough,LE125RD,UK,Berckhan,Sophie,DivisionofPlantandCropSciences,UniversityofNottingham,SuttonBoningtonCampus,Loughborough,LE125RD,UK,SousaCorreia,Cristina,DivisionofPlantandCropSciences,UniversityofNottingham,SuttonBoningtonCampus,Loughborough,LE125RD,UK,Gladstone,Natasha,DivisionofPlantandCropSciences,UniversityofNottingham,SuttonBoningtonCampus,Loughborough,LE125RD,UK,Holdsworth,MichaelJ.,DivisionofPlantandCropSciences,UniversityofNottingham,SuttonBoningtonCampus,Loughborough,LE125RD,UK1DivisionofPlantandCropSciences,UniversityofNottingham,UnitedKingdomOxygen(O2)playsmajorroleinavarietyofplantbiochemicalandphysiologicalprocesses.Areductioninavailableoxygenleadstohypoxia,causedforexamplebysubmergence/waterlogging.EvenduringsufficientexternalO2availability,tissuescanexperiencehypoxicenvironments(suchasbuds,tubersandseeds).Interestingly,someplantprocessesrequireahypoxicenvironment,suchasofmaizemalegermlinedevelopment(1).Therefore,understandingtheO2sensingmechanisminplantsiscrucial.ThesensingofO2andNOinplantsoccursthroughtheGroupVIIEthyleneResponsetranscriptionfactors(ERFVIIs).ERFVIIsarecontinuouslydegradedinsufficientO2/NOavailabilitythroughtheCys-Arg/N-endrulepathwayoftargetedproteolysis(2,3).ERFVIIs,thatinitiateMet-CysaredegradedbecauseofthepresenceofCysatposition1followingco-translationalexcisionofMet-1bymethionineamino-peptidase;SubstrateswithNt-oxidisedCys(producedinthepresenceofO2andNO)arerecognisedbytheN-endrulepathwayandubiquitinated.Insilicoanalysisrevealedthepresenceof246Cys-2proteinsinArabidopsis(4).WeanalysedthecapacityofselectedproteinsfromthiscohorttobesubstratesoftheCys-Arg/N-endrulepathwayinvitroandinvivo.TheeffectofO2/NOonstabilizationofputativenovelN-endrulesubstratesalongwiththeirfunctionalrelevancewillbediscussed.1.M.J.Considineetal.,LearningToBreathe:DevelopmentalPhaseTransitionsinOxygenStatus.TrendsPlantSci22,140-153(2017).2.D.J.Gibbsetal.,HomeostaticresponsetohypoxiaisregulatedbytheN-endrulepathwayinplants.Nature479,415-418(2011).3.F.Licausietal.,OxygensensinginplantsismediatedbyanN-endrulepathwayforproteindestabilization.Nature479,419-422(2011).4.D.J.Gibbs,J.Bacardit,A.Bachmair,M.J.Holdsworth,TheeukaryoticN-endrulepathway:conservedmechanismsanddiversefunctions.TrendsCellBiol24,603-611(2014).Keywords:Post-transnationalregulation;N-endrule;Oxygen;Nitricoxide;Abstract#290.Thioredoxinsasversatileredoxregulatorsofphotosyntheticmetabolisminfluctuatinglightenvironments(Submission99)InaThormählen1,Armbruster,Ute,MPI-MPPotsdam-Golm,Issakidis-Bourguet,Emmanuelle,IPS2Paris-Saclay,Cejudo,FranciscoJavier,UniversityofSeville,Geigenberger,Peter,LMUMunich1LudwigMaximiliansUniversityMunich,GermanyThioredoxins(Trx)aresmallandubiquitousoxidoreductaseswiththiol-disulfideexchangeactivity,whichenablesthepost-translationalmodificationoftargetenzymeconformationsandredoxactivationstates.InchloroplastsofArabidopsis,10differentclassicalTrxisoformsareknownandrepresentalight-dependentreductionsystemconnectedtothephotosyntheticferredoxin-Trxreductasesystem.However,about10yearsagoanadditionalplastidialTrx-basedsystemwasdiscovered.TheNADP-dependentthioredoxinreductaseC(NTRC)containsitsownTrxdomainnexttotheNTRdomainandactsasredoxregulatorbeingindependentontheelectrontransport

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chainofphotosynthesis,butrelyingonNADPHasreducingequivalent.OurresearchconcludesthatTrxisoformsoff-andm-typeincombinationwithNTRCplayimportantrolesinregulatingdistinctfunctionsofthephotosyntheticlightreaction,theCalvin-Bensoncycle,starchbiosynthesis,redoxhomoeostasisinchloroplastsandgrowthingeneral.Mostrecently,wewerepostulatingacrucialinfluenceofTrxsonthedynamicacclimationtofluctuatinglightenvironmentswithimpactsonphotosyntheticperformanceandplastidialmetabolism.Innature,plantscopestronglyfluctuatinglightintensitiesandtheversatileTrxsystemmightenableefficientresponsestobalancethesechangingenvironmentalconditions.Keywords:thioredoxin-basedredoxregulation;photosyntheticcarbonmetabolism;fluctuatinglightacclimation

Abstract#291.Aplant-specificchaperonerequiredfor26Sproteasomeassembly(Submission145)RichardMarshall1,Gemperline,DavidC.,UniversityofWisconsin,Lee,Kwang-Hee,UniversityofWisconsin,McLoughlin,Fionn.,WashingtonUniversityinSt.Louis,Zhao,Qingzhen,WashingtonUniversityinSt.Louis,Scalf,Mark,UniversityofWisconsin,Smith,Lloyd,M.,UniversityofWisconsin,Vierstra,RichardD.,WashingtonUniversityinSt.Louis1WashingtonUniversityinSt.Louis,UnitedStatesSelectiveproteindegradationineukaryotesisessentialforregulatingtheabundanceofcellularconstituents,maintainingproteostasisinresponsetoenvironmentalchallenge,andpermittingappropriatedevelopmentaltransitions.Oneprinciplerouteistheubiquitin-proteasomesystem(UPS),inwhichtargetproteinsaretaggedwithpoly-ubiquitinchainsthatfacilitaterecognitionanddegradationbythe26Sproteasome.Theproteasomeconsistsoftwofunctionallydistinctsub-complexes;the20Scoreprotease(CP)andthe19Sregulatoryparticle(RP).Acompleteproteasomecontainsatleast64subunits,whosecorrectassemblyrequiresanintricatesetofchaperonesworkinginspatiotemporalconcert.MassspectrometricanalysisofArabidopsis26SproteasomesaffinitypurifiedviatheCPorRPidentifiedasuiteofinteractingproteins,severalofwhichsharehomologytoknownyeastormammalianproteasomeassemblychaperones.TheseincludePBAC1-4(homologsoftheyeastPba1-Pba2andPba3-Pba4heterodimers)thatfacilitateCPα-ringassembly,UMP1thatco-ordinatesdockingofCPhalf-barrels,andNAS2,NAS6,HSM3andRPN14thatassembletheAAA-ATPaseringoftheRP.Anuncharacterizedproteinwithnoorthologsoutsideofplantswasalsoabundantlyidentified,termedPROTEASOME-ASSOCIATEDPROTEIN1(PAP1).LikePBAC1andPBAC2,PAP1containsaC-terminalHbYXmotifknowntoaiditsdockingbetweenadjacentCPα-subunits.PAP1appearstoformatrimericcomplexwithPBAC1/2inplantathatbindstoCPα-subunits.ThiscomplexcancomplementthecanavaninesensitivityphenotypeofayeastΔpba1Δpba2doublemutant,withatleasttwoHbYXmotifsrequired.T-DNAinsertionmutantsinPAP1andPBAC1showedreducedproteasomeactivity,increasedaccumulationofubiquitinconjugates,andup-regulationofthetranscriptionalregulonresponsivetoproteotoxicstress.ThesedatathusimplicatePAP1asacomponentofanovel,plant-specificproteasomeassemblychaperonecomplex.Keywords:26Sproteasome;coreprotease;regulatoryparticle;proteasomeassemblychaperone;ubiquitinAbstract#292.MechanismofRNS-dependentS-NitrosationandDenitrosationofCytoplasmicS-NitrosoglutathioneReductase(GSNOR)fromArabidopsisthaliana(Submission155)PatrickTreffon1,Guerra,Damian,Dept.ofObstetricsandGynecology,UniversityofColoradoDenver,Aurora,CO,USA,Truebridge,Ian,Dept.ofBiochemistryandMolecularBiology,UniversityofMassachusettsAmherst,Amherst,MA,USA,Ballard,Keith,Dept.ofBiochemistryandMolecularBiology,UniversityofMassachusettsAmherst,Amherst,MA,USA,Vierling,Elizabeth,Dept.ofBiochemistryandMolecularBiology,UniversityofMassachusettsAmherst,Amherst,MA,USA1UniversityofMassachusettsAmherst,UnitedStatesReversibleS-nitrosationofcriticalproteincysteinesduetoreactionwithnitricoxide(NO)anditsderivativesisaredox-dependentposttranslationalmodificationthatcontrolsplantphysiologicalprocesseslikegermination,stomatalclosure,root-andpollengrowth,aswellashormonalhomeostasis.RegulationofNO-levelsinplantaispredominantlyachievedbyreactionofreactivenitrogenspecies(RNS)withglutathione(GSH),therebyformingS-nitrosoglutathione(GSNO).GSNOhasbeenproposedtobeaprincipalNOreservoirduetoitsstabilityandthehighabundanceofGSHinlivingcells.ThehomodimericenzymeS-nitrosoglutathionereductase(GSNOR)attenuatesNO-dependenteffectsbycatabolizingGSNO.GSNO-breakdownisbelievedtosustaincellularredoxpoisebothbycurtailingRNS-burstsandbyregeneratingGSH.GSNORcontainsevolutionary-conservedcysteineresiduesthatarepronetoS-nitrosationbytheNOdonorsGSNO,S-Nitroso-N-acetylpenicillamine(SNAP)orS-nitrosocysteine(CysNO),leadingtoapartiallossofenzymeactivitythatcouldberecoveredbyreducingagentsinvitro.Proteinnitrosationwasfurtherconfirmedbyintactmassspectrometry,forwhichsignalsconsistentwithmono-,di-andtri-nitrosationwereobserved.Inaddition,GSNORdenitrosylationanalysiscatalyzedbysmalloxidoreductaseswillbeaddressed.ThesedatastronglyimplicateamechanismforRNSsignalingbymodulatingredox-dependentposttranslationalmodificationsofcertainproteins.ReducedGSNORactivityispredictedtoresultintheaccumulationofGSNO,itselfanagentofproteinS-nitrosation.ByallowingGSNOtoaccumulate,down-regulationofGSNORmayfacilitatemorerobustNOsignaling.Keywords:S-nitrosation;reactivenitrogenspecies;S-nitrosoglutathionereductase(GSNOR);redox-dependentposttranslationalmodification,cysteine,

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Abstract#293.ProteinDisaggregaseHSP101Interactswiththe26SProteasomeandFacilitatesProteinDegradation.(Submission157)FionnMcLoughlin1,MinsooKim,MaryFowler,RichardD.Vierstra,ElizabethVierling1WashingtonUniversity,UnitedStatesProteinsthatarevitaltocellsurvivalcanbecomeunfoldedduringheatstress,leadingtotheformationoftoxicaggregates.Molecularchaperones,proteasesandautophagicpathwaysarerequiredtoprotectcellsfromtheaccumulationofproteinaggregates.SmallHeatShockProteins(sHSP)formafirstlineofdefensebybindingtounfoldingproteinstopreventirreversibleproteinaggregation.HeatShockProtein(HSP)101subsequentlyactsasaproteindisaggregasetore-solubilizemisfoldedproteinscomplexedwithsHSPs.AnalysisoftheinsolubleproteinfractionafterheatstressinArabidopsisrevealedthatsHSP-boundproteinsareretainedlongerintheinsolublecellfractioninanhsp101nullmutant.Todeterminehowaggregatedproteinsarefurtherprocessed,co-affinitypurificationofHSP101wasconductedtoidentifyputativeco-factors.Severalsubunitsofthe26S-proteasomelid-complexwerefoundassociatedwithHSP101.Poly-ubiquitinatedproteinsaccumulatedmoreabundantlyinthehsp101mutantandinsHSP-RNAilinesafterheatstress.Additionally,disaggregationofthesepoly-ubiquitinatedproteinswasnecessarypriortodegradation,suggestingthattheinteractionofHsp101withthe26S-proteasomefacilitatesproteindegradation.ConfocalfluorescencemicroscopystudiesrevealedthatHSP101anda26Sproteasomesubunitaccumulateindistinctcytosolicfociduringheatstress,whereasHSP101co-localizedwithsHSPsandthestressgranulemarkerPoly-ABindingprotein2,suggestingthatproteindisaggregationanddegradationmightoccurinspecializedcytosolicfoci.Proteomicanalysisallowedtheidentificationofasubstantialnumberofubiquitinfootprintsandalargearrayofproteinsthatwereretainedintheinsolublefraction.GO-annotationanalysisrevealedasignificantenrichmentforRNA-bindingproteins,cysteine-typepeptidases,andubiquitin-proteinligasessheddingnewlightonprocessesthatareaffectedbyheatstress.Keywords:HSP101aggregationrefoldingubiquitinationdegradationAbstract#294.MassSpectrometricDissectionoftheSUMOylationSysteminArabidopsisthaliana(Submission160)SamuelYork1,Rytz,ThereseC.,WashingtonUniversityinSt.Louis,Scalf,Mark,UniversityofWisconsin-Madison,Smith,LloydM.,UniversityofWisconsin-Madison,Vierstra,RichardD.,WashingtonUniversityinSt.Louis1WashingtonUniversityinSt.Louis,UnitedStatesSmallUbiquitin-likeMOdifier(SUMO)isanessentialpost-translationalmodificationthathasbeenlinkedtostresstolerance.SUMObecomescovalentlyboundtolysineresiduesoftargetsviaanE1-E2-E3conjugationcascade,whichcanthenbereversedbyde-SUMOylatingproteases(DSPs)thatcleavetheisopeptidebond.Usingmassspectrometry(MS)inconjunctionwithastringentthree-steppurificationschemeforSUMOylatedproteinsbasedonatransgeniclinethatrescuesasumo1-1sumo2-1nullmutantwitha6His-SUMO1transgene,ourlabhascatalogedmorethan1,200SUMOylationsubstratesthatincludefactorsrelatedtoavarietyofnuclearprocesses,includingchromatinaccessibility,transcription,DNArepair,andRNAprocessingandexport.BycomparingtheMSprofilesofSUMOylatedproteinsinwild-typeversussiz1-2mutantlines,wehaveassignedanumberoftargetstothisE3whosefunctionsmayexplainthestresshypersensitivesiz1phenotype.AnotherlikelysourceofdiversityinSUMOylationisthemorethan15DSPsfoundinArabidopsis,manyofwhichdisplaydistinctlocations,cellular,tissueandtemporalexpressionpatterns,anduniquephenotypeswheneliminated.ImmunoblotanalysesrevealdistinctSUMOprofilesfordwarfedesd4-2plantsandsalthypersensitiveots1-1ots2-1plants,bothofwhichhyperaccumulateSUMOconjugatescomparedtowild-typeplants.ToidentifytheseDSPtargets,weintrogressedtheesd4-2andots1-1ots2-1nullmutationsinto6His-SUMO1plantsforsubsequentconjugatepurificationandMSidentification.WearealsoattemptingtoidentifySUMOconjugationsitesusinga6His-SUMO1(K0)variantdesignedforfootprintmappingbyMS.Theviabilityoflysine-less6His-SUMO1(K0)sumo1-1sumo2-1plantsshowsthatSUMO-SUMOandSUMO-UbiquitinchainformationisnotessentialinArabidopsis.Takentogether,thisworkshouldenhanceourunderstandingofSUMOylationdynamicsandhelpdefineitsrole(s)inplantstressdefense.Keywords:SUMO;post-translationalregulation;abioticstress;massspectrometry

Abstract#295.SelectiveAutophagyofBES1MediatedbyUbiquitinReceptorDSK2andE3UbiquitinLigaseSINAT2BalancesPlantGrowthandSurvival(Submission172)TrevorNolan1,Brennan,Benjamin,IowaStateUniversity,Yang,Mengran,HuazhongAgriculturalUniversity,Chen,Jiani,IowaStateUniversity,Zhang,Mingcai,ChinaAgriculturalUniversity,Li,Zhaohu,ChinaAgriculturalUniversity,Wang,Xuelu,HuazhongAgriculturalUniversity,Bassham,Diane,IowaStateUniversity,Walley,Justin,IowaStateUniversity,Yin,Yanhai,IowaStateUniversity1IowaStateUniversity,UnitedStatesPlantsencounteravarietyofstressesandmustfine-tunetheirgrowthandstressresponseprogramstobestsuittheirenvironment.BES1isatranscriptionfactorthatfunctionsasamasterregulatorintheBrassinosteroid(BR)signalingpathway,directingatranscriptionalnetworkthatregulatesthousandsofgenesinvolvedinplantgrowth,developmentandstressresponses.DespiteextensivecharacterizationofBES1incarryingoutBR-relatedgeneexpression,thepathwaysandcomponentsregulatingBES1proteinlevelsarenotcompletelyunderstood.WefoundthatBES1interactswiththeubiquitinreceptorproteinDSK2andistargetedtotheautophagypathwayduringstressviatheinteractionofDSK2withATG8,aubiquitin-likeproteindirectingautophagosomeformationandcargorecruitment(Nolanetal.,2017,DevelopmentalCell).DSK2isphosphorylatedbytheGSK3-likekinaseBIN2,anegativeregulatorintheBRpathway.BIN2phosphorylationofDSK2flankingitsATG8interactingmotifs(AIMs)promotestheinteractionofDSK2withATG8,therebytargetingBES1fordegradation.Accordingly,loss-of-functiondsk2mutantsaccumulateBES1,havealteredglobalgeneexpressionprofiles,and

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havecompromisedresponsestodroughtandfixed-carbonstarvationstresses.Additionally,wefoundthatSINATfamilyE3ubiquitinligasestargetBES1fordegradationinresponsetolight(Yangetal.,2017,DevelopmentalCell)andduringstarvationstressconditions(Nolanetal.,2017,DevelopmentalCell).OurresultsthusrevealapreviouslyunknownprocessbywhichplantscoordinategrowthandstressresponsesbytargetingacentralgrowthregulatortotheselectiveautophagypathwayandillustratethemechanismscontrollingthisprocessbyidentifyingDSK2astheautophagyreceptorforBES1andSINATasanE3ligasecontrollingBES1degradation.ThisresearchissupportedbygrantsfromNSF(IOS1257631),NIH(1R01GM120316)andthePlantScienceInstituteatIowaStateUniversity.Keywords:Autophagy;Ubiquitin;Brassinosteroid;Drought;E3UbiquitinLigase

Abstract#296.TheinterplaybetweenalternativepolyadenylationandRNAqualitycontrolasapotentialmechanismtorespondtoenvironmentalstressinArabidopsis(Submission177)LauradeLorenzo1,Sorenson,Reed,UniversityofCalifornia.,Bailey-Serres,Julia,UniversityofCalifornia.,Hunt,ArthurG.,UniversityofKentucky.1UniversityofKentucky,UnitedStatesAmajorchallengeofmodernagricultureistomaintaincropproductionunderadverseenvironmentalconditions.Onemolecularresponsetosuchchallengesinvolvesthealternativepolyadenylation(APA)ofmRNA.Inplants,itisunclearhowstressaffectstheproductionandfateofalternativemRNAisoforms.Usingagenome-scaleapproach,weshowhowthealternativepolyadenylationcontributetogeneregulationinresponsetohypoxiastress,analyzingthestabilitiesandtranslatabilitiesofArabidopsisRNAisoformsderivedfromproximalpoly(A)siteusage,andtheirproductionunderthiscondition.TheresultssuggestthateachclassofRNAisoformhasdifferentproperties.Thus,hypoxiastressleadtoincreasesinallnoncanonicalmRNAisoforms(polyadenylated3’endsthatmapto5’-UTRs,intronsandprotein-codingregions).RNAswith3’endswithinprotein-codingregionsandintronswerelessstablethanmRNAsthatendat3’-UTRpoly(A)sitesandwereunder-representedinpolysomes,suggestingthattheseRNAisoformsmaybesubjecttoquality-controlprocessesassociatedwithnonsense-mediateddecayornon-stopdecay(forintronicandprotein-codingregionisoforms,respectively).Incontrast,mRNAisoformswith3’endsthatliewithinannotated5’-UTRswereover-representedinpolysomes,andwereasstableascanonicalmRNAisoforms.Likewise,differentArabidopsismutantsimplicatedinRNAqualitycontrolandpost-transcriptionalgenesilencingwereevaluatedusing3’-end-directedcDNAtagslibraries.Takentogether,theseresultsshowthatalternativepoly(A)sitechoicemayre-directtranscriptionaloutputintoproductsthataresubjecttosurveillanceprocesses,andthusmayconstituteaformofnegativeregulation.Inaddition,theysuggestthattranscriptsderivedfrompolyadenylationwithin5’-UTRsmaybeanovelclassofRNA,whoserolesingeneexpressionareasyetunclear.Keywords:Alternativepolyadenylation,RNAqualitycontrol,translatome,nextgenerationsequencing,hypoxiaAbstract#297.LightDependentDegradationofPIF3viaSCFEBF1/2PromotesthePhotomorphogenicResponseinArabidopsis(Submission207)JIEDONG1,Ni,Weimin,UCBerkeley,Yu,Renbo,PekingUniversity,Deng,Xingwang,PekingUniversity,Chen,Haodong,PekingUniversity,Wei,Ning,YaleUniversity1YaleUniversity,UnitedStatesPlantseedlingsemergingfromdarknessintothelightenvironmentundergophotomorphogenesis,whichgivesthemtheformandbiochemistryforphotosynthesis.Duringthistransition,plantsmustrapidlyremovephotomorphogenicrepressorsaccumulatedinthedark.AmongthemisPHYTOCHROME-INTERACTINGFACTOR3(PIF3),akeytranscriptionfactorpromotinghypocotylgrowthagainstlightactivity.Herewereportthat,inresponsetolightactivationofphytochromephotoreceptors,EIN3-BINDINGFBOXPROTEINs(EBFs),EBF1andEBF2,mediatePIF3proteindegradationinamannerdependentonlight-inducedphosphorylationofPIF3.WhilePIF3bindsEBFsindependentlyoflight,therecruitmentofPIF3-EBFstothecoreSCFscaffoldisfacilitatedbylightsignalsorPIF3phosphorylation.WealsofoundthatLRBE3ubiquitinligasestargetPIF3andphyBprimarilyunderhighlightconditions,whereasEBF1/2vigorouslytargetPIF3degradationunderwidelightrangeswithoutaffectingphytochromes.Thus,SCFEBF1/2actasthephotomorphogenicE3satbothgeneticandmolecularlevels.Keywords:LightSignalTransduction;PIF3;proteindegradation;Phosphorylation;SCFAbstract#298.Protein-proteininteractionnetworkandmetabolitechannelinginplantmitochondrialtricarboxylicacidcycle(Submission233)ToshihiroObata1,Zhang,Youjun,Max-Planck-InstituteofMolecularPlantPhysiology,Beard,KatherineFM,UniversityofOxford,Swart,Corné,Max-Planck-InstituteofMolecularPlantPhysiology,Nikoloski,Zoran,Max-Planck-InstituteofMolecularPlantPhysiology,Graf,Alexander,Max-Planck-InstituteofMolecularPlantPhysiology,Ratcliffe,RGeorge,UniversityofOxford,Sweetlove,LeeJ,UniversityofOxford,Fernie,AlisdairR,Max-Planck-InstituteofMolecularPlantPhysiology1UniversityofNebraskaLincoln,UnitedStatesPlantmitochondrialtricarboxylicacid(TCA)cycleisknowntobedynamicallyregulatedinrelationtothemetaboliccontext.Wehypothesizedthattheinteractionofenzymeproteinsmediatingmetabolicchanneling,calledas“metabolon”,isapartofregulatory

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mechanismofthispathway.Inordertoidentifywhichpartsofthepathwayformmetabolon,thebinaryinteractionsof38TCAcyclerelatedenzymesofArabidopsisweretested.Assumingtransientnatureofenzyme-enzymeinteractions,threeindependenttechniques,affinitypurification-massspectrometry(AP-MS),split-luciferaseandyeasttwo-hybridassays,areusedtoincreasethechanceofcapturingweakinteractions.The(semi-)quantitativescoresgeneratedbyeachmethodwerecompromisedbyaSTATISbasedmethodtogeneratesinglescorereflectingthereliabilityoftheinteraction.Within741testedbinaryproteinpairs,158wererevealedtointeract.Thesepairsincludetheproteinpairsofknownenzymecomplexesaswellasthosebetweencatalyticsubunitsmediatingsequentialreactionsofthecycle,includingfumarase/malatedehydrogenase(MDH),MDH/citratesynthase(CSY),CSY/aconitaseandaconitase/isocitratedehydrogenase.Channelingoffumarateandcitrateweredemonstratedbyisotopedilutionexperimentswithisolatedpotatomitochondria.TheseresultsindicatepresenceofMDH/CSYmetaboloninplantmitochondriaandsuggesttheconservedcompositionofmetabolonamongkingdomsoflife.WealsoidentifiedmanyinteractionsbetweenenzymeswhichdonotcatalyzeadjacentreactionsintheTCAcycle.AdditionallyAP-MSanalysissuggestedmitochondrialproteinswhichcaninteractwithTCAcycleenzymes.Possiblefunctionsoftheseinteractionswillalsobediscussed.Keywords:protein-proteininteraction;metabolicregulation;metabolitechanneling;tricarboxylicacidcycle;metabolonAbstract#299.RegulationofAGO1homeostasisbytheF-boxproteinFBW2(Submission305)ThibautHacquard1,MarionClavel,BenoîtDerrien,MariekeDubois,AdrienTrolet,PascalGenschik1IBMP-CNRS,FranceRNAsilencingisamolecularmechanism,whichusessmallnon-codingRNAmoleculestonegativelyregulategeneexpressionthroughtheactivityofARGONAUTEproteins.ItisusedbymostEukaryotestoshapetheirtranscriptomeandcopewithchangesandstressesdisturbingtheirdevelopmentalprogram.RNAsilencingalsoplaysamajorroleinantiviraldefenseinplantsandinverterbrates.InArabidopsisthaliana,lossorreducedactivityofthemainmiRNAeffectorARGONAUTE1(AGO1)leadstodeathorseveredevelopmentaldefects.Interestingly,overaccumulationofAGO1alsoharmsplantdevelopment.AlthoughAGO1expressionistightlycontrolledbyanautoregulatoryloopinwhichAGO1targetsitsownmessenger,littleisknownaboutitspost-translationalregulation.Inplants,theTurnipYellowVirustriggerstheautophagicdegradationofAGO1byhijackingtheubiquitinmachinerywiththeviralF-boxproteinP0.ThisraisesthequestionofanendogenousregulationofAGO1attheproteinlevel.OurworkfocusesonFBW2,anA.thalianaF-boxproteinthathaspreviouslybeenshowntoaffectAGO1homeostasis.HerewecouldshowthatFBW2co-immunoprecipitateswithcomponentsoftheSCFcomplex,acommonE3ubiquitin-ligase,andinteractsdirectlywithAGO1.FBW2triggersthedegradationnotonlyofAGO1,butalsootherAGOproteins.Interestingly,FBW2itselfisanunstableproteinsubjectedtoproteasomaldegradation.WhilelossoroverexpressionofFBW2hasalimitedimpactonAGO1proteinlevelinawild-typegeneticbackground,itdrasticallyaffectsAGO1stabilityinmutantsdeficientinthebiogenesisofsmallRNAs,suggestingaroleofFBW2intheturnoveroftheunloadedformofAGO1.Notably,overexpressionofFBW2doesnotsuppressRNAsilencingwhichisincontrasttothepoleroviralF-boxproteinP0.Together,theseresultshighlightanovelroleforFBW2inthecontrolofAGO1homeostasisandprovidenewinsightsinpost-translationalcontroloftheplantssilencingmachinery.Keywords:RNAsilencing;F-box;Ubiquitin;ProteolysisAbstract#300.DoesthecircadianclockregulateribosomalproteinS6phosphorylation?(Submission344)RamyaEnganti1,Cakir,Ozkan,UniversityofTennesseeKnoxville,Cho,SungKi,UniversityofTennesseeKnoxville,Toperzer,Jody,UniversityofTennesseeKnoxville,vonArnim,Albrecht,UniversityofTennesseeKnoxville1UniversityofTennesseeKnoxville,UnitedStatesThecircadianclockorchestratesasubstantialportionofplantgeneexpression,includingattheleveloftranslation.Specifically,ourlabrecentlyestablishedthatribosomeloadingofindividualArabidopsismRNAsfluctuatesoverthedielday-nightcycleinawaythatisjointlyorchestratedbythecircadianclockandexternalstimuli.Forexample,ribosomalproteinmRNAsdisplaycoordinatedribosomeloadingthatmainlypeaksatnight.Phosphorylationofcertainribosomalproteinshasbeenshowntofluctuateoverthedielcycle.OnesuchproteinisRIBOSOMALPROTEINofSMALLSUBUNIT6(RPS6),whichundergoesphosphorylationatmultipleresiduesinitsC-terminaltailandisunderthecontroloftheTORpathway.Inotherorganisms,theroleoftheclockandenergymetabolismfortranslationhasalsobeenapproached,butclockcontrolofpRPS6hasnotbeenexaminedintheabsenceofexogenoussugars.Here,weshowthatphospho-RPS6(pRPS6)cyclesoveralight-darkcycleinbothwildtypeandtheclockdeficientCCA1-overexpressingstrain.Inwildtypeplantsgrownunderconstantlight(cLL),pRPS6doesnotcyclebutfluctuatesinanerraticfashion.ThesedatasuggestthattheclockisneithernecessarynorsufficientforpRPS6cycles.Instead,giventhatshiftsbetweenlightanddarknessprofoundlyaffectpRPS6,asdoabioticstresstreatments,itappearsthatpRPS6isunderlightcontrolanditintegrateslightandstresssignalingpathways.WealsoshowthatpRPS6isregulatedinasite-specificfashioninapolysomecontext,especiallyatnight.Thisphosphorylationpatterninthepolysomesisinturnaffectedbystresstreatmentssuchascoldstressandheatshock.AlthoughtheregulationofpRPS6iswellconservedinhighereukaryotes,itspreciseroleremainsobscure.Therefore,ourresultthatpRPS6isindependentofclockfunctionyethighlycorrelatedwithpolysomeloadinghelpstonarrowdownthepossiblephysiologicalroleofthisenigmaticevent.Keywords:Phosphorylationofaribosomalprotein

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Abstract#301.ExplorationofregulatorymechanismsunderlyingABA-independentSnRK2sactivationunderosmoticstressconditions(Submission350)JunroMogami1,Soma,Fumiyuki,GraduateSchoolofAgriculturalandLifeSciences,TheUniversityofTokyo,Japan,Sato,Karin,GraduateSchoolofAgriculturalandLifeSciences,TheUniversityofTokyo,Japan,Sato,Yuta,GraduateSchoolofAgriculturalandLifeSciences,TheUniversityofTokyo,Japan,Takahashi,Fuminori,CenterforSustainableResourceScience,RIKEN,Japan,Shinozaki,Kazuo,CenterforSustainableResourceScience,RIKEN,Japan,Yamaguchi-Shinozaki,Kazuko,GraduateSchoolofAgriculturalandLifeSciences,TheUniversityofTokyo,Japan1TheUniversityofTokyo,JapanSubclassIIISnRK2proteinkinases,centralpositiveregulatorsofABAsignalingdownstreamofPYR/PYLs/RCARsABAreceptors,orchestrateABA-regulatedmolecularresponses,includingtheinductionofstress-responsivegenesviaactivatingAREB/ABFtranscriptionfactorsunderosmoticstressconditions.SeedplantshaveacquiredothertypesofABA-unresponsive,osmoticstress-activatedSnRK2s;subclassISnRK2s.SubclassISnRK2sregulatemRNAdecayviaphosphorylatingVARICOSE,anmRNAdecappingactivator,andalleviategrowthretardationunderosmoticstressconditionsinArabidopsis(SomaandMogamietal.,2017).Despitetheirpivotalrolesinadaptiveresponsesunderwater-deficitstressconditions,regulatorymechanismsunderlyingtheactivationofthesekinasesremainlargelyunknown.Inthisstudy,toaddressregulatorymechanismsunderlyingABA-independentSnRK2sactivation,wesoughttoidentifynovelinteractorsofSnRK2sbyemployinganimprovedCo-IPmethodandLC-MS/MS.SeveralcandidatesincludingproteinkinasesandphosphataseswereidentifiedasnovelinteractorsofSnRK2s.SomeofthemareconfirmedtophysicallyinteractwithSnRK2s.MolecularandfunctionalrelationshipbetweenSnRK2sandthesenovelinteractorswillbediscussed.StructuralBiology:Abstract#302.PhotosensingandThermosensingbyPhytochromeBRequiresbothProximalandDistalFeaturewithintheDimericPhotoreceptor(Submission143)ErnestBurgie1,Hu,Weiming,McLoughlin,Katrice,Lye,Shu-Hui,Orville,AllenM.,Vierstra,RichardD.1WashingtonUniversityinSt.Louis,UnitedStatesPhytochromes(Phys)areacollectionofbilin-containingphotoreceptorsthathelpplantsperceivetheirambientlightenvironmentthroughphotointerconversionbetweenred-light(Pr)-andfar-redlight(Pfr)-absorbingstates.PfralsorevertsbacktoPrbyalight-independentreaction,whichforsomePhyisoformsishighlysensitivetotemperature,thusallowingthemtoactastemperaturesensors.CrystallographicstudiesofArabidopsisPhyBandbacterialrelativesexpressedrecombinantlyrevealedthatmultiplefeatureswithinthephotosensorymoduleworkcollectivelytotransduceangstrom-scalechangesinthebilinintonanometer-scalemovementswithinthedimericcomplex.ThroughdomainanalysisofPhyBcoupledwithphotoconversionandthermalreversionassays,weidentifiedseveralfeaturesthatimpactPr-Pfrinterconversion.TheseincludetheC-terminalhistidine-kinase-relateddomainthatencouragesdimerization,thePHY-domainhairpin,andahighly-conservedpatchjustupstreamoftheN-terminalPeriod/Arnt/Sim(PAS)domain,whichuponremovalgeneratesvariantswithdramaticallyacceleratedthermalreversionrates.WealsodiscoveredthatthenatureofthebilininfluencesPfrstability.WhereasincorporationofthenativebilinphytochromobilinintoPhyBgeneratesaphotoreceptorwitharobustPfr-to-Prthermalreversionrate,thatassembledwiththecyanobacterialversion,phycocyanobilin,containinganethylinsteadofavinylsidechainattheC18position,hasadramaticallystabilizedPfr.Tounderstandthephotoconversionprocessindetail,wehaveappliedserialfemtosecondX-raydiffractiontoabacterialPhyfromDienococcusradiodurans.Preliminarydatacapturedthefirst3-DsnapshotofthePr-PfrphotoconversionatphysiologicaltemperatureswithinitialmovementscenteredattheDpyrroleringofthebilin.Collectively,ourstudiesshouldfacilitatetheredesignofPhysforimprovedcropproductionandasoptogenetictools.Keywords:phytochromes;photoreceptors;X-raycrystallography;single-particleelectronmicroscopy;serialfemtosecondcrystallographyAbstract#303.Mechanisticinsightsintofloralshedding(Submission209)JuliaSantiago1,BenjaminBrandt,MariWildhagen,SebastianAugustin,OctaviaRoman,MelinkaButenko,MichaelHothorn1UniversityofLausanne,SwitzerlandPlantsconstantlyrenewduringtheirlifecycleandthusrequiretoshedsenescentanddamagedorgans.Floralabscissioniscontrolledbytheleucine-richrepeatreceptorkinase(LRR-RK)HAESAandthepeptidehormoneIDA.ItisunknownhowexpressionofIDAintheabscissionzoneleadstoHAESAactivation.HereweshowthatIDAissenseddirectlybytheHAESAectodomain.CrystalstructuresofHAESAincomplexwithIDArevealahormonebindingpocketthataccommodatesanactivedodecamerpeptide.AcentralhydroxyprolineresidueanchorsIDAtothereceptor.TheHAESAco-receptorSERK1,apositiveregulatorofthefloralabscissionpathway,allowsforhigh-affinitysensingofthepeptidehormonebybindingtoanArg-His-AsnmotifinIDA.Thissequencepatternisconservedamongdiverseplantpeptides,suggestingthatplantpeptidehormonereceptorsmayshareacommonligandbindingmodeandactivationmechanismKeywords:receptorkinase,cellseparation,membranesignaling,structurebiology,ligandsensingmecahanism

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Abstract#304.AnArabidopsisMUBE2StructureRevealsNewRegulatoryOpportunitiesintheUbiquitinSystem(Submission247)BrianDownes1,Lu,Xiaolong,SaintLouisUniversityBiology,Malley,Konstantin,SaintLouisUniversityBiochemistry,Brenner,Caitlin,SaintLouisUniversityBiology,Koroleva,Olga,SaintLouisUniversityBiochemistry,Korolev,Sergey,SaintLouisUniversityBiochemistry1SaintLouisUniversity,UnitedStatesUbiquitin(Ub)isaproteinmodifierthatcontrolsprocessesrangingfromproteindegradationtoendocytosis,butearly-actingregulatorsofthethree-enzymeubiquitylationcascadeareunknown.Here,wereportthattheprenylatedMembrane-anchoredUbiquitin-foldprotein(MUB)isanearly-actingregulatorofsubfamilyspecificE2activation.AnAtMUB3:AtUBC8co-crystalstructuredefineshowMUBsinhibitE2~UbformationusingacombinationofE2backsidebindingandaMUB-uniqueLapBarLoop(LBL)toblockE1access.SinceMUBstetherArabidopsisGroupVIE2enzymes(relatedtoHsUbe2DandScUbc4/5)totheplasmamembrane,andinhibitE2activationatphysiologicalconcentrations,theyshouldfunctionaspotentplasmamembranelocalizedregulatorsofUbchainsynthesisineukaryotes.OurfindingsdefineabiochemicalfunctionforMUB,afamilyofhighlyconservedUb-foldproteins,andprovidetheinitialexampleofselectiveactivationbetweencognateUbE2s,previouslythoughttobeconstitutivelyactivatedbyE1s.Keywords:E1,E2,Ubiquitin,MUB,Membrane-anchoredUbiquitin-foldAbstract#305.Evolutionaryconservationofstructureandfunctionintheplantaldehydedehydrogenase12family(Submission259)DavidKorasick1,Tanner,John,UniversityofMissouri-Columbia1UniversityofMissouri-Columbia,UnitedStatesThealdehydedehydrogenase(ALDH)superfamilyofenzymescatalyzesabroadrangeofbiologicallyimportantreactions.AlthoughseveralALDHsubfamilieshavebeenthoroughlycharacterizedstructurally,biochemically,andgenetically,otherALDHsuperfamilymembersremainuncharacterized.OnesuchsubgroupisALDH12fromplants.ALDH12hasbeenannotatedaspossessingthefunctionofL-glutamate-γ-semialdehydedehydrogenase(GSALDH,alsocalledALDH4A1).GSALDHproteinsfunctioninthesecondstepofprolinecatabolism,whichisatwostepprocessinwhichprolineisconvertedtoglutamate.Interestingly,ALDH12familymembersfromplantsbearverylowsequenceidentitytotheannotatedGSALDHisozymes(<30%identity).Herein,wedescribethestructuralandbiophysicalcharacterizationofZeamaysALDH12.Further,wedocumentastructuredeterminationpipelineforsolvingthephaseproblemforproteinsthatshareverylowsequenceidentitytoproteinscurrentlyintheProteinDataBank.ZmALDH12isanovelmemberoftheGSALDHfamilyofenzymes.AlthoughtheactivesitebearsstrongresemblancetoALDH4A1isozymesfromotherorganisms,theoverallquaternarystructureisnovelforGSALDHs.SAXSandanalyticalultracentrifugationanalysisrevealZmALDH12istetramericinsolution.ShapereconstructionfromexperimentalSAXSdatarevealstheinsolutiontetramerisconsistentwiththeincrystallotetramer.Overall,ouranalysisprovidesbothamethodfordifficultstructuraldeterminationbymolecularreplacementandstructuralanalysisofanovelplantenzymethatbroadensthecomplexityoftheALDHsuperfamily.Keywords:structuralbiology;prolinecatabolism;X-raycrystallography;smallangleX-rayscattering;analyticalultracentrifugationAbstract#306.SignalingmechanismofUV-BphotoreceptorfromArabidopsis(Submission260)XiaojingYang1,Zeng,Xiaoli,UniversityofIllinoisatChicago,Ren,Zhong,UniversityofIllinoisatChicago,Montano,Sherwin,UniversityofIllinoisatChicago,Zhao,Kaihong,HuazhongAgriculturalUniversity1UniversityofIllinoisatChicago,UnitedStatesUVR8isaplantphotoreceptorthatmediatesresponsestoUV-B(280-315nm)ofthesolarspectrum[1].UVR8perceivesUV-Bsignalsvialight-induceddimerdissociation,whichtriggersarangeofcellularresponsesincludingphoto-morphogenesis,circadianrhythmandphoto-protection[2,3].UVR8isuniqueamongallknownphotoreceptors:itdoesnotrequirecofactorstocaptureaUVphoton.StaticcrystalstructuresandmutationalstudiessuggestedthatclusteredtryptophanresiduesatthedimerinterfaceareresponsibleforUV-BperceptioninArabidopsisthalianaUVR8(AtUVR8)[4,5].WeemployeddynamiccrystallographytostudythephotoperceptionmechanismofAtUVR8,inparticular,light-inducedstructuraleventsleadinguptodimerdissociationremainelusiveatthemolecularlevel.Specifically,weappliedtemperature-scancryo-crystallography[6]tocapturetransientlight-inducedsignalingeventsinphotoactiveUVR8crystals[7].Wehavedeterminedstructureintermediatesat1.6Åresolutionthatcorrespondtoearlystructuraleventsontheps-nstimescale[8].Directobservationsoflight-inducedstructuralchangesunambiguouslyestablishtheoriginorepicenterofUV-BsignalingintheAtUVR8structure,andrevealasequenceofmoleculareventsbeyondtheepicenterthateventuallyleadtodimerdissociation[7].WealsoexaminetheroleofeachtryptophanresidueasapigmentbasedontheTDDFTcalculationsandproposethatUV-absorbingresiduesinUVR8collectivelyconstitutealight-harvestingantennasimilartothoseincyanobacteriaandplants[7,9].TheseantennapigmentscollectbroadbandUV-Birradiation,funnelexcitationenergytotheepicenterandtriggeraUV-B-inducedstructuralsignal.References[1]G.I.Jenkins,PlantCellOnline26,21(2014).[2]G.I.Jenkins,Annu.Rev.PlantBiol.60,407(2009).[3]M.HeijdeandR.Ulm,TrendsPlantSci.17,230(2012).[4]J.M.Christie,etal.Science335,1492(2012).[5]D.Wu,etal.Nature484,214(2012).[6]X.Yang,etal.Nature479,428(2011).[7]X.Zeng,etal.Nat.Plants1,14006(2015).[8]Z.Liu,etal.J.Phys.Chem.Lett.5,69(2014).[9]Q.Wu,etal.Phys.Chem.Chem.Phys.17,10786(2015).Keywords:dynamiccrystallography;photoreceptor;light-inducedstructuralchanges

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SystemsorSyntheticBiology,Bioinformatics,Modeling:Abstract#307.AssemblingtheArabidopsisMitochondrialDNAReplisome(Submission126)StewartMorley1,Nielsen,Brent,BYU1BrighamYoungUniversity,UnitedStatesReplisomesincludeproteinsandinteractionsrequiredtoreplicateDNAandincludeorigin-bindingproteins,DNAhelicases,DNAprimases,andDNApolymerases.ReplisomesrequiredfornuclearDNAreplicationaremuchmorecomplexthanthoserequiredformitochondrialDNAreplication.Typically,mitochondrialreplisomesconsistoffewerproteinsthatarebacterialinnature.Plantmitochondriahaveauniquenuclear-encodedsetofproteinstoreplicateDNA,whichareorthologoustoproteinsfoundinmitochondriafromotherspecies.Forexample,ArabidopsispossessestwomitochondrialDNApolymerasescalledPol1AandPol1BwhichareorthologoustohumanmitochondrialDNAPOLgamma.Similarly,Arabidopsispossessesahelicase-primaseproteincalledTwinklewhichisorthologoustothehumanTWINKLEprotein.InvitrostudieshavereconstitutedthehumanminimalmitochondrialDNAreplisome.ThisreplisomeconsistsofPOLgammaandTWINKLEandisenhancedbythepresenceofsingle-strandedDNAbindingprotein(mtSSB).Similarly,theT7phagereplisomeconsistsoftheproteinsgp5(DNApolymerase),gp4(helicase-primase),andgp2.5(singlestrandedbindingprotein).WehypothesizethatArabidopsismaintainsasimilarminimalmitochondrialreplisomeconsistingofPol1AorPol1BinteractingwiththeTwinkleDNAhelicase-primaseandmtSSB.WhenperformingamultiplesequencealignmentoftheseArabidopsisproteinstosimilarproteinsinotherplants,weobserveregionsofhomologyandvariability.Whilethehomologousregionsrepresenttheconserveddomainsofeachprotein,wehypothesizethatthevariableregionscorrespondtoareaswheretheproteinsinteractwitheachother.Usingayeast-two-hybridapproach,wearedirectlymeasuringwhichdomainsofeachproteininteractwithoneanother.Keywords:mitochondria;replisome;DNAreplication;YeasttwohybridAbstract#308.Prolinesintransitpeptidesarecrucialforefficienttranslocationofpreproteinsintochloroplasts(Submission276)DongWookLee1,Hwang,Inhwan,PohangUniversityofScienceandTechnology1PohangUniversityofScienceandTechnology,Korea,RepublicofChloroplastsimportdifferenttypesofpreproteinsaslinearpolypeptidesthroughimportchannels.Toc75functionsasacommonchannelforimportingallproteinsthroughtheouterenvelopeofthecellmembrane,andtheN-terminalsignalsequenceortransitpeptide(TP)containsallthenecessaryinformationforimportintochloroplaststhroughtheToc75channel.However,despiteagreatdealofstudyonproteinimportintochloroplasts,theexactmechanismremainselusive.Herein,weprovideevidencethatprolineresiduesintheTParecrucialforefficienttranslocationofpreproteinsthroughthechloroplastenvelope.Proline-lessTPsweredefectivetovaryingdegrees,dependingonthetypeofproteinimported;solubleproteinsdisplayedonlyaminordefect,whereastransmembranedomain(TMD)-containingoraggregation-proneproteinsshowedseveredefects,andwereinappropriatelylocalizedattheenvelopemembraneorformedaggregates,respectively.TheimportdefectsofTMD-containingpreproteinswithproline-lessTPswerephenocopiedinhsp93-Vplantsandadditivewiththedefectofhsp93-V.Basedontheseresults,weproposethatprolineresiduesinTPsplayacrucialroleintheefficienttranslocationofpreproteinsthroughchannels,particularlythosewithTMD(s).Keywords:chloroplastbiogenesis;transitpeptides;proteintranslocation;prolineresidues;Hsp93chaperoneAbstract#309.SyntheticApproachRevealsDynamicAuxinSignalinginArabidopsisandMaize(Submission374)BritneyMoss1,Galli,Mary,WaksmanInstitute,RutgersUniversity,Gallavotti,Andrea,WaksmanInstitute,RutgersUniversity1WhitmanCollege,UnitedStatesThehormoneauxinregulatesmyriadprocessesduringthelifeofaplant-fromrootandshootdevelopmenttoenvironmentalresponses.Understandinghowauxinregulatessuchdiverseprocessesnecessitatescharacterizationofthespecificsignalingmodules(receptors,repressors,transcriptionfactors)thatenableplantcellstodetectandrespondtoauxin.RecapitulationoftheArabidopsisnuclearauxinsignalingsysteminyeasthasshownthatauxinrepressors(Aux/IAAs)exhibitarangeofauxin-induceddegradationrateswhichcanbetuneddependingonidentityoftheco-expressedauxinreceptorandofspecificaminoacidsequenceswithintherepressors.SubsequentplantstudiesconfirmedthatAux/IAAsshowsimilardegradationdifferencesinArabidopsisandthatAux/IAAdegradationdynamicsarehighlycorrelatedwiththerateofdevelopmentalevents.Wearenowusingtheyeastsystemtofunctionallyannotateauxinsignalingmodulesinthecropplantmaize.Theultimategoalistodefineandcharacterizecomponentsofauxinsignalingmodulescrucialduringdevelopmentofmaizereproductivestructures,thetasselandtheear.WehaveshownthatasubsetofmaizeAux/IAAsknowntobeexpressedinreproductivetissuescanbefluorescently-tagged,expressedinyeast,andfluorescencelevelsdetectedbymicroscopyandfluorescenceflowcytometry.Additionally,maizeAux/IAAsexpressedinyeastweredegradedinthepresenceofauxinandanArabidopsisauxinreceptorprotein.WearecurrentlyexploringtherangeofauxinresponsedynamicsforthefullcadreofmaizeAux/IAAsexpressedinreproductivetissue,andhaveplanstoexpandthesestudiestoincludemaizeauxinreceptorsandtranscriptionfactors.Keywords:auxin;syntheticbiology;Aux/IAA;yeast;development

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Abstract#310.Araport:TheArabidopsisInformationPortal(Submission378)ChrisTown1,AgnesChan,J.CraigVenterInstitute,VivekKrishnakumar,J.CraigVenterInstitute,SergioContrino,UniversityofCambridge,ErikFerlanti,TexasAdvancedComputingCenter,JosueCoronel,TexasAdvancedComputingCenter,JoeStubbs,TexasAdvancedComputingCenter,RionDooley,TexasAdvancedComputingCenter,StephenMock,TexasAdvancedComputingCenter,GosMicklem,TexasAdvancedComputingCenter,MattVaughn,TexasAdvancedComputingCenter1J.CraigVenterInstitute,UnitedStatesAraport(https://www.araport.org)providesaone-stopdataplatformforArabidopsisandotherplantscientists.InAraport,userscansearch,analyze,anddownloadawidearrayofdatathroughthecorecomponentsThaleMineandJBrowse.Araporthasalsoreleasedanextensiveannotationupdate,Araport11,fortheCol-0referencegenome.ThaleMineisadatawarehouseforretrievingthelatestAraport11genomeannotation,integratedwithRNA-seqexpression,coexpression,physicalandgeneticinteractions,pathways,seedstocks,publications,andmore.ThaleMinealsoprovidesauser-friendlyinterfaceforrunninggenelistenrichmentanalysis,buildingdataqueries,exportingdatatables,andsaving/sharingwork.Araport11isacomprehensiveannotationupdateforbothgenemodelsandfunctionalassignmentsusingover100publicRNA-seqdatasets.Theupdateincludesvalidatingandaddingspliceisoforms,aswellasgenomicfeaturessuchasnoveltranscribedregions,non-codinggeneclasses,upstreamopenreadingframes(uORFs),andpseudogenes.TopromoteandenhancedatasharingbycommunitymembersusingAraport,thenextphaseoftheprojectwillincludedevelopingsimplemechanismsforuserstoautomaticallyintegratetheirdatasets(includingmetadata)withAraportfordiscoveryandreusebyotherresearchers.Forexample,userswouldbeabletocreatepublicdatatracks(e.g.RNA-seqalignmentsorexpressionprofiles,communitygenomeannotation,othergenomicfeatures)intheAraportJBrowse,simplybyprovidingtheappropriateGFForBAMfilealongwithitsassociatedmetadata.TheArabidopsisInformationPortalisfundedbyagrantfromtheUSNationalScienceFoundation(#DBI-1262414)andco-fundedbyagrantfromtheUKBiotechnologyandBiologicalSciencesResearchCouncil(BB/L027151/1).Keywords:Genomics;Bioinformatics;DataIntegration;DataAnalysis;Abstract#311.Modelingthetranscriptionalcircuitregulatingsecondarycellwallbiosynthesis(Submission385)GinaTurco1,HannahVahldick,DianeHan,MichaelSavageau,SiobhanBrady1UCDavis,UnitedStatesPlantsecondarycellwalls(SCWs)areintegralincellmorphology,mechanicalsupportandtransportofsolutesandnutrientsintheplant.TheSCWisalsoamajorrenewableresource.Itiscomprisedpredominatelyofthepolymerscellulose,hemicelluloseandlignin.Thesepolymersareimportantintheproductionofpaper,pulp,feedstockandbiofuel.Bychangingthecompositionofthesepolymerswecangeneratehigheryieldingbiomass/biofuelcrops.ThisprojectfocusesonthetranscriptionalregulationguidingdepositionoftheSCWinxylemcells.ThexylemSCWcomprisethemajorityofplantbiomass.Theaimofmyprojectistomodelthetranscriptionfactors(TFs)governingxylemSCWbiosynthesisfordevelopmentofhighbiomasscrops.Werecentlymappedthetranscriptionalregulatorynetwork(TRN)modelingxylemSCWbiosynthesisinArabidopsis.WithinourTRNIidentifiedthepresenceof99feedforwardloop(FFL)regulatorymotifs.MathematicalmodelingofFFLsandinvivoexperimentsinsinglecelledorganismssuggestthattheseFFLsproducedistinctregulatorybehaviors,suchaspulsesinexpression,delaysinexpressionandswitchlikebehaviors.LittleisknownabouttheregulatorybehaviorsaffordedbytheseFFLsinmulticellularorganismslikeplants.IhypothesizethatFFLsareimportantinplants,andinparticularinconfirmingtightspatialregulationofSCWbiosynthesis.Keywords:xylem;transcriptionalregulatorynetwork;computationalmodeling

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TranslationalBiology:Abstract#312.Effectofhigherploidylevelsonplantgrowthandbiomasscomposition(Submission22)SanderCorneillie1,Vanholme,Bartel,PSB-VIBUGent,Boerjan,Wout,PSB-VIBUGent1VIB-UGent,BelgiumImprovingplantproductionisanecessitytoguaranteefoodsecurityinthefaceofarapidlygrowingworldpopulation.Inaddition,plantbiomassiscurrentlytheonlyavailablerenewablefeedstocktoreplacepetro-basedchemicals.Inordertoincreasetheuseoflignocellulosicbiomassasasustainablesourceforthebio-economy,bothbiomassproductionandcompositionneedtobeoptimized.Polyploidizationorwholegenomeduplicationcanplayaroleinachievingthesegoals.Theincreaseinbiomassyielduponpolyploidizationiswellknown,buttheeffectonbiomasscompositionislesswellstudied.Togetadditionalinsightsintotheeffectsofpolyploidizationonplantgrowthandbiomasscomposition,wedecidedtostudythegrowth,yield,andbiomasscompositionofaseriesofautopolyploidArabidopsisthalianaCol-0plants,includingtetraploids,hexaploidsandoctaploids.Besidesanelaboratephenotypicanalysiswherebydifferentgrowthparametersweredetermined,weperformedathoroughcellwallcharacterizationandperformedsaccharificationexperimentsonthedrybiomass.Itistoourknowledgethefirsttimethattrendsingrowthandbiomasscompositionwerequantifiedinasetofplantswhichdifferonlyintheirdegreeofploidy.Besidesthefundamentalinsights,ourresearchshowsthatpolyploidycouldpotentiallyplayaroleinbreedingprogramstoobtaineconomicallyvaluableplantsthatcouldbeusedasafeedstockforthebio-economyKeywords:Polyploidy;Biomasscomposition;Biofuels;CellwallAbstract#313.Rapidlydomesticatingthenewoilseedcroppennycress(Thlaspiarvense)bytranslatingfindingsfromArabidopsisresearch(Submission68)MichaelaMcGinn1,Johnson,Evan,UniversityofMinnesota,Esfahanian,Malihe,IllinoisStateUniversity,Daniels,Erin,UniversityofMinnesota,Marks,M.David,UniversityofMinnesota,Sedbrook,John,IllinoisStateUniversity1IllinoisStateUniversity,UnitedStatesPennycress(Thlapsiarvense)isamemberoftheBrassicaceaefamilycloselyrelatedtoArabidopsisthatholdsconsiderableagronomicandeconomicpotentialasawinterannualoilseedcovercrop.Pennycresspossessesauniquecombinationofattributesincludingextremecoldtolerance,rapidgrowth,over-winteringgrowthhabit,andanaturalabilitytoproducecopiousamountsofseedshighinoilandprotein.Pennycresscouldgeneratebillionsoflitersofoilannuallythroughouttemperateregionsoftheworldwithoutdisplacingfoodcropsorrequiringlandusechanges,e.g.growingdouble-croppedbetweencornandsoybeansinotherwisevacantfields.Thediploidgenomeofpennycresshasbeensequenced,revealingitshares85%sequenceidentitywiththeArabidopsisgenome.ThelimitedgeneticdivergencebetweenArabidopsisandpennycressallowsstraightforwardtranslationofknowledgegatheredfromdecadesofArabidopsisresearch.WehavegeneratedlargepennycressEMSmutantpopulationsandidentifiedmutants/mutationsequivalenttothoseidentifiedinArabidopsis.Largeforwardgeneticscreenshaveuncoveredmanymutantswithimprovedagronomictraitsincludingreducedseeddormancy,reducedseedpodshatter,improvedoilquality,andimprovedseedmealquality.WehavealsodevelopedanAgrobacterium-mediatedfloraldiptransformationprotocolandusedtheCRISPR-Cas9genomeeditingtechniquetogenerateloss-of-functionmutationsintrait-improvinggenesincludingFATTYACIDELONGASE(FAE1;resultedinthe“zeroerucicacid”seedoiltraitequivalenttocanola).Thispresentationwillhighlightthegeneticandgermplasmresourceswehavedeveloped,therapidprogresswehavemadeindomesticatingpennycress,andtheutilityofpennycressasamodelsystem.Keywords:Pennycress;Biodiesel;Biofuel:Model/Cropsystemtranslationandconversion;CRISPR-Cas9Abstract#314.Stressgranules-mediatedtranslationalcontroloftheplantimmunitytriggeredbysalicylicacid(Submission69)MianZhou1,Wang,Wei,IowaStateUniversity1IowaStateUniversity,UnitedStatesStressgranules(SGs)areassembliesoftranslational-stalledmRNAsandspecificproteins.Inresponsetovariousstresses,SGsareformedrapidlyincytoplasmtotransientlyinhibitthetranslation.Studiesinmammaliancellsshowthatmutationsthatalterstressgranuleformationcontributetosomeneurodegenerativediseasesandcancers.AlthoughSGs-mediatedtranslationalcontrolofimmunityinmammaliancellsiswellstudied,thefunctionofSGsinplantdefenseislargelyunknown.Inthisstudy,wefoundthattheexogenoustreatmentofsalicylicacid(SA),akeyplantimmunesignal,triggerstheSGsformationinadditiontotranscriptomechanges.Surprisingly,ourresultsshowedthatSA-inducedSGsformationisindependentofbothknownSAsignalingpathwayandcanonicalSGsformationpathway,whichrequireseIF2αphosphorylation.WefurtherconductedamassspectrometryexperimentusingseedlingscontainingGFP-taggedRbp47b,acommonSGmarkerproteininArabidopsis.TheresultshowsthatSGsmarkerproteins,suchasUBP1andpoly-Abindingproteins,aswellasspecificsignalingproteinsarerecruitedintoSGs,indicatingthatSGsmayfunctionasasignalinghubtocommunicatea‘stateofemergency’andmodulategrowthanddefenseaccordingly.Consistentwiththishypothesis,themutantofaSGcomponentTudorStaphylococcalNuclease(TSN)displayedahypersensitivitytoSAwithacompromisedgrowthphenotype.Furthermore,weareconductingaRNA-bindingproteinimmunoprecipitationexperimentfollowedbysequencingtofindmRNAstrappedtoSGs.Insummary,ourstudyprovidesanotherlayeroftranslationalregulationofplantimmunity,whichinvolvestranslationrepressiontriggered-SGformationandrecruitmentofsignalingproteinsintoSGstoprovideacellularprotectionmechanismagainstalethaloutcomeandensurearapidrecoveryafterstress.

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Keywords:stressgranules;plantdefense;salicylicacidAbstract#315.TheArabidopsisthalianaMYBtranscriptionfactorETC2confershigheryieldandseedsizeintransgenicsoybean(Glycinemax)(Submission77)WushengLiu1,Ji,Hao,UniversityofPittsburgh,Peng,Yanhui,UniversityofTennessee,Knoxville,Mazarei,Mitra,UniversityofTennessee,Knoxville,Lin,Jingyu,UniversityofTennessee,Knoxville,Millwood,Reginald,UniversityofTennessee,Knoxville,Shao,Yuanhua,UniversityofTennessee,Knoxville,Saleem,Muhammad,UniversityofPittsburgh,Hauser,Marie-Theres,BOKU-UniversityofNaturalResourcesandLifeSciences,Vienna,Austria,Traw,M.Brian,UniversityofPittsburgh,Stewart,C.Neal,Jr.,UniversityofTennessee,Knoxville1UniversityofTennessee,Knoxville,UnitedStatesSeedsizeandyieldaretwoofthemostimportantagriculturaltraitsincropseventhoughtheunderlyinggeneticandmolecularmechanismsregulatingbothtraitsarestilllargelyunknown.TheArabidopsisthalianaMYBtranscriptionfactor,EnhancerofTRYandCPC2(AtETC2),isknowntocontroltrichomepatterning.HereweidentifiedanimportantnovelfunctionoftheAtETC2geneincontrollingseedsizeandyieldbygenome-wideassociationstudy(GWAS),recombinantinbredlinesanalysis,andquantitativetraitlocimapping.ItwassubsequentlyfoundthatT-DNAinsertionknockoutmutantshadsignificantlysmaller(upto16.3%)seedmassandmore(upto31.3%)trichomes.Complementationexperimentsweresufficienttorestorethenormalseedsizeandtrichomenumber.Overexpressionof35S::AtETC2intransgenicArabidopsisresultedinsignificantlyincreasedseedsizebyupto36.4%togetherwith87.5%fewertrichomesperplantrelativetothenon-transgenicparent.WhentheArabidopsisgenewasoverexpressedinsoybean,theresultantT2plantshadsimilarseed-sizegainstothetransgenicArabidopsisinbothgreenhouseandfieldstudies.Transgenicsoybeanleafmorphology,includingtrichomenumber,wasnotdifferentfromthenon-transgenicsoybean.Inadditiontoseedweightandwidthbeinggreaterinsometransgenicsoybeanlinesgrowninthefield,theyalsohadincreasedtotalseedyield,protein,andoilcontentrelativetothecontrols.TheseresultsprovidenewinsightsintothepreviouslyunidentifiedfunctionoftheAtETC2gene,increaseourunderstandingofthefunctionsofMYBregulatorsinplants,andsuggestapproachesthatmayleadtoincreasedagriculturaloutput.Keywords:AtETC2;Genome-wideassociationstudy;seedweight;Arabidopsis;soybean

Abstract#316.PhenotypingSolutionsforBasicandAppliedResearchinPlantBiologyandAgriculture(Submission116)ToddDeZwaan11LemnaTecCorporation,UnitedStatesHumanshavebeenphenotypingplantsforover10,000years.Beginningwiththedomesticationofagriculturalcrops,plantphenotypingisthecornerstoneforimprovingagronomictraitsthatincreaseyield.Thedemandforphenotypinghasincreaseddramaticallyinrecentdecadesastheexponentialaccumulationofgenomedatahasacceleratedourabilitytobreedandmodifycropspecies.However,theabilitytorapidlyandreliablyphenotypeplantscontinuestobeabottleneckinbasicplantresearchandthedevelopmentofnextgenerationproducts.Thisisachallengethatcutsacrossresearchareas,includingbreeding,agchemistry,biotechnology,andbiologicals.LemnaTec'sScanalyzersuiteofproductsprovideresearchersandbreederswithavarietyofhigh-resolutionimagingsensorsthatenablethemtoreliablyphenotypeplantsforthediscoveryanddevelopmentofnewagricultureproducts.Scanalyzerproductsrangeintermsofscaleandthroughputtomeettheneedsofindividualresearchers,butallarecapableofaccuratelymeasuringplantfeaturesthatarecrucialforyieldinthefieldsuchasleafarea,chlorophyllcontent,plantheight,growthrate,stressresponse,tipburn,biomass,droughttolerance,andmanymore.ThispresentationwilldescribeLemnaTecphenotypingapplicationsinlaboratory,greenhouse,andfieldsettings,andwilldiscusshowtheresultsarebeingusedforbasicandappliedresearchprograms.Keywords:phenotyping;phenomics;imageanalysis;imagingsensors;automationAbstract#317.Atightlyregulatedgeneticselectionsystemwithsignaling-activeallelesofphytochromeB(Submission134)WeiHu1,Lagarias,JClark,UCDavis1UniversityofCaliforniaDavis,UnitedStatesSelectablemarkersderivedfromplantgenescircumventthepotentialriskofantibiotic/herbicide-resistancegenetransferintoneighboringplantspecies,endophyticbacteriaandmycorrhizalfungi.Towardthisgoal,wehaveengineeredandvalidatedsignalingactiveallelesofphotoreceptorphytochromeB(eYHB)asplant-derivedselectionmarkergenesinthemodelplantArabidopsisthaliana.Byprobingtherelationshipofheatshockinductionconditionsandconstructsizetooptimalphenotypicselection,weprovedthateYHB-basedallelesarerobustsubstitutesforantibiotic/herbicide-dependentmarkergenesaswellassurprisinglysensitiveindicatorsofoff-targettransgeneexpression.Keywords:phytochromephotoreceptor;plantgene-basedselectablemarkercassette;fidelityoftransgeneexpression

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Abstract#318.Targetedphenylalanineinseedlingdevelopment:coatingstoreducecellularstress(agriculture),anddevelopmentofnutraceuticalextracts(medicine)(Submission138)KateWarpeha1,Thnaibat,Nayfah,UIC,Zaheer,Shamaila,UIC,Orozco-Nunnelly,Danielle,UIC,Muhammad,DurreShahwar,UIC,Niblack,Terry,OhioStateUniversity,Reuter-Carlson,Ursula,UniversityofIllinoisUrbana,Park,Thomas,UIC1UniversityofIllinoisatChicago,UnitedStatesThephenylalanine(Phe)biosyntheticactivityofArogenateDehydratase3(ADT3)coordinatesROShomeostasis,cotyledondevelopmentandcontributestogrowthanddevelopmentprocessesinArabidopsisthaliana(Arabidopsis)seedlings(Paraetal.,2016).Pirin1(PRN1)proteinactivityimpactscellelongationandphenylpropanoidscontentinyoungtissues(Orozco-Nunnellyetal.,2014;2015).Fromstudyingactionsofthesetwoproteinsandsubsequentimpactonchemotypeoftheseedling,wemadeachemicalcoatingtopromotedevelopmentanddefense(USPatent#8,492,614),andsubsequentlypursuedgeneticmethodstooverproducepolyphenolsatadevelopmentallyrelevanttimeinplants.Abioticsignalinghasbeenusedintheprocesstoboostdefensemechanismsandrigor.Seedlingresponseswerestudiedin>10planttypesofeconomicimportance,withcommonchemicalphenotypes(chemotypes)acrossspecies,increasingvaluetoagriculture.Inthehumandiet,flavonoidsarecommonphytochemicals,andhydroxycinnamicacidamides(HCAAs)arefoundinseedsandseedlings,activeincellulardefense.AlibraryofmutantswasmadeutilizingcommonBroccoli(Brassicaoleraceavar.italica)toproducehighpolyphenollinesbystressinductioninordertocapturedesiredchemotypescomparabletoourArabidopsiscoating/genotypicresults.Toavoidself-incompatibilityandtomaintainlineswedevelopedavegetativepropagationmethod.Chronicinflammationprecedesandunderliesmanychronicconditions(includingpain)affectingmorethan100millionpeopleintheUSA.Prototypesoftheextractshavebeentestedinvivoandshowpromisingresultsforfuturedevelopment.Currentmedicationincludingnon-narcotic(NSAIDs)andnarcoticdrugs,presentseriousdrawbacksincludinglackofefficacy,toxicsideeffects,tolerance,andaddiction.Makingeffectiveanti-inflammatoryextractsfromplantswithoutaddictionortoleranceisthegoalfortranslationaladvancement.Keywords:Phenylalanine;ReactiveOxygenSpecies;AbioticandBioticStress;NutraceuticalProducts;ChemotypeAbstract#319.Withdrawn

Abstract#320.Investigatingthemolecular,physiological,andarchitecturalchangesthatunderliegrafting-inducedvigor(Submission246)MargaretFrank1,Chitwood,Daniel,DonaldDanforthPlantScienceCenter,Meyers,Blake,DonaldDanforthPlantScienceCenter1DonaldDanforthPlantScienceCenter,UnitedStatesGraftinghasbeenusedtoincreaseyield,especiallyinthecontextofbioticandabioticstressforover2000years.AlthoughrecentexperimentalevidencesuggeststhatmobileRNAs,proteins,andsmallmoleculesmayplayanimportantroleinthemechanismthroughwhichgraftingimpactsplantgrowthandphysiology,thepreciseidentityofthesesignalsandthemechanismsbywhichtheyacttoaffectyieldremainlargelyunexplored.Intomato,thegraftingofelitefruitproducingshoots(scions)ontovigorous,interspecifichybridrootsystemssignificantlyincreasesyield.Wedemonstratethatthisphenomenonofgrafting-inducedvigorfunctionsinabi-directionalmanner;vigorcanbereciprocallytransferredfromtherootandshootsystemsofaninterspecifichybrid(SolanumlycopersicumxS.habrochaites)intothereciprocallygraftedshootandrootsystemsofdomesticatedtomato(S.lycopersicum).Associatedwiththisphenomenonofgrafting-inducedvigorwehaveidentifiedasweetofdevelopmental,physiological,ionomic,andmolecularphenotypes.Mostsurprisinglywefindthousandsofdifferentiallyexpressedgenesthatareinducedbyheterografting,andhundredsofmobilemRNAsthatareconsistentlytransferredacrossthegraft-junction.WeareaddinganewlayertothisgraftingequationbyinvestigatingthemobilityofsmallRNAsacrossthegraft-junction,andexploringtherelativeimportanceofmRNAsandsmallRNAsincontributingtografting-inducedvigor.Keywords:Grafting;tomato;long-distancesignaling;graft-transmissiblemRNAsAbstract#321.Theoriginandevolutionofasexchromosomepairingardenasparagus(Submission248)AlexHarkess1,VanderHulst,Ron,Limgroup,Bowers,John,UniversityofGeorgia,Mercati,Francesco,NationalResearchCouncilofItaly,Riccardi,Paolo,Bayer,Falavigna,Agostino,ConsiglioperlaRicercainAgricolturael’analisidell'economiaagraria(CREA),Xu,Chunyan,BGI,Meyers,BlakeC,DonaldDanforthPlantScienceCenter,Groenendijk,John,GreenAcresLifeSciences,Sunseri,Francesco,UniversitàMediterraneadegliStudidiReggioCalabria,Leebens-Mack,James,UniversityofGeorgia1DonaldDanforthPlantScienceCenter,UnitedStatesSexchromosomeshaveevolvedfromautosomeshundredsoftimesacrossthetreeoflifeyetthemolecularandevolutionaryprocessesunderlyingthesetransitionsremainobscure.Gardenasparagus(AsparagusofficinalisL.),adioeciousspecieswitharecentlyevolvedhomomorphicsexchromosomepair,isidealforstudyingtheearliesteventsinsexchromosomeevolution.SequencingandcomparativeanalysisofYYmaleandXXfemaleasparagusgenomeshasimplicateda1Mbmale-specificregionontheasparagusYchromosome.Wehaveidentifiedtwoindependentmale-to-hermaphroditemutantsthatimplicateasinglegeneinthismale-specificregionasresponsiblefordominantlyinterruptingpistildevelopment.Antherdevelopmentisnotaffectedinthesemutantsbutmale-to-femaleconversionsareseenintwoothermutantswithdeletionsspanningthe1Mbnon-recombiningsexdeterminationregion.Thisregioncontains12gene

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modelsinadditiontothefemalesuppressorincludingahomologtotheArabidopsisanther-specificgeneDefectiveinTapetalDevelopmentandFunction1(TDF1).InsupportoftheamodelproposedbyCharlesworth&Charlesworth(TheAmericanNaturalist1978)fortheoriginofsexchromosomes,thesefindingimplythattheoriginofanon-recombiningsexdeterminingregionontheAsparagusproto-Ychromosomeinvolvedthelinkageofamalepromotinggenewithadominantsuppressoroffemaleorgandevelopment.Keywords:Sexchromosomes;dioecy;asparagus;genomics

Abstract#322.Expressionprofileofstress-responsiveArabidopsisthalianamiRNAsandtheirtargetgenesinresponsetoinoculationwithPectobacteriumcarotovorumsubsp.Carotovorum.A.T.Djami-Tchatchou1andK.Ntushelo1DepartmentofAgricultureandAnimalHealth,UniversityofSouthAfrica,SouthAfricaPectobacteriumcarotovorumsubsp.carotovorum(Pcc)isasoftrotbacteriumwhichuponentryintotheplantmaceratesplanttissuesbyproducingplantcellwalldegradingenzymes.Ithasawidehostrangewhichincludescarrot,potato,tomato,leafygreens,squashandothercucurbits,onion,greenpeppersandcassava.Duringplant-microbeinteractions,oneofthewaysofplantresponsetopathogeninfectionisthroughthesmallRNAsilencingmechanism.UnderpathogenattacktheplantutilizesmicroRNAstoregulategeneexpressionbymeansofmediatinggenesilencingattranscriptionalandpost-transcriptionallevel.Thisstudyaimstoassessforthefirsttime,theexpressionprofileofsomestress-responsivemiRNAanddifferentialexpressionpatternoftheirtargetgenesinArabidopsisthalianainoculatedwithPcc.Leavesoffive-week-oldArabidopsisthalianaplantswereinfectedwithPccandthequantitativerealtime-PCR,wasusedtoinvestigateafter0,24,48and72hourspostinfection,theexpressionprofilingofthestress-responsivemiRNAswhichinclude:miR156,miR159,miR169,miR393,miR396miR398,miR399andmiR408alongwiththeirtargetgeneswhichinclude:squamosapromoter-binding-likeprotein,mybdomainprotein101,nuclearfactorYsubunitA8,concanavalinA-likelectinproteinkinase,growthregulatingfactor4,coppersuperoxidedismutase,ubiquitin-proteinligaseandplantacyaninrespectively.Results:Ourfindingsshowedthattheoverexpressionof6miRNAsat24,48and72hoursafterinfectionresultedintherepressionoftheirtargetgenesandtheexpressionof2miRNAsdidn’taffecttheirtargetgenes.TheseresultsprovidethefirstindicationofthemiRNAsroleinresponsetotheinfectionofPccinA.thalianaandopennewvistasforabetterunderstandingofmiRNAregulationofplantresponsetoPcc.

Abstract#323.Systematicdiscoveryofnoveleukaryotictranscriptionalregulatorsusingnon-sequencehomologybasedprediction.FlaviaBossi1,JueFan1,JunXiao2,LilyanaChandra1,MaxShen2,YannivDorone1,3,DorisWagner2,SeungY.Rhee11DepartmentofPlantBiology,CarnegieInstitutionforScience,Stanford,California94305;2DepartmentofBiology,UniversityofPennsylvania,Philadelphia,Pennsylvania19104-6084;3DepartmentofBiology,StanfordUniversity,Stanford,California94305Themolecularfunctionofageneismostcommonlyinferredbysequencesimilarity.Therefore,genesthatlacksufficientsequencesimilaritytocharacterizedgenesaredifficulttoclassifyusingmostfunctionpredictionalgorithmsandhaveremaineduncharacterized.Toidentifynoveltranscriptionalregulatorssystematically,weusedafeature-basedpipelinetoscreenproteinfamiliesofunknownfunction.Thismethodpredicted43transcriptionalregulatorfamiliesinArabidopsisthaliana.Literaturecurationvalidated9ofthepredictedfamiliestobeinvolvedintranscriptionalregulation.Wetested33outofthe195predictedtranscriptionalregulatorsfortheirabilitytoactivatetranscriptionofareportergeneinplantaandfound12coactivators,5ofwhichwerepreviouslyunknown.Toinvestigateothermechanismsofactioninwhichthesepredictedregulatorsmightwork,welookedforphysicalinteractorsofacandidatethatwecallCHIQUITA1(CHIQ1),whichdidnotshowtransactivationactivityinplanta.CHIQ1interactedwithothermembersofitsownfamilyandasubunitofthePolycombRepressiveComplex2toregulatetranscription.Phenotypicanalysisofmutantlinescarryingaknock-outallelechiq1-1havesmallerorganswithfewerandsmallercells.ThephenotypeswerecomplementedbyCHIQ1.CellcyclemarkerstudiesindicatedthatCHIQ1affectsthedurationofcellproliferation.Atranscriptomeanalysisperformedinchiq1-1seedlingsidentified~170mis-regulatedgenesthatincluderegulatorsofcellexpansionandhormoneresponsesaswellasgenesthatencoderibosomalproteins.Ourresultsdemonstratethefeasibilityofassigningmolecularfunctiontoproteinsofunknownfunctionwithoutdependingonsequencesimilarity.Inparticular,weidentifiednoveltranscriptionalregulatorsusingbiologicalfeaturesenrichedintranscriptionfactors.