Phytohormone Profiling of Wheat Seedlings in Responses to Hessian Fly Infestation
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Transcript of Phytohormone Profiling of Wheat Seedlings in Responses to Hessian Fly Infestation
Phytohormone Profiling of Wheat Seedlings in Responses to Hessian Fly Infestation
Lieceng Zhu1, Xiang Liu2, Ming-Shun Chen3
1Fayetteville State University2North Carolina State University3USDA-ARS in Manhattan, Kansas
Wheat - Hessian Fly Interaction
A gene for gene model
Incompatible Compatible
AvirulentVirulent
Control
• Physically damage plants
• Limited to a few cells
• Induces nutritive tissue formation at feeding sites (Harris et al. 2006)
Characteristics of Larval Feeding
• Sessile • Feed like pathogen
• Shift in carbon & nitrogen metabolism (Zhu et al. 2008)
• Differential genome-wide gene expression (Liu et al. 2007)
NC
CK
R
NC
S
NC
Question
How are responses of wheat seedlings to Hessian fly feeding regulated?
Phytohormone Profiling
GC-MS Analysis
Gas Chromatography
DetectorSeparator
Mass Spectrometry
• Determine concentration of several types of phytohormone simultaneously
Treatments
Genotype Sample 24 H 72 H
CK CK
Feeding sites R R
Molly S S
CK CK
Second leaf R R
S S
Results & Discussions
Phytohormone Profiling
• 10 phytohormone/related compounds detected
IAA, SA, CA, BA, JA, OPDA, 18:3, 18:1, 18:2 & 18:0 FA
• IAA, SA, JA, OPDA, 18:1, 18:3 were affected at feeding sites
• No changes in second leaves
• Implication: Impacts of HF feeding on phytohormones is localized
Compatible Interaction
• IAA increased– Major form of Auxin
• Implication: IAA contributes to susceptibility
Incompatible Interaction
• SA & OPDA increased
– Concentration (ng/ g fresh weight)
11 fold
8 fold
35 fold
18 fold
SA OPDA
18:3 FA
Membrane lipids
LOX2
AOS
AOC
OPDA
OPR3
JA
Response • 18:3 & 18:1 FA increased• JA decreased at 24 H• Implication:
– JA may not regulate resistance– OPDA & SA may regulate resistant responses
Gene Expression in JA Pathway
LOX 2
AOS
At VSP2
28S RNA
C R S C R S C R S
24H 48H 72H
18:3 FA
Membrane lipids
LOX2
AOS
AOC
OPDA
OPR3
JA
AtVSP2
(JA responsive)
• LOX2 & AOS: Compatible Incompatible • AtVSP2: Compatible Incompatible at 24 & 48H
• Implication:– OPDA was regulated at transcription level– AtVSP2 may be induced by OPDA– AtVSP2 is important in resistance
Summary
• Impact of HF larval feeding is localized• OPDA & SA may act together in wheat resistance to HF• IAA plays a role in susceptibility of wheat plants • Increases in OPDA in incompatible interaction is partially regulated
through gene transcription• AtVSP2 protein may be induced by OPDA & is critical to wheat
resistance to HF
Acknowledgement
• KSU Lipidomics Center– Dr. Richard Jeannotte, Ms. Alex Sparks
• Grant P20 MD001089 from the National Institutes of Health, NCMHD, the Department of Health & Human Services