GENETIC ANALYSIS OF F~ POPULATIONS FROM CROSSES …. 34 1955... · 2017. 7. 12. · gene and 3rty...
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PROC. S. I). ACAD. SCI. XXXIV {J9551 GENETIC ANALYSIS OF F~ POPULATIONS FROM CROSSES INVOLVING COLCHICINE-INDUCED MUTANTS IN SORGHUM I ADSTIlAI,"l' A. E. Foster, J. G. Hoss, and C. J. Fran7.kc South Dakota Slate College, Brookings 21 ColchJclne treated seedllngs of a true breeding variety oC sorghum, Ex- perimental 3, were found to differ In appearance from untreated check!> 0,21. The treated plants were In no case polyploid, as might be expected, but reo Wined the diploId chromosome number. Careful cytological cXilminallon. by Harpstead 13>,of the melotlc stages of the treatC'd material, the untreated material. and theIr F'a crosses. showed no abnormal pairing relalionshJps. or detectable chromosomal abnormality. It had also been observed that certain -of the changed -plants bred true for these new characteristics in succeeding g~nerallons. From these findings II was r-ostulated thut colchh.:ine caused a 1iomallc reduction of the chromosomes with a concurrent mutagenic effect .und Subsloquent restoration to the dIploid number. A cell thus formed could then perhaps. because of chance genotypic or positional advantage, take over the gro\\'ing point and form homoz.ygou~ tissue of a different genot).pc than the ortglnal embryo. To determine whether the mutations were limited to one part of one l'IU'Olllosome, or Jf they might be scattered randomly throughout several 1'I1I'olllosomes. an F. population of 720 plants from a cross between a col. 'l:hh'lnc.Jnduce<l mutant and Its untreated full sib was studied. 'ruhle I lists the charaCters which were studied and also the coded mean 'VI'lhll' of these for the treated and untreated parents. Some of the characters l1hl 11Iltuppear to be changed while others were widely dUYeJ'enl. Very little 1'!lI'lI11t)'pic difference is Indicated hetween the mutant and Its untreated full 'Ill fill' diJYs 10 heading and length of lear, but the F. data showed transgres. tll\'t, tR'ijregutlon Indicating that genes affecting maturity had been mutated. I\N would be expected, dIstribution curves Indicating quantitative In. l"'I'Hunce were also found for the other charactcl's with the exception of the Ill'l'.encc or awns. The mutation or a large number of genes affecting these dlhl'llcu:rs was Indicated The (lualJtative character, presence or absence of awns, was InherIted III u :1:) ratio ;lnd Is therefore due to a single gene difference. Colchicine had 1'llllIR'lJthe OluWtlon of the dominant gene for awnless to the recessive gene "I'hl" Illvesllg.lllon was fiupportcd b)' a research grant PHSC.2086 rrom the N(Jtlunul Cancer Jm;Utute, or the Nallonal In5tItute!) or Health, Public IJtollllh Sl'I'\'lcc.
Transcript of GENETIC ANALYSIS OF F~ POPULATIONS FROM CROSSES …. 34 1955... · 2017. 7. 12. · gene and 3rty...
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PROC. S. I). ACAD. SCI. XXXIV {J9551
GENETIC ANALYSIS OF F~ POPULATIONS FROMCROSSES INVOLVING COLCHICINE-INDUCED
MUTANTS IN SORGHUM I
ADSTIlAI,"l'
A. E. Foster, J. G. Hoss, and C. J. Fran7.kcSouth Dakota Slate College, Brookings
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ColchJclne treated seedllngs of a true breeding variety oC sorghum, Ex-perimental 3, were found to differ In appearance from untreated check!> 0,21.The treated plants were In no case polyploid, as might be expected, but reoWined the diploId chromosome number. Careful cytological cXilminallon. byHarpstead 13>,of the melotlc stages of the treatC'd material, the untreatedmaterial. and theIr F'a crosses. showed no abnormal pairing relalionshJps. ordetectable chromosomal abnormality. It had also been observed that certain-of the changed -plants bred true for these new characteristics in succeedingg~nerallons. From these findings II was r-ostulated thut colchh.:ine caused a1iomallc reduction of the chromosomes with a concurrent mutagenic effect.und Subsloquent restoration to the dIploid number. A cell thus formed couldthen perhaps. because of chance genotypic or positional advantage, take overthe gro\\'ing point and form homoz.ygou~ tissue of a different genot).pc thanthe ortglnal embryo.
To determine whether the mutations were limited to one part of onel'IU'Olllosome, or Jf they might be scattered randomly throughout several1'I1I'olllosomes. an F. population of 720 plants from a cross between a col.'l:hh'lnc.Jnduce
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22 PROC. S. D. ACAD. SCI. }""XXIV (I~55)
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TAIlI.F. I
COilED MEAXS FOil CIIARAt-'TEIIS II,I,USTI\ATI!I'G DU'.'ERE!I'CESIIETWlm!l' A COJ.cIlICI!I'E.IXlltJCED MUTANT AXD ITS
U!I'TlmATED .'U1,I, SIB
Character Mutant Untreated Full Sib
Days to HeadIng 5.00 4.96
Number of 'l'illers 5.40 .85
Length of Leaf 4.87 5.43
Width or Lear 1.65 7.32
Plant Height 6.39 J 3.13
Stem Diameter 4.88 7.68
Presence of Awns 1.00 0.00
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(01' awns. Correlations between thiS and the quantitative characters discussedabove showed no relationships. SInce a quallt3l1\'e character of this naturewould have no physl010'glcal relatlo'nshlp to any of the other characters, thislack of reJatlon!;hlp indIcates that "the'l:e, Is no linkage between this mutatedgene and 3rty ~r the'.oth~rs. These results indicate therefore, that the mula.genic effect of colchicIne Is not limited to onc locus but must effect mutationsat a large number of loci probabl)' on dtfferent chromo'somes.
IUIlJ.IOGIlAI'HY
1. F'ranzke. C. J. and Ross, J. G.. Colchicine-Induced Variants in Sorghum.Jour. Hered., 43, 107.115 119521.
2, Ross, J. G., Franzke, C. J., and Schuh, L. A:, Sludies on Colchlcine.In-duced Yarlants in Sorghum. Agron. Jour .. 46, 10.15 (1954).
3. Harpslcad. D. D., Ross. J. G., and ••..•.ranzke. C, J., The Nature of Chroma-tin Changes of Colchiclne.Induced Variants In Sorghum. Jour. Hercd .. 45,255.258 (19541.
