Identification Of Preharvest Germination Resistance Of Wheat Germplasm Resources And QTL Analysis Of Preharvest Germination Resistance In RIL Population

Wheat is one of the important food crops in the world and plays a very important role in agricultural production.Pre-harvest sprouting(PHS)refers to the phenomenon that wheat encounters continuous rainy weather during the harvest period,and mature wheat fails to harvest in time,resulting in the direct germination of grains on the spike.PHS will seriously reduce the yield and quality of wheat.In this study,305 wheat germplasm resources collected at home and abroad were used as materials,4 STS markers Tamyb10 D,Vp1B3,PM19-A1,Dorm-1 and 11 SSR markers Xbarc310,Xgwm344,Xgwm282,Barc294 were selected and the15 markers closely related to ear germination resistance,Combined with grain germination and ear germination tests,and verified the effectiveness of 15 STS markers and SSR markers related to ear germination.According to phenotypic and molecular tests,wheat materials with ear sprouting resistance were screened out.At the same time,QTL mapping of pre-harvest sprouting traits in RIL population constructed by Zhou 8425B/Xiaoyan 81 was analyzed in order to provide reference for molecular marker assisted breeding.The main results are as follows:1.The SGR of 305 domestic and foreign wheat materials ranged from 0.0%～100.0% with an average of 65.1%;The variation range of grain germination index is 0.0%～87.7%,and the average value is 40.3%;The variation range of whole panicle germination rate GP is0.0%～89.4%,and the average value is 13.6%.Among them,there are 200 white wheat and105 red wheat.Statistics showed that the mean and variation range of SGR,GI and GP in white wheat were slightly larger than those in red wheat.The correlation coefficients between wheat seed coat color and GP,SGR and GI were-0.391,-0.754 and-0.736,respectively,showing extremely significant negative correlation.A total of 24 wheat materials with high resistance to SGR,GI and GP were screened according to the phenotypic traits of pre-harvest sprouting.The average GP of these high resistant materials was 0.97%,and the variation range is 0%～8.1%;The average value of SGR is 4.29%,and the variation range is 0%～10.0%;the mean value of GI is 1.79%,and the range of variation is 0%～4.7%.Among the 24 highresistant wheat materials,except Fengyan 3,the other high-resistant varieties are all red-grain wheat,indicating that seed coat color had a significant indigenous effect on wheat ear sprouting resistance.2.In this study,the effectiveness of 15 pairs of STS markers and SSR markers related to pre-harvest sprouting resistance was verified,and only 5 markers could be used to identify pre-harvest sprouting resistance of tested materials,namely STS markers PM19-A1 and Tamyb10 D,and SSR markers Xgwm344,Barc294 and Xgwm282,the differences between different fragments amplified by these five markers in the tested materials were significant,and the other 10 markers showed no significant difference between genotypes in the tested materials,and the effectiveness needs to be further verified.According to the statistics of the five markers that can be used for the identification of ear germination resistance,it is found that there are 2,7,21,91 and 184 wheat materials with 4,3,2,1 and 0 resistance bands amplified from the five validity markers,and the average germination index is 9.1%,5.6%,15.7%,30.0% and 49.9% respectively.3.Five effective ear germination resistance markers and 24 wheat materials with high ear germination resistance were comprehensively analyzed.It was found that 22 wheat materials contained more than one effective molecular marker;Two wheat materials did not contain the resistance bands of effective molecular markers screened in this test,but had strong resistance to ear germination,which may be the reason why multiple genes jointly control wheat ear germination.The materials contained the resistance bands of molecular markers not detected in this test.Therefore,the combination of phenotypic identification and molecular markers can more accurately select wheat germplasm resources resistant to ear germination.4.Five QTL loci were found in the RIL population constructed by Zhou 8425B/Xiaoyan81,which were mainly located on chromosomes 1A,4A,6A,6B and 7A.The phenotypic variation explained by these loci ranged from 5.58%～30.95%.Among them,QPhs.nwafu-1A may be the newly discovered major QTL locus.In a single environment,there are four QTLs with phenotypic variation interpretation rate greater than 10.0% and two QTLs stably existed in the four environments.