Comprehensive Evaluation Of Drought Resistance Of Different Wheat Varieties And Association Analysis Between Drought Resistant Traits And SNP Markers

Wheat is one of the most important food crops in China even in the world.Drought is the environmental factors which have seriously impact on wheat production.Identification and breeding the varieties of drought-resistant is one of the effective ways to reduce the production losses from the drought.Therefore,it is important to screen the drought resistant wheat lines and explore the mechanism for drought resistant wheat breeding and production.1.In this study,119 wheat lines were tested during germination period under drought stress simulating by PEG-6000(-0.5Mpa).And the germination rate,coleoptile length,main root length,root number,dry matter weight were measured.The results showed that,the average of the five traits under drought treatment decrease 77.3%,40.0%,30.7%,16.7%and 78.0%than control and the drought treatment inhibited the growth inordinately of the varieties and increased the differences between different varieties.Analysis with the traits of drought resistance coefficient distribution,showed that the PEG-6000 simulation stress promoted the main radicle length elongation of some varieties.Moreover,D value calculated by the weighting membership function method had significantly positive correlation with drought resistance indices,such as the coleoptile length,root number various.And the germplasms were clustered using UPGMA algorithm with drought resistance coefficient,the material were divided into two major categories in the genetic distance of 0.82.According to this,the strongest drought-resistance germplasm are evaluated including Lovrin 13,Wennong 14,Chinese spring,Luomai 8,Lunxuan 987,Taishan 22,Shannon 17,Tainong 18,Yanhangxuan 2,Zhongyu6,Lumai14andTainong6258.2.Also,119 wheat lines were tested during seedling stage under drought stress simulating by PEG-6000(-0.5Mpa).A total of agronomic traits including the root length,main root length,root volume,root superficial area,plant height,root average diameter,etc were measured.The results showed that the 11 singles index could be integrated into 5 independent comprehensive components by using principal component analysis.The drought comprehensive resistance was evaluated by using membership function method based on the comprehensive indexes.The drought resistance indexes were chosen to evaluate the resistance drought by principal component analysis method.As following:the root related index(root length,root superficial area,root volume),plant morphological characteristics(plant height,main root length,root shoot ratio).The Youbao,Shannong17,Huaimai20 were rated as high drought-resistance varieties by membership function method.3.Thirdly,89 wheat lines cultivated in normal irrigation and rainfall-fed environment in Chengyang,Qingdao city for two years(2014-2015,2015-2016)for evaluating the drought resistant characters in field.Spike length(SL),uppermost internode length(UIL),length from flag leaf pulvinus to spike base(LFS),spikelet number(SN),grain number per spike(GNPS),plant height(PH),flag leaf length(FLL),flag leaf width(FLW)and thousand kernel weight(TKW)were measured.The Lu yuan 502,Zhou mai 24,Yan nong 5158,Huai mai 18,935106,Xin 296 and Zhong mai 175 were rated as high drought-resistance varieties by membership function method in 2014.The Zhou mai 26,Huai mai 33,Tai nong 18,Huai mai 31,Ji mai 5265,Huai mai 26,Yu mai 13,Nong da 3338,Xin mai 23,Huai mai 29 were rated as high drought-resistance varieties by membership function method in 2015.Huai mai 33,Lu yuan 502,Nong da 3338 were rated as high drought-resistance varieties by membership function method in two growing seasons.The muti-regression analysis was done between the D value and the drought-tolerant coefficient of each trait.The results revealed that DC of FLL,GNFS(or G),FLS,SN and UIL could explain 92%of the total variations in D value,Those five variables could be used as a combination to screen wheat germplasm for drought tolerance.4.Ultimately,119 testes lines was genotyped with the 90K SNP array and 26026 SNPs were obtained.Baseded on the genome-wide association study to disclose each trait in different wheat growing stage.A total of 68 SNPs were found to be associated with the tested traits(P<0.0001),which were located on chromosomes 1B、1D、2A、2D、3B、4A、4B、4D、5A、6A、6B、7A and 7B.Thereinto,13 associated SNPs were detected in two or more environments.