Genome-wide Association Study On Yield Traits And Drought Tolerance Under Irrigation And Drought Conditions In Wheat

Wheat is one of the most important crops in the world,one of the main tasks in wheat breeding is to obtain wheat varieties with high yield and high quality.The combine analysis of high-throughput SNPs and important agronomic traits of wheat has important significance in discovering important gene and QTL,marker-assisted selection in wheat breeding and molecular aggregation breeding important genes and map-based cloning.(1)In this study the wheat 90 K chip was used,in the polymorphism of SNPs,by removing the the SNP with smallest allele frequency(MAF)less than 5 %,and loss rate more than 15 %,9329 SNPs were remained.According to the information published by Wang et al.(2014),about 85.24 %(7952/9329)SNPs has genetic location information,which is distributed on 21 chromosomes.The results of group structure analysis showed that 134 cultivars were divided into two subgroups,including 121 varieties and 13 varieties,respectively.In this study,the LD distance of the whole genome was about 13 cM.(2)In this experiment,134 wheat cultivars were planted in 2 years,3 locations and 2 kinds of water treatment,and 11 phenotypic traits were investigated in 12 environments.In the seedling stage,hydroponics and PEG-6000 were used to simulate drought stress.After two experiments,10 phenotypic traits were investigated on shoot and root.Drought-resistant coefficient was used to evaluate drought resistance.Correlation analysis showed that there was a significant correlation between yield traits and drought resistance coefficient,and there was correlation between different drought resistance coefficients.(3)In this experiment,the drought resistance coefficient of plant height,yield and three yield factors(1000-grain weight,grain number per spike and spike number per square metre)were used to evaluate the sensitivity of wheat varieties to drought sensitivity.Lumai 21 as a check varieties of drought resistance evaluation,as the result 31 wheat varieties with high drought resistance were detected.These drought resistant wheat varieties include Pinzihan 36192,Heng 0628,Ji 5265,Shi 4185,Shijiazhuang 8,Shixin 618,Luohan 24,Luohan 8,Luozhen 1,Yumai 49,Zhouheimai 1,Canadian strong gluten wheat,Huaimai 16,LS4942,BSS,Dexuan 1,Gunong 35 xuan 21/USSR-22,Jimai 20,Jimai 21,Jining 16,Lumai 23,Shannong 1186,Shannongzimai 1,Shanrong 3,Taishan 21,Xin 289,Yannong 836,Linmai 6,Heixiaomai 76,Linhan 822,Chuan 35050.(4)GWAS analysis detect out 999 significant SNPs correlated to phenotypic traits and drought-resistant coefficient(DC),which explain 5.63 to 26.43 % of the phenotypic variation.Among the 999 SNPs,816 SNPs with genetic position,distributed on 453 sites in 21 chromosomes.236 SNPs genetic position contributed more than 10 % of phenotypic variation.A total of 740 QTLs were detected,and which explained the phenotypic variation of 6.15 % ~26.43 %,and 154 QTLs contributed more than 10 % of phenotypic variation.There were 69 QTLs expressed in normal and drought stress conditions.