Association Study Of Drought Resistance Related Traits In Wheat Seedling Stage And Selection Of Germplasm Resources

China is one of the largest wheat producing countries in the world,and the planting areais very broad.However,due to thelimitation of irrigation water condition,such as water source,field engineering,topography and so on,which results in thereduction of wheat production in many areas.Therefore,it is an important way to broaden the genetic basis and create special drought-resistant resources by studying the relationship between related traits and drought resistance of wheat in seedling stage,and excavating the gene loci related to drought resistance traits.In the present study,the related morphological and physiological indexes of wheatwere measuredat seedling stage based on a natural population consisting of 205 wheat varieties which were cultivated in sand bed under osmotic stress treatmentand contrast.The objectives of this study are both to screendrought tolerance germplasm resources and locate the important correlation sites by evaluating the drought resistance of experimental materials combined with the value of membership function,principal component analysis and comprehensive drought resistance coefficient,and using the genome-wide association study?GWAS?between markers and traits.The mainly results of this study were as follows:1.The phenotypic variation analysis of drought resistance related traits of wheatshowed that the coefficient of variation of eachtraits was different in twoenvironments.The coefficient of variation of SWLR?RWLR and MRL were less than 10%,and others were more than 10%.The coefficient of variation ofSDW,RFW,RDW,RSFW,RSDW,Pro and SS was exceeded 20% under drought stress,which indicated that these traits in the present study had great potential for improvement.2.The correlation analysisof drought resistance related traits of wheatshowed thatSH,CL,RN,MRL,SFW,SDW,RFW,RDW,RSFW and so on were significantly positively correlated with each other.There were also significant correlations between SS and SWLR,RWLR;Pro and RN,RSDW,RWLR.Integrated drought-resistant ability coefficient?D value?and CL,SFW,SDW,RFW,RDW,RSFW,Prowere significant or extremely significant correlation.The results showed that the relationship between drought resistance characters of wheat was close and drought-resistant mechanismswere complexrelatively.3.The principal component analysis ofdrought resistance related traits of wheatshowed that the cumulative contribution rate of the first five principal components was 80.53%.The corresponding comprehensive indexes were biological yield,biomass allocation ratio,root dry matter,SWLR and Pro.The first threebiological yield,biomass allocation ratio and root dry mattercan be used as drought resistance identification index in wheat seedling stage.4.The ability of drought resistanceof experimental materials was evaluated according to D value?comprehensive drought resistance coefficient?.There were 22 varieties with strong drought resistance which contains Fa0356,Tainong 19,W120287,W110143,sheng 32,Hemai 13,Xinong 529,Yuejin 5,Jinan 17,Shiluan02,Wo 85,sheng 93,D180,Weiyin84137,D209,Zhoumai 16,sheng 219,sheng 217,sheng 154,Yan99102,W110095,sheng 157 were selected.5.A total of 503 significantmarker-trait associations?MTAs?were identified by using the genome-wideassociation study?GWAS?.307 loci were detected under drought stress conditions,183 loci were detected under normal water conditions,and 13 significant MTAs related to D value were detected.There were 65 loci that were detected to have pleiotropism.In both environments,the significant lociincluded Tdurum_contig4974₃55located on chromosome 4B,wsnp_Ex_c14654₂2713386located on chromosome 7A,and the D_contig06359₁1 located on chromosome 7D were detected to control SS and SH.The contribution rate of phenotypic variation in these sitesranged from 12% to 14%.BS00093063₅1 was a stable expression of gene locusfor controlling RN on chromosome 6D,which was detected in both treatments,with contribution over 10%.The above significant loci are important correlation sitesfor controllingdrought resistance related traits in seedling stage of wheat,which can be further developed as molecular markers,laying the foundation for fine positioning.