Association Study Of Saline-alkali Resistance Related Traits At Wheat Germination Stage And Selection Of Germplasm Resources

Wheat is an important food crop in China,which is widely distributed.The saline-alkali land accounts for a quarter of the cultivable land.Therefore,it could be useful for wheat saline-alkali tolerance breeding in the future to study the relationship between related traits and saline-alkali tolerance,to select germplasm resources,and to develop important loci closely linked with saline-alkali tolerance.In this study,a natural population consisting of 205 wheat varieties?lines?were used as the material,and the morphological and physiological indexes of germination were measured under saline-alkali stress and control conditions by hydroponic method.The objectives of this study are used for comprehensive evaluation of saline-alkali tolerance with the value of membership function,principal component analysis,synthetic evaluation?D value?,cluster analysis.The genome-wide association study?GWAS?was carried out on the tested traits to identify loci;so as to provide references for gene discovery and marker-assisted selection of wheat saline-alkali tolerance.The mainly results of this study were as follows:1.Phenotypic variation analysis: The variation coefficient of each trait was different under saline-alkali stress and control conditions.The variation coefficient of SWC,RWC was less than 10% in two conditions,and the difference is small.The higher coefficient of variation was Pro,indicating that it was more sensitive to saline-alkali stress.2.Correlation analysis: The results showed that SH,CL,SFW,SDW,RSDW were significant correlation with each other in the two conditions.There were also significant correlations between SWC and MRL,SFW,RFW,RSFW,RSDW,SS.There were very significant correlations between RWC and RFW,RSFW,SWC.There were very significant correlation between Pro and MRL,RSDW,SWC,SS.3.Principal component analysis: Fourteen saline-alkali related indexes were summarized into five comprehensive indexes by principal component analysis,namely,shoot material,root/shoot weight,RWC,RN,and Pro,with a cumulative contribution rate of 82.557%.The high contribution rate of Shoot material,root/shoot Weight,RWC can be considered as selecting index for saline-alkali tolerance of wheat at germination stage.4.Selection of saline-alkali tolerant germplasm resources: On the basis of principal component analysis,it was divided into four categories according to D value by using cluster analysis.The seven high saline-alkali tolerant varieties accounting for 3.41% of the materials;18 saline-alkali tolerant varieties accounting for 8.78%;118 moderate saline-alkali tolerant varieties accounting for 57.56%;61 sensitive saline-alkali varieties accounting for 29.76% were selected.5.412 loci related to saline-alkali traits were detected by using the genome-wide association study?GWAS?.There loci were distributed on 20 chromosomes except chromosome 4D,explaining 5.29% to 11.03% of the phenotypic variation.220 loci were detected under saline-alkali conditions,192 loci were detected under control conditions.There were 41 loci that were detected to have pleiotropism.Under saline-alkali and control conditions,chromosome 7D IAAV9104 was detected to control SS.In addition,wsnp_Ra_c11532₁8688426 of chromosome 5A and RAC875_c66770₂08 of chromosome 7A were detected to control SFW and SDW.Wsnp_Ex_c12675₂0144479 of chromosome 2B,Kukri_c46421₁68 and BobWhite_c7260₁97 of chromosome 4A were detected to control CL.The important locus controlling SH was detected on chromosome 5B.6.Chromosome 3A wsnp_Ex_c11048₁7916681 and wsnp_Ku_c4886₈753646,3B BobWhite_c1895₁953,4A Excalibur_c1439₈80,5B Jagger_c4951₁22,6A wsnp_Ex_c6604₁1441822 and Kukri_c1779₁63,6D BS00093063₅1,7A BS00023117₅1,these loci were correlated with saline-alkali tolerant traits of wheat by using the genome-wide association study with saline-alkali tolerance coefficient of each traits.