Screening Of Wheat Drought-tolerant Germplasm Resources And Genome-wide Association Analysis Of Related Traits (Triticum Aestivum L.)

Wheat is one of the main food crops in China.wheat production in arid and semi-arid regions accounts for more than half of China’s total wheat production.Therefore,screening wheat germplasm drought,drought-related genes to explore,providing drought-resistant material and genetic basis for breeding wheat in arid and semiarid areas have the great significance.In the experiment,under the conditions of rainfed（DS,drought treatment）and irrigation（WW,well watered）,the natural population consisting of 236 wheat varieties（lines）was used as the experimental material to measure the drought-related traits,screening of drought-resistant germplasm resources using three different drought resistance assessment methods.Based on the SSR marker data detected on 21 chromosomes of wheat,the association between markers and traits is based on the analysis of population structure.Analysis,detection and control of significant correlation sites of drought-related traits,provide reference for wheat molecular marker-assisted selection breeding and drought-resistant QTL cloning.Below are key research findings:1.Using the comprehensive drought tolerance coefficient,drought tolerance index and comprehensive drought tolerance coefficient based on the membership function method,three different drought resistance evaluation methods were used to screen out six wheat varieties with high resistance,namely Funo,Abbondanza and Mengke No.3.C,Yu 30691-3-6,You Manghong 18,Baiquan 565（Yu）,accounting for 2.5% of the tested materials;5 sensitive wheat varieties,Mianyang 26,Mianyang 31,Kaifeng No.10,Nongda 116,Di Youzao,accounting for 2.1% of the test materials.2.Genetic diversity of 236 wheat cultivars（lines）was detected using 106 SSR markers.The results showed that 106 pairs of primers detected 874 allelic variations with an average of 8.24 allelic variations ranging from 2 to 23;The major alleles frequency（MAF）ranged from 0.177 to 0.987 with an average of0.545.The polymorphism information content（PIC）ranged from 0.026 to 0.895 with an average of 0.550.These results indicate that these wheat varieties have a high genetic diversity at the molecular level.3.Association analysis of drought-related traits and 106 SSR markers in 4 environments,using a mixed linear model（MLM）,associated with 47 SSR markers,a total of 54 significant associations（P<0.01）loci,associated loci The phenotypic interpretation rate（R2）ranged from 5.72% to 30.73%,andsignificant association sites were detected on other chromosomes except 1B,6A,7A,7B,and 7D,Among them,25 significant association sites were detected under drought conditions,and 29 significant association sites were detected under irrigation conditions.Four SSR markers detected significant association sites in multiple environments,among them,Xgwm164（1A）was found to be significantly associated with plant height in all four environments,Xgwm55（6D）was also significantly associated with plant height and the number of spikelets（top 1）at the top of the spikes in two environments,Xgwm429（2B）detected significant association with spike length in two environments,Xwmc415（5B）detected significant association with kernel number per spike in two environments.Eight SSR markers were significantly associated with two or more traits,of which Xgwm164（1A）was significantly associated with plant height and top 1 at the same time;Xgwm232（1D）was significantly associated with the kernel number per spike and top 1;Xgwm95（2A）is also significantly associated with top 2 and top 3;Xgwm102（2D）is significantly associated with the kernel number per spike,top 2 and top 3;Xgwm285（3B）is also significantly associated with top 3 and base 3;Xcfd266（5D）is simultaneously significantly correlated with kernel number per spike and top 3;Xgwm132（6B）was significantly associated with panicle length and top 1;Xgwm55（6D）was also significantly associated with plant height,spike length,top 1,top 3 and base 1.4.Through the analysis of the phenotypic effect of allelic variation,the excellent allelic variation of each related locus was screened,including the excellent allelic variation Xgwm164-1A₁₁₈ with a plant height of 4.24 cm;the excellent allele with an ear length of 0.75 cm could be increased.Variation Xgwm429-2B₂₀₇;can increase the excellent allelic variation Xwmc415-5B₁₅₄ with 1.07 spikes per plant;can increase the excellent allelic variation of main grain of 1.93 capsules Xgwm232-1D₁₃₈;can increase the excellent allelic variation of 0.92 g with 1000-grain weight Xgwm610-4A₁₇₀;can increase the excellent allelic variation of the first spikelet at the top of the spikelet 0.14,Xgwm132-6B₁₂₈;can increase the excellent allelic variation of the second spikelet at the top of the spikelet 0.19,Xgwm102-2D₁₄₂,can Increasing the number of firming grains of the third spikelet at the top of the 0.20 grain is Xgwm102-2D₁₄₂;the excellent allelic variation of the grain size of the first spikelet at the base of 0.07 can be increased by Xgwm55-6D₁₂₈;the second spikelet of the base can be increased.Excellent allelic variation of 0.17 granules Xgwm5-3A₁₆₈;excellent allelic variation of 0.34 granules of the third spikelet at the base Xcfe172-3D₁₄₄.