Genome-wide Association Analysis And Excellent Germplasm Identification Of Wheat Seed Vigor Related Traits

As the main grain crop in China,wheat plays an irreplaceable role in ensuring the food security of Chinese people.Seed contains all the genetic information of plants,which is an important information of agricultural production.Seed vitality,which is a comprehensive measure of seed quality,directly affects sowing quality and seedling emergence,and is an important factor in determining yield.High vitality seeds germinate quickly and neatly,grow robustly,and yield high.However,there are few studies on wheat seed vitality,and the molecular mechanism is not clear.In this study,404 wheat germplasm with wide genetic background were used as experimental materials,and 23 seed vigor related traits were measured and evaluated comprehensively from three aspects: morphological index,resistance index and physiological and biochemical index,to explore the relationship between seed vigor and related traits,and to screen wheat germplasm resources with excellent vigor.Genotypic information and vigor-related trait parameters were combined with genome-wide association analysis to identify loci controlling vigor-related traits in wheat germplasm.The main research results are as follows:1.Based on three different phenotypic identification methods,404 wheat germplasms were phenotypically identified for seed vigor related traits.The results showed that culture environment and genotype had significant influence on seed vigor.In this study,germination potential,germination rate,germination index and other traits can be used to comprehensively reflect the vigor of seeds.Based on principal component analysis,23 seed vigor related traits were treated with dimensionality reduction.Six key evaluation factors controlling seed vigor were obtained,which were aging simple vigor index,aging vigor index,aging germination rate,aging germination index,aging germination potential and vigor index,accounting for87.08% of all trait indexes.Based on cluster analysis,404 wheat germplasm were divided into five vigor levels,and the performance of vigor related traits of high vigor wheat seeds was significantly better than that of other vigor wheat seeds.among which K25 seed from International Arid Zone Agricultural Research Center(ICARDA)had the highest vigor,with Germination energy of 89.33% and Germination percentage of 98.67%.2.Based on 660 K high density SNP chip,404 wheat samples were scanned by whole gene and combined with phenotype for genome-wide association analysis.31 significant association loci related to wheat seed vigor were identified on chromosomes 3A,3B,4A,4B,5B,6B,7A and 7B.It could explain 2.85%-5.90% of phenotypic variation.Four potential new loci for controlling wheat seed vigor were obtained through comprehensive analysis of previous reports.3.By using the genome sequence information and bioinformatics technology to identify the candidate genes in the significantly associated regions,a total of 126 genes were obtained.These candidate genes were mainly related to the functions of ATP-dependent zinc metalloproteinase,E3 ubiquitin protein ligase,cytochrome P450 family proteins,etc.