Mining Of Genetic Loci And Candidate Genes Conferring Pod And Seed Related Traits In Soybean

Soybean is an important food and oil crop in the world.Pod and seed are the essential harvested organs in soybean,not only directly affect the formation of yield and quality,but also play a vital function in fresh vegetable variety registration and product export.However,pod and seed related characteristics are quantitative traits which controlled by multiple genes,and was difficult to improve through the conventional breeding strategy.In view of this,one natural population and another recombinant inbred line(RIL)population were analyzed to detect the genetic loci and candidate genes controlling pod and seed related traits through the genome-wide association study(GWAS)and linkage mapping methods.The results could provide selection molecular markers and candidate genes for pod and seed traits in soybean genetic improvements.The main results are as follows:1.The genetic variations and correlations of eight pod and seed related traits in soybean natural population and RIL population were identified.The relative wide genetic variations on eight related traits(pod length,pod width,pod weight,seed weight,seed length,seed width,ratio of seed length to width and seed area)of natural population were detected with the coefficient of variation ranged from 4.15%～22.87%;the relative wide genetic variations on eight traits of RIL population were also detected with the coefficient of variation ranged from 3.68%～28.34%.In addition,the significant or extremely significant correlations among these related traits were detected,except for the ratio of seed length to width.2.Fifteen associated SNPs were identified across multiple environments or controlling various traits,and some responsible genes were screened out.Based on the eight related traits under four different environments,fifteen associated SNPs were identified on ten chromosomes across multiple environments or controlling various traits and eleven of them were further verified via the BLUP values.Two SNPs(ss715620336 and ss715620343)on chromosome 15 were associated with six related traits across multiple environments.Based on these,some candidate genes participating in the cell wall structural remodeling,and gibberellin and ethylene pathway were screened out with different expressions in different pod developmental-stages between the large and small pod soybean varieties.3.Eight linkage additive QTL clusters were identified across multiple environments or controlling various traits,and some candidate genes were screened out.Based on the eight related traits under four different environments,eight additive QTL clusters were identified on seven chromosomes with phenotypic variation explained(PVE)ranged from 5.28%to 17.30%across multiple environments or controlling various traits and six were further verified via the BLUP values.One pleictropism QTL on chromosome 20 with PVEs 8.92%～17.30%were linked with pod weight,seed weight,length and area under multiple environments.Based on these,some candidate genes were screened out with different expressions in different pod developmental-stages between the two RIL parents.Based on these results,the conclusions were:Relative wide genetic variations on eight related traits(pod length,pod width,pod weight,seed weight,seed length,seed width,ratio of seed length to width and seed area)of natural and RIL populations were detected with the coefficient of variation 4.15%～22.87%and 3.68%～28.34%.The significant or extremely significant correlations among these related traits were detected,except for the ratio of seed length to width.Fifteen associated SNPs were identified on ten chromosomes across multiple environments or controlling various traits,and eleven were further verified via the BLUP values.Eight QTL clusters were identified on seven chromosomes with PVEs 5.28%～17.30%across multiple environments or controlling various traits and six were further verified via the BLUP values.Some candidate genes were screened out with different expressions in different pod developmental-stages between large and small pod soybean varieties.