Agronomic Traits, Genetic Diversity And Association Analysis Of Breeding Target Traits In Soybean

In order to breed high yield and high quality soybean, analyze the genetic diversity of parent materials, discover elite alleles related to agronomic traits and provide useful information for hybridization combination of parent materials and molecular assisted breeding, in this study, the 19 phenotypic traits (plant weight, plant height, pod height, stem diameter, branch number, node number of main stem, the number of pods on main stem, pods per branch,1-seed pod number,2-seed pod number,3-seed pod number, 4-seed pod number, shriveled pods, pest-bitten seed number, total pods,50-seed weight, weight per plant, protein content and fat content) of a natural population consisting of 90 soybean cultivars were studied by correlation analysis, principal component analysis and cluster analysis method to research the relationship between the phenotypic traits. Meanwhile, the 90 materials were genotyped for polymorphism to analyze the genetic diversity by using 59 SSR markers. The genotyping data of 46 SSR markers selected was used to analyze population structure, and then association analysis between SSR markers and 18 soybean agronomic traits was performed to discover elite alleles using TASSEL2.1 MLM (Mixed Linear Model) programs. The results showed:1. The relationship between 19 phenotypic traits was determined through the correlation analysis for the phenotypic traits of the 90 materials.17 agronomic traits could be transformed to 5 principal components through the principal component analysis. The 90 materials were divided into 3 groups through the clustering analysis.2. A total of 154 alleles were found from 50 markers which appeared to be polymorphic among the 59 markers. Polymorphism information content (PIC) ranged from 0.042 to 0.765 with the mean of 0.521 and Shannon index ranged from 0.1066 to 1.6804 with the mean of 0.8241. Genetic distance ranged from 0.0307 to 1.4529, with the mean of 0.7015.3. Population structure analysis showed that the population of these materials was composed of 4 subpopulations. Seven SSR markers were found to associate with branch number, weight of 100 seeds, growth period, node number of main stem, leaf shape and protein content under the Tassel2.1 GLM program, and the rate of explanation for phenotypic variations of related marker ranged from 0.003 to 0.339. Elite allelic genes, such as Satt263-A279, Satt156-A203, and Satt567-A112 and so on, were determined by analyzing the relationship between different allelic variation genes of associated loci and phenotype effects. These results provide evidence for cloning high quality genes and can be further utilized in breeding programs.