Genome-Wide Association Studies For Fatty Acid Component Traits In Soybean

Soybean is a main oil crop wordwide, and its production accounts for about39%of all the world oil crops. It provides major edible oil for human, in which fatty acid components have an important impact on its quality. Therefore, it is important to investigate their genetic foundations.Previous studies on fatty acid components in soybean are derived from bi-parental segregation populations and association mapping with a small amount of markers. To overcome these shortcomings, it is necessary to carry out genome-wide association studies (GWAS) with high throughput SNP markers. In this study, therefore,285soybean cultivars, randomly sampled from soybean cultivars in China, were measured for palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid in2011and2012, and scanned by84,443SNP markers. The above information was used to conduct GWAS by mixed linear model (MLM) approach in TASSEL software. Then, the associated SNP markers were used to predict candidate genes for the above five traits using bioinformatics method. Main results were as follows.First,654and558SNP markers were associated with the above five traits in2011and2012, respectively, under the critical value of-log10P≥3. Among these QTL,111and41QTL were for palmitic acid;47and52QTL for stearic acid;147and110QTL for oleic acid;138and140QTL for linoleic acid;211and215QTL for linolenic acid; the number of all these QTL was867; the number of the common QTL across the two years was206, including5QTL for palmitic acid, one QTL for stearic acid,65QTL for oleic acid,65QTL for linoleic acid, and70QTL for linolenic acid; and the number of QTL that were associated with more than two traits was112in2011and73in2012.The number of QTL each Mb in the20chromosomes are0.62,0.83,1.60,0.63,1.30,0.99,1.22,1.07,1.07,0.61,0.64,0.90,0.81,1.20,0.60,1.93,0.93,0.79,0.59and0.82, respectively. Although it is slightly larger in chromosomes6and9, it follows uniform.Second,1,269genes were observed around all the associated SNP markers, and191associated markers are just located in175genes. Among these genes,94genes are homozygote with lipid genes in Arabidopsis thaliana,26associated SNP markers were just placed in17genes, and152associated SNP markers were around near80genes, and associated markers exist both in and around3genes.As compared with previous studies,61common markers associated with the above five traits were observed within500Kb. Among these markers,7soybean homology lipid genes were found to be around10associated markers, and9markers were found to be in8soybean genes.