Association mapping of oil content and fatty acid components in soybean

Abstract

Soybean is a globally important oil crop, and the flavour, stability and nutritional value of soybean oil is dependent on the relative proportions of five primary fatty acids. In this study, association mapping was performed to identify molecular markers associated with QTL regions related to oil traits in soybean. Oil and fatty acid contents were measured in soybean accessions grown under field conditions for 2 years. Based on polymorphisms at 142 SSR loci, 94 soybean accessions were divided into two clusters corresponding to accessions from Asian and American gene pools. Linkage disequilibrium (LD) among the SSR loci suggested a structure across the soybean genome (LD decay) of approximately 12 cM. Pairwise kinship estimates among the accessions showed low values. A mixed linear model (MLM) adjusted using false discovery rate (FDR) and minimum Bayes factor (BFmin) values identified 110 strongly associated marker-traits. Oleic acid content had the highest number of associated SSR loci (33), followed by linoleic acid (26), palmitic acid (24), oil (16) and linolenic acid (14). Specific alleles at eight loci yielded high performing soybeans with respect to fatty acid content, and these are presented in a crossing matrix. Analysis of SSR loci and oil traits confirmed previous findings, and many new markers were also identified that may be useful for quickly improving oil traits in soybean.