Genome-Wide Association Analysis-Based Mining of Quality Genes Related to Linoleic and Linolenic Acids in Soybean

Soybean fat contains five principal fatty acids, and its fatty acid composition and nutritional value depend on the type of soybean oil, storage duration, and conditions. Among the fat contents, polyunsaturated fatty acids, such as linoleic acid and linolenic acid, play an essential role in maintaining human life activities; thus, increasing the proportions of the linoleic acid and linolenic acid contents can help improve the nutritional value of soybean oil. Our laboratory completed SLAF-seq whole genome sequencing of the natural population (292 soybean varieties) in the previous growth period. In this study, genome-wide association analysis (GWAS) was performed based on the natural population genotypic data and three-year phenotypic data of soybean linoleic acid and linolenic acid contents, and a significant single nucleotide polymorphisms (SNPs) locus (Gm13_10009679) associated with soybean oleic acid content was repeatedly detected over a span of 3 years using the GLM model and MLM model. Additionally, another significant SNP locus (Gm19_41366844) correlated with soybean linolenic acid was identified through the same models. Genes within the 100 Kb interval upstream and downstream of the SNP loci were scanned and analyzed for their functional annotation and enrichment, and one gene related to soybean linoleic acid synthesis (Glyma.13G035600) and one gene related to linolenic acid synthesis (Glyma.19G147400) were screened. The expressions of the candidate genes were verified using qRT-PCR, and based on the verification results, it was hypothesized that Glyma.13G035600 and Glyma.19G147400 positively regulate linoleic acid and linolenic acid synthesis and accumulation, respectively. The above study lays the foundation for further validating gene functions, and analyzing the regulatory mechanisms of linoleic acid and linolenic acid synthesis and accumulation in soybean.