Identification of a Potential Gene for Elevating ω-3 Concentration and Its Efficiency for Improving the ω-6/ω-3 Ratio in Soybean

This present study was to identify a novel candidate gene that contributes to the elevated α-linolenic acid (ALA, ω-3) concentration in PE2166 from mutagenesis of Pungsannamul. Major loci qALA5_1 and qALA5_2 were detected on chromosome 5 of soybean through quantitative trait loci mapping analyses of recombinant inbred lines. With next-generation sequencing of parental lines and Pungsannamul and recombinant analyses, a potential gene, Glyma.05g221500 (HD), controlling elevated ALA concentration was identified. HD is a homeodomain-like transcriptional regulator that may regulate the expression level of microsomal ω-3 fatty acid desaturase (FAD3) genes responsible for the conversion of linoleic acid into ALA in the fatty acid biosynthetic pathway. In addition, we hypothesized that a combination of mutant alleles, HD, and either of microsomal delta-12 fatty acid desaturase 2-1 (FAD2-1) could reduce the ω-6/ω-3 ratio. In populations where HD, FAD2-1A, and FAD2-1B genes were segregated, a combination of a hd allele from PE2166 and either of the variant FAD2-1 alleles was sufficient to reduce the ω-6/ω-3 ratio in seeds.