Two high-oleic-acid soybean mutants, M23 and KK21, have disrupted microsomal omega-6 fatty acid desaturase, encoded by GmFAD2-1a

Elevating the oleic acid content of soybean (Glycine max (L.) Merr.) is a major focus of breeding programs. Previously, we created two high-oleic-acid soybean mutants, M23 and KK21, by X-irradiation. We expected them to have modifications in genes encoding microsomal omega-6 fatty acid desaturase. The objectives of this study were to evaluate which members of the GmFAD2 gene family contribute to oleic acid production during seed maturation, to characterize the mutant genes, and to establish molecular markers for breeding of high-oleic-acid soybeans. Three GmFAD2 genes were expressed in developing seeds; the gene products of GmFAD2-1a and GmFAD2-1b were more active than that of GmFAD2-2a during seed development. We identified different nucleotide modifications in GmFAD2-1a in M23 and KK21. Using nuclease-cleaved DNA fragment-length polymorphisms, we developed a novel molecular marker to distinguish between KK21 mutant and wild-type alleles. This information could be useful for improving soybean oil quality by using the mutant genes from M23 or KK21, and for screening novel high-oleic-acid soybean mutants.