Cosegregation of Candidate Genes for Oleate Biosynthesis with Quantitative Trait Loci for Oleic Acid Seed Content in Soybean.

The increase of oleic acid content in soybean oil improves its nutritional value and oxidative stability. Elucidation of the genetic factors controlling oleate content will facilitate the incorporation of the high oleate trait in soybean germplasm. Previous studies reported oleate quantitative trait loci (QTLs) with minor and moderate effects. Isoforms of the FAD2 gene (FAD2-1A, FAD2-1B and FAD2-2B), encoding the ω-6 desaturase enzymes, have been tested for association with oleate content. FAD2-1A cosegregated with an oleate QTL with moderate effects. In this study, additional candidate genes for oleate biosynthesis, such as more isoforms of the FAD2-2 gene, the FAD6 gene and the isoforms of AAPT1 gene, were mapped in different linkage groups of soybean genome and their cosegregation with oleate QTLs was investigated. Two mapping populations consisting of 118 F5-derived lines from the cross of N97-3363-3 x PI423893 and 231 F3-derived lines from the cross of N98-4445A x PI423893 were used in order to determine whether the candidate genes for oleate biosynthesis are associated with oleic acid seed content. The two populations were previously used for mapping oleate QTLs. This study revealed that one of the isoforms of AAPT1 gene and the FAD6 gene explained part of oleate and linolenate variation in soybean oilseeds, respectively.