Jason D. Gillman, USDA-ARS, Columbia, MO and Crystal Heim, Department of Plant Sciences, University of Missouri, Columbia, MO
It is of interest to breeders to obtain soybean oil of modified composition so as not to require chemical hydrogenation. For instance, edible oil high in saturated fats is desirable for solid fat baking applications. In the past, it has been generally accepted that diets high in saturated fat are linked to incidence of coronary heart disease. Interestingly, new research has shown that stearic acid, a long-chain saturated fatty acid, does not have the same cholesterolemic effects in humans as its shorter chain counterparts. Unfortunately, soybean oil generally contains only ~4% stearic acid, and greater than 20% must be achieved to meet current market demands. The development of multiple mutants with elevated stearic acid content presented a unique opportunity to investigate the genetic basis for extremely elevated stearic acid in line A6 (~28% of total seed oil, compared to ~4% in typical cultivars). To that end, a recombinant inbred line (RIL) population was developed by crossing A6 to a mutant with moderately elevated stearic acid (194D, stearic acid is ~11% of total seed oil). We employed Genotyping-by-Sequencing (GBS), which is a simple, repeatable, and robust method for identifying single nucleotide polymorphisms (SNPs) using methylation-sensitive restriction enzymes to obtain genomic sequence of reduced complexity. A total of 27,672 GBS SNPs were identified, with an average SNP coverage of 10.98-fold per locus. A dense genetic linkage map was constructed from 2,977 high-quality SNP markers obtained from GBS. Using phenotypic data from 173 RILs over three environments, 23 QTL were identified for eight traits in soybean, including four additive QTL for seed stearic acid content. Identification of the underlying genes contributing to the elevated seed stearic acid trait will contribute significantly to future breeding endeavors to develop soybean germplasm which meets the market requirement of >20% seed stearic acid content.