Redesigning soybean with improved oil and meal traits

Key Message

Soybean seed oil and meal composition traits can be combined without interference to provide additional value to the crop.

Abstract

Soybean [Glycine max (L.) Merr.] is an important crop worldwide; its overall value comes from seed oil and high protein meal. The development of soybean varieties with allele combinations for improved oil and meal quality is expected to provide a compositional value bundle for soybean. The high oleic and low linolenic acid seed oil trait (HOLL; > 70% oleic and < 3% linolenic acid) is targeted to optimize the health and functional properties of soybean oil. For soybean meal, metabolizable energy is improved by altering the carbohydrate profile with increased sucrose and decreased anti-nutritional factors, raffinose family of oligosaccharides (RFOs). Previous research identified four variant alleles of fatty acid desaturase (FAD) genes and two raffinose synthase (RS) genes necessary for the HOLL trait in soybean oil and Low or Ultra-Low (UL) RFO traits in soybean meal, respectively. We employed a molecular marker-assisted breeding approach to combine six alleles conferring the desired soybean oil and meal value traits. Eight environment field trials were conducted with twenty-four soybean lines to evaluate phenotypic interactions among the variant alleles of FAD and RS genes. The results indicated that the four FAD gene alleles conditioned the HOLL fatty acid profile of the seed oil regardless of the allele status of the RS genes. Independent of the allele combination of the FAD genes, soybean with two variant alleles of the RS genes had the desired RFO trait in the seeds. The results confirm the feasibility of soybean variety development with this unique combination of oil and meal traits.