Characterization of the Genetic and Environmental Effects Underlying Soybean Seed Protein Concentration in Two Recombinant Inbred Populations

Soybean (Glycine max (L.) Merrill) is a significant source of high-quality plant-based protein. An increased awareness of soybean health benefits has spurred a greater demand for soy-based food products, which has attracted attention from researchers, soybean growers and food processors. Soybean seed protein concentration is a complex trait that is influenced by genotype, environment and genotype-by-environment interaction effects, and is negatively associated with seed yield. The main objectives of this study were to: (i) determine the effects of genotype and genotype-by-environment interaction on seed protein concentration; and (ii) identify quantitative trait loci (QTL) associated with seed protein concentration suitable for marker-assisted selection. Genotypic and phenotypic data were collected from multi-environment trials of two recombinant inbred line (RIL) populations, derived from the high-protein cultivar, AC X790P (49%, dry weight basis), and low protein commercial cultivars, S18-R6 (41%) and S23-T5 (42%). Genotype, environment and genotype-by-environment interaction effects significantly affected seed protein concentration and seed yield. Significant correlations between seed protein concentration and seed yield were not observed in either population, and GGE biplots made it possible to identify for competitive high-protein genotypes. Seventy-nine QTL associated with seed protein concentration (with R2 ranging from 4.1% to 24.4%) were identified, 14 of which (with R2 ranging from 10.0% to 20.7%) were deemed desirable for marker-assisted selection.