Environmental stability and genetic effect of soybeans differing in mutant allele combinations between rs and mips1 genes for soluble carbohydrate profiles

Raffinose and stachyose (raffinose family oligosaccharides [RFOs]) in soybeans [Glycine max (L.) Merr.] are anti-nutritional carbohydrate components. Previous studies identified mutant alleles of raffinose synthase (rs) 2 and 3 and d-myo-inositol-3-phosphate synthase 1 (mips1) to increase sucrose and reduce RFOs content. Although earlier studies investigated the effects of rs2 and rs3 mutations, a mips1 mutation has not been tested yet. The objectives of this study were (1) to investigate the genetic effects and environmental stabilities of rs2, rs3, and mips1 mutations across 18 environments and (2) to evaluate germination rates of genotypes carrying these mutations. Sucrose was significantly affected by all environmental factors (year, location, and planting dates). However, raffinose was not affected by planting dates, and stachyose was only affected by location. The rs2 mutant allele (rs2W331-) and mips1 showed the highest environmental stability for sucrose and raffinose, respectively. For stachyose, the wild-type check showed the highest environmental stability. The lines with mips1 mutation showed significantly higher sucrose (11.1%) and lower raffinose (0.5%) and stachyose (0.6%) content than other genotypes across environments. The lines tested in field emergence tests showed no significant difference from the check. Lines with mips1 and rs2W331-, respectively, showed significantly higher germination rates than the check in the accelerated aging test. In contrast, a line with mips1 showed a significantly higher germination rate than the check in the standard germination test. Desirable carbohydrate allele combinations will facilitate the development of new cultivars with modified carbohydrate profiles that are beneficial to human food and animal feed.