Natural variation in tocopherols, B vitamins, and isoflavones in seeds of 13 Korean conventional soybean varieties

Abstract Soybean seeds are excellent sources of tocopherols, B vitamins, and isoflavones, which are well known for their health benefits. This study investigated the influence of environment and genotype on these constituents across 13 Korean soybean varieties cultivated in three locations during the 2017–2019 growing seasons. Statistical analyses, employing both univariate and multivariate methods, revealed significant impacts of genetic and environmental factors on the composition of tocopherols, B vitamins, and isoflavones. Through permutational univariate analysis of variance, the primary contributors to each measured component were identified. Genotype strongly influenced the levels of β- and δ-tocopherols, whereas the interaction between location and year predominantly affected α- and γ-tocopherols. Vitamin B1 content was predominantly determined by genotype, whereas B3 and B6 were influenced by annual variations. Vitamin B2 level was primarily affected by the interplay between environmental and genotypic effects. Genotype had a significant effect on isoflavone components, with the exception of daidzein. Furthermore, early maturing varieties and those with black seed coats exhibited low levels of isoflavone components and total isoflavones, suggesting a relationship between maturity group and seed coat color in isoflavone variation. These findings can be used as reference values for compositional equivalence assessment of genetically modified soybeans.