Selection of null genotype without four proteins (KTI, lectin, P34, and 7S α′ subunit) in black soybeans with green cotyledons

Abstract

Black-soybean seeds with green cotyledons are widely used owing to their high levels of bioactive compounds such as anthocyanin and lutein. However, they also contain antinutritional components (e.g., the KTI, lectin, P34, and 7S-α′-subunit proteins) that reduce the nutritional and functional value of the seeds. This study aimed to select a new, improved soybean line with black seed coats and green cotyledons and without the KTI, lectin, P34, and 7S-α′ -subunit proteins (i.e., with the titilelep34p34cgy1cgy1 genotype). Using four germplasms, a breeding population and 151 F2 seeds with black seed coats and green cotyledons were obtained. Nine F2 seeds with the recessive titip34p34cgy1cgy1 genotype were selected and planted in a field to grow F2 plants. Two F2 plants with the lele genotype were identified, after which one plant with elite agronomic traits was selected. The titilelep34p34cgy1cgy1genotype was confirmed in random F3 seeds harvested from the selected F2 plant. The seeds sown in the field displayed a short stem length and a neutral 100-seed weight of 48 cm and 26.5 g, respectively. Meanwhile, the color of their seed coats was black, and that of the cotyledons was green. This newly selected line can be used as a parent line to breed cultivars of varied colors, with green cotyledons, and without the KTI, lectin, P34, and 7S-α′-subunit antinutrient proteins. © 2025 Korean Society for Plant Biotechnology.