Breeding of Black Soybean Line with ti and le Allele

Soybean is an economically important leguminous seed crop for feed and food products that are rich in seed protein, oil and saccharides. Also, black soybean has been known as medicinal food. However, Kunitz trypsin inhibitor (KTI) and lectin proteins are a main antinutritional factor in mature black soybean seed. The genetic removal of the KTI and lectin proteins will improve the nutritional value of black soybean seed. The objective of this research was to develop a new black soybean lines with double recessive allele for both KTI and lectin protein. A total of 179 F2 seeds were obtained from the cross of ‘Gaechuck#1’ (Le/Le, ti/ti genotype) and ‘LE-16’ (le/le, Ti/Ti genotype) parents. The segregation ratios for the presence or absence of KTI and lectin proteins in the F2 seed generation were well fitted to an expected 3:1 ratio. The segregation ratios of 9:3:3:1 (113 Ti_Le_:28 Ti_lele:30 titiLe_:8 titilele) between Ti gene and Le gene in F2 seed generation were observed (χ2=3.71, P=0.5-0.1). From eight F2 seeds with double recessive allele (ti/ti, le/le genotype), one new strain (titilele, both KTI, and lectin protein free) was developed. New strain has black seed coat, black hilum and green cotyledon in mature seed and 100-seed weight was 19.5 g. This strain will be helpful in breeding program for selecting black soybean line with lacking both KTI and lectin protein.