Allelic diversity and geographical pattern at soybean Kunitz trypsin inhibitor single locus in Chinese wild soybean (Glycine soja Sieb. & Zucc.)

P>Soybean Kunitz trypsin inhibitor (SKTI) is extensively studied for its biological function, anti-nutritional feature, transgenic insect-resistant breeding and as a genetic marker for tracing the origin and dissemination of soybeans. In this study, SKTI was revealed to exist with a high level of polymorphism at its single locus in the genus Glycine subgenus Soja. We investigated 5612 individual plants of Chinese wild soybean for polymorphic variation and geographical distribution of SKTI in China. As a result, five new variants were detected. These variants were Tibi7, Tih, Tii, Tij and Tik. Together with the known variants at this locus, the sum surprisingly has accounted up to at least eight electrophoretically distinguishable variants at this locus in Chinese wild soybean. This strongly suggests that Chinese wild soybean has high level of polymorphism at SKTI locus, and this protein has high mutability in the phylogenetic history of SKTI. The geographical pattern of the polymorphism indicated that the variability of SKTI abounded in Northeast China and Tib allele existed with high frequency in the southeastern littoral of China.