Determination of Kunitz trypsin inhibitor types in soybean (Glycine max) and wild soybean (Glycine soja)

Abstract

Among the antinutritional factors present in the soybean seed, the main ones ate the protease inhibitors. Soybean seeds contain two major protease inhibitor classes - the Kunitz (KTI) trypsin inhibitor and the Bowman-Birk (BB) trypsin-chymotrypsin inhibitor. Approximately 80% of the trypsin inhibition is caused by KTI. Soybean KTI has several polymorphic types, which are controlled by codominant multiple alleles at a single locus. Of these types, Tia and Tib are predominant types. In total 10 soybean varieties (7 cultivated and 3 wild) was analyzed. In order to determine the type of KITT present, PCR-RFLP using restriction enzyme Mse I (Tru1 I) was performed. Tib type was found in cultivated as well as in wild soybean varieties. Using a pair of primers for KTI3 gene fragment of about 700 bp was amplified in all analyzed varieties, including the Kunitz variety, lacking active trypsin inhibitor. DNA extracted from the Kunitz variety and other varieties mixed equally and used for SNP analysis.