Variation of seed α-amylase inhibitors in the common bean

Variation of seed α-amylase inhibitors was investigated in 1 154 cultivated and 726 non-cultivated (wild and weedy) accessions of the common bean, Phaseolus vulgaris L. Four α-amylase inhibitor types were recognized based on the inhibtion by seed extracts of the activities of porcine pancreatic α-amylase and larval α-amylase and larval α-amylase of the Mexican bean weevil, Zabrotes subfasciatus Boheman. Of the 1 880 accessions examined most (1 734) were able to inhibit porcine pancreatic α-amylase activity, but were inactive against the Z. subfasciatus larval α-amylase; 41 inhibited only the larval α-amylase activity, 52 inhibited the activities of the two α-amylases, and 53 did not inhibit the activity of either of the α-amylases. The four different inhibitor types were designated as αAI-1, αAI2, αAI-3, and αAI-0, respectively. These four inhibitor types were identified by the banding patterns of seed glycoproteins in the range of 14-20 kDa by using SDSpolyacrylamide gel electrophoresis. Additionally, four different banding patterns were recognized in accessions with αAI-1, and were designated as αAI-1a, 1b, 1c, and 1d. Two different patterns of the accessions lacking an α-amylase inhibitory activity were identified and designated as αAI-0a and αAI-0b. The largest diversity for seed α-amylase inhibitors was observed in non-cultivated accessions collected from Mexico where all eight inhibitor types were detected. The possible relationships between the variation of seed α-amylase inhibitors and bruchid resistance are discussed.