Gamma-Irradiation Induced Alterations in Mungbean α-amylase Inhibitory Activities : Effects on α-amylase and Development of Mungbean Weevil (Callosobruchus maculatus)

Abstract

Crude α-amylase inhibitors, the protein and the non-protein parts, were extracted from seeds of standard mungbean varieties KPS1 and CN36 and the mutant lines M5-16 and M5-29, derived from CN36 by gamma-irradiation. Only the protein part was found to produce substantial inhibition when tested against α-amylase from adult mungbean weevil (Callosobruchus maculatus) and barley malt (Type VIIIA) with 4-5 times greater percentage inhibition by the extracts from the mutants than those from the standard varieties. In the in vivo study, feeding larval C. maculatus with seeds of KPS1 and M5-29 treated with 0.5% solution of the proteinaceous inhibitor extracted from M5-16 resulted in a significant reduction in the average number of emerging adults. The effects of the two standard varieties and the two mutant lines seeds, with and without seed coats, on two parameters related to the development of the weevil ie., the average number of eggs laid and the number of emerging adults, were also investigated. No significant differences were found in the average numbers of egg laid on seeds, with and without seed coats, of all varieties/lines. However, significant reduction in the average number of emerging adults were observed in mutant seeds, with or without seed coats, as compared with the standards.