Insecticidal activity of an alpha-amylase inhibitor-like protein resembling a putative precursor of alpha-amylase inhibitor in the common bean, Phaseolus vulgaris L.

alpha-Amylase inhibitor (alpha AI) in the common bean, Phaseolus vulgar is L., protects seeds from insect pests such as the cowpea weevil (Callosobruc hus maculatus) and the azuki bean weevil (C. chinensis). Cultivars which la ck aAI still show resistance to both bruchids. These cultivars have a glyco protein that reacts with anti-alpha AI-1 antibodies. The glycoprotein with a molecular mass of 29 kDa (Gp29) was purified and the encoding gene was is olated. The primary structure of Gp29 is the same as alpha-amylase inhibito r-like protein (AIL) from which the encoding gene has already been isolated . AIL resembles a putative precursor of alpha AI, even though it does not f orm the active inhibitor. However, AIL has some inhibitory effect on the gr owth of C. maculatus but not C. chinensis. The presence of AIL alone is ins ufficient to explain the bruchid resistance of common bean cultivars lackin g alpha-AI. Common bean seeds appear to contain several factors responsible for the bruchid resistance. (C) 1999 Elsevier Science B.V. All rights rese rved.