BEAN ALPHA-AMYLASE INHIBITOR CONFERS RESISTANCE TO THE PEA WEEVIL (BRUCHUS-PISORUM) IN TRANSGENIC PEAS (PISUM-SATIVUM L)

Bruchid larvae cause major losses of grain legume crops throughout the world. Some bruchid species, such as the cowpea weevil and the azuki bean weevil, are pests that damage stored seeds. Others, such as the pea weevil (Brochus pisorum), attack the crop growing in the field. We transferred the cDNA encoding the alpha-amylase inhibitor (alpha-AI) found in the seeds of the common bean (Phaseolus vulgaris) into pea (Pisum sativum) using Agrobacterium-mediated transformation. Expression was driven by the promoter of phytohemagglutinin, another bean seed protein. The alpha-amylase inhibitor gene was stably expressed in the transgenic pea seeds at least to the T-5 seed generation, and alpha-AI accumulated in the seeds up to 3% of soluble protein. This level is somewhat higher than that normally found in beans, which contain 1 to 2% alpha-AI. In the T-5 seed generation the development of pea weevil larvae was blocked at an early stage. Seed damage was minimal and seed yield was not significantly reduced in the transgenic plants. These results confirm the feasibility of protecting other grain legumes such as lentils, mungbean, groundnuts, and chickpeas against a variety of bruchids using the same approach. Although alpha-AI also inhibits human alpha-amylase, cooked peas should not have a negative impact on human energy metabolism.