Lima bean (Phaseolus lunatus) seed coat phaseolin is detrimental to the cowpea weevil (Callosobruchus maculatus)

The presence of phaseolin (a vicilin-like 7S storage globulin) peptides in the seed coat of the legume Phaseolus lunatus L. (lima bean) was demonstrat ed by N-terminal amino acid sequencing. Utilizing an artificial seed system assay we showed that phaseolin, isolated from both cotyledon and testa tis sues of P. lunatus, is detrimental to the nonhost bruchid Callosobruchus ma culatus (F) (cowpea weevil) with ED50 of 1.7 and 3.5%, respectively. The le vel of phaseolin in the seed coat (16.7%) was found to be sufficient to det er larval development of this bruchid. The expression of a C. maculatus-det rimental protein in the testa of nonhost seeds suggests that the protein ma y have played a significant role in the evolutionary adaptation of bruchids to legume seeds.