Research is proposed to further understand the structure, function, evolution and the regulation of synthesis of antinutrient proteinase inhibitor proteins that are present in plant tissues as defensive proteins against invading insects and pathogens. The proteins were first identified, isolated, and characterized in the PI's laboratory, and were subsequently found to be synthesized in potato, tomato, and alfalfa leaves in response to insect attacks or to severe mechanical wounding. As part of studies of wound signal transduction systems that regulate the expression of proteinase inhibitor genes in plants, the PI's lab has isolated and characterized several proteinase inhibitor genes from tomato and potato plants. With these genes they have been able to study the structure, organization, and regulation of proteinase inhibitor gene families that are expressed in response to both developmental and environmental signals. They have recently discovered an 18 amino acid polypeptide as a new signaling molecule for the proteinase inhibitors, and have found a volatile signalling molecule for the inhibitors, and have found a volatile signalling molecule for the inhibitors, methyl jasmonate. In the interest of practical applications, several proteinase inhibitor genes have been used by the PI successfully to genetically engineer plants to improve their defense against predators.