Plants respond to physical injury, such as that caused by foraging insects, by synthesizing proteins that function in general defense and tissue repair. In tomato plants, one class of wound-responsive genes encodes proteinase inhibitor (pin) proteins shown to block insect feeding. Application of many different factors will induce or inhibit pin gene expression. Ethylene is required in the transduction pathway leading from injury, and ethylene and jasmonates act together to regulate pin gene expression during the wound response.