ISOLATION OF SIGNALING MUTANTS OF TOMATO (LYCOPERSICON-ESCULENTUM)

As a first step towards developing a genetic system for investigating signaling processes in plants, we have developed a screen for signalin g mutants deficient in a wound response. We have isolated two mutants of tomato that lack detectable production of proteinase inhibitors ind uced systemically in leaves by wounding. The mutants are deficient in the induction of both proteinase Inhibitor I and proteinase Inhibitor II but can be induced to respond at near wild-type levels by methyl ja smonate, a known elicitor of inhibitor production in tomato. While com pletely deficient in systemic production of proteinase inhibitors, bot h mutants produce some proteinase inhibitor in wounded leaves. This ev idence suggests the existence of two signaling pathways, one local and one systemic, that regulate the induction of proteinase inhibitor syn thesis in response to wounding.