The influence of plant age on wound induction of proteinase inhibitors in tomato

Abstract

Proteinase inhibitors can be induced by wounding in shoots of tomato (Lycopersicon esculentum [L.] Mill. cv. Moneymaker). These inhibitors are toxic to insects, but their ecological importance is not clear. Published work suggests that proteinase inhibitors may be wound‐inducible in tomato only while the plants are young (less than 30 days). In the present investigation the influence of plant age on wound‐inducible proteinase inhibitor was re‐assessed using tomato plants grown in an outdoor polythene tunnel, with natural lighting and without supplementary heat. In contrast to previous findings, proteinase inhibitor was shown to be induced by wounding in plants of all ages. However, the systemic efficacy of wounds was much reduced in mature plants, possibly because such plants have outgrown the range of the wound‐signalling system.