THE INFLUENCE OF PLANT-AGE ON WOUND INDUCTION OF PROTEINASE-INHIBITORS IN TOMATO

Proteinase inhibitors can be induced by wounding in shoots of tomato ( Lycopersicon esculentum [L.] Mill. cv. Moneymaker). These inhibitors a re toxic to insects, but their ecological importance is not clear. Pub lished 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 p roteinase inhibitor was re-assessed using tomato plants grown in an ou tdoor polythene tunnel, with natural lighting and without supplementar y heat. In contrast to previous findings, proteinase inhibitor was sho wn to be induced by wounding in plants of all ages. However, the syste mic efficacy of wounds was much reduced in mature plants, possibly bec ause such plants have outgrown the range of the wound-signalling syste m.