AN HYDRAULIC INTERPRETATION OF RAPID, LONG-DISTANCE WOUND SIGNALING IN THE TOMATO

Localised wounding causes rapid and systemic induction of proteinase i nhibitors in tomato (Lycopersicon esculentum L.). The signalling syste m which coordinates this response is not known. Recent work has shown that systemic hydraulic signals are transmitted from wound sites in to mato, but that these cannot by themselves induce proteinase inhibitors . Here, it is demonstrated that the hydraulic signal is nevertheless a n essential requirement for the systemic induction of proteinase inhib itors by localised treatments. It is also shown that mass flows simila r to those associated with the wound-induced hydraulic signal, can con vey a variety of solutes rapidly throughout the shoot. It is concluded that long-distance wound signalling in the tomato occurs by xylem tra nsmission of soluble elicitors in the mass flows induced by wounding.