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

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