1. Plant-generated stress signals. We are looking at the putative role of electrical and hydraulic signals as complements to hormonal signals in the rapid integration of plant activity in response to wounding and other stresses.
Working primarily with sunflower, we have been able to show differences between the genuine electrical signal (action potential, AP) and the hydraulic signal with its local electrical aftermath (variation potential, VP). The AP is evoked most readily by electrical stimulus and is transmitted with almost constant velocity and magnitude and electrical changes precede minor tissue deformations. In contrast, the VP is evoked most readily by flame-wounding and the change in tissue deformation precedes, and appears to elicit, changes in membrane potential which decrease with distance from the region stimulated.
2. Transcriptional and translational responses to stress signals. Working primarily with tomato, we have shown that both the AP and the VP induce the accumulation of proteinase inhibitor I and II (pinl, pin2) mRNA in leaves distant from the region stimulated. Total pin mRNA accumulation is rapid, massive and transient and precedes pin mRNA accumulation into polysomes by a few hours.