9310508 Davies Plants are confronted with potentially harmful environmental factors such as insect attack, drought, heat, cold and UV irradiation. They have evolved strategies of accommodation, whereby they can perceive and respond to such stimuli without them resulting in death. These strategies require integrated mechanisms where stressful conditions experienced by one part of the plant elicit responses in distant parts. Some of these responses need to be extremely rapid, and thus conventional explanations involving manufacture and transport of diffusible chemicals (hormones) may not be sufficient. This proposal fcuses on two types of rapidly-generated and transmitted signals which we have described recently in both sunflower and tomato: action potentials (APs), which result from the activity of voltage-sensitive (voltage-gated) ion channels; and variation potentials (VPs), which are based on pressure-sensitive (stretch-activated) ion channels and result from rapid changes in the hydraulic condition of cells and tissues in proximity to the xylem. In the research proposed here, we will perform treatments to selectively evoke or repress either or both of these electrical signals in order to determine their role in modulating the expression (up-regulation and down-regulation) of various genes. ***
