The major goal of this research is to investigate the role of stimulus-induced intracellular potential changes in the coordination of plant responses to gravity. The principal investigator has shown that gravistimulation induces rapid membrane hyperpolarization along the upper side and depolarization along the lower side of the elongation zone of bean roots. This indicates ether that cells in this region detect gravity directly or that there is very rapid signal transmission from the putative gravity-detecting region at the root tip. These alternatives will be tested by investigating electrical changes in 1) other species, 2) roots from which the caps have been removed, and 3) roots of mutants with impaired communication between the cap and the elongation zone. These experiments will be coupled with computer- based analysis of growth rate distribution and curvature development during the response in order to establish a link between electrical perturbations, signal transmission and growth modifications. These studies would improve our understanding of the interaction of plants with their environments, and may enhance jour ability of modify or control plant growth. //
