Abstract
Stomatal movement originates from changes in the shape of the guard cells and is discussed in combination with vacuole. We observed vacuolar structures in guard cell during stomatal opening and closing using Vicia and transgenic Arabidopsis line expressing GFP-AtVam3p. Detailed observation of confocal images demonstrated numerous intrar-vacuolar membrane structures in the closed stomata while they mostly disappeared in the open-stomata. Introduction of a morphological parameter, vacuolar complexity, could evaluate the stomatal morphological changes numerically. A 3-D reconstruction using our software REANT revealed a unified vacuolar structure even when they seemed to be compartmented at the single confocal image in the closed stomata. Furthermore, calculation of the vacuolar volume and its surface area by REANT showed a parallel increase and decrease of the vacuolar volume during stomatal opening and closing while the surface area was maintained. These results suggest that stomatal vacuoles maintain their membrane as intra-vacuolar structures when closing stomata.
