title: Intra-vacuolar reserves of membranes during stomatal closure: the possible role of guard cell vacuoles estimated by 3-D reconstruction.
abstract: Stomatal apertures are regulated by morphological changes in guard cells which have been associated with guard cell vacuolar structures. To investigate the contribution of guard cell vacuoles to stomatal movement, we examined the dynamics of vacuolar membrane structures in guard cells and evaluated the changes in vacuolar volumes and surface areas during stomatal movement. Using a transgenic Arabidopsis line expressing green fluorescent protein (GFP)-AtVAM3, we have found that the guard cell vacuolar structures became complicated during stomatal closure with the appearance of numerous intra-vacuolar membrane structures. A three-dimensional (3-D) reconstruction using our originally developed software, REANT (reconstructor and analyzer of 3-D structure), and photobleaching analysis revealed the continuity of the vacuolar structures, even when they appeared to be compartmented in confocal images of closed stomata. Furthermore, calculations of the surface area by REANT revealed an increase in vacuolar surface area during stomatal closure but a decrease in the surface area of the guard cells. Movement of a vital staining dye, FM4-64, to the vacuolar membrane was accelerated during ABA-induced stomatal closure in Vicia faba. These results suggest that the guard cell vacuoles store some portion of the excess membrane materials produced during stomatal closure as intra-vacuolar structures.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Natsumaro
authors.initials: N
authors.lastname: Kutsuna
authors.forename: Yuuko
authors.initials: Y
authors.lastname: Kanazawa
authors.forename: Noriaki
authors.initials: N
authors.lastname: Kondo
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Hasezawa
authors.forename: Toshio
authors.initials: T
authors.lastname: Sano
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D021621:Imaging, Three-Dimensional; D008856:Microscopy, Fluorescence; D019441:Plant Epidermis / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000494:pharmacology; D054046:Plant Stomata / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012984:Software; D013997:Time Factors; D014617:Vacuoles / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D010937:Plant Growth Regulators; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D000040:Abscisic Acid