Journal Article

Abscisic acid induces oscillations in guard-cell cytosolic free calcium that involve phosphoinositide-specific phospholipase C

McAinsh, M.R, Montgomery, L.T, Gray, J.E, Hetherington, A.M, Staxen, I. (Lancaster University, UK.), Pical, C

1999

Overview

Oscillations in cytosolic free Ca2+ concentration ([Ca2+]cyt) are an important component of Ca2+-based signal transduction pathways. This fact has led us to investigate whether oscillations in [Ca2+]cyt are involved in the response of stomatal guard cells to the plant hormone abscisic acid (ABA). We show that ABA induces oscillations in guard-cell [Ca2+]cyt. The pattern of the oscillations depended on the ABA concentration and correlated with the final stomatal aperture. We examined the mechanism by which ABA generates oscillations in guard-cell [Ca2+]cyt by using 1-(6-([17 beta-3-methoxyestra- 1,3,5(10)-trien-17-yl]amino)hexyl)-1H-pyrrole 2,5-dione (U-73122), an inhibitor of phosphoinositide-specific phospholipase C (PI-PLC)-dependent processes in animals. U-73122 inhibited the hydrolysis of phosphatidylinositol 4,5-bisphosphate by a recombinant PI-PLC, isolated from a guard-cell-enriched cDNA library, in a dose-dependent manner. This result confirms that U-73122 is an inhibitor of plant PI-PLC activity. U-73122 inhibited both ABA-induced oscillations in [Ca2+]cyt and stomatal closure. In contrast, U-73122 did not inhibit external Ca2+-induced oscillations in guard-cell [Ca2+]cyt and stomatal closure. Furthermore, there was no effect of the inactive analogue 1-(6-([17 beta- 3-methoxyestra-1,3,5(10)-trien-17-yl] amino)hexyl)-2,5-pyrrolidinedione on recombinant PI-PLC activity or ABA-induced and external Ca2+-induced oscillations in [Ca2+]cyt and stomatal closure. This lack of effect suggests that the effects of U-73122 in guard cells are the result of inhibition of PI-PLC and not a consequence of nonspecific effects. Taken together, our data suggest a role for PI-PLC in the generation of ABA-induced oscillations in [Ca2+]cyt and point toward the involvement of oscillations in [Ca2+]cyt in the maintenance of stomatal aperture by ABA

• Publisher: National Academy of Sciences of the United States of America,National Acad Sciences,National Academy of Sciences,The National Academy of Sciences
• Subject: ABA / abscisic acid / ACTIVIDAD ENZIMATICA / ACTIVITE ENZYMATIQUE / Animal cells / Biological Sciences / Biology / Botany / CALCIO / CALCIUM / CATION / CATIONES / CATIONS / CDNA libraries / CELLS / CELLULE / CELULAS / CITOPLASMA / COMMELINA / COMMELINA COMMUNIS / CYTOPLASM / CYTOPLASME / cytosol / enzyme activity / ENZYME INHIBITORS / ENZYMIC ACTIVITY / Epidermis / ESTERASAS / ESTERASE / ESTERASES / ESTOMA / Flowers & plants / Guard cells / INHIBIDORES DE ENZIMAS / INHIBITEUR D'ENZYME / inorganic ions / MOUVEMENT / MOVEMENT / MOVIMIENTO / Perfusion / phospholipase C / Plant cells / REGULATION / Signal transduction / Signatures / STOMATA / stomatal movement / STOMATE / TEMPORAL VARIATION