title: The mutual effect of extracellular Ca2+, abscisic acid, and pH on the rate of stomatal closure.
abstract: An analysis of the rate of stomatal closure in epidermal strips of Commelina communis L. induced by different calcium concentrations (10 nM to 1 mM) demonstrated a biphasic dependency, the initial process of closure being more calcium dependent. This dependency was more evident at pH 7 than pH 5 of the bathing medium. Addition of low concentrations of abscisic acid (10 nM) induced a broadening of the Ca(2) dependency, while 10 microM abscisic acid increased the rate of stomatal closure in the whole Ca(2+) range and to a large extent abolished the calcium-induced effects. Such results indicate an interaction of external protons, Ca(2+), and abscisic acid, and possible competition for the membrane associated binding sites of the mechanism(s) responsible for the regulation of stomatal closure.
authors.affiliation: Faculty of Agriculture, University of Belgrade, Serbia and Montenegro. ljprokic@agrifaculty.bg.ac.yu
authors.forename: Ljiljana
authors.initials: L
authors.lastname: Prokić
authors.forename: Zorica
authors.initials: Z
authors.lastname: Jovanović
authors.forename: Radmila
authors.initials: R
authors.lastname: Stikić
authors.forename: Zeljko
authors.initials: Z
authors.lastname: Vucinić
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology*; D002413:Cations, Divalent; D034822:Commelina / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology; D018526:Plant Transpiration / Q000187:drug effects* / Q000502:physiology; D014867:Water / Q000378:metabolism
chemical_list: D002413:Cations, Divalent; D014867:Water; D000040:Abscisic Acid; D002118:Calcium