The mutual effect of extracellular Ca2+, abscisic acid, and pH on the rate of stomatal closure.
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.
Prokić
Ljiljana
L
Faculty of Agriculture, University of Belgrade, Serbia and Montenegro. ljprokic@agrifaculty.bg.ac.yu
Jovanović
Zorica
Z
Stikić
Radmila
R
Vucinić
Zeljko
Z
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
D002413:Cations, Divalent; D014867:Water; D000040:Abscisic Acid; D002118:Calcium