Plasma Membrane Depolarization Induced by Abscisic Acid in Arabidopsis Suspension Cells Involves Reduction of Proton Pumping in Addition to Anion Channel Activation, Which Are Both Ca²⁺ Dependent

• Published in: Plant physiology (Bethesda) 2004-05, Vol.135 (1), p.231-243
• Main Authors: Mathias Brault, Zahia Amiar, Anne-Marie Pennarun, Michèle Monestiez, Zongshen Zhang, Daniel Cornel, Dellis, Olivier, Knight, Heather, François Bouteau, Jean-Pierre Rona
• Format: Article
• Language: English
• Subjects: Abscisic Acid - pharmacology; Anions; Arabidopsis - cytology; Arabidopsis - drug effects; Arabidopsis - metabolism; Biological and medical sciences; Calcium; Calcium - metabolism; Calcium Signaling - drug effects; Cell kinetics; Cell Membrane - drug effects; Cell Membrane - metabolism; Cell membranes; Cell physiology; Cells, Cultured; Depolarization; Development and Hormone Action; Electric current; Electric potential; Fundamental and applied biological sciences. Psychology; Guard cells; Hydrogen-Ion Concentration; Ion Channels - metabolism; Membrane Potentials - drug effects; Plant cells; Plant Growth Regulators - pharmacology; Plant physiology and development; Plasma membrane and permeation; Proton Pump Inhibitors; Proton pumps; Proton Pumps - metabolism; Proton-Translocating ATPases - antagonists & inhibitors; Proton-Translocating ATPases - metabolism; Protons
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.104.039255

In Arabidopsis suspension cells a rapid plasma membrane depolarization is triggered by abscisic acid (ABA). Activation of anion channels was shown to be a component leading to this ABA-induced plasma membrane depolarization. Using experiments employing combined voltage clamping, continuous measurement of extracellular pH, we examined whether plasma membrane H+-ATPases could also be involved in the depolarization. We found that ABA causes simultaneously cell depolarization and medium alkalinization, the second effect being abolished when ABA is added in the presence of H+ pump inhibitors. Inhibition of the proton pump by ABA is thus a second component leading to the plasma membrane depolarization. The ABA-induced depolarization is therefore the result of two different processes: activation of anion channels and inhibition of H+-ATPases. These two processes are independent because impairing one did not suppress the depolarization. Both processes are however dependent on the [Ca2+]cyt increase induced by ABA since increase in [Ca2+]cyt enhanced anion channels and impaired H+-ATPases.