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.
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 [Ca(2+)](cyt) enhanced anion channels and impaired H(+)-ATPases.
Brault
Mathias
M
Laboratoire d'Electrophysiologie des Membranes, EA 3514, Université Paris 7, 75251 Paris 05, France. brault@ccr.jussieu.fr
Amiar
Zahia
Z
Pennarun
Anne-Marie
AM
Monestiez
Michèle
M
Zhang
Zongshen
Z
Cornel
Daniel
D
Dellis
Olivier
O
Knight
Heather
H
Bouteau
François
F
Rona
Jean-Pierre
JP
D000040:Abscisic Acid / Q000494:pharmacology*; D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D006863:Hydrogen-Ion Concentration; D007473:Ion Channels / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects; D010937:Plant Growth Regulators / Q000494:pharmacology; D054328:Proton Pump Inhibitors; D017494:Proton Pumps / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism
D007473:Ion Channels; D010937:Plant Growth Regulators; D054328:Proton Pump Inhibitors; D017494:Proton Pumps; D000040:Abscisic Acid; D006180:Proton-Translocating ATPases; D002118:Calcium