Intracellular Ca2+ stores could participate to abscisic acid-induced depolarization and stomatal closure in Arabidopsis thaliana.
In Arabidopsis thaliana cell suspension, abscisic acid (ABA) induces changes in cytosolic calcium concentration ([Ca(2+)](cyt)) which are the trigger for ABA-induced plasma membrane anion current activation, H(+)-ATPase inhibition, and subsequent plasma membrane depolarization. In the present study, we took advantage of this model to analyze the implication of intracellular Ca(2+) stores in ABA signal transduction through electrophysiological current measurements, cytosolic Ca(2+) activity measurements with the apoaequorin Ca(2+) reporter protein and external pH measurement. Intracellular Ca(2+) stores involvement was determined by using specific inhibitors of CICR channels: the cADP-ribose/ryanodine receptor (Br-cADPR and dantrolene) and of the inositol trisphosphate receptor (U73122). In addition experiments were performed on epidermal strips of A. thaliana leaves to monitor stomatal closure in response to ABA in presence of the same pharmacology. Our data provide evidence that ryanodine receptor and inositol trisphosphate receptor could be involved in ABA-induced (1) Ca(2+) release in the cytosol, (2) anion channel activation and H(+)-ATPase inhibition leading to plasma membrane depolarization and (3) stomatal closure. Intracellular Ca(2+) release could thus contribute to the control of early events in the ABA signal transduction pathway in A. thaliana.
LEM (EA 3514), Université Paris Diderot-Paris7, Paris, France.
Patrice
P
Meimoun
Guillaume
G
Vidal
Anne-Sophie
AS
Bohrer
Arnaud
A
Lehner
Daniel
D
Tran
Joël
J
Briand
François
F
Bouteau
Jean-Pierre
JP
Rona
D000040:Abscisic Acid / Q000494:pharmacology*; D000468:Alkalies / Q000378:metabolism; D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D003470:Culture Media; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism*; D015640:Ion Channel Gating / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects*; D054046:Plant Stomata / Q000187:drug effects / Q000502:physiology*; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D013997:Time Factors
D000468:Alkalies; D003470:Culture Media; D053496:Inositol 1,4,5-Trisphosphate Receptors; D019837:Ryanodine Receptor Calcium Release Channel; D000040:Abscisic Acid; D002118:Calcium