Intracellular Ca²⁺stores could participate to abscisic acid-induced depolarization and stomatal closure inArabidopsis thaliana

Abstract

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.

Deciphering early events involved in hyperosmotic stress-induced programmed cell death in tobacco BY-2 cells

“…In BY-2 cells, these [Ca 2+ ] cyt increases were inhibited by the calcium channel blockers La 3+ and Gd 3+ but not by dantrolene and U73122, inhibitors of calcium-induced calcium release channels and of the inositol triphosphate receptor, respectively, known to be efficient in plants (Meimoun et al , 2009). This suggests that the [Ca 2+ ] cyt increase was not due to Ca 2+ release from intracellular Ca 2+ stores, but to an influx through plasma membrane-permeable Ca 2+ channels.…”

Molecular Mechanisms of Abscisic Acid Action in Plants and Its Potential Applications to Human Health

“…These rapid responses are most likely conserved, at least at the qualitative level, as they have also been observed in cell cultures (Meimoun et al, 2010).…”

Deciphering the dual effect of lipopolysaccharides from plant pathogenicPectobacterium

“…51 The experiments were run simultaneously in 7 £ 5 mL flasks (control and tests) each containing 2 mL of suspension cells under continuous shaking. Simultaneous changes in pH were measured by using ELIT 808 ionometer with pH sensitive combined electrodes functioning in parallel.…”