ABA activates multiple Ca(2+) fluxes in stomatal guard cells, triggering vacuolar K(+)(Rb(+)) release.

ABSTRACT: The mechanisms by which abscisic acid (ABA) activates the release of K(+)(Rb(+)) from the vacuole of stomatal guard cells, a process essential for ABA-induced stomatal closure, have been investigated by tracer flux measurements. The form and timing of the ABA-induced efflux transient could be manipulated by treatments that alter three potential Ca(2+) fluxes into the cytoplasm, the influx from the outside and two pathways of internal release, those dependent on phospholipase C (inhibited by ) and cyclic ADP-ribose (inhibited by nicotinamide). Ba(2+), acting as a competitive inhibitor of Ca(2+) influx but also as an inhibitor of internal release, was an effective inhibitor of the transient. The results suggest that a threshold level of cytoplasmic Ca(2+) is required for the initiation of th

SUBMITTER: MacRobbie EA 

PROVIDER: S-EPMC17347 | biostudies-literature | 2000 Oct

REPOSITORIES: biostudies-literature