These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: PYR/PYL/RCAR abscisic acid receptors regulate K+ and Cl- channels through reactive oxygen species-mediated activation of Ca2+ channels at the plasma membrane of intact Arabidopsis guard cells.
    Author: Wang Y, Chen ZH, Zhang B, Hills A, Blatt MR.
    Journal: Plant Physiol; 2013 Oct; 163(2):566-77. PubMed ID: 23899646.
    Abstract:
    The discovery of the START family of abscisic acid (ABA) receptors places these proteins at the front of a protein kinase/phosphatase signal cascade that promotes stomatal closure. The connection of these receptors to Ca(2+) signals evoked by ABA has proven more difficult to resolve, although it has been implicated by studies of the pyrbactin-insensitive pyr1/pyl1/pyl2/pyl4 quadruple mutant. One difficulty is that flux through plasma membrane Ca(2+) channels and Ca(2+) release from endomembrane stores coordinately elevate cytosolic free Ca(2+) concentration ([Ca(2+)]i) in guard cells, and both processes are facilitated by ABA. Here, we describe a method for recording Ca(2+) channels at the plasma membrane of intact guard cells of Arabidopsis (Arabidopsis thaliana). We have used this method to resolve the loss of ABA-evoked Ca(2+) channel activity at the plasma membrane in the pyr1/pyl1/pyl2/pyl4 mutant and show the consequent suppression of [Ca(2+)]i increases in vivo. The basal activity of Ca(2+) channels was not affected in the mutant; raising the concentration of Ca(2+) outside was sufficient to promote Ca(2+) entry, to inactivate current carried by inward-rectifying K(+) channels and to activate current carried by the anion channels, both of which are sensitive to [Ca(2+)]i elevations. However, the ABA-dependent increase in reactive oxygen species (ROS) was impaired. Adding the ROS hydrogen peroxide was sufficient to activate the Ca(2+) channels and trigger stomatal closure in the mutant. These results offer direct evidence of PYR/PYL/RCAR receptor coupling to the activation by ABA of plasma membrane Ca(2+) channels through ROS, thus affecting [Ca(2+)]i and its regulation of stomatal closure.
    [Abstract] [Full Text] [Related] [New Search]