Stomatal closure by fast abscisic acid signaling is mediated by the guard cell anion channel SLAH3 and the receptor RCAR1

S-type anion channels are direct targets of abscisic acid (ABA) signaling and contribute to chloride and nitrate release from guard cells, which in turn initiates stomatal closure. SLAC1 was the first component of the guard cell S-type anion channel identified. However, we found that guard cells of...

Full description

Saved in:
Bibliographic Details
Published in:Science signaling 2011-05, Vol.4 (173), p.ra32-ra32
Main Authors: Geiger, Dietmar, Maierhofer, Tobias, Al-Rasheid, Khaled A S, Scherzer, Sönke, Mumm, Patrick, Liese, Anja, Ache, Peter, Wellmann, Christian, Marten, Irene, Grill, Erwin, Romeis, Tina, Hedrich, Rainer
Format: Article
Language:English
Subjects:
Abscisic Acid - metabolism
Animals
Anions
Arabidopsis - cytology
Arabidopsis - metabolism
Arabidopsis Proteins - physiology
Carrier Proteins - physiology
Fluorescence
Ion Channels - physiology
Nitrates - metabolism
Phosphorylation
Plant Stomata - physiology
Signal Transduction
Xenopus laevis
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:S-type anion channels are direct targets of abscisic acid (ABA) signaling and contribute to chloride and nitrate release from guard cells, which in turn initiates stomatal closure. SLAC1 was the first component of the guard cell S-type anion channel identified. However, we found that guard cells of Arabidopsis SLAC1 mutants exhibited nitrate conductance. SLAH3 (SLAC1 homolog 3) was also present in guard cells, and coexpression of SLAH3 with the calcium ion (Ca2+)-dependent kinase CPK21 in Xenopus oocytes mediated nitrate-induced anion currents. Nitrate, calcium, and phosphorylation regulated SLAH3 activity. CPK21-dependent SLAH3 phosphorylation and activation were blocked by ABI1, a PP2C-type protein phosphatase that is inhibited by ABA and inhibits the ABA signaling pathway in guard cells. We reconstituted the ABA-stimulated phosphorylation of the SLAH3 amino-terminal domain by CPK21 in vitro by including the ABA receptor-phosphatase complex RCAR1-ABI1 in the reactions. We propose that ABA perception by the complex consisting of ABA receptors of the RCAR/PYR/PYL family and ABI1 releases CPK21 from inhibition by ABI1, and then CPK21 is further activated by an increase in the cytosolic Ca2+ concentration, leading to its phosphorylation of SLAH3. Thus, the identification of SLAH3 as the nitrate-, calcium-, and ABA-sensitive guard cell anion channel provides insights into the relationship among stomatal response to drought, signaling by nitrate, and nitrate metabolism.
ISSN:1945-0877
1937-9145
DOI:10.1126/scisignal.2001346