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Sci. Signal., 29 November 2011
Vol. 4, Issue 201, p. re4
[DOI: 10.1126/scisignal.2002164]


A Brand New START: Abscisic Acid Perception and Transduction in the Guard Cell

Archana Joshi-Saha1, Christiane Valon1, and Jeffrey Leung1*

1 Institut des Sciences du Végétal, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2355, 1 Avenue de la Terrasse, Bâtiment 23, 91198 Gif-sur-Yvette, France.

Gloss: The combined daily consumption of fresh water ranges from 200 to 700 liters per capita per day in most developed countries, with ~70% used for agricultural needs. With the looming prospect of global water crisis, the success in deciphering the early steps in the signal transduction of the stress hormone abscisic acid (ABA) has ignited hopes that crops can be engineered with the capacity to maintain productivity while requiring less water input. ABA can accumulate 10- to 30-fold in plants under drought stress relative to unstressed conditions. The hormone triggers diverse adaptive pathways, permitting plants to withstand temporary bouts of water shortage. One experimental model to unravel the details of ABA signaling mechanisms is based on the hormone’s ability to elicit stomatal closure—a rapid cellular response used by plants to limit water loss through transpiration. Each stoma, or pore, is contoured by two specialized kidney-shaped cells called guard cells. The stomatal pores are the primary portals for photosynthetic carbon dioxide uptake and, by triggering closure of these pores, drought negatively affects photosynthesis and, consequently, biomass. The stomatal aperture widens and narrows by expansion and contraction, respectively, of these flanking guard cells caused by changes in the intracellular concentrations of ions and organic solutes. These events require coordination of ion channels, which generate a specific pattern of electrical signals that relay the ABA stimulus. A soluble ABA receptor that turns on and off the activities of a kinase and phosphatase pair is at the heart of the signaling complex. Results distilled from the latest structural studies on these ABA receptors, characterized by the so-called START domain, are beginning to tender exciting promise for rational design of agonists and antagonists for modulating stress adaptive ability in plants. With 4 figures, 2 tables, and 127 citations, this Review charts the extraordinary progress on understanding how ABA controls membrane transport mechanisms that evoke the stomatal closing pathway. More background details are available with the teaching tools at

* Corresponding author. E-mail, leung{at}

Citation: A. Joshi-Saha, C. Valon, J. Leung, A Brand New START: Abscisic Acid Perception and Transduction in the Guard Cell. Sci. Signal. 4, re4 (2011).

Intertissue Signal Transfer of Abscisic Acid from Vascular Cells to Guard Cells.
T. Kuromori, E. Sugimoto, and K. Shinozaki (2014)
Plant Physiology 164, 1587-1592
   Abstract »    Full Text »    PDF »
Ethylene-Induced Flavonol Accumulation in Guard Cells Suppresses Reactive Oxygen Species and Moderates Stomatal Aperture.
J. M. Watkins, P. J. Hechler, and G. K. Muday (2014)
Plant Physiology 164, 1707-1717
   Abstract »    Full Text »    PDF »
FRET-based reporters for the direct visualization of abscisic acid concentration changes and distribution in Arabidopsis.
R. Waadt, K. Hitomi, N. Nishimura, C. Hitomi, S. R. Adams, E. D. Getzoff, and J. I. Schroeder (2014)
eLife Sci 3, e01739
   Abstract »    Full Text »    PDF »
Controlling Hormone Action by Subversion and Deception.
J. Leung (2012)
Science 335, 46-47
   Abstract »    Full Text »    PDF »

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