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  • The EMBO Journal (2007) 26, 3216 - 3226
  • doi:10.1038/sj.emboj.7601750

Published online: 7 June 2007

Constitutive activation of a plasma membrane H+-ATPase prevents abscisic acid-mediated stomatal closure

Sylvain Merlot1, Nathalie Leonhardt2,a, Francesca Fenzi1,a, Christiane Valon1, Miguel Costa2,b, Laurie Piette2, Alain Vavasseur2, Bernard Genty2, Karine Boivin1, Axel Müller3, Jérôme Giraudat1 and Jeffrey Leung1

  1. Institut des Sciences du Végétal, Centre National de la Recherche Scientifique, UPR 2355, Gif-sur-Yvette, France
  2. CEA Cadarache, DSV, UMR 6191 CEA-CNRS, DEVM, LEMS and LEMP, St Paul les Durance Cedex, France
  3. CarboGen AG, Aarau, Switzerland

Correspondence to:

Jeffrey Leung, CNRS Science de la Vie, Institut des Sciences du Végétal, UPR 2355, 1 Avenue de la Terrasse Bat. 23, Gif-sur-Yvette, 91190, France. Tel.: +33 1 69 82 38 12; Fax: +33 1 69 82 36 95; E-mail: Leung@isv.cnrs-gif.fr

aPresent address: Laboratório de Ecofisiologia Molecular, Instituto de Tecnologia Química e Biológica (ITQB), 2781-901 Oeiras, Portugal

bThese authors contributed equally to this work

Received 15 January 2007; Accepted 16 May 2007

Light activates proton (H+)-ATPases in guard cells, to drive hyperpolarization of the plasma membrane to initiate stomatal opening, allowing diffusion of ambient CO2 to photosynthetic tissues. Light to darkness transition, high CO2 levels and the stress hormone abscisic acid (ABA) promote stomatal closing. The overall H+-ATPase activity is diminished by ABA treatments, but the significance of this phenomenon in relationship to stomatal closure is still debated. We report two dominant mutations in the OPEN STOMATA2 (OST2) locus of Arabidopsis that completely abolish stomatal response to ABA, but importantly, to a much lesser extent the responses to CO2 and darkness. The OST2 gene encodes the major plasma membrane H+-ATPase AHA1, and both mutations cause constitutive activity of this pump, leading to necrotic lesions. H+-ATPases have been traditionally assumed to be general endpoints of all signaling pathways affecting membrane polarization and transport. Our results provide evidence that AHA1 is a distinct component of an ABA-directed signaling pathway, and that dynamic downregulation of this pump during drought is an essential step in membrane depolarization to initiate stomatal closure.

  • Keywords:

    • acidification,
    • AHA1,
    • necrosis,
    • salicylic acid,
    • transpiration