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Constitutive activation of a plasma membrane H + ‐ATPase prevents abscisic acid‐mediated stomatal closure
Author(s) -
Merlot Sylvain,
Leonhardt Nathalie,
Fenzi Francesca,
Valon Christiane,
Costa Miguel,
Piette Laurie,
Vavasseur Alain,
Genty Bernard,
Boivin Karine,
Müller Axel,
Giraudat Jérôme,
Leung Jeffrey
Publication year - 2007
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601750
Subject(s) - abscisic acid , guard cell , biology , atpase , microbiology and biotechnology , hyperpolarization (physics) , fusicoccin , biochemistry , biophysics , enzyme , gene , chemistry , organic chemistry , nuclear magnetic resonance spectroscopy
Light activates proton (H + )‐ATPases in guard cells, to drive hyperpolarization of the plasma membrane to initiate stomatal opening, allowing diffusion of ambient CO 2 to photosynthetic tissues. Light to darkness transition, high CO 2 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 CO 2 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.