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  • The EMBO Journal (2003) 22, 2623 - 2633
  • doi:10.1093/emboj/cdg277

NADPH oxidase AtrbohD and AtrbohF genes function in ROS-dependent ABA signaling in Arabidopsis

June M. Kwak1, Izumi C. Mori1, Zhen-Ming Pei2, Nathalie Leonhardt1, Miguel Angel Torres3, Jeffery L. Dangl3, Rachel E. Bloom1, Sara Bodde1, Jonathan D.G. Jones4 and Julian I. Schroeder1

  1. Cell and Developmental Biology Section, Division of Biological Sciences and Center for Molecular Genetics, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0116, USA
  2. Biology Department, Duke University, Durham, NC 27708, USA
  3. Department of Biology, CB 3280, 108 Coker Hall, University of North Carolina, Chapel Hill, NC 27599-3280, USA
  4. The Sainsbury Laboratory, John Innes Centre, Colney, Norwich NR4 7UH, UK

Correspondence to:

June M. Kwak, E-mail: jkwak@biomail.ucsd.edu

Received 17 December 2002; Accepted 15 April 2003; Revised 27 March 2003

Reactive oxygen species (ROS) have been proposed to function as second messengers in abscisic acid (ABA) signaling in guard cells. However, the question whether ROS production is indeed required for ABA signal transduction in vivo has not yet been addressed, and the molecular mechanisms mediating ROS production during ABA signaling remain unknown. Here, we report identification of two partially redundant Arabidopsis guard cell-expressed NADPH oxidase catalytic subunit genes, AtrbohD and AtrbohF, in which gene disruption impairs ABA signaling. atrbohD/F double mutations impair ABA-induced stomatal closing, ABA promotion of ROS production, ABA-induced cytosolic Ca2+ increases and ABA- activation of plasma membrane Ca2+-permeable channels in guard cells. Exogenous H2O2 rescues both Ca2+ channel activation and stomatal closing in atrbohD/F. ABA inhibition of seed germination and root elongation are impaired in atrbohD/F, suggesting more general roles for ROS and NADPH oxidases in ABA signaling. These data provide direct molecular genetic and cell biological evidence that ROS are rate-limiting second messengers in ABA signaling, and that the AtrbohD and AtrbohF NADPH oxidases function in guard cell ABA signal transduction.

  • Keywords:

    • abscisic acid,
    • calcium channels,
    • guard cell,
    • reactive oxygen species,
    • stomata