title: NADPH oxidase AtrbohD and AtrbohF genes function in ROS-dependent ABA signaling in Arabidopsis.
abstract: 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 Ca(2+) increases and ABA- activation of plasma membrane Ca(2+)-permeable channels in guard cells. Exogenous H(2)O(2) rescues both Ca(2+) 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.
authors.affiliation: 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. jkwak@biomail.ucsd.edu
authors.forename: June M
authors.initials: JM
authors.lastname: Kwak
authors.forename: Izumi C
authors.initials: IC
authors.lastname: Mori
authors.forename: Zhen-Ming
authors.initials: ZM
authors.lastname: Pei
authors.forename: Nathalie
authors.initials: N
authors.lastname: Leonhardt
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Torres
authors.forename: Jeffery L
authors.initials: JL
authors.lastname: Dangl
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Bloom
authors.forename: Sara
authors.initials: S
authors.lastname: Bodde
authors.forename: Jonathan D G
authors.initials: JD
authors.lastname: Jones
authors.forename: Julian I
authors.initials: JI
authors.lastname: Schroeder
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant; D006861:Hydrogen Peroxide / Q000378:metabolism; D009154:Mutation; D019255:NADPH Oxidases / Q000737:chemistry / Q000378:metabolism*; D021122:Protein Subunits; D017382:Reactive Oxygen Species / Q000378:metabolism; D015290:Second Messenger Systems; D015398:Signal Transduction
chemical_list: D015220:Calcium Channels; D018744:DNA, Plant; D021122:Protein Subunits; D017382:Reactive Oxygen Species; D000040:Abscisic Acid; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases; D002118:Calcium