title: Calcium channels activated by hydrogen peroxide mediate abscisic acid signalling in guard cells.
abstract: Drought is a major threat to agricultural production. Plants synthesize the hormone abscisic acid (ABA) in response to drought, triggering a signalling cascade in guard cells that results in stomatal closure, thus reducing water loss. ABA triggers an increase in cytosolic calcium in guard cells ([Ca2+]cyt) that has been proposed to include Ca2+ influx across the plasma membrane. However, direct recordings of Ca2+ currents have been limited and the upstream activation mechanisms of plasma membrane Ca2+ channels remain unknown. Here we report activation of Ca2+-permeable channels in the plasma membrane of Arabidopsis guard cells by hydrogen peroxide. The H2O2-activated Ca2+ channels mediate both influx of Ca2+ in protoplasts and increases in [Ca2+]cyt in intact guard cells. ABA induces the production of H2O2 in guard cells. If H2O2 production is blocked, ABA-induced closure of stomata is inhibited. Moreover, activation of Ca2+ channels by H2O2 and ABA- and H2O2-induced stomatal closing are disrupted in the recessive ABA-insensitive mutant gca2. These data indicate that ABA-induced H2O2 production and the H2O2-activated Ca2+ channels are important mechanisms for ABA-induced stomatal closing.
authors.affiliation: Division of Biology, Cell and Developmental Biology, and Center for Molecular Genetics, University of California at San Diego, La Jolla 92093-0116, USA.
authors.forename: Z M
authors.initials: ZM
authors.lastname: Pei
authors.forename: Y
authors.initials: Y
authors.lastname: Murata
authors.forename: G
authors.initials: G
authors.lastname: Benning
authors.forename: S
authors.initials: S
authors.lastname: Thomine
authors.forename: B
authors.initials: B
authors.lastname: Klüsener
authors.forename: G J
authors.initials: GJ
authors.lastname: Allen
authors.forename: E
authors.initials: E
authors.lastname: Grill
authors.forename: J I
authors.initials: JI
authors.lastname: Schroeder
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D015640:Ion Channel Gating; D009154:Mutation; D018408:Patch-Clamp Techniques; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D015220:Calcium Channels; D017382:Reactive Oxygen Species; D000040:Abscisic Acid; D006861:Hydrogen Peroxide