Planta (2007) 225:1421–1429 DOI 10.1007/s00425-006-0450-6
ORIGINAL ARTICLE
Hydrogen peroxide production is an early event during bicarbonate induced stomatal closure in abaxial epidermisof Arabidopsis
V. A. Kolla · A. Vavasseur · A. S. Raghavendra
Received: 16 July 2006 / Accepted: 6 November 2006 / Published online: 8 December 2006© Springer-Verlag 2006
AbstractThe presence of 2mM bicarbonate in theincubation medium induced stomatal closure in abaxialepidermis of Arabidopsis. Exposure to 2mM bicarbon-ate elevated the levels of H2O2 in guard cells within5min, as indicated by the Xuorescent probe, dichloro-Xuorescein diacetate (H2DCF-DA). Bicarbonate-induced stomatal closure as well as H2O2 productionwere restricted by exogenous catalase or diphenyleneiodonium (DPI, an inhibitor of NAD(P)H oxidase).The reduced sensitivity of stomata to bicarbonate andH2O2 production in homozygous atrbohD/F doublemutant of Arabidopsis conWrmed that NADP(H) oxi-dase is involved during bicarbonate induced ROS pro-duction in guard cells. The production of H2O2 wasquicker and greater with ABA than that with bicarbon-ate. Such pattern of H2O2 production may be one ofthe reasons for ABA being more eVective than bicar-bonate, in promoting stomatal closure. Our resultsdemonstrate that H2O2 is an essential secondary mes-senger during bicarbonate induced stomatal closure inArabidopsis.
KeywordsArabidopsis · CO2 eVects · H2O2-reactive oxygen species · Stomatal closure · Signal transduction
AbbreviationsABAAbscisic acidDPIDiphenylene iodonium
H2DCF-DADichloroXuorescein diacetateMJMethyl jasmonatePI3PPhosphatidylinositol 3-phosphateROSReactive oxygen species
Introduction
Stomatal movements are brought out through volumechanges in guard cells in response to various factorssuch as light, temperature, CO2, or phytohormones(Willmer and Fricker 1996). The stomatal opening isstimulated by light while stomata close in response tohormones such as abscisic acid (ABA) or methyl jasm-onate (MJ). Depending on the ambient concentration,CO2 can either stimulate opening or causes closure ofstomata (Assmann 1999). Such paradoxical eVects ofCO2 are still awaiting a rational explanation.
During the past two decades, extensive work hasbeen done to study various aspects of stomatal closureinduced by ABA (Assmann 1993; Giraudat 1995;Schroeder etal. 2001). In contrast to studies withABA, only limited information is available on themechanism of perception and participation of varioussignaling components during stomatal closure inducedby CO2 (Vavasseur and Raghavendra 2005). We haveused external bicarbonate as a source of CO2. Theactual level of CO2 within cells when bicarbonate isadded depends on the pH of the medium (Tsuzuki1983). Bicarbonate is used extensively during the stud-ies on photosynthesis by chloroplasts or protoplasts(Riazunnisa etal. 2006). Bicarbonate was also used
V. A. Kolla · A. S. Raghavendra (&)
Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, Indiae-mail: asrsl@uohyd.ernet.in
A. Vavasseur
CEA/Cadarache-DSV-DEVM,
Laboratoire des Echanges Membranaires et Signalisation, UMR 6191 CNRS-CEA, Universitée de la Meéditerranée, 13108 St Paul lez Durance, Cedex, France
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