title: Guard cell-specific inhibition of Arabidopsis MPK3 expression causes abnormal stomatal responses to abscisic acid and hydrogen peroxide.
abstract: MAP kinases have been linked to guard cell signalling. Arabidopsis thaliana MAP Kinase 3 (MPK3) is known to be activated by abscisic acid (ABA) and hydrogen peroxide (H(2)O(2)), which also control stomatal movements. We therefore studied the possible role of MPK3 in guard cell signalling through guard cell-specific antisense inhibition of MPK3 expression. Such transgenic plants contained reduced levels of MPK3 mRNA in the guard cells and displayed partial insensitivity to ABA in inhibition of stomatal opening, but responded normally to this hormone in stomatal closure. However, ABA-induced stomatal closure was reduced compared with controls when cytoplasmic alkalinization was prevented with sodium butyrate. MPK3 antisense plants were less sensitive to exogenous H(2)O(2), both in inhibition of stomatal opening and in promotion of stomatal closure, thus MPK3 is required for the signalling of this compound. ABA-induced H(2)O(2) synthesis was normal in these plants, indicating that MPK3 probably acts in signalling downstream of H(2)O(2). These results provide clear evidence for the important role of MPK3 in the perception of ABA and H(2)O(2) in guard cells.
authors.affiliation: Laboratorio de Fisiología, Biología Molecular y Celular, IFIByNE - CONICET, Facultad de Ciencias Exactas y Naturales - UBA, 1428 Buenos Aires, Argentina.|Instituto Leloir, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina.
authors.forename: Gustavo E
authors.initials: GE
authors.lastname: Gudesblat
authors.affiliation: Laboratorio de Fisiología, Biología Molecular y Celular, IFIByNE - CONICET, Facultad de Ciencias Exactas y Naturales - UBA, 1428 Buenos Aires, Argentina.
authors.forename: Norberto D
authors.initials: ND
authors.lastname: Iusem
authors.affiliation: School of Life Sciences, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, UK.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Morris
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D017360:Arabidopsis / Q000166:cytology / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism; D016373:DNA, Antisense / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism*; D019441:Plant Epidermis / Q000166:cytology* / Q000502:physiology; D018515:Plant Leaves / Q000166:cytology* / Q000502:physiology; D030821:Plants, Genetically Modified; D015398:Signal Transduction; D014170:Transformation, Genetic
chemical_list: D029681:Arabidopsis Proteins; D016373:DNA, Antisense; D000040:Abscisic Acid; D006861:Hydrogen Peroxide; D048052:Mitogen-Activated Protein Kinase 3