Protein phosphorylation is a prerequisite for intracellular Ca2+ release and ion channel control by nitric oxide and abscisic acid in guard cells

Authors

  • Sergei Sokolovski,

    1. Laboratory of Plant Physiology and Biophysics, Bower Building, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK, and
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    • These authors contributed equally to this work.

  • Adrian Hills,

    1. Laboratory of Plant Physiology and Biophysics, Bower Building, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK, and
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    • These authors contributed equally to this work.

  • Rob Gay,

    1. Laboratory of Plant Physiology and Biophysics, Bower Building, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK, and
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    • These authors contributed equally to this work.

  • Carlos Garcia-Mata,

    1. Inst. de Investigaciones Biologicas, Universidad Nacional de Mar del Plata, 7600 Mar del Plata Buenos Aires, Argentina
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  • Lorenzo Lamattina,

    1. Inst. de Investigaciones Biologicas, Universidad Nacional de Mar del Plata, 7600 Mar del Plata Buenos Aires, Argentina
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  • Michael R. Blatt

    Corresponding author
    1. Laboratory of Plant Physiology and Biophysics, Bower Building, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK, and
      (fax +44 0 141 330 4447; e-mail m.blatt@bio.gla.ac.uk).
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(fax +44 0 141 330 4447; e-mail m.blatt@bio.gla.ac.uk).

Summary

Recent work has indicated that nitric oxide (NO) and its synthesis are important elements of signal cascades in plant–pathogen defence, and are a prerequisite for drought and abscisic acid (ABA) responses in Arabidopsis thaliana and Vicia faba guard cells. NO regulates inward-rectifying K+ channels and Cl channels of Vicia guard cells via intracellular Ca2+ release. However, its integration with related signals, including the actions of serine–threonine protein kinases, is less well defined. We report here that the elevation of cytosolic-free [Ca2+] ([Ca2+]i) mediated by NO in guard cells is reversibly inhibited by the broad-range protein kinase antagonists staurosporine and K252A, but not by the tyrosine kinase antagonist genistein. The effects of kinase antagonism translate directly to a loss of NO-sensitivity of the inward-rectifying K+ channels and background (Cl channel) current, and to a parallel loss in sensitivity of the K+ channels to ABA. These results demonstrate that NO-dependent signals can be modulated through protein phosphorylation upstream of intracellular Ca2+ release, and they implicate a target for protein kinase control in ABA signalling that feeds into NO-dependent Ca2+ release.

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