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

Plant J. 2005 Aug;43(4):520-9. doi: 10.1111/j.1365-313X.2005.02471.x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abscisic Acid / physiology*
  • Calcium / physiology*
  • Calcium Signaling / physiology
  • Carbazoles / pharmacology
  • Cell Membrane / physiology
  • Genistein / pharmacology
  • Indole Alkaloids
  • Ion Channels / physiology*
  • Membrane Potentials
  • Nitric Oxide / physiology*
  • Phosphorylation
  • Plant Proteins / metabolism*
  • Protein Kinase Inhibitors / pharmacology
  • Protein Kinases / metabolism
  • Protein Processing, Post-Translational
  • Staurosporine / pharmacology
  • Vicia faba / cytology
  • Vicia faba / physiology*


  • Carbazoles
  • Indole Alkaloids
  • Ion Channels
  • Plant Proteins
  • Protein Kinase Inhibitors
  • Nitric Oxide
  • Abscisic Acid
  • staurosporine aglycone
  • Genistein
  • Protein Kinases
  • Staurosporine
  • Calcium