ABA-activated SnRK2 protein kinase is required for dehydration stress signaling in Arabidopsis

Plant Cell Physiol. 2002 Dec;43(12):1473-83. doi: 10.1093/pcp/pcf188.


Protein phosphorylation has pivotal roles in ABA and osmotic stress signaling in higher plants. Two protein phosphatase genes, ABI1 and ABI2, are known to regulate these signaling pathways in Arabidopsis: The identity of ABA-activated protein kinases required for the ABA signaling, however, remains to be elucidated. Here we demonstrate that two protein kinases, p44 and p42, were activated by ABA in Arabidopsis T87 cultured cells, and at least one protein kinase, p44, was activated not only by ABA but also by low humidity in Arabidopsis plants. Analysis of T-DNA knockout mutants and biochemical analysis using a specific antibody revealed that the p44 is encoded by a SnRK2-type protein kinase gene, SRK2E. The srk2e mutation resulted in a wilty phenotype mainly due to loss of stomatal closure in response to a rapid humidity decrease. ABA-inducible gene expression of rd22 and rd29B was suppressed in srk2e. These results show that SRK2E plays an important role in ABA signaling in response to water stress.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abscisic Acid / pharmacology*
  • Arabidopsis / enzymology*
  • Arabidopsis / physiology
  • Arabidopsis Proteins*
  • Cell Line
  • Cells, Cultured
  • Enzyme Activation / drug effects
  • Gene Expression Regulation, Plant / drug effects
  • Mitogen-Activated Protein Kinase 1 / drug effects
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases / drug effects
  • Mitogen-Activated Protein Kinases / metabolism
  • Mutation
  • Osmotic Pressure / drug effects
  • Phenotype
  • Phosphoprotein Phosphatases / genetics
  • Phosphoprotein Phosphatases / metabolism
  • Plant Epidermis / cytology
  • Plant Epidermis / drug effects
  • Plant Epidermis / physiology
  • Plant Growth Regulators / pharmacology*
  • Protein Serine-Threonine Kinases / drug effects
  • Protein Serine-Threonine Kinases / metabolism*
  • Signal Transduction / drug effects*
  • Signal Transduction / physiology
  • Water / pharmacology


  • Arabidopsis Proteins
  • Plant Growth Regulators
  • Water
  • Abscisic Acid
  • AtSR1 protein, Arabidopsis
  • Protein Serine-Threonine Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases
  • ABI1 protein, Arabidopsis
  • ABI2 protein, Arabidopsis
  • Phosphoprotein Phosphatases