A protein kinase target of a PDK1 signalling pathway is involved in root hair growth in Arabidopsis

EMBO J. 2004 Feb 11;23(3):572-81. doi: 10.1038/sj.emboj.7600068. Epub 2004 Jan 29.


Here we report on a lipid-signalling pathway in plants that is downstream of phosphatidic acid and involves the Arabidopsis protein kinase, AGC2-1, regulated by the 3'-phosphoinositide-dependent kinase-1 (AtPDK1). AGC2-1 specifically interacts with AtPDK1 through a conserved C-terminal hydrophobic motif that leads to its phosphorylation and activation, whereas inhibition of AtPDK1 expression by RNA interference abolishes AGC2-1 activity. Phosphatidic acid specifically binds to AtPDK1 and stimulates AGC2-1 in an AtPDK1-dependent manner. AtPDK1 is ubiquitously expressed in all plant tissues, whereas expression of AGC2-1 is abundant in fast-growing organs and dividing cells, and activated during re-entry of cells into the cell cycle after sugar starvation-induced G1-phase arrest. Plant hormones, auxin and cytokinin, synergistically activate the AtPDK1-regulated AGC2-1 kinase, indicative of a role in growth and cell division. Cellular localisation of GFP-AGC2-1 fusion protein is highly dynamic in root hairs and at some stages confined to root hair tips and to nuclei. The agc2-1 knockout mutation results in a reduction of root hair length, suggesting a role for AGC2-1 in root hair growth and development.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3-Phosphoinositide-Dependent Protein Kinases
  • Arabidopsis / cytology
  • Arabidopsis / genetics
  • Arabidopsis / growth & development*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Cell Nucleus / metabolism
  • Cytokines / metabolism
  • Enzyme Activation / genetics
  • Enzyme Activation / physiology
  • G1 Phase / physiology
  • Gene Expression Regulation, Plant
  • Indoleacetic Acids / metabolism
  • Phosphorylation
  • Plant Roots / cytology
  • Plant Roots / genetics
  • Plant Roots / growth & development*
  • Plants, Genetically Modified
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Protein-Serine-Threonine Kinases / metabolism*
  • RNA Interference
  • Signal Transduction / genetics
  • Signal Transduction / physiology*


  • Arabidopsis Proteins
  • Cytokines
  • Indoleacetic Acids
  • Protein Kinases
  • 3-Phosphoinositide-Dependent Protein Kinases
  • AGC2-1 protein, Arabidopsis
  • Protein-Serine-Threonine Kinases