MAPK target networks in Arabidopsis thaliana revealed using functional protein microarrays

Genes Dev. 2009 Jan 1;23(1):80-92. doi: 10.1101/gad.1740009. Epub 2008 Dec 18.


Signaling through mitogen-activated protein kinases (MPKs) cascades is a complex and fundamental process in eukaryotes, requiring MPK-activating kinases (MKKs) and MKK-activating kinases (MKKKs). However, to date only a limited number of MKK-MPK interactions and MPK phosphorylation substrates have been revealed. We determined which Arabidopsis thaliana MKKs preferentially activate 10 different MPKs in vivo and used the activated MPKs to probe high-density protein microarrays to determine their phosphorylation targets. Our analyses revealed known and novel signaling modules encompassing 570 MPK phosphorylation substrates; these substrates were enriched in transcription factors involved in the regulation of development, defense, and stress responses. Selected MPK substrates were validated by in planta reconstitution experiments. A subset of activated and wild-type MKKs induced cell death, indicating a possible role for these MKKs in the regulation of cell death. Interestingly, MKK7- and MKK9-induced death requires Sgt1, a known regulator of cell death induced during plant innate immunity. Our predicted MKK-MPK phosphorylation network constitutes a valuable resource to understand the function and specificity of MPK signaling systems.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Arabidopsis / enzymology*
  • Arabidopsis / growth & development
  • Arabidopsis / physiology
  • Arabidopsis Proteins / metabolism
  • Cell Death / physiology
  • Gene Expression
  • Gene Expression Regulation, Plant
  • Gene Regulatory Networks / genetics
  • Gene Regulatory Networks / physiology*
  • Glucosyltransferases
  • MAP Kinase Kinase 7 / metabolism
  • Mitogen-Activated Protein Kinase Kinases
  • Mitogen-Activated Protein Kinases / metabolism*
  • Phosphorylation
  • Protein Array Analysis
  • Recombinant Fusion Proteins / metabolism
  • Tobacco / enzymology
  • Transcription Factors / metabolism


  • Arabidopsis Proteins
  • Recombinant Fusion Proteins
  • Transcription Factors
  • Glucosyltransferases
  • SGT1 protein, Arabidopsis
  • Mitogen-Activated Protein Kinases
  • BUD1 protein, Arabidopsis
  • MAP Kinase Kinase 7
  • MKK9 protein, Arabidopsis
  • Mitogen-Activated Protein Kinase Kinases