A major role of the MEKK1-MKK1/2-MPK4 pathway in ROS signalling

Andrea Pitzschke, Armin Djamei, Frédérique Bitton, Heribert Hirt*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

234 Scopus citations


Over the last few years, it has become evident that reactive oxygen species (ROS) signalling plays an important role in various physiological responses, including pathogen defense and stomatal opening/closure. On the other hand, ROS overproduction is detrimental for proper plant growth and development, indicating that the regulation of an appropriate redox balance is essential for plants. ROS homeostasis in plants involves the mitogen-activated protein kinase (MAPK) pathway consisting of the MAPK kinase kinase MEKK1 and the MAPK MPK4. Phenotypic and molecular analysis revealed that the MAPK kinases MKK1 and MKK2 are part of a cascade, regulating ROS and salicylic acid (SA) accumulation. Gene expression analysis shows that of 32 transcription factors reported to be highly responsive to multiple ROS-inducing conditions, 20 are regulated by the MEKK1, predominantly via the MEKK1-MKK1/2-MPK4 pathway. However, MEKK1 also functions on other as yet unknown pathways and part of the MEKK1-dependent MPK4 responses are regulated independently of MKK1 and MKK2. Overall, this analysis emphasizes the central role of this MAPK cascade in oxidative stress signalling, but also indicates the high level of complexity revealed by this signalling network.

Original languageEnglish (US)
Pages (from-to)120-137
Number of pages18
JournalMolecular plant
Issue number1
StatePublished - Jan 2009
Externally publishedYes


  • Differential gene expression
  • MEKK1
  • MKK1
  • MKK2
  • MPK4
  • Mitogen-activated protein kinases
  • Reactive oxygen species
  • Redox homeostasis
  • Stress signalling

ASJC Scopus subject areas

  • Molecular Biology
  • Plant Science


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