OsCERK1-Mediated Chitin Perception and Immune Signaling Requires Receptor-like Cytoplasmic Kinase 185 to Activate an MAPK Cascade in Rice

Mol Plant. 2017 Apr 3;10(4):619-633. doi: 10.1016/j.molp.2017.01.006. Epub 2017 Jan 19.


Conserved pathogen-associated molecular patterns (PAMPs), such as chitin, are perceived by pattern recognition receptors (PRRs) located at the host cell surface and trigger rapid activation of mitogen-activated protein kinase (MAPK) cascades, which are required for plant resistance to pathogens. However, the direct links from PAMP perception to MAPK activation in plants remain largely unknown. In this study, we found that the PRR-associated receptor-like cytoplasmic kinase Oryza sativa RLCK185 transmits immune signaling from the PAMP receptor OsCERK1 to an MAPK signaling cascade through interaction with an MAPK kinase kinase, OsMAPKKKε, which is the initial kinase of the MAPK cascade. OsRLCK185 interacts with and phosphorylates the C-terminal regulatory domain of OsMAPKKKε. Coexpression of phosphomimetic OsRLCK185 and OsMAPKKKε activates MAPK3/6 phosphorylation in Nicotiana benthamiana leaves. Moreover, OsMAPKKKε interacts with and phosphorylates OsMKK4, a key MAPK kinase that transduces the chitin signal. Overexpression of OsMAPKKKε increases chitin-induced MAPK3/6 activation, whereas OsMAPKKKε knockdown compromises chitin-induced MAPK3/6 activation and resistance to rice blast fungus. Taken together, our results suggest the existence of a phospho-signaling pathway from cell surface chitin perception to intracellular activation of an MAPK cascade in rice.

Keywords: CERK1; MAPK cascade; MAPKKKε; RLCK185; plant innate immunity; receptor-like cytoplasmic kinase.

MeSH terms

  • Chitin / metabolism*
  • Gene Expression Regulation, Plant / genetics
  • Gene Expression Regulation, Plant / physiology
  • Mitogen-Activated Protein Kinases / genetics
  • Mitogen-Activated Protein Kinases / metabolism*
  • Oryza / enzymology*
  • Oryza / metabolism*
  • Oryza / physiology
  • Pathogen-Associated Molecular Pattern Molecules / metabolism
  • Plant Immunity / genetics
  • Plant Immunity / physiology*
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism*
  • Signal Transduction / genetics
  • Signal Transduction / physiology


  • Pathogen-Associated Molecular Pattern Molecules
  • Plant Proteins
  • Chitin
  • Protein Serine-Threonine Kinases
  • Mitogen-Activated Protein Kinases