An XA21-associated kinase (OsSERK2) regulates immunity mediated by the XA21 and XA3 immune receptors

Mol Plant. 2014 May;7(5):874-92. doi: 10.1093/mp/ssu003. Epub 2014 Jan 30.


The rice XA21 immune receptor kinase and the structurally related XA3 receptor confer immunity to Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial leaf blight. Here we report the isolation of OsSERK2 (rice somatic embryogenesis receptor kinase 2) and demonstrate that OsSERK2 positively regulates immunity mediated by XA21 and XA3 as well as the rice immune receptor FLS2 (OsFLS2). Rice plants silenced for OsSerk2 display altered morphology and reduced sensitivity to the hormone brassinolide. OsSERK2 interacts with the intracellular domains of each immune receptor in the yeast two-hybrid system in a kinase activity-dependent manner. OsSERK2 undergoes bidirectional transphosphorylation with XA21 in vitro and forms a constitutive complex with XA21 in vivo. These results demonstrate an essential role for OsSERK2 in the function of three rice immune receptors and suggest that direct interaction with the rice immune receptors is critical for their function. Taken together, our findings suggest that the mechanism of OsSERK2-meditated regulation of rice XA21, XA3, and FLS2 differs from that of AtSERK3/BAK1-mediated regulation of Arabidopsis FLS2 and EFR.

Keywords: Xanthomonas oryzae pv. oryzae; immune receptor kinases; immunity; rice.; somatic embryogenesis receptor kinase (SERK).

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brassinosteroids / metabolism
  • Brassinosteroids / pharmacology
  • Flowers / genetics
  • Gene Expression Regulation, Plant / drug effects
  • Gene Silencing
  • Immunity, Innate
  • Mutation
  • Oryza / genetics
  • Oryza / immunology*
  • Oryza / metabolism
  • Oryza / microbiology*
  • Phosphorylation / drug effects
  • Plant Leaves / genetics
  • Plant Proteins / chemistry
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • Protein Multimerization
  • Protein Serine-Threonine Kinases / chemistry
  • Protein Serine-Threonine Kinases / metabolism*
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Receptor Protein-Tyrosine Kinases / metabolism*
  • Signal Transduction / drug effects
  • Steroids, Heterocyclic / pharmacology
  • Xanthomonas / physiology


  • Brassinosteroids
  • Plant Proteins
  • Steroids, Heterocyclic
  • Xa21 protein, Oryza sativa
  • Receptor Protein-Tyrosine Kinases
  • Xa26 protein, Oryza sativa
  • Protein Serine-Threonine Kinases
  • brassinolide