Lotus japonicus symRK-14 uncouples the cortical and epidermal symbiotic program

Plant J. 2011 Sep;67(5):929-40. doi: 10.1111/j.1365-313X.2011.04645.x. Epub 2011 Jul 1.


SYMRK is a leucine-rich-repeat (LRR)-receptor kinase that mediates intracellular symbioses of legumes with rhizobia and arbuscular mycorrhizal fungi. It participates in signalling events that lead to epidermal calcium spiking, an early cellular response that is typically considered as central for intracellular accommodation and nodule organogenesis. Here, we describe the Lotus japonicus symRK-14 mutation that alters a conserved GDPC amino-acid sequence in the SYMRK extracellular domain. Normal infection of the epidermis by fungal or bacterial symbionts was aborted in symRK-14. Likewise, epidermal responses of symRK-14 to bacterial signalling, including calcium spiking, NIN gene expression and infection thread formation, were significantly reduced. In contrast, no major negative effects on the formation of nodule primordia and cortical infection were detected. Cumulatively, our data show that the symRK-14 mutation uncouples the epidermal and cortical symbiotic program, while indicating that the SYMRK extracellular domain participates in transduction of non-equivalent signalling events. The GDPC sequence was found to be highly conserved in LRR-receptor kinases in legumes and non-legumes, including the evolutionarily distant bryophytes. Conservation of the GDPC sequence in nearly one-fourth of LRR-receptor-like kinases in the genome of Arabidopsis thaliana suggests, however, that this sequence might also play an important non-symbiotic function in this plant.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Amino Acid Motifs
  • Amino Acid Sequence
  • Calcium / metabolism
  • Calcium Signaling / genetics*
  • Conserved Sequence
  • Gene Expression Regulation, Plant
  • Glomeromycota / physiology
  • Glomeromycota / ultrastructure
  • Lotus / genetics
  • Lotus / microbiology
  • Lotus / physiology*
  • Lotus / ultrastructure
  • Molecular Sequence Data
  • Mutation
  • Mycorrhizae / physiology*
  • Mycorrhizae / ultrastructure
  • Phenotype
  • Plant Epidermis / genetics
  • Plant Epidermis / microbiology
  • Plant Epidermis / physiology
  • Plant Epidermis / ultrastructure
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Plant Root Nodulation / physiology
  • Plant Roots / genetics
  • Plant Roots / microbiology
  • Plant Roots / physiology
  • Plant Roots / ultrastructure
  • Protein Kinases / genetics
  • Protein Kinases / metabolism
  • Rhizobium / physiology*
  • Rhizobium / ultrastructure
  • Seedlings / genetics
  • Seedlings / microbiology
  • Seedlings / physiology
  • Seedlings / ultrastructure
  • Sequence Alignment
  • Symbiosis / genetics*


  • NIN protein, Lotus japonicus
  • Plant Proteins
  • Protein Kinases
  • Calcium