HAR1 mediates systemic regulation of symbiotic organ development

Nature. 2002 Nov 28;420(6914):426-9. doi: 10.1038/nature01231. Epub 2002 Nov 6.


Symbiotic root nodules are beneficial to leguminous host plants; however, excessive nodulation damages the host because it interferes with the distribution of nutrients in the plant. To keep a steady balance, the nodulation programme is regulated systemically in leguminous hosts. Leguminous mutants that have lost this ability display a hypernodulating phenotype. Through the use of reciprocal and self-grafting studies using Lotus japonicus hypernodulating mutants, har1 (also known as sym78), we show that the shoot genotype is responsible for the negative regulation of nodule development. A map-based cloning strategy revealed that HAR1 encodes a protein with a relative molecular mass of 108,000, which contains 21 leucine-rich repeats, a single transmembrane domain and serine/threonine kinase domains. The har1 mutant phenotype was rescued by transfection of the HAR1 gene. In a comparison of Arabidopsis receptor-like kinases, HAR1 showed the highest level of similarity with CLAVATA1 (CLV1). CLV1 negatively regulates formation of the shoot and floral meristems through cell-cell communication involving the CLV3 peptide. Identification of hypernodulation genes thus indicates that genes in leguminous plants bearing a close resemblance to CLV1 regulate nodule development systemically, by means of organ-organ communication.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Chromosome Mapping
  • Cloning, Molecular
  • DNA, Plant / analysis
  • DNA, Plant / genetics
  • Genes, Plant / genetics
  • Genetic Complementation Test
  • Lotus / enzymology*
  • Lotus / genetics
  • Lotus / growth & development*
  • Lotus / metabolism
  • Molecular Sequence Data
  • Mutation / genetics
  • Nitrogen Fixation*
  • Plant Roots / enzymology
  • Plant Roots / genetics
  • Plant Roots / growth & development
  • Plant Roots / metabolism
  • Plant Shoots / enzymology
  • Plant Shoots / genetics
  • Plant Shoots / metabolism
  • Protein-Serine-Threonine Kinases / chemistry
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • RNA, Plant / analysis
  • RNA, Plant / genetics
  • Receptor Protein-Tyrosine Kinases / chemistry
  • Receptor Protein-Tyrosine Kinases / genetics
  • Signal Transduction
  • Soybeans / chemistry
  • Soybeans / genetics
  • Symbiosis*
  • Transplants


  • Arabidopsis Proteins
  • DNA, Plant
  • RNA, Plant
  • Receptor Protein-Tyrosine Kinases
  • CLV1 protein, Arabidopsis
  • Protein-Serine-Threonine Kinases

Associated data

  • GENBANK/AB092808
  • GENBANK/AB092809
  • GENBANK/AB092810
  • GENBANK/AB092811