Nodulation of legumes by members of the beta-subclass of Proteobacteria

Nature. 2001 Jun 21;411(6840):948-50. doi: 10.1038/35082070.


Members of the Leguminosae form the largest plant family on Earth, with around 18,000 species. The success of legumes can largely be attributed to their ability to form a nitrogen-fixing symbiosis with specific bacteria known as rhizobia, manifested by the development of nodules on the plant roots in which the bacteria fix atmospheric nitrogen, a major contributor to the global nitrogen cycle. Rhizobia described so far belong exclusively to the alpha-subclass of Proteobacteria, where they are distributed in four distinct phylogenetic branches. Although nitrogen-fixing bacteria exist in other proteobacterial subclasses, for example Herbaspirillum and Azoarcus from the phylogenetically distant beta-subclass, none has been found to harbour the nod genes essential for establishing rhizobial symbiosis. Here we report the identification of proteobacteria from the beta-subclass that nodulate legumes. This finding shows that the ability to establish a symbiosis with legumes is more widespread in bacteria than anticipated to date.

MeSH terms

  • Betaproteobacteria / classification
  • Betaproteobacteria / isolation & purification
  • Betaproteobacteria / physiology*
  • Burkholderia / classification
  • Burkholderia / genetics
  • DNA, Bacterial
  • DNA, Ribosomal
  • Fabaceae / microbiology*
  • Genes, Bacterial
  • Molecular Sequence Data
  • Mutagenesis
  • Nitrogen Fixation*
  • Phylogeny
  • Plant Roots / microbiology
  • Plants, Medicinal*
  • RNA, Bacterial / genetics
  • RNA, Ribosomal, 16S / genetics
  • Symbiosis


  • DNA, Bacterial
  • DNA, Ribosomal
  • RNA, Bacterial
  • RNA, Ribosomal, 16S

Associated data

  • GENBANK/AJ302311
  • GENBANK/AJ302312
  • GENBANK/AJ302313
  • GENBANK/AJ302314
  • GENBANK/AJ302315
  • GENBANK/AJ302321
  • GENBANK/AJ306730