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Letters to Nature

Nature 387, 394-401 (22 May 1997) | doi:10.1038/387394a0; Accepted 14 April 1997

Molecular basis of symbiosis between Rhizobium and legumes

Christoph Freiberg, Rémy Fellay*, Amos Bairoch†, William J. Broughton*, André Rosenthal & Xavier Perret*

  1. Insitut für Molekulare Biotechnologie, Abteilung Genomanalyse, Beutenbergstrasse 11, 07745 Jena, Germany
  2. * Laboratoire de Biologie Moléculaire des Plantes Supérieures, Université de Genève, 1 ch. de l'Impératrice, 1292 Chambésy/Genève, Switzerland
  3. † Biochimie Médicale, Centre Médical Universitaire, Université de Genève, 1 rue Michel-Servet, 1211 Genève 4, Switzerland
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Access to mineral nitrogen often limits plant growth, and so symbiotic relationships have evolved between plants and a variety of nitrogen-fixing organisms. These associations are responsible for reducing 120 million tonnes of atmospheric nitrogen to ammonia each year. In agriculture, independence from nitrogenous fertilizers expands crop production and minimizes pollution ot water tables, lakes and rivers. Here we present the complete nucleotide sequence and gene complement of the plasmid from Rhizobium sp. NGR234 that endows the bacterium with the ability to associate symbolically with leguminous plants. In conjunction with transcriptional analyses, these data demonstrate the presence of new symbiotic loci and signalling mechanisms. The sequence and organization of genes involved in replication and conjugal transfer are similar to those of Agrobacterium, suggesting a recent lateral transfer of genetic information.