Resumo: The fixation and transformation of atmospheric dinitrogen into ammonia and hence into organic e compounds is a crucial part of the nitrogen cycle. Nitrogenase, the enzyme responsible, has a wide taxonomie distribution in the bacteria and archaea, but is confined to a limited number of species. Among these, rhizobia, whieh form nodules on the roots of legumes, are recognised as the main contributors of biologieally-fixed nitrogen. Until recently, it has been generally accepted that legumes are nodulated exelusively by members of the alfa-proteobaeteria belonging to a number of related genera in the family Rhizobiaceae. In this document we review some results from recent studies that presents the newly-discovered beta-rhizobia which challenge the accepted century-old dogma that only Rhizobium and its relatives can nodulate legumes and provide a biodiversity dimension that was totally unexpected 6 years ago.

Ano de publicação: 2006

Tipo de publicação: Folhetos

Unidade: Embrapa Cerrados