Rhizobia: the family is expanding.

Abstract

Until recently, nitrogen fixing rhizobia that form symbiotic relationships were exclusively classified in the α-subclass of Proteobacteria. The identification of rhizobia within Proteobacteria from the β-subclass, including Burkholderia and Ralstonia, shows that the ability to establish a symbiosis with legumes is more widespread.

Isolation, Characterization and Symbiotic Efficiency of Nitrogen-Fixing and Heavy Metal-Tolerant Bacteria from a Coalmine Wasteland

“…This bacterium, when re-inoculated, could induce nodule formation with a relative efficiency of 50 % ( Table 5). The nodulation ability of V. sativa may be due to a lateral gene transfer from the symbiotic genus Rhizobium into Burkholderia, since symbiotic genes are not very different between α and β-rhizobia (Moulin et al, 2002;Chen et al, 2003).…”

Microbiological process in agroforestry systems. A review

“…Over the last few years, however, several other species of α-proteobacteria have been shown to nodulate legumes (Moulin et al 2002). These include strains of Methylobacterium that nodulate Crotalaria and Lotononis (Jaftha et al 2002;Sy et al 2001a and b); Blastobacter denitrificans, which nodulates Aeschynomene indica (van Berkum and Eardly 2002); and Devosia strains that nodulate Neptunia natans (Rivas et al 2002).…”

Molecular Signals and Receptors: Communication Between Nitrogen-Fixing Bacteria and Their Plant Hosts

“…that nodulate legumes via the root hair nodulation pathway have nod genes similar to those found in the Alphaproteobacteria for nodulating legumes (Moulin et al 2001(Moulin et al , 2002. However, so far, only one Nod factor structure has been determined, which was isolated from a strain originally identified as Bradyrhizobium aspalati (Boone et al 1999).…”

“…Besides the well-known Rhizobiaceae (Alphaproteobacteria), several bacteria that are Betaproteobacteria have been identified as capable of establishing nitrogen-fixing nodules on legumes, including bacteria in the genus Cupriavidus and the genus Burkholderia (Chen et al 2003a(Chen et al , b, 2006(Chen et al , 2007(Chen et al , 2008Moulin et al 2001Moulin et al , 2002. These beta-rhizobia not only nodulate legumes but also possess genes similar to those employed by the Alphaproteobacteria to nodulate legumes via the root hair nodulation pathway (Fig.…”