The Rhizobiaceae is a family of Pseudomonadota comprising multiple subgroups that enhance and hinder plant development. Some bacteria found in the family are used for plant nutrition and collectively make up the rhizobia. Other bacteria such as '' Agrobacterium tumefaciens'' and '' Rhizobium rhizogenes'' severely alter the development of plants in their ability to induce crown galls or hairy roots, respectively. The family has been of an interest to scientists for centuries in their ability to associate with plants and modify plant development. The Rhizobiaceae are, like all Pseudomonadota,

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wa ...

. They are

aerobic Aerobic means "requiring air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Aerobic respiration, the aerobic process of cel ...

, and the cells are usually rod-shaped.Garrity, George M.; Brenner, Don J.; Krieg, Noel R.; Staley, James T. (eds.) (2005). Bergey's Manual of Systematic Bacteriology, Volume Two: The Proteobacteria, Part C: The Alpha-, Beta-, Delta-, and Epsilonproteobacteria. New York, New York: Springer. . Many species of the Rhizobiaceae are

diazotrophs Diazotrophs are bacteria and archaea that fix gaseous nitrogen in the atmosphere into a more usable form such as ammonia. A diazotroph is a microorganism that is able to grow without external sources of fixed nitrogen. Examples of organisms that d ...

which are able to fix nitrogen and are symbiotic with plant roots.

Genera

Rhizobiaceae comprises the following genera: * ''

Agrobacterium ''Agrobacterium'' is a genus of Gram-negative bacteria established by H. J. Conn that uses horizontal gene transfer to cause tumors in plants. '' Agrobacterium tumefaciens'' is the most commonly studied species in this genus. ''Agrobacterium'' i ...

'' Conn 1942 (Approved Lists 1980) * '' Allorhizobium'' de Lajudie ''et al''. 1998 * ''

Ciceribacter ''Ciceribacter'' is a bacterial genus of the family Rhizobiaceae. Phylogeny The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature List of Prokaryotic names with Standing in Nomenclature (LPSN ...

'' Kathiravan ''et al''. 2013 * '' Endobacterium'' Menéndez ''et al''. 2021 * '' Ensifer'' Casida 1982 * ''

Gellertiella ''Gellertiella hungarica'' is a species of Gram-negative bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic mic ...

'' Tóth ''et al''. 2017 * '' Georhizobium'' Cao ''et al''. 2020 * ''

Hoeflea ''Hoeflea'' is a genus of Gram-negative, strictly aerobic, oxidase- and catalase-positive, non-spore-forming, rod-shaped bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one bi ...

'' Peix ''et al''. 2005 * ''

Lentilitoribacter ''Lentilitoribacter'' is a genus of Gram-negative, aerobic, non-spore-forming bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domai ...

'' Park ''et al''. 2013 * ''

Liberibacter ''Liberibacter'' is a genus of Gram-negative bacteria in the Rhizobiaceae family. Detection of the liberibacteria is based on PCR amplification of their 16S rRNA gene with specific primers. Members of the genus are plant pathogens mostly transm ...

'' Fagen ''et al''. 2014 * ''

Martelella ''Martelella'' is a genus of Gram-negative, oxidase- and catalase-positive, strictly aerobic, non-spore-forming bacteria from the family of Rhizobiaceae The Rhizobiaceae is a family of Pseudomonadota comprising multiple subgroups that enhance ...

'' Rivas ''et al''. 2005 * ''

Mycoplana ''Mycoplana'' is a genus of Gram-negative bacteria. The cells are slightly curved or irregularly shaped rods. Initially, the cells can form filaments, which can also be branched. After some time, the filaments break up into irregular rods. ''Myc ...

'' Gray and Thornton 1928 (Approved Lists 1980) * "'' Neopararhizobium''" Hördt ''et al''. 2020 * '' Neorhizobium'' Mousavi ''et al''. 2015 * "'' Onobrychidicola''" Ashrafi et al. 2022 * ''

Pararhizobium ''Pararhizobium'' is a genus of Gram-negative soil bacteria that fix nitrogen. Some species of ''Pararhizobium'' form an endosymbiotic nitrogen-fixing association with roots of legumes A legume () is a plant in the family Fabaceae (or Legum ...

'' Mousavi ''et al''. 2016 * ''

Peteryoungia ''Peteryoungia'' is a genus of bacteria from the family Rhizobiaceae. Phylogeny The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature List of Prokaryotic names with Standing in Nomenclature ...

'' Rahi et al. 2021 * '' Pseudorhizobium'' Kimes ''et al''. 2017 * ''

Rhizobium ''Rhizobium'' is a genus of Gram-negative soil bacteria that fix nitrogen. ''Rhizobium'' species form an endosymbiotic nitrogen-fixing association with roots of (primarily) legumes and other flowering plants. The bacteria colonize plant cells ...

'' Frank 1889 (Approved Lists 1980) * '' Shinella'' An ''et al''. 2006 * '' Sinorhizobium'' Chen et al. 1988 * '' Xaviernesmea'' Kuzmanović et al. 2022

Phylogeny

The currently accepted taxonomy is based on the

List of Prokaryotic names with Standing in Nomenclature List of Prokaryotic names with Standing in Nomenclature (LPSN) is an online database that maintains information on the nomenclature, naming and Taxonomy (biology), taxonomy of prokaryotes, following the taxonomy requirements and rulings of the In ...

(LPSN). The phylogeny is based on whole-genome analysis.

References

{{Authority control Plant nutrition Hyphomicrobiales