The Rhizobiaceae is a family of

Pseudomonadota Pseudomonadota (synonym "Proteobacteria") is a major phylum of gram-negative bacteria. Currently, they are considered the predominant phylum within the domain of bacteria. They are naturally found as pathogenic and free-living (non- parasitic) ...

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 Rhizobia are diazotrophic bacteria that fix nitrogen after becoming established inside the root nodules of legumes (Fabaceae). To express genes for nitrogen fixation, rhizobia require a plant host; they cannot independently fix nitrogen. I ...

. Other bacteria such as ''

Agrobacterium tumefaciens ''Agrobacterium tumefaciens'' (also known as ''Rhizobium radiobacter'') is the causal agent of crown gall disease (the formation of tumours) in over 140 species of eudicots. It is a rod-shaped, Gram-negative soil bacterium. Symptoms are cause ...

'' and ''

Rhizobium rhizogenes ''Rhizobium rhizogenes'' (formerly ''Agrobacterium rhizogenes'') is a Gram-negative soil bacterium that produces hairy root disease in Dicotyledon, dicotyledonous plants. ''R. rhizogenes'' induces the formation of proliferative multiple-branched ...

'' 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, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

. 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 cellu ...

, 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 organisms capable of nitrogen fixation, i.e. converting the relatively inert diatomic nitrogen (N2) in Earth's atmosphere into bioavailable compound forms such as ammonia. Diazotrophs are typically microorganisms such as bacteria ...

which are able to fix nitrogen and are

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

with plant roots.

Genera

Rhizobiaceae comprises the following genera: * ''

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

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

'' Kathiravan ''et al''. 2013 * '' Endobacterium'' Menéndez ''et al''. 2021 * '' Ensifer'' Casida 1982 * '' Gellertiella'' Tóth ''et al''. 2017 * '' Georhizobium'' Cao ''et al''. 2020 * '' Hoeflea'' Peix ''et al''. 2005 * '' Lentilitoribacter'' Park ''et al''. 2013 * '' Liberibacter'' Fagen ''et al''. 2014 * '' Martelella'' Rivas ''et al''. 2005 * '' Mycoplana'' Gray and Thornton 1928 (Approved Lists 1980) * "'' Neopararhizobium''" Hördt ''et al''. 2020 * '' Neorhizobium'' Mousavi ''et al''. 2015 * "'' Onobrychidicola''" Ashrafi et al. 2022 * '' Pararhizobium'' Mousavi ''et al''. 2016 * '' Peteryoungia'' 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 ce ...

'' Frank 1889 (Approved Lists 1980) * '' Shinella'' An ''et al''. 2006 * ''

Sinorhizobium ''Ensifer'' (often referred to in literature by its synonym ''Sinorhizobium'') is a genus of nitrogen-fixing bacteria (rhizobia), three of which ('' Ensifer meliloti'', '' Ensifer medicae'' and '' Ensifer fredii'') have been sequenced. Etymology ...

'' 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 naming and taxonomy of prokaryotes, following the taxonomy requirements and rulings of the International Code of Nomenclatu ...

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

References

{{Authority control Plant nutrition Hyphomicrobiales