Agrobacterium radiobacter

Agrobacterium radiobacter
Scientific classification
Domain:	Bacteria
Kingdom:	Pseudomonadati
Phylum:	Pseudomonadota
Class:	Alphaproteobacteria
Order:	Hyphomicrobiales
Family:	Rhizobiaceae
Genus:	Agrobacterium
Species:	A. radiobacter
Binomial name
Agrobacterium radiobacter (Beijerinck and van Delden 1902) Conn 1942 (Approved Lists 1980)
Type strain
ATCC 19358[1][a]

Agrobacterium radiobacter is the type species of the genus Agrobacterium, a genus of Gram-negative bacteria that cause tumors in plants. It was incorrectly synonymized with Agrobacterium tumefaciens until 2022.^[1] This species is widely found in soil, in plant rhizospheres, and in human clinical specimens. Some members such as B6 harbor a tumor-inducing (Ti) plasmid and cause crown gall disease in plants. The type strain ATCC 19358 does not carry such a plasmid and is nonpathogenic.^[3]

The incorrect synonimization with A. tumefaciens was due to a strain B6 (ATCC 23308) being assigned as the type strain of A. tumefaciens in 1980, when B6 should be classified as A. radiobacter.^[1] One consequence is that this B6 strain is very well-studied in the lab.^[4] Another consequence is that research done on "A. tumefaciens" between 1980 and 2022 are possibly describing A. radiobacter instead. To determine the actual species, one should look up the 16S or genomic sequences of the strain used in the study.

Strain K84 produces agrocin 84, a type of bacteriocin, that inhibits the growth of Agrobacterium tumefaciens (possibly a misidentified A. radiobacter) which causes the disease.^[5] Strain K1026, which is descended from K84 by the removal of potentially-pathogenic DNA sequences, has been used as a biopesticide on stone fruit (such as cherries and plums), nut trees, and ornamentals to protect them from crown gall disease.^[6] Strain K84 and its descendant K1016 are now properly classified as belonging to Rhizobium rhizogenes.^[7][8]