title: Analysis of core genes supports the reclassification of strains Agrobacterium radiobacter K84 and Agrobacterium tumefaciens AKE10 into the species Rhizobium rhizogenes.
abstract: Some strains of the former genus Agrobacterium have high biotechnological interest and are currently misclassified. Consequently, in this study, the taxonomic status of the non-pathogenic strain Agrobacterium radiobacter K84, used in biological control, and the tumourigenic strain Agrobacterium tumefaciens AKE10, able to regenerate tobacco transgenic plants, was revised. The phylogenetic analysis of the chromosomal genes rrs, atpD and recA showed that they should be reclassified into Rhizobium rhizogenes. The analysis of virulence genes located in the Ti plasmid (pTi) outside T-DNA showed a common phylogenetic origin among strains AKE10, R. rhizogenes 163C and A. tumefaciens (currently R. radiobacter) C58. However, the genes located inside the T-DNA, mainly the 6b gene, of strain AKE10 were phylogenetically close to those of strain 163C but divergent from those of strain C58. Furthermore, the T-DNA of tumourigenic strains from R. rhizogenes conferred on them the ability to regenerate tumour tissue resembling fasciation in tobacco plants. These results showed the existence of a highly mosaic genetic organization in tumourigenic strains of the genus Rhizobium and provided evidence of the involvement of T-DNA from tumourigenic strains of R. rhizogenes in fasciation of Nicotiana leaves. The data further suggested that pathogenic strains of Rhizobium could be good models to analyse bacterial evolution.
authors.affiliation: Departamento de Microbiología y Genética, Edificio Departamental de Biología, Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain. evp@gugu.usal.es
authors.forename: Encarna
authors.initials: E
authors.lastname: Velázquez
authors.forename: José Luis
authors.initials: JL
authors.lastname: Palomo
authors.forename: Raúl
authors.initials: R
authors.lastname: Rivas
authors.forename: Hilario
authors.initials: H
authors.lastname: Guerra
authors.forename: Alvaro
authors.initials: A
authors.lastname: Peix
authors.forename: Martha E
authors.initials: ME
authors.lastname: Trujillo
authors.forename: Pablo
authors.initials: P
authors.lastname: García-Benavides
authors.forename: Pedro F
authors.initials: PF
authors.lastname: Mateos
authors.forename: Hiroetsu
authors.initials: H
authors.lastname: Wabiko
authors.forename: Eustoquio
authors.initials: E
authors.lastname: Martínez-Molina
mesh_terms: D016960:Agrobacterium tumefaciens / Q000145:classification / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics; D010802:Phylogeny; D018515:Plant Leaves / Q000382:microbiology; D011938:Rec A Recombinases / Q000235:genetics; D012231:Rhizobium / Q000145:classification / Q000235:genetics; D054680:Ribosome Subunits, Small, Bacterial / Q000235:genetics; D014026:Nicotiana / Q000382:microbiology; D014157:Transcription Factors / Q000235:genetics; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D008565:Membrane Proteins; C036483:T-DNA; D014157:Transcription Factors; D011938:Rec A Recombinases