Rhizobium tumorigenes sp. nov. a novel plant tumorigenic bacterium isolated from cane gall tumors on thornless blackberry

摘要

Four plant tumorigenic strains 932, 1019, 1078^T and 1081 isolated from cane gall tumors on thornless blackberry (Rubus sp.) were characterized. They shared low sequence identity with related Rhizobium spp. based on comparisons of 16S rRNA gene (≤98%) and housekeeping genes atpD, recA and rpoB (<90%). Phylogenetic analysis indicated that the strains studied represent a novel species within the genus Rhizobium, with Rhizobium tubonense CCBAU 85046^T as their closest relative. Furthermore, obtained average nucleotide identity (ANI) and in silico DNA–DNA hybridization (DDH) values calculated for whole-genome sequences of strain 1078^T and related Rhizobium spp. confirmed the authenticity of the novel species. The ANI-Blast (ANIb), ANI-MUMmer (ANIm) and in silico DDH values between strain 1078^T and most closely related R. tubonense CCBAU 85046^T were 76.17%, 84.11% and 21.3%, respectively. The novel species can be distinguished from R. tubonense based on phenotypic and chemotaxonomic properties. Here, we demonstrated that four strains studied represent a novel species of the genus Rhizobium, for which the name Rhizobium tumorigenes sp. nov. is proposed (type strain 1078^T = DSM 104880^T = CFBP 8567^T). R. tumorigenes is a new plant tumorigenic species carrying the tumor-inducing (Ti) plasmid.