Genomic Analyses of Rose Crown Gall-Associated Bacteria Revealed Two New Agrobacterium Species: Agrobacterium burrii sp. nov. and Agrobacterium shirazense sp. nov.
Agrobacterium tumefaciensspecies complex contains a set of diversebacterial strains, most of which are well known for their pathogenicity onagricultural plants causing crown gall diseases. Members ofA. tumefaciensspecies complex are classified into several taxonomically distinct lineagescalled“genomospecies”(13 genomospecies until early 2021). Recently, twogenomospecies, G19 (strains RnrT, Rew, and Rnw) and G20 (strains OT33Tand R13) infectingRosasp. plants in Iran, were described based onbiochemical and molecular-phylogenetic data. Whole genome sequence-based core-genome phylogeny followed by average nucleotide identity(ANI) and digital DNA-DNA hybridization (dDDH) calculations performedin this study suggested that genomospecies G19 and G20 could bedescribed as two novel and standalone species. In the phylogenetic tree,these two new genomospecies were clustered separately from othergenomospecies/species ofA. tumefaciensspecies complex. Moreover,both ANI and dDDH indices between the G19/G20 strains and otherRhi-zobiaceaemembers are clearly below the accepted thresholds for pro-karyotic species description. Hence,Agrobacterium burriisp. nov. isproposed to encompass the G19 strains, with RnrT=CFBP8705T=DSM112541Tas type strain.Agrobacterium shirazensesp. nov. is also proposed toinclude G20 strains, with OT33T= CFBP 8901T= DSM 112540Tas type strain.