Isolation and characterization of Agrobacterium vacciniicorymbosi sp. nov. originating from crown galls in blueberry (Vaccinium corymbosum) in Serbia

Seven bacterial isolates were obtained from crown gall in blueberry plants (Vaccinium corymbosum) growing in Serbia in 2020. Phylogenetic analysis of the novel isolates using four housekeeping genes - atpD, dnaK, glnA, and rpoB, as well as gene 16 S rRNA - revealed their distinct position, separate from other known Agrobacterium species, but closest to A. vaccinii, A. rosae and A. rubi. Genome sequencing of one of these blueberry isolates revealed less than 86% average nucleotide identity (ANI) between the blueberry isolate and type strains of Agrobacterium species, indicating that it does not belong to any previously described species. Although genome sequencing revealed absence of the tumor-inducing (Ti) plasmid, stabbing the crown region with bacterial cultures induced gall-like structures formed on blueberry plants (cultivar Duke). Phenotypically, these blueberry isolates were differentiated from closely related Agrobacterium species in their utilization of dulcitol, d-tagatose and xylitol. On the basis of these results, Serbian blueberry isolates are considered to represent a novel species of the genus Agrobacterium, for which the name Agrobacterium vacciniicorymbosi sp. nov. is proposed, with BA1120^T (NCPPB 4800 = CFBP 9290) as the type strain. This isolate and BA2520 (NCPPB 4801 = CFBP 9291) have been deposited in public collections of plant pathogenic bacteria.