Four non-pathogenic strains isolated from the galls on blueberry plants (Vaccinium corymbosum) were characterized by using polyphasic taxonomic methods. Based on 16S rRNA gene phylogeny, strains were clustered within the genus Agrobacterium. Furthermore, multilocus sequence analysis (MLSA) based on the partial sequences of atpD, recA and rpoB housekeeping genes and whole-genome-based phylogeny indicated that the strains studied form a novel Agrobacterium species. Analyses showed that the strains belong to "rubi" sub-clade of Agrobacterium genus and their closest relatives are Agrobacterium rubi and "Agrobacterium bohemicum". Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) comparisons between genome sequences of representative strains B7.6T and B19.1.4, and their closest relatives, confirmed the distinct phylogenetic position of studied strains, because obtained values were considerably below the proposed thresholds for the species delineation. The four strains studied were phenotypically distinguishable from other species of the genus Agrobacterium. Overall, polyphasic characterization showed that the strains studied represent a novel species of the genus Agrobacterium, for which the name Agrobacterium vaccinii sp. nov. is proposed. The type strain of A. vaccinii is B7.6T (=CFBP 8740T = LMG 31849T).
Keywords: Genome; MLSA; Plant disease; Tumours.
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