ABSTRACT
The Gram-positive Clavibacter genus is currently divided into seven species (C. michiganensis, C. nebraskensis, C. capsici, C. sepedonicus, C. tessellarius, C. insidiosus and C. zhangzhiyongii) and three subspecies (C. michiganensis subsp. californiensis, C. michiganensis subsp. chilensis and C. michiganensis subsp. phaseoli). Recent studies have indicated that the taxonomic rank of the subspecies must be re-evaluated. In this research, we assessed the taxonomy position of the three C. michiganensis subspecies and clarified the taxonomic nomenclature of other 75 Clavibacter strains. The complete genomes of the type strains of the three Clavibacter subspecies, type strain of C. tessellarius and C. nebraskensis A6096 were sequenced using PacBio RSII technology. Application of whole-genome-based computational approaches such as average nucleotide identity (ANI), digital DNA-DNA hybridization (dDDH), multi-locus sequence analysis (MLSA) of seven housekeeping genes (acnA, atpD, bipA, icdA, mtlD, recA and rpoB), phylogenomic tree reconstructed from 1,028 core genes, and ANI-based phylogeny pinpointed conclusive evidence to raise C. michiganensis subsp. californiensis to the species status. These results led us to propose the establishment of C. californiensis sp. nov. as a species with its type strain C55ᵀ (=CFBP 8216ᵀ=ATCC BAA-2691ᵀ). Moreover, the orthologous and in-silico dot plot analyses, along with the aforementioned bioinformatic strategies, revealed a high degree of homology between C. michiganensis subsp. chilensis and C. michiganensis subsp. phaseoli. Based on these outcomes, we proposed to combine both subspecies into a single taxon and elevate its rank to the species level as C. chilensis sp. nov., with ZUM3936ᵀ (= ATCC BAA-2690ᵀ = CFBP 8217ᵀ) as the type strain.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Repositories: CP040786-CP040787; CP040788-CP040791; CP040792-CP040794; CP040795-CP040796; CP040797
