sp. nov., a pathogen causing bacterial rot of lettuce in Japan.

Two phytopathogenic bacteria, MAFF 301380 and MAFF 301381, isolated from rot lesions of lettuce ( L. var. L.) in Japan, were characterized using a polyphasic approach. The cells were Gram-reaction-negative, aerobic, non-spore-forming, rod-shaped and motile with one to three polar flagella. Analysis of the 16S rRNA gene sequences showed that the strains belong to the genus and are closely related to subsp. CFML 96-198 (99.72 %), subsp. P515/12 (99.65 %), DSM 17152 (99.51 %), DSM 18928 (99.44 %), CIP 105460 (99.44 %) and DSM 29167 (99.44 %). The genomic DNA G+C content was 60.4 mol% and the major fatty acids consisted of summed feature 3 (C 7/C 6), C and summed feature 8 (C 7/C 6). Phylogenetic analysis using the gene sequences and phylogenomic analyses based on the whole genome sequences demonstrated that the strains are members of the subgroup but formed a monophyletic and robust clade separated from their closest relatives. The average nucleotide identity and digital DNA-DNA hybridization values between the strains and their closely related species were 88.65 % or less and 36.3 % or less, respectively. The strains could be distinguished from their closest relatives by phenotypic characteristics, pathogenicity towards lettuce and whole-cell MALDI-TOF MS profiles. The evidence presented in this study supports the classification of the strains as representing a novel species, for which we propose the name sp. nov., with the type strain MAFF 301380 (=ICMP 23838).