Pseudomonas brassicae sp. nov., a pathogen causing head rot of broccoli in Japan

Phytopathogenic bacteria, MAFF 212426, MAFF 212427 T , MAFF 212428 and MAFF 212429, were isolated from head rot lesions of broccoli ( Brassica oleracea L. var. italica Plenck) in Hokkaido, Japan, and subjected to polyphasic taxonomic characterization. The cells were Gram-reaction-negative, aerobic, non-spore-forming, motile with one or two polar flagella, rod-shaped and formed pale yellow colonies. Results of 16S rRNA gene sequence analysis showed that they belong to the genus Pseudomonas with the highest similarity to ‘ Pseudomonas qingdaonensis ’ JJ3 T (99.86 %), Pseudomonas laurentiana GSL-010 T (99.22 %), Pseudomonas huaxiensis WCHPs060044 T (99.01 %), Pseudomonas japonica NBRC 103040 T (98.87 %) and Pseudomonas alkylphenolica KL28 T (98.73 %). The genomic DNA G+C content was 63.4 mol% and the major fatty acids (>5 % of the total fatty acids) were summed feature 3 (C 16 : 1  ω7 c / C 16 : 1  ω6 c ), C 16 : 0 , summed feature 8 (C 18 : 1  ω7 c / C 18 : 1  ω6 c ) and C 17 : 0 cyclo. Multilocus sequence analysis using the partial rpoD , gyrB and rpoB gene sequences and phylogenomic analyses based on the whole genome sequences demonstrated that the strains are members of the Pseudomonas putida group, but form a monophyletic, robust clade separated from their closest relatives. Average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values corroborated their novel species status, with 88.39 % (ANI) and 35.8 % (dDDH) as the highest scores with ‘ P. qingdaonensis ’ JJ3 T . The strains were differentiated from their closest relatives by phenotypic characteristics, pathogenicity on broccoli, and whole-cell MALDI-TOF mass spectrometry profiles. The phenotypic, chemotaxonomic and genotypic data showed that the strains represent a novel Pseudomonas species, for which the name Pseudomonas brassicae sp. nov. is proposed. The type strain is MAFF 212427 T (=ICMP 23635 T ).