Pseudomonas kitaguniensis sp. Nov., a pathogen causing bacterial rot of welsh onion in japan

Abstract

Five Gram-reaction-negative, aerobic, motile with one to three polar flagella, rod-shaped bacterial strains, MAFF 212408T, MAFF 212409, MAFF 212410, MAFF 301498 and MAFF 730085, were isolated from diseased Welsh onion (Allium fistulosum L.) in Japan. Analysis of their 16S rRNA gene sequences showed that they belong to the genus Pseudomonas with the highest similarity to Pseudomonas extremaustralis 14-3T (99.86%), Pseudomonas antarctica CMS 35T (99.79%) and Pseudomonas poae DSM 14936T (99.72%). The genomic DNA G+C content was 59.5 mol% and the major fatty acids (>5%) were summed feature 3, C16:0, summed feature 8 and C12:0 2-OH. Multilocus sequence analysis using the rpoD, gyrB and rpoB gene sequences and phylogenomic analysis based on the 90 core genes demonstrated that the strains are members of the P. fluorescens subgroup, but are distant from all closely related species. Average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) analysis confirmed low genomic relatedness to their closest relatives [below the recommended thresholds of 95% (ANI) and 70% (dDDH) for prokaryotic species delineation]. The strains were characterized by using API 20NE and Biolog GEN III tests, and inoculation tests in Welsh onion, showing that they are phenotypically differentiated from their closest relatives. Based on the genetic and phenotypic evidence, the strains should be classified as representing a novel species, for which the name Pseudomonas kitaguniensis sp. nov. is proposed. The type strain is MAFF 212408T (=ICMP 23530T).