Pectobacterium araliae sp. nov., a pathogen causing bacterial soft rot of Japanese angelica tree in Japan.

Phytopathogenic bacteria (MAFF 302110 ^T and MAFF 302107) were isolated from lesions on Japanese angelica trees affected by bacterial soft rot in Yamanashi Prefecture, Japan. The strains were Gram-reaction-negative, facultatively anaerobic, motile with peritrichous flagella, rod-shaped, and non-spore-forming. The genomic DNA G+C content was 51.1 mol % and the predominant cellular fatty acids included summed feature 3 (C _16 : 1  ω7 c and/or C _16 : 1  ω6 c ), C _16 : 0 , summed feature 8 (C _18 : 1  ω7 c and/or C _18 : 1  ω6 c ), summed feature 2 (comprising any combination of C _12 : 0 aldehyde, an unknown fatty acid with an equivalent chain length of 10.928, C _16 : 1 iso I, and C _14 : 0 3OH), and C _12 : 0 . Phylogenetic analyses based on 16S rRNA and gyrB gene sequences, along with phylogenomic analysis utilizing whole-genome sequences, consistently placed these strains within the genus Pectobacterium . However, their phylogenetic positions did not align with any known species within the genus. Comparative studies involving average nucleotide identity and digital DNA-DNA hybridization with the closely related species indicated values below the thresholds employed for the prokaryotic species delineation (95-96 % and 70 %, respectively), with the highest values observed for Pectobacterium polonicum DPMP315 ^T (92.10 and 47.1 %, respectively). Phenotypic characteristics, cellular fatty acid composition, and a repertoire of secretion systems could differentiate the strains from their closest relatives. The phenotypic, chemotaxonomic, and genotypic data obtained in this study show that MAFF 302110 ^T /MAFF 302107 represent a novel species of the genus Pectobacterium , for which we propose the name Pectobacterium araliae sp. nov., designating MAFF 302110 ^T (=ICMP 25161 ^T ) as the type strain.