Abstract
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) ω7c and/or C(16 : 1) ω6c), C(16 : 0), summed feature 8 (C(18 : 1) ω7c and/or C(18 : 1) ω6c), 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.