Acidovorax sacchari sp. nov., a pathogen causing red stripe of sugarcane in Japan

Phytopathogenic bacteria (MAFF 311311^T and MAFF 311313) were isolated from sugarcane plants exhibiting leaf stripe symptoms associated with red stripe disease in Okinawa Prefecture, Japan. The strains were Gram-reaction-negative, aerobic, motile with one polar flagellum, rod-shaped and non-spore-forming. The genomic DNA G+C content was 69.0 mol%, and the major cellular fatty acids (>10 % of the total fatty acids) included summed feature 3 (C_{16 : 1} <i> ω7c</i> and/or C_{16 : 1} <i> ω6c</i>), C_{16 : 0} and summed feature 8 (C_{18 : 1} <i> ω7c</i> and/or C_{18 : 1} <i> ω6c</i>). Phylogenomic analyses using whole-genome sequences consistently placed these strains within the genus <i>Acidovorax</i>. However, their phylogenetic positions did not correspond to any known species within this genus. Comparative analyses, including average nucleotide identity and digital DNA-DNA hybridization with closely related species, yielded values below the thresholds for prokaryotic species delineation (95-96 and 70 %, respectively), with the highest values observed for <i>Acidovorax oryzae</i> ATCC 19882^T (93.98 and 54.3 %, respectively). Phenotypic characteristics, cellular fatty acid composition and a repertoire of secretion systems and their effectors can differentiate these strains from their closest relatives. The phenotypic, chemotaxonomic and genotypic data obtained in this study indicate that MAFF 311311^T and MAFF 311313 constitute a novel species within the genus <i>Acidovorax</i>, for which we propose the name <i>Acidovorax sacchari</i> sp. nov., with MAFF 311311^T (=ICMP 25276^T) designated as the type strain.