Curtobacterium uvaldense sp. nov., Falsirhodobacter allii sp. nov., Pseudomonas texasensis sp. nov., Three Novel Species Isolated from Onions in Texas, USA

Abstract Bacterial strains 20TX0008 T and 20TX0035 T were isolated from the symptomatic onion foliage in 2020, and a bacterial strain 21TX0197 T was isolated from the symptomatic onion bulb in 2021. Pathogenicity assays confirmed the two strains isolated from foliage to be non-pathogenic, while the strain 21TX0197 T was found to be pathogenic. Phylogenetic analysis using the 16 S rRNA gene revealed the closest resemblance of 20TX0008 T , 20TX0035 T , and 21TX0197 T to the genera Curtobacterium , Falsirhodobacter , and Pseudomonas , respectively. For the respective genus, strains 20TX0008 T showed the greatest 16 S rRNA sequence similarity with Curtobacterium caesinilyticum GDMCC 1.2667 T (99.7%), 20TX0035 T with Falsirhodobacter deserti W402 T (99.1%), and 21TX0197 T with Pseudomonas uvaldensis 20TX0172 T (99.4%). In the phylogenetic trees based on whole genome sequences, all three strains formed a distinct, well-supported branch that separated them from their closely related species within the same genus. The genomic similarity, based on average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH), revealed that the novel strains had values below the species delineation thresholds (ANI < 95% and dDDH < 70%), confirming the novelty of all these strains. Based on genomic and phenotypic characteristics, we propose three novel species, Curtobacterium uvaldense sp. nov. (type strain 20TX0008 T =LMG 33207 T =NCIMB 15480 T ), Falsirhodobacter allii sp. nov. (type strain 20TX0035 T =LMG 33208 T =NCIMB 15477 T ), and Pseudomonas texasensis sp. nov. (type strain 21TX0197 T =LMG 33210 T =NCIMB 15479 T ).