Discovery and pathogenic potential analysis of Pseudomonas monteilii A2: A novel tobacco pathogen

A systematic elucidation of pathogenic factors and molecular evolution in tobacco leaf pathogens is pivotal for green precision prevention and control. In this study, isolate A2 was obtained from diseased tobacco leaves, and its strong pathogenicity to tobacco was confirmed through pin-prick inoculation following Koch's postulates. Phylogenetic analysis, average nucleotide identity (ANI), and digital DNA-DNA hybridization (dDDH) results clearly identified A2 as Pseudomonas monteilii . Whole-genome sequencing revealed that A2 is enriched in genes associated with metabolic regulation, environmental adaptation, and virulence. Gene families linked to pathogenic potential, including acetyltransferases, phosphatidylserine-associated proteins, two-component heavy metal response transcriptional regulators, von Willebrand factor type A proteins, TIGRFAM RND efflux system outer membrane lipoprotein NodT, and multicopper oxidoreductases, exhibited significant expansion or contraction, suggesting optimization of host adaptability. Integrated multidimensional annotations from the Virulence Factor Database (VFDB), Pathogen-Host Interactions Database (PHI-base), and Carbohydrate-Active Enzymes Database (CAZy) indicate that A2 pathogenicity is driven by a composite “structure–metabolism–regulation” network involving motility-related structures, secretion systems, and polysaccharide metabolism, with the lipopolysaccharide biosynthesis gene waaF serving as a critical node for outer membrane stability and immune evasion. In summary, this is the first confirmed P. monteilii isolate pathogenic to tobacco, expanding the known host range of this species and providing novel genomic insights into its phytopathogenic mechanisms.