Novel Lytic Bacteriophage PAT-A: Isolation, Characterization, Genome Analysis, and Biocontrol Potential Against...

Agrobacterium tumefaciens, a destructive pathogen causing crown gall disease, results in substantial agricultural losses. Traditional chemical and existing biocontrol methods are limited by environmental pollution, pesticide resistance, and low efficacy, while bacteriophages emerge as a promising alternative due to their high host specificity, environmental compatibility, and low resistance risk. In this study, we isolated and characterized a lytic phage (PAT-A) targeting A. tumefaciens, evaluating its biological traits, genomic features, and biocontrol potential. The host strain A. tumefaciens CL-1 was isolated from cherry crown gall tissue and identified by 16S rDNA sequencing. Phage PAT-A was recovered from orchard soil via the double-layer agar method, showing a tadpole-shaped morphology (60 nm head diameter, 30 nm tail length) under transmission electron microscopy (TEM). Nucleic acid analysis confirmed a double-stranded DNA genome, susceptible to DNase I but resistant to RNase A and Mung Bean Nuclease. PAT-A exhibited an optimal MOI of 0.01, tolerated wide pH and temperature ranges, but was sensitive to UV (titer declined after 15 min of irradiation) and chloroform (8% survival at a 5% concentration). Whole-genome sequencing revealed a 44,828 bp genome with a compact structure, and phylogenetic/collinearity analyses placed it in the Atuphduvirus genus (Autographiviridae). Biocontrol experiments on tobacco plants demonstrated that PAT-A significantly reduced crown gall incidence. Specifically, simultaneous inoculation of PAT-A and A. tumefaciens CL-1 resulted in the lowest tumor incidence (12.0%), while pre-inoculation of PAT-A 2 days before pathogen exposure achieved an incidence rate of 33.3%. In conclusion, PAT-A is a novel strictly lytic phage with favorable biological properties and potent biocontrol efficacy against A. tumefaciens, enriching phage resources for crown gall management and supporting phage-based agricultural biocontrol strategies.