Characterization of Bacteriophages as Biocontrol Agents Against Crown Gall Disease in Egypt

Crown gall is a devastating disease with severe economic impacts, particularly in nurseries cultivating mango and other stone fruit trees. Virulent strains of Agrobacterium tumefaciens cause the disease. In this study, water samples were collected from agricultural drains in Beni-Suef, Egypt, to isolate bacteriophages. A bacteriophage was successfully isolated using A. tumefaciens strain AUMCB-455, a known crown gall pathogen. Genome characterization and electron microscopy were employed to identify the virus, which was assigned as vB_AgrP-B1 and classified to the family Podoviridae. The bacteriophage remained active at 65°C and optimal at pH 7, with a dilution endpoint of 10⁻11. Plaque formation was influenced by various salts, sugars, and heavy metals at different concentrations (10 mM, 1 mM, 0.1 mM); salts either enhanced or inhibited plaques, sugars increased plaque numbers, while heavy metals suppressedF plaque formation. In a controlled laboratory assay, the application of vB_AgrP-B1 to infected carrot tuber discs effectively inhibited the formation of crown galls caused by A. tumefaciens AUMCB-455. These findings highlight the potential of vB_AgrP-B1 as a biocontrol agent for managing crown gall disease.