| dc.description.abstract | Citrus canker, caused by Xanthomonas axonopodis pv. citri (Xac), is one of the most devastating citrus diseases that affects citrus production worldwide. The current recommended means to control canker are windbreaks, copper sprays, and control of leafminer, its insect vector, with copper sprays being most effective. However, there is growing concern about the buildup of copper in groves leading to phytotoxicity, decreased plant productivity, copper resistance development, and copper contamination of ground and river water. The goal of this study was to develop a non-copper based treatment for citrus canker. Using virulent bacterial viruses (phages) that specifically targeted to Xac is an approach that is not harmful to humans, animals, plants, associated beneficial microflora, or the environment. I report here the isolation and characterization of three virulent phages for Xac that differ in host range and morphology.
Genomic analysis showed that CCP504 is a phiKMV-like phage, CCP513 is a novel siphophage, and CCP509 is a T4-like phage type, respectively. All three phages appear to utilize type IV pili as their primary receptors for adsorption. Greenhouse studies were conducted to evaluate the efficacy of phage therapy to control canker formation on Hamlin sweet oranges using a phage cocktail composed of three KMV-like podophages (CCP504, CCP505 and CCP511) and one siphophage (CCP513). Both pre- and post-treatments with this phage cocktail at an MOI of 20 resulted in a significant reduction in lesion formation on leaves of the treated plants as compared to non-treated plants. My research demonstrates that bacteriophages can serve as an alternative control strategy for Xac that is both environmentally friendly and sustainable. | en |
