Exploring diversity of bacterial spot associated Xanthomonas population of pepper in Southwest Florida

    Authors and Affiliations
    • Miss Aastha Subedi, University of Florida, 3463, Plant Pathology, 2550 Hull Road, Gainesville, Florida, United States, 32611-7011; [email protected]
    • Dr. Jerry Minsavage, University of Florida, 3463, Gainesville, Florida, United States; [email protected]
    • Dr. Jeffrey B. Jones, University of Florida Institute of Food and Agricultural Sciences, 53701, Plant Pathology, 2553 Fifield Hall, University of Florida, Plant Pathology Department, Gainesville, Florida, United States, 32611, University of Florida; [email protected]
    • Dr. Erica Goss, University of Florida, Plant Pathology, PO Box 110680, Gainesville, Florida, United States, 32611; [email protected]
    • Dr. Pamela Roberts, University of Florida, Plant Pathology, 2686 SR 29 N, Immokalee, Florida, United States, 34142, 239-658-3400, 239-658-3469, United States; [email protected]

      Bacterial spot caused by spp. is a significant disease that challenges pepper growers worldwide and is particularly severe in a hot and humid environment. Understanding the pathogen’s population biology is critical for sustainable disease management. The goal of this study was to characterize the species, race, and bactericide sensitivity of bacterial spot-associated Xanthomonas collected from pepper in Florida. A survey of pepper production fields in Southwest Florida between 2019-2021—covering two counties, eight farms, and two transplant facilities— resulted in the isolation of 542 Xanthomonas euvesicatoria (X. euvesicatoria) and 35 Xanthomonas perforans (X. perforans) strains. Four races were identified on pepper, of which most strains were race P1 (42%), race P6 (26%), race P3 (24%), and less common was race P4 (8%). All X. perforans strains were characterized as race P1 and showed a compatible reaction on tomato. Sixty-two and 96% of strains were sensitive to copper sulfate and streptomycin, respectively. One farm that did not use copper to manage the disease contained only copper-sensitive strains and was the only farm with race P3 strains. Strains were assayed for starch hydrolysis activity of which a third of X. euvesicatoria strains were strongly amylolytic, a characteristic not typically observed in X. euvesicatoria. All X. perforans strains produced bacteriocins against X. euvesicatoria in-vitro. The Xanthomonas population causing bacterial spot-on pepper in Southwest Florida is diverse and dynamic; thus, regular monitoring provides pertinent information to plant breeders and growers for designing disease management strategies. Key words: Bacterial-spot, Xanthomonas, pepper, races, copper, streptomycin, amylase, bacteriocin