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TECHNICAL SESSION: Population diversity of plant pathogenic bacteria

It’s complicated: The Xanthomonas perforans population across Florida commercial tomato fields
Jeannie Klein - University of Florida. Erica Goss- University of Florida, Sujan Timilsina- University of Florida, Gerald Minsavage- University of Florida, Jeffrey Jones- University of Florida, Peter Abrahamian- Gulf Coast Research and Education Center, University of Florida, James Fulton- Univ

Bacterial spot of tomato (BST), caused by Xanthomonas euvesicatoria, X. gardneri, X. perforans, and X. vesicatoria, is one of the most economically important diseases of tomato. In Florida, prior surveys determined that X. perforans (Xp) is the primary cause of BST and detected dramatic shifts within the Xp population over the past 30 years despite the lack of a clear selective pressure. These population shifts have adversely impacted the efficacy of control measures and resistance breeding efforts in tomato. We characterized 585 Xanthomonas isolates from symptomatic tissue in 70 commercial tomato fields throughout Florida in fall 2017 and found that Xp remains the primary cause of BST in Florida. The Xp population consisted of three phylogenetic groups and tomato races 3 (8%) and 4 (92%). Further characterization revealed that 99.8% of strains were resistant to copper, 25% of strains were resistant to streptomycin, 51% of strains produced bacteriocins, and effector profiles, that impact host range, were highly variable among the Xp strains. Our results indicate that the composition of the Xp population in Florida is complex and varies within and among fields. We will use this strain collection to test for associations between genetic variation and tomato production chain variables.