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POSTERS: Phytobiomes

Bacterial community response to bacterial spot disease and resistance in tomatoes.
Adam Bigott - University of Wisconsin-Madison. Samuel Hutton- University of Florida, Gary Vallad- Gulf Coast Research and Education Center, University of Florida, Jeri Barak- University of Wisconsin-Madison, Richard Lankau- University of Wisconsin-Madison

Bacterial spot of tomato and pepper is a disease complex caused by Xanthomonas spp. Because bacterial spot resistance does not exist in tomato, accelerated genetics have been used to transfer broad spectrum bacterial resistance by incorporating the pathogen recognition receptor EFR from Arabidopsis thaliana to enhance pattern triggered immunity (PTI) as well as Bs2 from pepper for effector triggered immunity (ETI) specific to Xanthomonas spp. The aim of this project is to determine how disease as well as broad and narrow spectrum resistance influence phyllosphere bacterial and fungal community structure. In order to investigate this, 16s and ITS amplicon sequencing were performed on leaf wash extracts collected from three separate field trials inoculated with X. perforans in Florida. Across all plants in each of the three seasons, Xanthomonas was the most abundant taxon. In concordance with bacterial spot disease rating data, Xanthomonas represented a significantly smaller proportion of the community in plants expressing Bs2. The effects of EFR expression were less pronounced than Bs2 and varied by season. While not as dramatic as the effect of Bs2 expression, plants expressing EFR had slightly lower disease ratings, but no difference in the relative abundance of Xanthomonas. Fungal phyllosphere communities did not consistently differ by plant genotype. Further analysis seeks to delimit whether expression of ETI or Xanthomonas reshape bacterial community structure.