Summary of Awards to Date

Characterization of the synergistic interaction between Salmonella enterica and Zanthomonas vesicatoria in the tomato phyllosphere.

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Sep. 1, 2009 - Aug. 31, 2011

Award Number


Funding Agency

Center for Produce Safety


Jeri D. Barak-Cunningham, Ph.D.
University of Wisconsin-Madison


The incidence of salmonellosis caused by the consumption of fresh produce has surpassed outbreaks associated with the consumption of animal products and continues to rise. Tomato is one of the most likely produce associated with Salmonellosis outbreaks from consumption of contaminated produce. Salmoenlla fails to grow on tomato plants or fruit in the field. However, in the presence of the plant pathogen Xanthomonas vesicatoria, Salmonella can grow, even in the absence of plant disease. A growing Salmonella population on the tomato plant leads to a higher incidence of contaminated fruit. Experiments will be preformed that identify the mechanisms that allows growth of Salmonella with X. vesicatoria. Also, the specificity of this interaction will be tested by examining another foliar pathogen of tomato and determining whether Salmonella can grow during co-colonization of it. Finally, the genes that have previously been identified as important for Salmonella colonization of seedlings will be characterized for their function. To determine the function of these genes, biofilm, plant, and swarm assays and protein sequence analysis will be completed. Completion of this work will confirm whether Salmonella and X. vesicatoria form a dual-genera biofilm on the leaf surface; confirm the specificity of this interaction; and expand our knowledge of the genetic mechanisms that allow Salmonella to colonize plants. Understanding the interaction of Salmonella with other bacteria on plants is a first step toward solving the food safety crisis of contaminated produce.