Purpose: The purpose of this study was to evaluate fruit and leaves of thirteen tomato cultivars (Solanum lycopersicum) with distinct phenotypes for their susceptibility to Salmonella epiphytic colonization.
Methods: Field-grown fruit or gnotobiotically-grown seedling leaves were spot inoculated with either a laboratory strain of S. Typhimurium or a tomato outbreak-associated strain of S. Newport. Salmonella were retrieved and enumerated using direct plating after 24h for fruit and 72h for seedling leaves. Differences in log CFU/unit of sample detected between levels of treatments were tested for significance using one-way ANOVA and Tukey’s HSD test.
Results: Epiphytic colonization of tomato fruit by S. enterica was cultivar-dependent and serotype-specific, but did not necessarily correlate with seedling leaf colonization. Fruit of cultivar ‘Heinz-1706’ were the least colonized by S. Newport, and ‘Mobox’ by S. Typhimurium, while the highest populations were retrieved from fruit of ‘Nyagous’, ‘LA4013’ and ‘Florida 91 VFF’ (P < 0.05). By contrast, seedling leaves supporting the lowest populations were ‘Florida 91 VFF’, ‘Movione’ and ‘Nyagous’ (P < 0.05). The tomato outbreak strain of S. Newport attained higher population densities on fruit than S. Typhimurium (P = 0.0002), suggesting better adaptation to tomato fruit colonization.
Significance: These data reveal that susceptibility of tomato fruit to Salmonella colonization is highly variable and could be one criterion for cultivar selection for cultivation.