Purpose: Due to the ESVA’s endemic population of R. solanacearum and S. Newport, the purpose of this study was to investigate the association between these two pathogens. The survival of S. Newport within tomatoes, symptomatic and asymptomatic for bacterial wilt, was examined.
Methods: Tomato fruit were collected from plants expressing symptoms of bacterial wilt (symptomatic) and plants not expressing bacterial wilt symptoms (asymptomatic) on the ESVA during the 2011 and 2012 summer growing season. Following collection, fruit were inoculated with 8 log CFU/ml S. Newport via vacuum infiltration and incubated for 48 hours at 13°C. S. enterica within the internal fruit tissues was then quantified by surface sterilizing and homogenizing the fruit, and plating the homogenate onto XLT-4. ANOVA was used to analyze results and means were separated using Tukey’s HSD at α = 0.05.
Results: S. enterica recovery was significantly greater in fruit originating from asymptomatic (5.15 log CFU/g) versus symptomatic (4.91 log CFU/g) plants (n = 50; P = 0.0127). Fruit collected from asymptomatic plants also had a significantly higher internal pH (4.60) than fruit collected from symptomatic plants (4.37; P < 0.0001).
Significance: These results suggest that R. solanacearum affects internal tomato fruit pH, which may reduce S. Newport survival in the fruit. This study supports previous research findings reporting phytopathogen influence on human pathogen survival in fruits and vegetables.