Little is known about the abiotic factors contributing to the preharvest persistence of Salmonella in tomato tissues. Therefore, we investigated the effects of specific environmental conditions and contamination methods on the persistence and dissemination of Salmonella enterica subsp. enterica serotype Typhimurium (JSG626) in tomato plants. When plants were sprayed on the leaves with a JSG626-contaminated solution, JSG626 persistence in the phyllosphere (bacteria located on the surface of the inoculated foliage and stem tissues) was lower at higher temperatures (30°C day/25°C night) than at lower temperatures (20°C day/15°C night). However, wounding cotyledons with contaminated tools improved JSG626 persistence and the internalization rate (2.27%) in planta compared to spray inoculation (0.004%). The systemic dissemination of JSG626 to other tissues increased when contaminated plants were grown under low relative humidity (<40%); however, JSG626 was only detected in the root systems at later sampling times (between 21 and 98 days postinoculation [dpi]). Further, after tomato scions were grafted onto rootstocks using contaminated cutting tools, dissemination of JSG626 was preferentially basipetal and occasionally acropetal in the plants, with higher persistence rates and loads of JSG626 in root systems compared to foliar tissues. JSG626 was detected in the grafting point and root systems up to 242 dpi; however, none of the fruits harvested from contaminated plants between 90 and 137 dpi were positive for JSG626. This study demonstrates that environmental temperature and relative humidity could be good indicators for estimating the persistence of Salmonella enterica in tomato plants. Further, root systems may represent a risk for long-term persistence of Salmonella enterica in tomato plants.
|Journal||Applied and Environmental Microbiology|
|State||Published - Jun 1 2019|
Bibliographical noteFunding Information:
We thank Rosario A. Candelero for technical support. This research was supported by U.S. Department of Agriculture National Institute for Food and Agriculture (NIFA) Agriculture and Food Research Initiative (AFRI) grant 2013-67018-21240 and by state and federal funds appropriated to the Ohio Agricultural Research and Development Center, The Ohio State University. The plant experiments were conducted in accordance with the NIH Guidelines for Research Involving Recombinant DNA Molecules and performed following the Institutional Biosafety Committee (IBC) protocol 2008R0021-R1. The authors declare no conflict of interests.
© 2019 American Society for Microbiology.
- Environmental temperature
- Mechanical damage
- Relative humidity
- Salmonella Typhimurium
ASJC Scopus subject areas
- Food Science
- Applied Microbiology and Biotechnology