Salmonella Typhimurium reduces the population of several phytopathogens in tomato plants
Loic Deblais: Department of Plant Pathology, The Ohio State University
<div><em>Salmonella</em> is an important cause of wide-scale gastroenteritis outbreaks related to the consumption of contaminated fruits and vegetables worldwide. The presence of phytopathogens can influence <em>Salmonella</em> survival <em>in planta;</em> however little is know about the interactions between <em>Salmonella</em> and phytopathogens. Experiments were conducted to assess the interactions of <em>S</em>. Typhimurium LT2 (<em>S</em>T) with <em>Xanthomonas gardneri</em> (<em>Xg</em>, the causal agent of bacterial spot of tomato) or with <em>Clavibacter</em> <em>michiganensis</em> subsp. <em>michiganensis</em> (<em>Cmm</em>, the causal agent of canker of tomato), in three-week-old ‘Tiny Tim’ tomato seedlings (n=64). The populations of the plant and foodborne pathogens were monitored weekly for 21 days by counting colony-forming units (CFU). When an <em>S</em>T suspension (10<sup>8</sup> CFU/ml) was co-inoculated with <em>Xg</em> (100:1 ratio) at the same time using leaf spray inoculation, the <em>Xg</em> population was reduced by 0.55-log at 7 days post inoculation (DPI) until 21DPI, where <em>Xg</em> was 1.47-log lower in presence of <em>S</em>T compared to the plants infected with <em>Xg</em> alone (P<0.05). Similar results were observed when <em>S</em>T was co-inoculated with <em>Cmm </em>(100:1 ratio) at the same time using cotyledon clip inoculation. The <em>Cmm</em> population was 1.38-log lower in presence of <em>S</em>T at 7DPI until 21DPI (0.54-log reduction) compared to the plants infected with <em>Cmm</em> alone (P<0.05). Future experiments will focus on understanding the mechanism(s) causing the reduction of <em>Xg</em> and <em>Cmm</em> populations <em>in planta</em> in presence of <em>S</em>T<em>.</em></div>
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