title: Consequences of disrupting Salmonella AI-2 signaling on interactions within soft rots.
abstract: Within soft rots, Salmonella spp. reach population densities 10- to 100-fold higher than within intact plants. The hypothesis that Salmonella spp. exchange AI-2 signals with Pectobacterium carotovorum to increase its competitive fitness was tested using mutants involved in AI-2 production (luxS) or perception (lsrACDBF or lsrG). Co-infections of a wild-type Salmonella sp. and its AI-2 mutants (at ≈3 to 10(4)) were established in green or red tomato ('FL 47' or 'Campari' for 3 or 5 days) as well as tomato co-infected with Pectobacterium (at 10(9)) or its luxS mutant. There were no significant differences in the competitive fitness of Salmonella, indicating that AI-2 signaling is not a major input in the interactions between these organisms under the tested conditions. A Salmonella lsrG::tnpR-lacZ resolvase in vivo expression technology (RIVET) reporter, constructed to monitor AI-2-related gene expression, responded strongly to the luxS deletion but only weakly to external sources of AI-2. Growth in soft rots generally decreased RIVET resolution; however, the effect was not correlated to the luxS genotype of the Pectobacterium sp. The results of this study show that AI-2 signaling offers no significant benefit to Salmonella spp. in this model of colonization of tomato or soft rots.
authors: Department of Soil and Water Science, University of Florida, Gainesville, FL, USA. cec9@ufl.edu
authors: Clayton E
authors: CE
authors: Cox
authors: Michael
authors: M
authors: McClelland
authors: Max
authors: M
authors: Teplitski
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D060085:Coinfection; D005506:Food Contamination; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D005838:Genotype; D006714:Homoserine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D007783:Lactones / Q000378:metabolism* / Q000494:pharmacology; D018551:Solanum lycopersicum / Q000382:microbiology* / Q000502:physiology; D009154:Mutation; D016973:Pectobacterium carotovorum / Q000235:genetics / Q000254:growth & development* / Q000502:physiology; D010935:Plant Diseases / Q000382:microbiology*; D011133:Polysaccharide-Lyases; D011401:Promoter Regions, Genetic / Q000235:genetics; D053038:Quorum Sensing; D045522:Recombinases; D012475:Salmonella / Q000235:genetics / Q000254:growth & development* / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D045522:Recombinases; D006714:Homoserine; D011133:Polysaccharide-Lyases; C023911:pectate lyase