APS Homepage

Poster: Molecular & Cellular Plant-Microbe Interactions: MPMI


The role of the tomato genotype in susceptibility to Salmonella enterica
M. TEPLITSKI (1), M. Teplitski (1), M. Marvasi (2), J. Giovannoni (3) (1) University of Florida, U.S.A.; (2) Middlesex University, United Kingdom; (3) Boyce Thompson Institute, Cornell University, U.S.A.

Tomatoes were linked to multiple outbreaks of salmonellosis. A hypothesis that some tomato genotypes are less conducive to Salmonella growth was tested. A screen of 30 cultivars revealed 10-1,000 fold differences in the ability of this human pathogen to multiply within fruits. Expression of Salmonella genes involved in the interactions was tomato cultivar- and ripening-dependent. Salmonella reached lower numbers within immature fruit, however, pigment accumulation per se did not have an effect on its growth within tomatoes. Salmonella reached similar population densities in tomatoes carrying green flesh or Hyper pigmented mutations. Growth of Salmonella was reduced in the tomato genotypes with defects in ethylene synthesis, perception and signal transduction. While mutation in the ripening-related ethylene receptor Nr resulted only in a modest reduction in Salmonella numbers within tomatoes, strong reduction of the Salmonella growth was observed in rin and nor tomato mutants. A commercial cultivar Sebring heterozygous for rin was less susceptible to Salmonella under the greenhouse conditions than other large-fruited varieties. No significant differences in growth of Salmonella within green and red tomatoes of cv. Sebring were observed in the greenhouse experiments, consistent with the hypothesis that ethylene signaling is responsible for the phenotype of green tomatoes. However, in the field, the phenotype of the cv. Sebring was masked by environmental conditions.