Differential interaction of human pathogens with plants
D. ROY (1), S. Panchal (1), M. Melotto (1). (1) University of Texas-Arlington, Arlington, TX, U.S.A.
Each year roughly 48 million cases of human food poisoning or hospitalization occur due to consumption of fresh produce contaminated with human pathogens. The understanding of the early events of human pathogen and plant interaction is necessary to prevent this. In this study, we assessed plant defense responses induced by the fully pathogenic bacteria <i>Escherichia coli</i> O157:H7 and <i>Salmonella enterica</i> serovar Typhimurium SL1344 in both <i>Arabidopsis thaliana</i> and lettuce (<i>Lactuca sativa</i>). Stomatal assay of plants were performed under normal and higher humid conditions to examine the effect of relative humidity on plant defense against those human pathogens. Further, to test the post invasion behavior of those pathogens, survival of the pathogens inside apoplast was tested as well under differential humid condition. Lastly, to assess whether human pathogens can also regulate <i>Arabidopsis</i> defense responses in the whole leaves, we evaluated the expression level of the <i>Arabidopsis</i> marker gene <i>PR1</i> that is associated with immunity against bacteria. Unlike SL1344, O157:H7 induced strong plant immunity at both pre-invasion and post-invasion steps of infection. <i>PR1</i> gene expression was also found to be higher in O157:H7 infected <i>Arabidopsis</i> leaf. These results suggest plant might recognize and respond to some human pathogens more effectively than others. This knowledge can be useful in developing good agricultural practice and minimizing outbreaks related to fresh produce.
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