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Transcriptional responses of Escherichia coli O157:H7 during plant immunity and plant disease

Amelia Lovelace: University of Georgia

<div>Human enteric pathogens such as <em>Escherichia coli </em>O157:H7 are frequently associated with produce-borne illness, even though they are generally unable to replicate efficiently in association with plant tissues. In part this is due to the broad spectrum microbe-restricting plant immune response. The plant pathogenic bacterium <em>Pseudomonas syringae </em>has evolved to overcome plant immunity resulting in conditions that are favorable for bacterial multiplication. Human enteric pathogens are able to exploit the permissive conditions created by <em>P. syringae</em> to opportunistically achieve high loads in plant tissues which could represent an important source of produce contamination. Our research aims to characterize the response of human enteric pathogens in the context of plant immunity and disease. The interactions between <em>E. coli </em>O157:H7, <em>Pseudomonas syringae </em>pv. tomato and model hosts <em>Arabidopsis thaliana</em> and <em>Nicotiana benthaminana </em>were characterized in a co-inoculation assay. We observed that <em>P. syringae </em>creates a conducive environment for proliferation of <em>E. coli</em> in the apoplast with E.<em> coli</em> populations increasing significantly when co-inoculated with <em>P. syringae </em>but not when co-inoculated with a type III secretion system mutant. Transcriptome analysis of <em>E. coli </em>under disease-mimicking and plant immune conditions through a disease reconstitution assay reveals unique responses to the conditions human pathogens experience during exposure to plant immunity and plant disease.</div>