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<p>Fresh produce are the most likely vehicle for foodborne illness to humans in the US and Salmonella enterica is the most likely bacterial cause. Fundamental research is needed to understand the mechanisms by which human enteric bacterial pathogens (HEBPs) benefit from phytophagous Hemipterans, to develop effective pathogen control and management strategies.</p><p>The objectives of this project include characterize 1) insect factors that influence HEBP survival and dispersal in and among plants,</p><p>2) how plant defense changes due to insect feeding, and</p><p>3) mechanisms used by HEBPs to survive internalization and passage through the alimentary canal of phytophagous hemipterans.</p>
<p>In Objective 1, we will measure the damage to leaves by phloem-feeding insects by measuring conductance on leaves feed upon by leafhopperor aphid. In addition, we will examine honeydew as a growth medium and dispersal mechanism for HEBPs. A leafhopper which has ingested S. enterica or EcO157 will be housed on non-inoculated leaves along with non-inoculated insects which will be tested over time for the presence of HEBPs. Since females tend to kick excretions away to protect their eggs, we will also examine contamination of non-inoculated insects with regard to the sex of the inoculated insect.</p><p>In Objective 2, we will determine if plant-immunity related hormones influence HEBP populations. This will be carried out by 1) analysis of the expression of JA and SA inducible marker genes in plants inoculated with S. enterica or EcO157 with and without insect infestation, 2) assessment of the accumulation of endogenous JA and SA in plants infested with phytophagous insects and inoculated with HEBPs, and 3) evaluation of HEBP survival and insect performance in plants deficient in JA or SA compared to wild-type.</p><p>In Objective 3, we will use bacterial mutant analysis to identify the essential S. enterica insect colonization factors, characterize the mechanisms employed, and compare strategies among HEBPs.</p>