Location: Produce Safety and Microbiology Research
Project Number: 2030-42000-050-03-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 25, 2015
End Date: Sep 24, 2020
1. Identify genetic determinants involved in the apoplastic and epiphytic colonization of produce by Salmonella enterica and the role of plant systemic acquired resistance (SAR) in S. enterica persistence on produce. 2. Characterize the function of S. enterica plant colonization genes identified with mutant library screens and barcoded sequencing 3. Use single deletion mutants of S. enterica to further characterize the interaction of the human pathogen with the plant basal plant defense system.
S. enterica mutant input libraries, provided by the University of California, Irvine (UCI), will be screened in leafy vegetables by inoculation and recovery of leaf apoplastic and epiphytic bacterial cells at the ARS. Plants will have been treated, or not, with SAR-inducing compounds. The output libraries will be sent to UCI for DNA extraction and barcoding, and each tag will be sequenced by Illumina HiSeq. Sequence analysis will be performed at UCI to identify mutants that have a different proportional representation among the output libraries of 1) different treatments (SAR-induced vs non-induced plants) and 2) different leaf habitats (phyllosphere vs apoplast) in comparison with that in the input library. Candidate genes that may have a role in apoplastic or epiphytic colonization of S. enterica, and/or in the S. enterica response to SAR, will be characterized and their function in plant colonization will be assessed using deletion mutants provided by UCI.