Location: Produce Safety and Microbiology Research
Project Number: 2030-42000-052-010-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Oct 1, 2020
End Date: Dec 30, 2021
1. Identify genetic determinants involved in the apoplastic and epiphytic colonization of produce by Salmonella enterica and the role of plant systematic 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 y Illuminia HiSeq. Sequence analysis will be performed at UCI to identify mutants that have a different proportional repesentation among the output libraries of 1) different treatments (SAR-induced vs non-induced plants) and 2) different leaf habitants (phllosphere 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 detection mutants provided by UCI.