title: Effects of plant antimicrobial phenolic compounds on virulence of the genus Pectobacterium.
abstract: Pectobacterium spp. are among the most devastating necrotrophs, attacking more than 50% of angiosperm plant orders. Their virulence strategy is based mainly on the secretion of exoenzymes that degrade the cell walls of their hosts, providing nutrients to the bacteria, but conversely, exposing the bacteria to plant defense compounds. In the present study, we screened plant-derived antimicrobial compounds, mainly phenolic acids and polyphenols, for their ability to affect virulence determinants including motility, biofilm formation and extracellular enzyme activities of different Pectobacteria: Pectobacterium carotovorum, P. brasiliensis, P. atrosepticum and P. aroidearum. In addition, virulence assays were performed on three different plant hosts following exposure of the bacteria to selected phenolic compounds. These experiments showed that cinnamic, coumaric, syringic and salicylic acids and catechol can considerably reduce disease severity, ranging from 20 to 100%. The reduced disease severity was not only the result of reduced bacterial growth, but also of a direct effect of the compounds on important bacterial virulence determinants, including pectolytic and proteolytic exoenzyme activities, that were reduced by 50-100%. This is the first report revealing a direct effect of phenolic compounds on virulence factors in a wide range of Pectobacterium strains.
authors.affiliation: Department of Plant Pathology and Microbiology and the Otto Warburg Minerva Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel; Department of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. Electronic address: janakra.joshi@mail.huji.ac.il.
authors.forename: Janak Raj
authors.initials: JR
authors.lastname: Joshi
authors.affiliation: Department of Plant Pathology and Microbiology and the Otto Warburg Minerva Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel. Electronic address: saul.burdman@mail.huji.ac.il.
authors.forename: Saul
authors.initials: S
authors.lastname: Burdman
authors.affiliation: Department of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. Electronic address: lipsky@volcani.agri.gov.il.
authors.forename: Alexander
authors.initials: A
authors.lastname: Lipsky
authors.affiliation: Department of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. Electronic address: irisy@volcani.agri.gov.il.
authors.forename: Iris
authors.initials: I
authors.lastname: Yedidia
mesh_terms: D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D044043:Pectobacterium / Q000187:drug effects* / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology; D016973:Pectobacterium carotovorum / Q000187:drug effects / Q000472:pathogenicity; D010935:Plant Diseases / Q000382:microbiology; D010944:Plants / Q000737:chemistry* / Q000187:drug effects / Q000382:microbiology; D059808:Polyphenols / Q000302:isolation & purification / Q000494:pharmacology*; D014774:Virulence / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D059808:Polyphenols
keywords: Biofilm; Motility; Pectobacterium; Phenolics; Plant cell wall degrading enzymes; Virulence determinants