title: N-acyl-homoserine-lactone quorum sensing in tomato phytopathogenic Pseudomonas spp. is involved in the regulation of lipodepsipeptide production.
abstract: Pseudomonas corrugata and Pseudomonas mediterranea are two closely related phytopathogenic bacteria both causal agents of tomato pith necrosis. P. corrugata produces phytotoxic and antimicrobial cationic lipodepsipeptides (LDPs) which are thought to act as major virulence factors. Previous studies have demonstrated that P. corrugata CFBP 5454 has an N-acyl homoserine lactone (AHL) quorum sensing (QS) system PcoI/PcoR and that LDP production occurs at high population densities. No molecular studies on virulence have thus far been reported for P. mediterranea. In this study, we show that P. mediterranea also produces LDPs as well as possessing an AHL-dependent QS system, designated PmeI/PmeR, which is highly homologous to the PcoI/R system of P. corrugata producing and responding to C(6)-AHL. Downstream of pmeI, a partial DNA sequence revealed the presence of a homolog of the rfiA gene of P. corrugata which encodes a transcriptional regulator involved in bacterial virulence. Pathogenicity tests and MALDI-TOF spectra of wild-type strains of both bacterial species and their respective QSs and rfiA derivative mutants revealed that, in the absence of LDPs, the strains induce very weak symptoms indicating that LDPs may act as major virulence factors. Mutational analysis of both QS systems suggests that their mode of action is in places different.
authors.affiliation: Science and Technology Park of Sicily, z.i. Blocco Palma I, Str.le Lancia 57, 95121 Catania, Italy. glicciardello@pstsicilia.org
authors.forename: Grazia
authors.initials: G
authors.lastname: Licciardello
authors.forename: Cinzia P
authors.initials: CP
authors.lastname: Strano
authors.forename: Iris
authors.initials: I
authors.lastname: Bertani
authors.forename: Patrizia
authors.initials: P
authors.lastname: Bella
authors.forename: Alberto
authors.initials: A
authors.lastname: Fiore
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Fogliano
authors.forename: Vittorio
authors.initials: V
authors.lastname: Venturi
authors.forename: Vittoria
authors.initials: V
authors.lastname: Catara
mesh_terms: D054742:Acyl-Butyrolactones / Q000378:metabolism*; D023181:Antimicrobial Cationic Peptides / Q000235:genetics* / Q000378:metabolism; D047630:Depsipeptides / Q000096:biosynthesis*; D008074:Lipoproteins / Q000096:biosynthesis*; D018551:Solanum lycopersicum / Q000382:microbiology; D009154:Mutation; D010641:Phenotype; D010935:Plant Diseases / Q000382:microbiology*; D011401:Promoter Regions, Genetic; D011549:Pseudomonas / Q000235:genetics / Q000378:metabolism*; D053038:Quorum Sensing / Q000235:genetics*; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D054742:Acyl-Butyrolactones; D023181:Antimicrobial Cationic Peptides; D047630:Depsipeptides; D008074:Lipoproteins; D037521:Virulence Factors