title: Plant flavonoids target Pseudomonas syringae pv. tomato DC3000 flagella and type III secretion system.
abstract: Flavonoids are among the most abundant plant secondary metabolites involved in plant protection against pathogens, but micro-organisms have developed resistance mechanisms to those compounds. We previously demonstrated that the MexAB-OprM efflux pump mediates resistance of Pseudomonas syringae pv. tomato (Pto) DC3000 to flavonoids, facilitating its survival and the colonization of the host. Here, we have shown that tomato plants respond to Pto infection producing flavonoids and other phenolic compounds. The effects of flavonoids on key traits of this model plant-pathogen bacterium have also been investigated observing that they reduce Pto swimming and swarming because of the loss of flagella, and also inhibited the expression and assembly of a functional type III secretion system. Those effects were more severe in a mutant lacking the MexAB-OprM pump. Our results suggest that flavonoids inhibit the function of the GacS/GacA two-component system, causing a depletion of rsmY RNA, therefore affecting the synthesis of two important virulence factors in Pto DC3000, flagella and the type III secretion system. These data provide new insights into the flavonoid role in the molecular dialog between host and pathogen.
authors.affiliation: Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain.
authors.forename: Paola
authors.initials: P
authors.lastname: Vargas
authors.forename: Gabriela A
authors.initials: GA
authors.lastname: Farias
authors.forename: Joaquina
authors.initials: J
authors.lastname: Nogales
authors.forename: Harold
authors.initials: H
authors.lastname: Prada
authors.forename: Vivian
authors.initials: V
authors.lastname: Carvajal
authors.forename: Matilde
authors.initials: M
authors.lastname: Barón
authors.forename: Rafael
authors.initials: R
authors.lastname: Rivilla
authors.forename: Marta
authors.initials: M
authors.lastname: Martín
authors.forename: Adela
authors.initials: A
authors.lastname: Olmedilla
authors.forename: María-Trinidad
authors.initials: MT
authors.lastname: Gallegos
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D058947:Bacterial Secretion Systems; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D005407:Flagella / Q000378:metabolism*; D005419:Flavonoids / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D018551:Solanum lycopersicum / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D026901:Membrane Transport Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D044224:Pseudomonas syringae / Q000378:metabolism* / Q000472:pathogenicity; D012333:RNA, Messenger / Q000096:biosynthesis; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D005419:Flavonoids; C091100:GacA protein, Bacteria; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D037521:Virulence Factors; C074165:lemA protein, bacterial