title: Bacterial subfamily of LuxR regulators that respond to plant compounds.
abstract: Pseudomonas fluorescens are rhizobacteria known for their biocontrol properties. Several antimicrobial functions are crucial for this process, and the experiments described here investigate the modulation of their expression during the plant-bacterium interaction. The role of a LuxR family regulator in interkingdom signaling has been investigated using genome-scale transcriptome analysis, gene promoter studies in vivo and in vitro, biocontrol assays, and response to plant compounds. PsoR, a LuxR solo or orphan regulator of P. fluorescens, was identified. PsoR is solubilized and activates a lux-box-containing promoter only in the presence of macerated plants, suggesting the presence of a plant molecule(s) that most likely binds to PsoR. Gene expression profiles revealed that genes involved in the inhibition of plant pathogens were affected by PsoR, including a chitinase gene, iron metabolism genes, and biosynthetic genes of antifungal compounds. 2,4-Diacetylphloroglucinol production is PsoR dependent both in vitro and in vivo. psoR mutants were significantly reduced for their ability to protect wheat plants from root rot, and damping-off caused by Pythium ultimum infection. PsoR most likely senses a molecule(s) in the plant and modulates expression of genes that have a role in biocontrol. PsoR and related proteins form a subfamily of LuxR family regulators in plant-associated bacteria.
authors.affiliation: Bacteriology Group, International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy.
authors.forename: Sujatha
authors.initials: S
authors.lastname: Subramoni
authors.forename: Juan F
authors.initials: JF
authors.lastname: Gonzalez
authors.forename: Aaron
authors.initials: A
authors.lastname: Johnson
authors.forename: Maria
authors.initials: M
authors.lastname: Péchy-Tarr
authors.forename: Laurène
authors.initials: L
authors.lastname: Rochat
authors.forename: Ian
authors.initials: I
authors.lastname: Paulsen
authors.forename: Joyce E
authors.initials: JE
authors.lastname: Loper
authors.forename: Christoph
authors.initials: C
authors.lastname: Keel
authors.forename: Vittorio
authors.initials: V
authors.lastname: Venturi
mesh_terms: D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology*; D011551:Pseudomonas fluorescens / Q000187:drug effects* / Q000235:genetics; D011775:Pythium / Q000472:pathogenicity*; D014157:Transcription Factors / Q000378:metabolism*; D014908:Triticum / Q000737:chemistry / Q000276:immunology* / Q000382:microbiology*
chemical_list: D014157:Transcription Factors