Motility-mediated regulation of virulence in Pseudomonas syringae

Abstract We have investigated Pseudomonas syringae pv. tabaci –plant interactions using a large variety of virulence-related mutants. A flagellin-defective mutant, Δ fliC , lost flagellar motility and the ability to produce N -acyl homoserine lactones; it had reduced ability to cause disease symptoms, but the expression of genes encoding a multidrug efflux pump transporter, mexEFoprN , was activated. A type IV pili (T4P)-defective mutant, Δ pilA , lost swarming motility, had reduced expression of hrp -related genes and virulence toward the host tobacco plant, but expression of the genes encoding another multidrug efflux pump transporter, mexABoprM , was activated. These results suggest that the genes regulating flagella- and T4P-mediated motilities also regulate expression of other virulence-related genes.