Fig 5.

Upregulation of rhlA and fliC in cells of P. syringae grown on paper discs. GFP fluorescence of WT P. syringae carrying either a constitutively expressed gfp reporter gene (p519n-gfp), a fusion of a gfp reporter gene with the promoter region of rhlA (pPrhlA-gfp), or a fusion of a gfp reporter gene with the promoter region of fliC (pPfliC-gfp). Strains were assayed after overnight growth either on agar plates (white bars) or on filter paper discs placed on agar plates (gray bars). The error bars represent the standard deviations of the mean cell-normalized GFP fluorescence. Promoter expression was significantly different in the strain grown on hydrated paper compared to a plate-grown strain at a confidence level of P < 0.05 (∗) or P < 0.01 (∗∗) as determined by a t test.