Figure 3.
β‐Glucuronidase (GUS) assays for the determination of the quantitative evaluation of in planta promoter activity of strains ResPlipA, ResPlipArev and ResPhrpA. Tomato plants were inoculated by the dip method with inoculum concentrations of 108 colony‐forming units (cfu)/mL (A) or 106 cfu/mL (B). GUS activity in leaf extracts was determined 24, 48 and 72 h after inoculation (hai) in (A), and 48, 72 and 96 hai in (B), using the fluorometric substrate 4‐methylumbelliferyl‐β‐d‐glucuronide (MUG). Data represent averages and standard deviations (SDs) of GUS activity per cfu (three replicates per treatment per time point, each replicate being composed of five leaf discs) of one experiment of two with similar results. Different letters in each graph indicate significant differences (P= 0.05) among treatments according to Tukey–Kramer test and analysis of variance (anova). MU, 4‐methylumbelliferine.