Fig. 5

GT and LR show similar bacterial population declined, but variable levels of SA-dependent immune responses. (A) Escherichia coli O157:H7 and Salmonella enterica ser. Typhimurium 14028s population kinetics in leaves of Green Towers (GT), Lollo Rossa (LR), and Red Tide (RT). Apoplastic bacterial population size was estimated by serial dilution plating method using surface sterilized leaves collected at 0-, 3- and 7-days post inoculation. Three plants were used for each sampling point and graphs show combined data from two independent experiments (n = 6). (B) Temporal production of reactive oxygen species after elicitation with mock (black lines) or bacterial solutions. The curve peak (16–18 min after elicitation) was used to assess statistically significant differences among the genotypes. (C) Callose deposition was quantified as the area covered by deposits (mm²) over cm² leaf at 24 h after inoculations Graphs in B and C show the peak value (n = 24) or callose deposition area (n = 3), respectively, of bacterium-treated samples normalized by the mock-treated samples. Different letters on the top of adjacent boxes (i.e., within the plant genotype or days post inoculation) indicate significant statistical differences among the means calculated with ANOVA followed by Tukey’s test (α = 0.05)