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. 2019 Oct 7;21(1):139–144. doi: 10.1111/mpp.12876

Figure 1.

Figure 1

GacA negatively regulates type III secretion in Pseudomonas syringae pv. tomato DC3000. (A) GFP fluorescence of DC3000 and AC811 avrPtopromoter:gfp reporter strains. Bacteria were incubated in minimal medium (MM) with 10 mM fructose and 400 µM citric acid. Graphed are means ± SE of GFP fluorescence normalized to OD600 and background fluorescence from empty vector strains, n = 4. Data are representative of three independent experiments. Asterisks denote significant difference between strains based on t‐test, ***P < 0.001. (B) AvrPto levels in DC3000 and AC811 incubated in MM supplemented with 200 µM citric acid and/or 10 mM fructose as indicated. Upper panel is immunoblot detection of AvrPto in treated bacteria after 5 h. Lower panel is Coomassie Brilliant Blue (CB) staining of blot as a loading control. (C) GFP fluorescence of DC3000 and ΔgacA‐1 carrying avrPto promoter:gfp reporter plasmids. Bacteria were incubated in MM with 10 mM fructose and 400 µM citric acid. Graphed are means ± SE of GFP fluorescence normalized to OD600 and background fluorescence from empty vector strains, n = 4. Data are representative of three independent experiments. Asterisks denote significant difference between strains based on t‐test, ***P < 0.001. (D) cAMP levels in Arabidopsis leaves infected with DC3000 or AC811 strains carrying an AvrPto‐adenylate cyclase reporter (AvrPto‐CyaA). Graphed data are means ± SE of cAMP levels in infected tissue sampled at 3 and 5 h post‐infection (hpi), normalized to total protein content of samples. Data were pooled from three independent experiments, n = 9. **P < 0.01; *P < 0.05 based on t‐test.