Fig 4. Amino acid transport and T3SS-inducing functions of the aat/aau locus are genetically separable.
(A) Growth of DC3000 and ΔaatP strains in M9 minimal medium supplemented with 10 mM glutamate. Graphed are means of optical density at λ = 600 nm (OD600), n = 3. (B) GFP fluorescence from DC3000, ΔaatP, and ΔaauR avrRpm1promoter:gfp reporter strains cultured in minimal medium (MM) with 10 mM fructose (open bars) or 10 mM fructose and 200 μM glutamate (filled bars) for 6 hours. Graphed are means ± SE of GFP fluorescence normalized to OD600 and background fluorescence from empty vector strains; n = 4. Asterisk denotes significant difference based on t-test comparison with DC3000, P < 0.01; abbreviation ns is not significant, α = 0.05. (C) GFP fluorescence of Arabidopsis leaf tissue syringe-infiltrated with 1 x 108 cfu/mL of DC3000, ΔaatP or ΔaauR strains each carrying a hrpLpromoter:gfp reporter plasmid. Graphed are means ± SE of GFP fluorescence from infected tissue 6 hours post-infection, n = 4. Asterisk denotes significant difference based on t-test comparison with DC3000, P < 0.01; abbreviation ns is not significant, α = 0.05. (D) 1 x 106 cfu/mL of DC3000, ΔaatP or ΔaauR strains were syringe-infiltrated into Arabidopsis leaves. Leaf bacteria populations were enumerated on day 0 and day 3 by serial dilution plating of leaf extracts. Graphed are log-transformed means ± SE of bacteria from infected plants, n = 3 for day 0 and n = 4 for day 3. Small-case letters denote significance groupings based on pairwise t-tests, P < 0.05. Results in all panels are representative of 3 independent experiments.