A seedling flood-inoculation assay for the analysis of virulence factors in the pathogenicity of Pseudomonas syringae pv. tomato DC3000 ( Pst DC3000) interactions with Arabidopsis. A. Disease phenotype of Arabidopsis seedlings flood-inoculated with a bacterial suspension of Pst DC3000, COR- mutant DB29 and type III secretion system (TTSS) mutant hrcC at a concentration of 5 × 106 CFU/ml. Mock-inoculated seedlings were flooded with sterile distilled H2O containing 0.025% Silwet L-77. Photographs were taken 3 dpi. B. Bacterial populations of Pst DC3000, DB29 and hrcC mutants in Arabidopsis. Bacterial populations were quantified at 0, 2 and 4 dpi. Vertical bars indicate the standard errors for three independent experiments. C. Ion leakage from Arabidopsis seedlings flooded with water (mock) or Pst DC3000, DB29 and hrcC mutants. The measurements were taken 3 dpi. Values show the percentage of total ions.