Analysis of nonhost resistance responses of Arabidopsis using seedling flood-inoculation assay. A. Phenotypes of Arabidopsis seedlings flood-inoculated with nonhost pathogens including Pseudomonas syringae pv. tabaci (Psta), Pseudomonas syringae pv. glycinea (Psg), Pseudomonas syringae pv. tomato T1 (Pst T1) and Xanthomonas campestris pv. vesicatoria (Xcv) at a concentration of 5 × 107 or 5 × 106 CFU/ml. Photographs were taken at 1 or 3 dpi. B. Ion leakage from Arabidopsis seedlings flooded with water (mock) or Psta, Psg, Pst T1 or Xcv at high bacterial density (5 × 107 CFU/ml) at 1 dpi. Bars show the percentage of total ions. C. Bacterial populations of Pst DC3000, Psta, Psg, Pst T1 or Xcv in Arabidopsis were quantified at 0 and 3 dpi. Vertical bars indicate the standard errors for three independent experiments.