A, Stomatal aperture in Col-0 leaves surface-inoculated with mock or DC3118 at 108 CFU/ml under ambient or high RH; B, Stomatal aperture in Col-0 leaves surface-inoculated with different treatments under high RH. Data in A and B represent means of 120 stomatal aperture measurements from three replicates ±SEM. Asterisks denote significant differences as analyzed by two-tailed t-test (***, P<0.001; ns, no statistical difference); C, Progression of disease symptom in Col-0 plants with the following treatments: (I) RH = 60%, mock; (II) RH≥90%, mock; (III) RH = 60%, DC3118 (108 CFU/ml); (IV) RH≥90%, DC3118 (108 CFU/ml); (V) RH≥90%, DC3118 (108 CFU/ml) + ABA (20 µM).