Figure 6. Resistance induction assays against Botrytis cinerea and Pseudomonas syringae pv. tomato (Pst).

Arabidopsis detached leaves were treated on the lower surface with 150 µM CP, sterile distilled water (control) or 0.1% chitosan for 24 h before pathogen inoculation. (A) B. cinerea strain PM10 was inoculated by placing a single 10-µl drop of a suspension 2×10⁵ conidia ml⁻¹ in 1% Sabouraud Maltose Broth on a side of the middle vein. Infected leaves were incubated for 3 days at 22°C before taking photos and measuring the lesion size. (B) Pst strain DC3000 was inoculated by placing a single 10-µl drop of a suspension 10⁸ colony-forming units (CFU) ml⁻¹ (OD₆₀₀ = 0.2) in sterile distilled water containing 0.02% Silwet L-77 on a side of the middle vein. Infected leaves were incubated for 3 days at 28°C before taking photos and determining bacterial titer. (C) Measurement of the lesion diameter (mm) ± SD after 3 days of incubation with B. cinerea (n = 8). (D) Counting of CFU mg⁻¹±SD after 3 days of incubation with Pst DC3000 (n = 8). Statistically significant differences among treatments are indicated at P≤0.05.