Figure 1. Peroxidases are involved in the inhibition of the stomatal opening of cpr5 and acd6 mutants. Four- to 6-week-old leaves were floated on buffer solution, containing 50 mM KCl, 50 μM CaCl₂, 10 mM MES-Tris, pH 6.15. The stomatal aperture was measured after 2 h of incubation in the dark condition (Initial) and after 2 h of incubation in the dark condition and 3 h of incubation under light (Control). SHAM (2 mM), azide (1 μM), or DPI (20 μM) was added to the assay solution 30 min before light condition. Values are means ± SE (n ≥ 3). * indicates a significant difference from Control (P < 0.05), which is determined by the Student t-test.