FIGURE 6.

ALA inhibits H₂O₂- and Ca²⁺-induced stomatal closures. (A,B) ALA inhibits exogenous H₂O₂-induced stomatal closure. Isolated epidermal strips of wild-type Arabidopsis were incubated in either buffer alone or containing 200 μM H₂O₂, 200 μM H₂O₂ + 0.5 mg L^-1 ALA, respectively, while P₃ peels were incubated in either buffer or containing 200 μM H₂O₂ at 25°C under light (240 μmol m^-2 s^-1). One hour later, images (A) were recorded and stomatal apertures (B) were determined. (C,D) ALA inhibits exogenous Ca²⁺-induced stomatal closure. Isolated epidermal strips of wild-type Arabidopsis were incubated in either buffer alone or containing 2 mM CaCl₂, 2 mM CaCl₂ + 0.5 mg L^-1 ALA, respectively, while P₃ peels were incubated in either buffer or containing 2 mM CaCl₂ at 25°C under light (240 μmol m^-2 s^-1). One hour later, images (C) were recorded and stomatal apertures (D) were determined. Images (A,C) were recorded by light microscopy (Nikon TE100, 400×), using a fitted camera (MShot Digital Imaging System). Scale bar: 10 μm. Values are the means of 90 measurements ± SE from three independent experiments. Different small letters represent significant difference between treatments (P < 0.01).