Figure 3.

Initial responses to red light in guard cells in whole leaves. Mature leaves were harvested from dark-adapted plants (0 min) and kept in the dark (Dk) for 60 min or illuminated with red light (RL; 600 µmol m^–2 s^–1) for the indicated times. A, Immunohistochemical detection of the phosphorylation of PM H⁺-ATPase in guard cells using anti-pThr antiserum. Leaves were illuminated for 5, 10, 30, or 60 min. Typical fluorescence and bright-field images (top) and quantification of the fluorescence intensities (bottom) are shown. Arrowheads indicate guard cells. Data represent means of relative values from three independent measurements with sd. Daggers denote that the mean is statistically significantly higher than at 0 min set to 1. N.S., Not significant (one-tailed one-sample Student’s t test: ^†, P < 0.05; ^††, P < 0.005; and N.S., P > 0.07). Bar = 50 µm. B, Measurement of red light-induced stomatal opening. Leaves were illuminated for 15, 30, 45, or 60 min. Data represent means of representative values from three independent measurements with sd. Asterisks denote statistically significant increases of the mean compared with that of 0 min (one-tailed Dunnett’s test: *, P < 0.05; **, P < 0.01; ***, P < 0.005; and N.S., P = 0.717).