FC reduces cytosolic pH in guard cells during ABA-induced stoamatal closure. Guard cells of Vicia faba shown in image (A) were treated with MES/KCl buffer alone, (B) with 10 μM ABA, (C) 0.1 μM FC, (D) 0.1 μM FC +10 μM ABA for 3 h at 25°C. The guard cells shown in image (a–d) are the representative of guard cells shown in image (A–D). (E) The average fluorescence intensity of guard cells in images (A–D), data are means ± s.e. Values in (D) with different letters are significantly different at P <0.05 based on Fisher LSD post hoc test. Other explanations are the same as in Figure 2.