Seeds of V. faba L. cv.
House Ryousai were purchased from Kyouwa Seed Co. (Chiba, Japan).
Plants were grown in a growth chamber for 5 to 8 weeks at 23 °C under a 16 h light/8 h dark cycle (50 mmol m-2 s-1) regime.
Epidermal strips were peeled from the abaxial surface from young,fully expanded leaves.
For stomatal opening, epidermal strips were floated in a Petri dish (diameter, 9 cm) containing the opening medium