Energy Supply for Stomatal Opening in Epidermal Strips of Commelina benghalensis

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Abstract
The influence of light or darkness on stomatal opening in epidermal strips of C. benghalensis was evaluated in the presence or absence of O2 and/or metabolic inhibitors. Opening was restricted in N and was promoted by NADH and acids of the tricarboxylic acid cycle (succinate and .alpha.-ketoglutarate) in CO2-free air in light and in darkness. The enhancement by light of stomatal opening was prevalent under N or in the presence of the respiratory inhibitors (sodium azide and oligomycin). Respiratory inhibitors decreased the opening in light or darkness under CO2-free air but exhibited no effect under N; phosphorylation uncouplers were inhibitory in light or darkness under both CO2-free air and N. Apparently oxidative phosphorylation is a basic source of energy for stomatal opening, although photophosphorylation could be an energy source.