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Short Communication

Energy Supply for Stomatal Opening in Epidermal Strips of Commelina benghalensis¹

Centro de Estudios Fotosinteticos y Bioquimicos (CEFOBI), Suipacha 531, 2000 Rosario, Argentina

The influence of light or darkness on stomatal opening in epidermal strips of Commelina benghalensis was evaluated in the presence or absence of O₂ and/or metabolic inhibitors. Opening was restricted in nitrogen and was promoted by NADH and acids of the tricarboxylic acid cycle (succinate and -ketoglutarate) in CO₂-free air in light as well as in darkness. The enhancement by light of stomatal opening was prevalent under nitrogen 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 nitrogen, whereas phosphorylation uncouplers were inhibitory in light or darkness under both CO₂-free air and nitrogen. The results suggest that oxidative phosphorylation is a basic source of energy for stomatal opening, although photophosphorylation could be an energy source.

¹ The work was initiated in the Department of Botany, Sri Venkateswara University, Tirupati, India.