Energy supply for stomatal opening in epidermal strips of Commelina benghalensis

Abstract

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 α-ketoglutarate) in CO₂-free air in ght as well as in darkness. The enhancement by light of stomatal opening was prevalent under nitrogen or in the presence of the respiratory Inhibitors (sodim azide and olgomycin). Respiratory inibitors decreased the opening in light or darness 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 nitrgen. The results suggest that oxidative phosphorylation is a basic source of energy for stomatal opening, although photopbosphorylation could be an energy source.