Suppression of the stomatal opening by morphactins in isolated epidermal strips

The effects of three morphactins, chlorflurenol, flurenol andEMD 7301 W, were examined on the stomatal aperture using isolatedepidermal strips of Commelina benghalensis. Morphactins produced,a striking decrease in the stomatal opening in light but hadno effect on stomatal closure in darkness. Various catalystsand inhibitors of photophosphorylation had no influence on themorphactin-induced stomatal closure. The stimulatory effectsof ATP, pyruvate and KC1 on stomatal opening were suppressedby the morphactins. The cytokinin, benzyladenine stimulatedthe stomatal opening even in the presence of a morphactin. Theinfluence of morphactins on the stomatal aperture closely resembledthe effect of abscisic acid. ¹Present address: Central Plantation Crops Research Institute,Regional Station, Vittal 574243, Karnataka, India. (Received September 16, 1975; )