| Abstract: | Closure of stomata of Commelina communis L. leaf epidermis causedby abscisic acid (ABA) was inhibited by sodium azide, potassiumcyanide and hypoxic conditions. Azide was more effective thancyanide at low concentrations, but the cyanide effect couldbe enhanced by addition of salicylhydroxamic acid, providingindirect evidence for cyanide-resistant respiration in epidermaltissue. Azide also inhibited ABA-induced closure of ‘isolated’ stomata and shrinkage of guard cell protoplasts.The results indicate that metabolic energy is required for ABAaction involving solute loss from the guard cells. Possiblemechanisms of action are discussed. |
