Stomatal opening induced by acetylcholine is associated with cytoskeletal components

Acetylcholine (Ach) is a key component of animal cholinergic system. Recent experiments demonstrated that Ach, choline acetyltransferase, acetylcholinesterase and Ach receptors are present in all parts of plants and have many functions, including inducing stomatal movement. The authors' previous work has evidenced that microtubules and microfilaments are involved in regulating both stomatal closing and opening. The present investigation is to determine whether stomatal opening induced by Ach is associated with microtubules and microfilaments, The results showed that Ach could induce stomatal opening of Vicia faba L, with or without addition of KCl in the dark. Ach also stimulated protoplast swelling in a K+-free solution in the dark. However, the induction was partially suppressed when the strips and protoplasts were pretreated with either cytochalasin B, an inhibitor of F-actin polymerization, or oryzalin, an inhibitor of plant microtubule polymerization. Thus, our data suggest for the first time that stomatal opening induced by Ach is associated with the dynamics of microtubules and microfilaments.