Effects of Colchicine, Vinblastine, Cytochalasin B and Phalloidin on the Seismonastic Movement of<i>Mimosa pudica</i>Leaf and on Motor Cell Ultrastructure

Abstract

Fleurat-Lessard, P., Roblin, G., Bonmort, J. and Besse, C. 1988. Effects of colchicine, vinblastine, cytochalasin B and phalloidin on the seismonastic movement of Mimosa pudica leaf and on motor cell ultrastructure.—J. exp. Bot. 39: 209–221. Colchicine at 1 × 10−3 mol dm−3 does not affect the seismonastic movement of Mimosa pudica leaves but disrupts microtubules in motor cells. Vinblastine at 5 × 10−3 mol dm−3 does not affect this movement and partly disrupts microtubules. Vinblastine at 1 × 10−4 mol dm−3 always disrupts microtubules, even after a 12 h reversibility when the movement is restored. These drugs, applied at the same respective concentrations, do not alter cytoplasmic and vacuolar fibrils. Cytochalasin B and phalloidin alter the seismonastic movement of Mimosa leaves when applied at concentrations of 1.25 × 10−3 and 2.4 × 10−4 mol dm−3 respectively. These drugs, used at the same respective concentrations, also affect the motor cell structure and, in particular, modify the arrangement and the structure of the fibrils but they do not destroy the microtubules. These data suggest that microtubules are not directly involved in the seismonastic reaction whereas fibrils, formed by thin (3.0 nm wide) filaments, may be implicated in this reaction.