The response of apical meristems of primary roots of Vicia faba L. to colchicine treatments

The effects of 0.5% and 0.025% solutions of colchicine on the passage of cells through the mitotic cycle in apical meristems of primary roots of Vicia faba have been examined. Both treatments affected cell progression through the mitotic cycle in the same way: S and G1 were shorter, and G2 and mitosis longer, than the corresponding control values. The duration of the various phases of the mitotic cycle were similar to those reported previously for apical meristems of lateral roots though cycle time itself was longer. Recovery of root proliferating tissues from colchicine-induced inhibition of growth is correlated with the presence of quiescent cells. Meristems which have no quiescent cells do not recover from eolchicine treatment, while meristems which contain many quiescent cells recover faster than those which contain few. The growth fraction and the proportion of proliferating cells with a short cycle time are linearly related to the duration of the S period in root meristems.