Effects of gibberellic acid and AMO-1618 on the development of vegetative systems in generatively matured thalli of Chara vulgaris L.

Abstract

Effects of GA₃ (10^-11-10^-4 M) and AMO-1618 (10^-6-10^-4 M) on the development of generatively matured thalli of Chara vulgaris were investigated during 21-day culture of plants in axenic conditions. It has been found that in the main bud the divisions of apical cells of the thalli are not stimulated by GA₃, whereas in the lateral buds the cell divisions are stimulated by higher GA₃ concentrations. Subsequent mitotic activity of the apical cells in the branches of the main axis is not stimulated by GA₃, whereas the lateral buds of these branches are activated. The development of rhizoids in younger nodes is accelerated by high GA₃ concentrations. The elongation of the polynuclear, internodal cells of the main axis and that of pleuridia are inhibited proportionally to the GA₃ concentration. AMO-1618 stimulates the development of new nodes, elongation of internodes and delays the activation of lateral buds as well as the formation of rhizoids. These results suggest that the GA₃-induced inhibition of elongation of the thalli and diminution of the apical domination is connected with a high level of endogenous gibberellins in the generatively matured thallus.