Ultrastructural changes of the root tip cells in barley induced by a comparatively low concentration of aluminum

Abstract

Abstract Ultrastructural changes of the root tip cells in barley induced by the application of 0.05 mol m-3 Al at pH 4.0 were investigated. The structure of the cells in the peripheral cap was altered within 1 h of aluminum treatment. The cells of the epidermis also showed similar morphological alterations to those of the peripheral cap cells within 12 h of aluminum treatment. The effects of aluminum on the cells of the peripheral cap and epidermis were characterized by the increase in the number of vesicles, unevenness of the surface of the protoplasm, increased electron density of the cytoplasmic matrix and swelling of the endoplasmic reticulum. Thickening of the cell wall, and accumulation of small vesicles around the Golgi apparatus were also observed in the cells of the peripheral cap treated with aluminum. Aluminum treatment for 12 to 24 h induced a progressive vacuolation in the cells of the peripheral cap, cap columella, apical meristem, cortex and stele.