ALUMINUM TOLERANCE OF ROOT CAP CELLS

The response of Aristida junciformis Trin et Rupr. roots after 48 h treatment with 12 ppm Al was examined. It was shown that roots of A. junciformis were able to withstand high concentrations of soluble Al. Some typical ultrastructural symptoms of Al toxicity, such as damage to the root apex, reduced mucilage production, the alteration in the columnar arrangement of root cap cells, the disruption of the polarity of the nuclei and amyloplasts in the central columella, damage to and a reduction in the number of dictyosomes in the peripheral cap cells and an increased incidence of vacuolation in cells immediately proximal to the root meristem, were present but at a low level. An unusual pattern of secretory vesicle production by the Golgi apparatus was noted which may give valuable clues as to the physiology of Al-tolerant plants and stress-tolerant plants in general.