Nucleolar dissolution induced by aluminium in root cells of Allium

Acidification of natural waters and soils leads to the release of aluminium, causing damage to living organisms. In the present experiments, growing roots of Allium cepa L. were exposed to water solution of AICl3 in concentrations from 10-5 to 10-1M. After a few days in concentrations around 10-3M. the roots showed macroscopical signs of being affected; they became bent and their terminal portions tended to loosen and drop off. Microscopically, the affected zone of the roots revealed a new cellular phenomenon: Nucleolar material was extruded from the nuclei into the cytoplasm forming elongated, rod-like bodies, which eventually divided into two, one distinct body at each pole of the cell. The derivation of these bodies from the nucleoli was further strengthened by the observation that they absorbed light green differentially Apparently, aluminium has a specific effect on the nucleoli of certain root cells.