The Effect of Aluminium and some other Trivalent Metal Cations on Cell Division in the Root Apices of Allium cepa

The morphological abnormalities of root systems treated withaluminium salts are such that they may be explained by an inhibitoryeffect of aluminium on either cell division or cell extension.Elongation of onion roots was completely inhibited after 6–8hours' treatment with 10^–3and 10^–4M aluminium sulphatesolutions. Examination of aceto-carmine squashes of root apicesshowed that the cessation of root elongation was closely correlatedwith the disappearance of mitotic figures. The time taken forcomplete inhibition of cell division and root elongation wasdependent on the ambient temperature. Abnormalities of the mitoticapparatus were not seen. Treatment of onion roots with othertrivalent metals, gallium, indium, and lanthanum, produced similarresults. It is concluded that some mechanism associated with cell divisionis highly sensitive to aluminium and is permanently damagedby short exposures. The results are not satisfactorily explainedby the well-known effect of aluminium on phosphorus uptake.