Localisation of aluminium in root tips of Zea mays and Vicia faba

Monocot species and dicot species differ widely in the composition of their cell walls, namely in the pectin content, and thus in potential At-binding sires. The effect of these differences on cellular localisation as well as on tissue distribution of Al was compared in root tips of Zea mays and Vic ia faba. The localisation of Al was assayed by Laser Microprobe Mass Analys is (LAMMA) after freeze-substitution. The radial mobility of Al was much lo wer in the roots of Vicia faba. In root tips of Zen mays, Al had reached th e stele already after 60 min while it was confined to the rhizodermis and o uter cortex cells in Vicia faba, indicating a stronger binding of Al in the cell walls of the dicot. This binding, however, had no influence on intrac ellular distribution. Within 60 min intracellular Al was detectable in both species. Nevertheless, by far the highest Al concentrations were always me asured in the cell wall.