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 Al-binding sites. 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 Vicia faba. The localisation of Al was assayed by Laser Microprobe Mass Analysis (LAMMA) after freeze-substitution. The radial mobility of Al was much lower in the roots of Vicia faba. In root tips of Zea mays, Al had reached the stele already after 60 min while it was confined to the rhizodermis and outer cortex cells in Vicia faba, indicating a stronger binding of Al in the cell walls of the dicoe. This binding, however, had no influence on intracellular distribution. Within 60 min intracellular Al was detectable in both species. Nevertheless, by far the highest Al concentrations were always measured in the cell wall.