Use of SIMS microscopy and electron probe X-ray microanalysis to study thesubcellular localization of aluminium in Vicia faba roots cells

Secondary ion mass spectrometry (SIMS), electron probe X-ray microanalysis (EPMA) and transmission electron microscopy (TEM) were used to study the ti ssular distribution and subcellular localization of aluminium (Al) precipit ate in roots of Vicia faba. The broad bean plant, grown in nitrate solution with 193 mu M Al3+ at pH 4.8, for 15 days showed Al deposits in the roots. Al accumulation was not detected in the stems nor in the leaves. Al was fo und mainly localized on the root's surfaces and within the cell walls of th e cortical cells. Al signal was not detected in the vascular tissues. Two w eeks exposure to Al caused ultrastructural changes in cortical cells and so metimes a complete disruption of these cells. Deposition of Al in form of i nsoluble complexes associated with phosphorus, appeared as electron opaque materials in the vacuoles of disrupted cortex cells and in the intercellula r inclusions. The leaves turned yellowish at the end of 15 days exposure. T he use of electron microprobe, to investigate the same tissues as the ones investigated by SIMS, provided complementary results on aluminium allocatio n.