Chelated lead transport in Pinus radiata:: an ultrastructural study

Pinus radiata plants, approximately 12 months old, were exposed to Pb(NO3)(2) in hydroponic culture, with and without the addition of the chelating agents H-EDTA and EDTA, for I week, Subsequently lead uptake was quantified in treated materials by flame atomic absorption spectrometry. While lead supplied in unchelated form accumulated predominantly in root tissue, lead chelated with either H-EDTA or EDTA was transported principally to the needles. With transmission electron microscopy, ultrastructural observations were carried out on ultra-thin sections derived from lead-treated P. radiata tissues. In root tissues, lead supplied in unchelated form was found exclusively in cell walls. In needles, lead accumulation due to treatment incorporating chelators was found in sites adjacent to cell walls and in intercellular spaces. The morphology of cellular components, such as mitochondria, dictyosomes, ribosomes and endoplasmic reticula, does not appear to have been adversely affected by the presence of lead. (C) 2002 Published by Elsevier Science B.V.