Ultrastrutural Studies and Zn, Cd and Pb Bioaccumulating Capacity By Andropogon Sp. Collected in a Zinc Mining Area.

The increasing interest in phytoremediation techniques has attracted considerable attention in studies with metal-accumulator plant species. Electron microscopy has been widely used under such conditions in order to investigate the elemental distribution as well as ultrastructural alterations in plant tissues. This study identified and characterized, by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and Transmission Electron Microscopy (TEM), the mechanisms underlying Zn, Cd, and Pb accumulation and tolerance in plants of a native species (Andropogon sp.) growing in a zinc mining area in Vazante (MG), Brazil. SEM and EDS images showed the formation of oxalate crystals in the shoots, with significant contents of Zn and Pb. Accumulation of all elements was detected in the intercellular spaces of both shoot and root tissues. TEM images presented detailed information on the morphology and localization of the studied elements, which can help understanding the mechanism of sequestration of such elements in roots and shoots. Andropogon sp. showed a great ability to tolerate high levels of Zn, Cd, and Pb using complex mechanisms, which includes ultrastructural alterations and metal accumulation in intercellular spaces and vacuoles, as well as formation of oxalate crystals.