Analysis of intercellular cadmium forms in roots and leaves of bush bean

We characterized and quantified the chemical form of cadmium (Cd) in intercellular solutions of the apparent free space (AFS) of roots and leaves of bush bean plants. Plants were grown in sand and treated daily for five days with Hoagland nutrient solution containing, respectively, 0.5 and 1 mM Cd(NO3)2. The intercellular solution was collected by infiltration-extraction procedure using successively distilled water, 5 mM CaCl2, and 5 mM EDTA in order to collect separately the water soluble, exchangeable, and complexed Cd. The ability of extractant solutions to remove Cd from the AFS of roots and leaves was: H2O < CaCl2 << EDTA, confirming that most of Cd was bound at the cell wall. Voltarimetric technique showed that water-soluble Cd in intercellular solutions of the root and leaf tissues was as the Cd2+ ion, suggesting that Cd might be taken up by the roots and transported to leaves as the free ion.