Abstract: A method of removing metal from a metal-containing substrate is provided. The method comprises (1) providing modified plants having an improved metal accumulating capability compared to unmodified plants by virtue of an increase in the concentration of histidine within the modified plants and (2) maintaining at least one such modified plant on the metal containing substrate under conditions such that the modified plant accumulates the metal from the substrate. The modified plant can be genetically engineered so as to be capable of increased production of histidine. Further, the increase in histidine concentration within the modified plants can also be achieved by administering a formulation comprising an effective concentration of histidine to the plants. A recombinant vector capable of transforming selected plant cells to augment the concentration of histidine in the plant cell, and a plant cell, plant cell culture or transgenic plant transformed with such a vector is also disclosed.