Phytotoxicity of heavy metals

Abstract

During the evolution of plants only a few heavy metals were incorporated in metabolic processes. Phytotoxicity of plants to various heavy metals occurs by surpassing critical levels. It depends on the capability of species, cultivars and genotypes to handle appropriately the uptake, translocation, incorporation into organic compounds and cellular compartmentation of these metals. These capabilities are not distributed in a random manner. Sensitivity to specific heavy metals is determined only by one to a few genes. Several principles are elaborated: at the cellular level it is the importance of the plasmamembrane integrity at the exposition to elevated concentrations of Ag, Cu, and Hg, the regulation of the concentrations of free metals in the cytosol, and the cytosolic decontamination by an enhanced transport across the tonoplast into the vacuole (compartmentation); at the whole plant level it is the translocation velocity from root to shoot and the ability of leaves to accumulate a high amount of metals.