Functions and homeostasis of zinc, copper, and nickel in plants

Abstract

Nutritional micronutrient deficiencies and exposure to pollutant metals threaten human health globally. Plant crops are at the beginning of a food chain that largely determines food metal contents. In order to survive, all organisms have to supply appropriate amounts of each micronutrient to the correct target apometalloproteins and at the same time avoid adventitious metal binding to non-target metal binding sites or other cellular compounds. This requires the operation of metal homeostasis networks, which orchestrate the mobilization, uptake, distribution, intracellular trafficking, chelation, and sequestration of all metal ions. Presumably as a result of time-dependent and local variations in bioavailable soil metal concentrations, plant metal homeostasis networks exhibit a remarkably high degree of plasticity and natural diversity. This is a review covering the current knowledge of metal-dependent processes and proteins, metal homeostasis and its regulation, and the molecular mechanisms underlying naturally selected metal hypertolerance and metal hyperaccumulation in higher plants. © Springer-Verlag Berlin Heidelberg 2006.