Phytoremediation of cadmium contamination: Overexpression of metallotionein in transgenic tobacco plants

The contamination of heavy metals by mining and combustion of fossil fuel has brought about significant deleterious consequences not only to environment but also to human health. Cadmium is a potentially toxic metal which causes renal dysfunction, pulmonary emphysema, and possibly bone demineralization. To explore the potential of plants to tolerate this metal, we engineered a model plant, Nicotiana tabacum, to express a metallothionein under the control of CaMV 35S promoter. Transgenic plants expressing metallothionein were able to grow in concentrations of up to 200 μM CdSO4. Nontransgenic plants promptly unde…