基因工程改良植物对重金属污染土壤的修复

利用基因工程改良植物，调整植物吸收、运输和富集重金属的能力以及它们对重金属的耐受性，开拓了植物修复的新领域。到目前为止，已有成功改变这些特性的少数例子。例如，汞离子还原酶可以改善植物抵抗力和提取能力，金属巯基蛋白可增强植物对镉的耐受力，铁还原酶和铁蛋白可增加植物对铁的吸收量。文章综述和讨论了这方面的研究进展及方向。

Genetic engineering in the improvement of plants for phytoremediation of heavy metal polluted soils

Heavy metal concentrations in soils are locally quite high and are increasing due to many human activities, leading to elevated risk for health and the environment. Phytoremediation may offer a viable solution to this problem and the approach is gain-ing increasing interest. Improvement of plants by genetic engineering, i.e., by modifying characteristics like metal uptake, transport and accumulation as well as metal tolerance, opens up new possibilities for phytoremediation. So far, only a few cases have been reported where one or more of these characteristics have been successfully altered. For example, mercuric ion reduction causes the improved resistance and phytoextraction, and metallothionein causes the enhanced cadmium tolerance. Ferric reductases increase iron uptake and ferritin increases Fe uptake. Transgenic plants evolve 10 times the amount of Hg0 compared to the control plants. Metallothioneins (MTs) gene were isolated from metal-tolerant Silene vulgaris and transferred into several metal-sensitive yeasts. Increases in both Cd and Cu tolerance were observed in the modified yeasts. These, together with other approaches and potentially promising genes for transformation of target plants are discussed in this paper. Improvement of plants by genetic engineering opens up new possibilities for phytoremediation of metal-polluted soils.