Laboratory of Plant Biotechnology and Improvement, Center of Biotechnology of Sfax (CBS), University of Sfax, Sfax, Tunisia.
Physiol Plant. 2021 Sep;173(1):384-393. doi: 10.1111/ppl.13447. Epub 2021 May 13.
Soil and water are among the most valuable resources on earth. Unfortunately, their contamination with heavy metals has become a global problem. Heavy metals are not biodegradable and cannot be chemically degraded; therefore, they tend to accumulate in soils or to be transported by streaming water and contaminate both surface and groundwater. Cadmium (Cd) has no known biological function but is one of the most toxic metals. It represents a serious environmental concern since its accumulation in soils is associated with health risks to plants, animals and humans. On the other hand, copper (Cu) and zinc (Zn) are heavy metals that are indispensable to plants but become toxic when their concentration in soils exceeds a certain optimal level. Plants have evolved many mechanisms to cope with heavy metal toxicity; vacuolar sequestration is one of them. Vacuolar sequestration can be achieved through either phytochelatin-dependent or phytochelatin-independent pathways. Most of the transgenic plants meant for phytoremediation described in the literature result from the manipulation of genes involved in the phytochelatin-dependent pathway. However, recent evidence has emerged to support the importance of the phytochelatin-independent pathway in heavy metal sequestration into the vacuole, with metal/H antiporters and proton pumps playing an important role. In this review, the importance of vacuolar proton pumps and metal/H antiporters transporting Cd, Cu, and Zn is discussed. In addition, the recent advances in the production of transgenic plants with potential application in phytoremediation and food safety through the manipulation of genes encoding V-PPase proton pumps is described.
土壤和水是地球上最有价值的资源之一。不幸的是，它们受到重金属的污染已经成为一个全球性的问题。重金属不可生物降解，也不能通过化学方法降解；因此，它们往往会在土壤中积累，或者被流水携带，污染地表水和地下水。镉 (Cd) 没有已知的生物学功能，但却是毒性最大的金属之一。由于其在土壤中的积累与植物、动物和人类的健康风险有关，因此它是一个严重的环境问题。另一方面，铜 (Cu) 和锌 (Zn) 是植物必需的重金属，但当它们在土壤中的浓度超过一定的最佳水平时，就会变得有毒。植物已经进化出许多机制来应对重金属毒性；液泡隔离就是其中之一。液泡隔离可以通过植物螯合肽依赖或非依赖途径来实现。文献中描述的大多数用于植物修复的转基因植物都是通过操纵参与植物螯合肽依赖途径的基因而产生的。然而，最近的证据表明，金属/H 反向转运蛋白和质子泵在重金属向液泡中隔离方面起着重要作用，非依赖植物螯合肽途径的重要性得到了支持。在这篇综述中，讨论了液泡质子泵和金属/H 反向转运蛋白在运输 Cd、Cu 和 Zn 方面的重要性。此外，还描述了通过操纵编码 V-PPase 质子泵的基因来生产具有应用于植物修复和食品安全的转基因植物的最新进展。
