植物超富集砷机制研究的最新进展

砷污染是全球环境热点问题之一,土壤砷污染治理是一个急需解决的难题.随着不同砷超富集植物的发现,植物修复技术因其投资和维护成本低、不易造成二次污染等优点而成为国际学术界研究的热点和前沿领域.深入理解超富集植物体内砷代谢和富集机制是有效利用植物修复技术来治理砷污染土壤的关键.近年来,植物超富集砷机制的研究取得了很大进展.已有的研究结果证明,蜈蚣草(P.vittata)对砷的吸收和转运能力显著高于非超富集植物,转运到地上部的砷主要储存在羽叶细胞的液胞中;蜈蚣草具有很强的抗氧化胁迫能力和五价砷(As(Ⅴ))还原能力;菌根共生有利于蜈蚣草的生长和砷的富集.有关植物超富集砷机制的分子生物学研究也取得了可喜的进展.砷酸盐还原酶基因(PvACR2)和植络素合成酶基因(PvPCS1)都被克隆并表征,cTPI同源基因(PV4-8)也被证明具有将As(Ⅴ)还原成三价砷(As(Ⅲ))的功能.尽管植物超富集砷机制的研究取得了迅速进展,但至今学术界仍没有全面理解为什么这些蕨类植物具有超富集砷的功能,相关功能基因、酶和转运蛋白的研究有待进一步深入.

Recent developments in understanding the mechanisms of arsenic hyperaccumulation in plants

Cleanup of arsenic As contaminated soils has become a major environmental concern around the globe. With the discovery of As hyperaccumulators (e.g. Pteris vittata L.), phytoremediation has attracted particular interest across the world, since it is considered as an environmentally-friendly and cost-effective technology for As decontamination. Knowledge of the mechanisms of As hyperaccumulation in P. vittata may contribute to the optimization of phytoremediation processes. Recent research has discovered that P. vittata is significantly more efficient than other plants in As accumulation and translocation, and in compartmentalization of As within the cell vacuole. This fern is also highly resistant to oxidative stress and efficiently reduces As (V). Arbuscular mycorrhizal symbiosis is beneficial to fern growth and As accumulation. The arsenate reductase gene (PvACR2) and phytochelatin synthase gene (PvPCS1) have been cloned and characterized. The cTPI homolog PV4- 8 has also been shown to function as an arsenate reductase, reducing As (V) to As (III). Although rapid advancements have been made in understanding the mechanism of As hyperaccumulation in plants, it is still not fully clear why these plants can hyperaccumulate As, and further studies should be concentrated on key functional genes, enzymes and transporters involved in As hyperaccumulation. This review summarizes the recent research advances and studies of the mechanisms of As hyperaccumulation in Pteris vittata and its application in phytoremediation.