植物螯合肽及其在抗重金属胁迫中的作用

Phytochelatins and their roles in phyto-tolerance to heavy metals: A review

植物螯合肽 (PCs)广泛存在于植物体中 ,与植物抗重金属胁迫关系密切。植物螯合肽及其复合物是一类富含半胱氨酸的低分子量化合物。现有研究证明 ,PCs由谷胱甘肽 (GSH)为底物的酶促反应合成 ,其合成受相关基因的调控 ,从模式植物拟南芥的突变体中已分离到与 PCs合成有关的几个基因。植物螯合肽首先与重金属离子结合形成低分子量 (LMW)复合物 ,以此形态经由细胞质进入液泡后 ,再与一个分子的植物螯合肽结合 ,形成对植物组织毒性较小的高分子量 (HMW)复合物 ,从而达到缓解重金属对植物的危害作用。就植物螯合肽及其复合物的结构、生物合成、基因调控及重金属解毒机理等进行了综述 。

Phytochelatins (PCs) commonly found in plants are verified to be closely related to the phyto-tolerance of metal heavy. Phytochelatins and their complexes are low molecular weight (LMW) complexes which are rich in cysteine analogues. It ha s been proven that PCs is synthesized through enzyme catalysis reaction using gl utathione (GSH) as the substrate and regulated by relevant genes. Genes involved in PC synthesis have been isolated and identified in the mutants of Arabidopsis, a model plant widely used in genetic study. The PCs in plants c an combine with heavy metal ions to form LMW compounds and then be transported i nto vacuole via symplast. The LMW complex may combine with another molecular of PC to form high molecular weight complex (HMW) with lower phytotoxicity which le ads to alleviate the phytotoxicity of heavy metal. In this paper, chemical struc ture, bio-synthesis and genetic regulation of phytochelatins and their compound s, as well as the processes and possible mechanisms related to the alleviation o f phytotoxicity of heavy metal are reviewed.