有机配体对超富集植物转运及解毒镍、锌的影响

The Effect of Organic Ligands on the Transport and Detoxification Processes of Nickel and Zinc in Hyperaccumulators

超富集植物是一类能大量吸收重金属并将其转运至地上部的特殊植物。这类植物体内通常含有高量的有机配体,如烟草胺、组氨酸等,可与其形成稳定的金属-配体复合物。现阶段针对超富集植物体内Ni、Zn的有机配体的研究较为充分。该研究综述了在根部运输及解毒、木质部转运和叶片解毒过程中有机配体与重金属的相互作用关系、超富集植物合成有机配体的分子机制以及有机配体和金属配合物的检测方法。综合来看,氨基酸类配体可能促进Ni、Zn在根部共质体中的迁移并缓解过量Ni、Zn的细胞毒性;在木质部运输过程中Ni、Zn则主要以水合离子形式赋存,与配体结合的比例相对较低;叶部赋存的Ni、Zn则主要通过与有机酸结合的形式进行解毒。由于现有的研究大部分针对有限的几种超富集植物及有限的几种有机配体,未来还需结合代谢组学及转录组学探索更多植物品种有机配体特征及其解毒的分子机制,从而为厘清植物超富集重金属的相关机制及其在植物提取方面的应用提供理论依据。

Hyperaccumulators are a group of specialized plants that absorb large amounts of heavy metals and store most of them in their aboveground parts.These plants are rich in organic ligands,such as nicotianamine and histidine,which can combine with metals to form metal-ligand complexes.At present,the studies on nickel and zinc organic ligands in plants are relatively sufficient.Therefore,this paper focuses on the interaction between organic ligands and heavy metals during root transport and detoxification,xylem transport and leaf detoxification processes,the molecular mechanism of organic ligand synthesis in hyperaccumulators,as well as methods for detection of organic ligands and metal complexes.To sum up,organic ligands may promote the migration of Ni and Zn in the symplasts of hyperaccumulators and alleviate the cytotoxicity of excess Ni and Zn.In the process of xylem transport,nickel and zinc mainly occur by hydrated ions,but the role of organic ligands is relatively weak in this process.Nickel and zinc mainly combine with organic acid for leaf detoxification.Since most of the findings come from a limited number of hyperaccumulators and organic ligands,it is necessary to combine metabonomics and transcriptomics to study the characteristics and molecular mechanisms about detoxification of organic ligands in more species of hyperaccumulators in the future,so as to provide theoretical basis for clarifying the relevant mechanisms of selective hyperaccumulation of heavy metals in plants and for the application of hyperaccumulators in phytoextraction.