Phytochelatins and their roles in heavy metal detoxification
Phytochelatins and their roles in heavy metal detoxification
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DOI：
10.1104/pp.123.3.825
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发表时间：
2000-07-01
期刊：
影响因子：
7.4
通讯作者：
Cobbett, CS
中科院分区：
文献类型：
--
作者：
Cobbett, CS
植物对重金属毒害的反应是多种多样的。这些反应包括金属离子的固定、排斥、螯合和区室化，以及更一般的应激反应机制如乙烯和应激蛋白的表达。Sanita di Toppi和Gabbrielli（1999年）对暴露于Cd的植物的这些机制进行了全面的综述，几十年来对Cd的研究数量最多，范围最广。了解这些机制的分子和遗传基础将是开发植物作为污染场地植物修复剂的重要方面（Salt等人，1998年）。重金属在植物和其他生物体内的解毒机制是通过配体螯合重金属，在某些情况下，配体-金属络合物被区室化。Rauser（1999）综述了几种配体的作用。柠檬酸、苹果酸等有机酸的胞外螯合作用在铝耐受机制中起重要作用。例如，苹果酸从根尖流出受到暴露于铝的刺激，并且与小麦中的铝耐受性相关（Delhaize和Ryan，1995）。拟南芥属的一些铝抗性突变体也具有增加的有机酸从根流出（Larsen等人，1998年）。有机酸和一些氨基酸，特别是His，也在细胞内和木质部汁液中的金属离子螯合中起作用（克雷默等人，1996; Rauser，1999）。肽配体包括金属硫蛋白（MT），小基因编码的富含Cys的多肽。我们目前对MT在植物，特别是拟南芥中的功能和表达的理解已经在其他地方进行了综述（Fordham-Wastton et al.，1998; Rauser，1999）。相比之下，本更新的主题植物螯合素（PC）是酶促合成的富含Cys的肽。最近的PC结构，生物合成和功能的审查是Rauser（1995）。其他最近的评论是由Zenk（1996）和Rauser（1999）。我们对PC生物合成和功能方面的理解的最新进展主要来自
Plants respond to heavy metal toxicity in a variety of different ways. Such responses include immobilization, exclusion, chelation and compartmentalization of the metal ions, and the expression of more general stress response mechanisms such as ethylene and stress proteins. These mechanisms have been reviewed comprehensively by Sanita di Toppi and Gabbrielli (1999) for plants exposed to Cd, the heavy metal for which there have been arguably the greatest number and most wide-ranging studies over many decades. Understanding the molecular and genetic basis for these mechanisms will be an important aspect of developing plants as agents for the phytoremediation of contaminated sites (Salt et al., 1998). One recurrent general mechanism for heavy metal detoxification in plants and other organisms is the chelation of the metal by a ligand and, in some cases, the subsequent compartmentalization of the ligandmetal complex.A number of metal-binding ligands have now been recognized in plants. The roles of several ligands have been reviewed by Rauser (1999). Extracellular chelation by organic acids, such as citrate and malate, is important in mechanisms of aluminum tolerance. For example, malate efflux from root apices is stimulated by exposure to aluminum and is correlated with aluminum tolerance in wheat (Delhaize and Ryan, 1995). Some aluminum-resistant mutants of Arabidopsis also have increased organic acid efflux from roots (Larsen et al., 1998). Organic acids and some amino acids, particularly His, also have roles in the chelation of metal ions both within cells and in xylem sap (Kramer et al., 1996; Rauser, 1999). Peptide ligands include the metallothioneins (MTs), small gene-encoded, Cys-rich polypeptides. Our current understanding of the functions and expression of MTs in plants, particularly Arabidopsis, have been reviewed elsewhere (Fordham-Skelton et al., 1998; Rauser, 1999). In contrast, the phytochelatins (PCs), the subject of this Update, are enzymatically synthesized Cys-rich peptides. The most recent review of PC structure, biosynthesis, and function in this journal was by Rauser (1995). Other more recent reviews are by Zenk (1996) and Rauser (1999). Recent advances in our understanding of aspects of PC biosynthesis and function are derived predominantly