伴矿景天植物螯合肽合酶基因的克隆及功能分析

彭佳师, 丁戈, 易红英, 龚继明*
中国科学院上海生命科学研究院植物生理生态研究所, 植物分子遗传国家重点实验室, 上海200032

通信作者:龚继明;E-mail: jmgong@sibs.ac.cn;Tel: 021-54924036

摘 要:

重金属超积累植物由于长期生长在高浓度的重金属环境中, 使得经由植物螯合肽(phytochelatins, PCs)解毒途径来应对重金属毒害代价高昂。我们从Zn/Cd超积累植物伴矿景天(Sedum plumbizincicola)中克隆了植物螯合肽合酶(phytochelatin synthase, PCS)基因SepPCS。该基因在裂殖酵母和拟南芥中表达后都具有PCS活性, 而且能够互补它们的PCs缺失突变体的Cd敏感表型。SepPCS在伴矿景天中的表达受到高浓度Cd处理的诱导。与其近亲非超积累生态型东南景天(S. alfredii)相比, 虽然伴矿景天地上部PCs与Cd的摩尔比远低于东南景天, 但是在高浓度Cd处理时PCs含量以及PCs与Cd的摩尔比急剧增加。我们推测在伴矿景天应对Cd毒害的过程中, PCs起到一定的作用, 并且在高浓度Cd胁迫时地上部PCs依赖的解毒作用有所加强。

关键词:植物螯合肽; Cd; 重金属; 伴矿景天; 超积累植物

收稿:2014-03-25   修定:2014-04-23

资助:国家自然科学基金委创新群体项目(31121063)。

Cloning and Functional Analysis of Phytochelatin Synthase Gene from Sedum plumbizincicola

PENG Jia-Shi, DING Ge, YI Hong-Ying, GONG Ji-Ming*
National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China

Corresponding author: GONG Ji-Ming; E-mail: jmgong@sibs.ac.cn; Tel: 021-54924036

Abstract:

Phytochelatin (PCs)-dependent mechanisms are costly for hyperaccumulators to detoxify toxic metals as they grow in heavy metal-rich habitats. In this study we report the isolation and functional characterization of the phytochelatin synthase (PCS) gene SepPCS from the hyperaccumulator Sedum plumbizincicola. Ectopic expression of SepPCS complemented PCs biosynthesis as well as cadmium (Cd) tolerance in the PCs-deficient yeast or Arabidopsis mutant Δpcs and cad1-3 respectively. SepPCS expression is up-regulated in response to high level Cd treatment. Furthermore, the molar ratio of PCs and Cd in S. plumbizincicola is far less than that in the non-hyperaccumulating ecotype of S. alfredii, though this ratio in S. plumbizincicola shoots increased rapidly when exposed to high concentration Cd treatments, consistent with the expression pattern of SepPCS. These results imply that PCs biosynthesis might play a minor role in Cd tolerance in the hyperaccumulator S. plumbizincicola, but the importance of this mechanism might increase with elevated Cd concentrations.

Key words: phytochelatin; cadmium; heavy metal; Sedum plumbizincicola; hyperaccumulators

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