Studies on phytoextraction and phytomining of heavy metals

本研究的主要目的是阐明金属结合肽、植物螯合素在重金属转运和体内平衡中的作用，并分析转运蛋白在重金属超富集植物Thlaspi japonicum和Mn超富集植物Chengiopanax scidophylloides中的功能. T.比较了北海道3个不同地区的日本血吸虫生态型的差异。T.无论生态类型和生境如何，japonicum植物都能够积累较高的Ni/Zn积累量。从T. Japonicum，命名为TjPCS。TjPCS转化的酵母表现出明显的Cd^<2+>耐受性。从镉超富集植物蓝蓟（Thlaspi caerulescens）中克隆了相同的基因.从T. Japonicum的基因组序列，并克隆了两个ZIP转运蛋白基因（TjZNT 1，2）和一个NRAMP基因（TjNRAMP 4）。TjZNT 1，2转化的酵母对Ni^2+的耐受性显著提高。相反，TjNRAMP 4的表达导致Ni^2+敏感性和Ni^2+浓度的升高. C. scidophylloides持续降低培养液的pH值，同时在培养基中增溶MnO_2。进一步研究各基因在植物中的表达，以阐明这些基因在植物中的作用，并利用转化植物进行植物修复。

The main purposes of this study are clarification of the role of metal-binding peptides, phytochelatin, and functional analysis of transporters in heavy metal transport and homeostasis using Ni hyperaccumulator Thlaspi japonicum and Mn hyperaccumulator Chengiopanax sciadophylloides, ordinary plants in Japan.1. Ni/Zn accumulation ability of T. japonicum ecotypes from three different areas in Hokkaido was compared. T. japonicum plants were able to accumulate high Ni/Zn accumulation regardless ecotype and habitat.2. The phytochelatin synthase gene was cloned from T. japonicum and designated as TjPCS. The yeast transformed with the TjPCSshowed an obvious Cd^<2+> tolerance. The same gene was cloned from a Cd hyperaccumulator plant Thlaspi caerulescens.3. Homologous genes of ZIP and NRAMP metal transporters were cloned from T. japonicum and two ZIP transporter genes (TjZNT1, 2) and one NRAMP gene (TjNRAMP4) were cloned. The yeast transformed with TjZNT1, 2 showed a marked increase in Ni^<2+> tolerance. In contrast, the expression of TjNRAMP4 caused elevation of Ni^<2+> sensitivity and Ni^<2+> concentration.4. C. sciadophylloides lowered the pH of the culture solution continuously and simultaneously solubilized MnO_2 in the medium Further studies on each gene expression in plants are needed to clarify the role of these genes in plants and to use the transformed plants for phytoremediation.