植物对重金属镉的吸收转运和累积机制

Cd是土壤污染的主要因素之一,痕量的Cd2 不仅对植物生长有毒害作用,同时对人体健康产生极大的危害.研究植物如何从土壤中吸收Cd2 ,并在整个植物体内运输和积累的机理,对开发植物修复技术及生态环境的恢复具有重要意义.近年研究表明:土壤微环境影响植物对Cd2 的吸收;植物根细胞壁通过选择性吸收可以吸附和固定土壤中的Cd2 ,其中大部分Cd2 被截留在细胞壁中,其余的则通过协助扩散或主动运输等方式透过细胞膜进入根细胞中;在根细胞中Cd部分累积在液泡中,部分则通过木质部运输到地上部分;茎叶部的大部分Cd2 通过络合作用被固定在液泡中,少量被截留在细胞壁和细胞质中.在植物结实期,Cd通过韧皮部进入籽实中,而籽粒中的Cd几乎不能运输到其他部分,主要通过食物链进入动物和人体中.本文综述了植物对Cd的吸收和运输机制方面的研究进展.

Uptake, translocation and accumulation of cadmium in plant

Cadmium (Cd) is highly toxic to plants even at low concentrations and influences plant growth and development. Research on Cd transport in plants is highly vital in phytoremediation and environmental restoration. Soil micro-environment greatly influences Cd²⁺ absorption in plants. Cd²⁺ is selectively absorbed through root cell wall and most of it remains in the cell wall while a small fraction enters the cell by diffusion or active transport in the membrane and yet another small amount of Cd²⁺ is deposited in cell vacuole. Cd²⁺ is transported from the root to the shoot system through xylem vessels. In the shoot system, most of the Cd remains in the vacuoles of shoots and leaves, while a few is deposited in the cell wall and cytoplasm. In the period of seed development, Cd can also be transferred in the seed through the phloem, and the accumulated Cd in seeds hardly moves to other parts of the plant. Furthermore, Cd can be easily transferred to animals and man through food chain. This paper provides an overview of Cd uptake from the soil, and its translocation and accumulation in plants and the metabolic system of animals.