水稻镉吸收及其在各器官间转运积累的研究进展

Research Progress on Cadmium Uptake and Its Transport and Accumulation Among Organs in Rice

随着土壤和大气沉降物中重金属污染的问题日益严峻,农作物重金属超标时有发生。土壤中的重金属难以降解,容易被植物根部吸收,在作物中积累;大气中的重金属沉降到叶片上,通过叶片吸收进入作物中,最终通过食物链被人类食用,危害人体健康。水稻是我国最重要的粮食作物,大米中存在镉超标问题。镉(Cd)是水稻的非必需元素,主要借助其他金属离子通道蛋白进入水稻根细胞,还可以通过叶片角质层的吸附内化和气孔的渗透作用进入水稻叶片。Cd依赖其他金属离子的转运体在水稻体内运输,Cd从土壤中吸收和植物内部的分配是一个动态过程,通过根吸收转运蛋白、根-地上部转运(木质部转运)和韧皮部的源-库转运(包括种子装载)驱动,实现器官间的转运分配。本文综述了水稻Cd的吸收与转运、器官间Cd的运输分配以及Cd向籽粒转运积累,以期为减少水稻籽粒中Cd含量的研究和解决我国南方部分种植地区Cd污染问题提供一些参考。

With deteriorating heavy metal pollution in soil and atmosphere,heavy metals contents in crops often exceeds the threshold.Heavy metals in soil are difficult to be degraded and are easily absorbed by plant roots and accumulated in crops.Heavy metals in atmosphere fall down on the surface of leaves and could enter into leaves through the stomata eventually,making their way into human body through the food chain and endangering human health.Rice is one of the most important food sources in China,and in some cases,cadmium content in rice exceeds the standard.Cadmium(Cd)is a non-essential element in rice and mainly enters rice root cells through other divalent ion channels.Besides,Cd can enter rice leaves by the adsorption and internalization of leaf cuticle and the permeation of stomatal.The transport of Cd in rice depends on the transporters of other metal ions.The uptake and distribution of Cd organs is a dynamic process,which is driven by transporters in roots,from root to shoot(xylem loading)and from source to sink in phloem(including seed loading).In this review,we elaborated the uptake of Cd from roots and leaves,the allocation of Cd among organs and the accumulation of Cd in rice grains.This review will lay a theoretical basis for reducing the content of Cd in rice grains and solving the problem about Cd pollution in some planting areas in South China.