摘要
镉是对生物毒性最强的污染物之一。过量的镉能够抑制植物的生长和光合作用,干扰矿质代谢并诱发氧化胁迫。硅作为一种有益元素,主要以Si(OH)_4的形态通过主动或被动方式被植物体吸收并转运到地上部分。硅对植物镉毒害具有缓解作用,但其缓解机制在不同物种、品种或生态型之间存在显著差异,并表现出一定的硅/镉浓度依赖性。总体上可概括为避性机制和耐性机制。避性机制包括:(1)在器官水平,减少植物根系对镉的吸收及其向地上部的转运;(2)在细胞水平,增强细胞壁对镉的吸附能力,减少共质体中镉的含量。耐性机制包括:(1)诱导细胞产生小分子螯合剂,增强对镉的螯合作用,减少细胞中游离态镉的含量;(2)增强抗氧化机制,减轻氧化胁迫;(3)改善光合作用和无机营养,促进植物生长。从植物对硅的吸收和转运、镉对植物的毒害作用以及硅对缓解植物镉毒害的生理生态机制3个方面进行了综述,并基于目前的研究现状和薄弱之处,对今后的研究重点进行了展望。
Cadmium is one of the most toxic pollutants, and excessive cadmium can inhibit plant growth and photosynthesis, interfere with mineral metabolism, and induce oxidative stress. Meanwhile, silicon is beneficial to plants and, after being actively or passively absorbed by plant roots and transported to other plant parts, mainly in the form of Si（OH）4, can alleviate cadmium toxicity. The mechanism underlying silicon-induced cadmium detoxicification in plants varies among species, cultivars, and ecotypes, showing a silicon/cadmium concentration-dependent manner. In general, the silicon-induced reversal of cadmium toxicity can be divided into two main mechanisms：avoidance and tolerance. The avoidance mechanism mainly functions （1） at the organ level, by reducing the absorption of cadmium by plant roots and/or its translocation from roots to shoots, and （2） at the cellular level, by enhancing the cadmium adsorption capacity of the cell wall and, therefore, reducing the influx of cadmium into the symplast. The tolerance mechanism also involves a variety processes, including （1） the induction of low molecular compounds that chelate cadmium ions, thereby reducing free cadmium concentrations; （2） the reduction of oxidative stress by enhancing antioxidant mechanisms; and （3） the improvement of photosynthesis and mineral nutrition, thus promoting plant growth. Here, we review recent advances in the mechanisms underlying cadmium toxicity, the uptake and transport of silicon, and silicon-induced cadmium detoxification in plants. Based on the weakness of previous studies, the need for further research is also discussed.
作者
刘彩凤
史刚荣
余如刚
张铮
LIU Caifeng;SHI Gangrong;YU Rugang;ZHANG Zheng(College of Life Sciences, Huaibei Normal University, Huaibei 235000, Chin)
出处
《生态学报》
CAS
CSCD
北大核心
2017年第23期7799-7810,共12页
Acta Ecologica Sinica
基金
国家自然科学基金项目(31370515
31671599)
关键词
硅
镉毒害
镉转运
避性
耐性
silicon
cadmium toxicity
cadmium translocation
avoidance
tolerance
