硅缓解植物重金属毒害机理的研究进展

硅对植物重金属胁迫具有重要的调节作用,研究表明:适当浓度的外源硅能够通过多种途径有效缓解重金属胁迫对植物生长发育的抑制和毒害作用,使植物内重金属富集系数和转运系数发生变化,减少植物对重金属的吸收积累;有效缓解重金属对细胞结构的伤害;促进植物生理生化代谢。硅缓解植物重金属毒害的机理可归纳为避逆作用和耐逆作用。避逆作用包括:提高土壤(介质)pH,改变其理化性质;改变土壤中重金属形态,使其沉积于土壤或根系周围,减少植物对重金属的吸收。耐逆作用包括:影响重金属在植物内转移、积累;刺激植物产生酚类物质并与重金属螯合;促进重金属离子在植物内区隔化分布,使其结合到细胞壁或液泡中;提高植物内抗氧化系统活性(SOD、POD、CAT、APX),有效清除重金属胁迫产生的活性氧。本文就近年来硅缓解重金属毒害作用及其机理的相关研究进行了归纳和总结,并对今后的研究重点进行了展望。

The Research Progresses on Mitigative Mechanism of Silicon on Heavy Metal Toxicity in Plant

Silicon plays en effective role in mitigating heavy metal stress. It has been reported that, appropriate concentration of exogenous silicon can alleviate the damage of heavy metal on plant growth by affecting the change of enrichment coefficient and translation coefficient of heavy metals, reducing the absorption and accumulation of heavy metal in plant, effectively mitigating the damage on plant cell and promoting physiological and biochemical metabolism of plant. The mechanism can be concluded as avoidance and tolerance. Avoidance includes improving the pH of growth media, changing its physicochemical properties, changing the forms of heavy metal and deposited in soil and decreasing the absorption of heavy metal. Tolerance includes affecting heavy metal transportation and accumulation in plant, stimulating production of phenolics, chelating with heavy metal, promoting compartmentalization of heavy metal ion in plant, causing it bounded in cell wall or vacuole, improving the activity of antioxidant system, such as SOD, POD, CAT and APX, and effectively removing active oxygen caused by heavy metal stress. In this paper, the effect and mechanism of silicon on heavy metal toxicity were summarized and induced, and on these bases, key research directions in future were prospected.