低浓度镉胁迫下2种水生植物体内植物络合素的响应

采用溶液培养方式,研究了水环境低浓度镉(Cd)(0.01～0.64 μmol/L)较长时间胁迫下漂浮植物水浮莲(Pistia stratiotes L.)和沉水植物伊乐藻(Elodea nuttallii)体内植物络合素(PCs)的响应规律.结果显示,2种水生植物对外界Cd胁迫表现出明显的吸收和积累效应,水浮莲体内PCs的响应明显强于伊乐藻.水浮莲体内的PCs诱导量与Cd处理浓度存在良好的剂量-效应关系,Cd浓度≥0.08 μmol/L水浮莲根系产生明显毒害效应并伴随根系PCs的诱导量急剧增加.回归分析显示,2种水生植物体内PCs的合成水平与Cd的生物毒性呈现一定的线性关系,表明PCs可作为重金属Cd胁迫的生物标记物指示水体中重金属的毒害程度.比较而言,水浮莲体内PCs对Cd污染更为敏感,可通过检测其根系PCs的含量来评价和预测实际水环境中Cd的污染.

Response of phytochelatins in two macrophytes exposed to environmentally relevant lower concentrations of cadmium

In this study a solution culture experiment was conducted to investigate the response of phytochelatins (PCs) in a floating aquatic plant Pistia stratiotes L. and a submerged one Elodea nuttallii exposed to a range of lower concentrations of cadmium (Cd) (0.01~0.64µmol/L). It was observed that two macrophytes showed obvious cumulative effects to lower concentrations of Cd exposure. PCs were significantly induced in P. stratiotes L. in a dose-dependent manner and increased with the increase of exogenous Cd concentrations. Cd concentrations at 0.08~0.64µmol/L were highly toxic to P. stratiotes L., accompanied by the dramatic production of PCs of plant tissues, especially in roots. Regressive analysis showed that there were linearly positive relationships between PC contents and Cd toxicity in E. nuttallii and P. stratiotes L.. It was indicated that PCs could be a promising biomarker for estimating Cd toxicity. Compared with E. nuttallii, PCs in roots of P. stratiotes L. was sensitive to Cd contamination and may be a sensitive indicator to reflect Cd toxicity in the aquatic ecosystem.