土壤外源Cd和Pb复合污染对小麦(Triticum aestivum L.)根系植物络合素和谷胱甘肽合成的影响

Phytochelatins and glutathione synthesis in roots of wheat(Triticum aestivum L.) under combined pollution of Cd and Pb:a pot study

采用盆栽实验研究了土壤外源Cd和Pb复合污染对小麦(Triticum aestivum L.)根系植物络合素(PCs)和谷胱甘肽(GSH)合成的影响。结果表明,土壤外源较高浓度Cd处理(≥3mg·kg-1)和高浓度Pb处理(630mg·kg-1)均抑制了小麦的生长,Cd和Pb复合处理加重了Cd的毒性;Pb处理小麦根内未检出PCs,仅检出GSH,但GSH并没有随Pb处理浓度的增加而增加。随Cd处理浓度(≥1mg·kg-1)的增加,小麦根内PCs和GSH含量显著增加;Cd和Pb复合处理增加了小麦根内PCs的合成水平,而降低了GSH的合成水平。回归分析显示,Cd及Cd和Pb复合污染小麦根内PCs的含量与小麦地上部生物量的抑制率保持相当好的线性关系。结果显示,PCs可用于评价土壤环境中Cd及Cd和Pb复合污染的毒性。

Phytochelatins （PCs） and glutathione （GSH） have been proposed as biomarkers for assessment of metal toxicity. However, most studies have generally been confined to one metal in hydroponics. In this study, a pot experiment was conducted to investigate PCs and GSH synthesis in roots of wheat （Triticum aestivum L.） under combined pollution of Cd and Pb. It was shown that higher concentrations of single Cd （≥ 3 mg·kg^-1） and single Pb （630 mg·kg^-1） added in soils inhibited the growth of wheat, respectively. Pb addition under the single Cd-treated soils enhanced Cd toxicity, accompanied by the gradual decrease of shoot biomass. HPLC fluorescence analysis clearly showed that GSH rather than PCs was detected in roots under the single Pb-treated soils, and yet did not increase with the increase of Pb concentrations added in soils. On the contrary, PCs and GSH was significantly induced in roots under the single Cd-treated soils （t〉 1 mg.kg1） and increased with the increase of Cd concentrations added in soils. Pb addition under the Cd-treated soils increased the levels of PCs in roots, whereas decreased the levels of GSH. There existed a positively linear relationship between PC concentrations in roots and inhibition rate of shoot biomass under both single Cd and combined treatments of Cd and Pb. It was further confirmed that PCs could be used as biomarkers for an evaluation of the toxicity of Cd or compound pollution of Cd and Pb in soils.