多环芳烃和镉土壤复合暴露条件下黑麦草的氧化应激指标变化

Changes of oxidative stress indexes of ryegrass(Lolium perenne L.)under compound exposure to polycyclic aromatic hydrocarbons and cadmium in soil

为了探究场地土壤多环芳烃(PAHs)和镉(Cd)在复合污染条件下的植物生物效应,本研究以黑麦草(Lolium perenne L.)为供试植物,采用土培方法进行染毒试验,分析了植物中4种典型氧化应激指标多酚氧化酶(Polyphenol oxidase,PPO)、磷酸烯醇式丙酮酸羧化酶(Phosphoenolpyruvate carboxylase,PEPC)、脯氨酸(Proline,Pro)和还原性谷胱甘肽(Reduced glutathione,GSH)的响应变化。结果表明:单一Cd染毒下,黑麦草的PPO活性呈下降趋势,PEPC活性以及Pro浓度均呈先上升后下降的趋势,GSH浓度呈上升趋势;单一PAHs染毒下,黑麦草的PPO活性呈下降趋势,PEPC活性以及Pro和GSH浓度均呈先上升后下降的趋势。因此,PAHs和Cd的单一污染胁迫下黑麦草生理系统均受到了影响,产生了氧化应激反应。与单一Cd染毒相比,Cd-PAHs复合染毒下,黑麦草的4种指标变化趋势均发生了显著变化(P<0.05)。PEPC和PPO的活性以及Pro和GSH浓度的显著下调可能是场地土壤高浓度PAHs和Cd复合污染的重要指征。在复合染毒胁迫下,黑麦草4种指标普遍呈现拮抗效应。研究表明重金属Cd和PAHs复合污染对典型植物氧化应激效应指标具有剂量-效应关系。

To explore the biological effects of polycyclic aromatic hydrocarbons(PAHs)and cadmium(Cd)in soil affected by compound pollution,this study involved an exposure test by the soil culture experiment using ryegrass(Lolium perenne L.),and analyzed the changes in four typical oxidative stress indices in plants,including polyphenol oxidase(PPO),phosphoenolpyruvate carboxylase(PEPC),proline(Pro),and reduced glutathione(GSH).The results showed that with exposure to Cd only,ryegrass PPO enzyme activity decreased,PEPC enzyme activity and Pro concentration first increased and then decreased,and GSH concentration increased.In contrast,with exposure to PAH only,ryegrass PPO enzyme activity decreased,while PEPC enzyme activity and the concentrations of Pro and GSH first increased then decreased.Therefore,when exposed to single stressors(PAH or Cd),the physiological systems within the ryegrass are affected,producing an oxidative stress response.We also found that compared with Cd exposure only,the four ryegrass indices changed significantly under compound exposure to Cd and PAH.The significant downregulation of PEPC and PPO enzyme activity and the concentration of Pro and GSH may be an important indicator of compound pollution of high-concentration PAH and Cd in soil.Moreover,the four ryegrass indices generally showed antagonistic effects under compound exposure stress.This study observed that compound heavy metal pollution,specifically Cd and PAHs,had dose-effect relationship with typical plant oxidative stress indices.