矿区废弃地先锋植物齿果酸模在Pb、Zn污染下抗氧化酶系统的变化

作为云南矿区废弃地常见的先锋植物,齿果酸模(Rumex dentatus)已形成对重金属污染的耐性生态型,是理想的逆境生态学研究实验材料.为进一步揭示不同抗氧化酶在先锋植物幼苗早期抗逆境的耐性机理中的作用,采集了来自云南兰坪铅锌矿废弃地的齿果酸模,观察其幼苗多种抗氧化酶在实验室模拟的重金属Pb与Zn单一污染条件下(浓度分别为0,1,5,10,50,100,200 mg/kg)的变化特征.结果表明:随着Pb与Zn单一污染浓度的增加,(1)MDA含量持续上升,与对照相比,在200 mg/kg Pb或Zn单一污染下,MDA分别显著上升了427%和330%;而(2)SOD,POD与CAT三者活性变化特征则各有不同.其中SOD活性呈现先升后降的趋势,POD活性则持续上升;而CAT活性很低,在Zn污染下未检测出,Pb污染下其变化无显著规律.相关性分析结果表明,Pb与Zn单一污染导致先锋植物齿果酸模幼苗产生膜脂过氧化,而抗氧化酶系统在抵御这种不良影响的耐性机制中发挥了一定的作用,且不同酶发挥的效用不同,其中POD发挥了主要作用.

Lead and zinc induced changes in activity of antioxidant enzymes of Rumex dentatus, a kind of pioneer plant growing on mine tailings

As one of common pioneer plants growing on mine tailings in Yunnan Province, Rumex dentatus has generated metal tolerant ecotype and could therefore be treated as an ideal experimental material for stress ecology study. To study the roles of different antioxidant enzymes in tolerance mechanism of pioneer plant early-stage seedling to stress, the variation characteristics of antioxidant enzymes of R. dentatus seedlings, sampled from Pb/Zn mine tailings in Lanping, Yunnan Province, were then investigated under exposing to different concentrations of Pb or Zn (0, 1, 5, 10, 50, 100, 200 mg/kg) for 48h in the laboratory. Our results showed that, with the increase of pollutant concentrations, (1) the content of malondialdehyde (MDA) went up sustainably, and had significantly increased respectively to 427% and 330% under the concentrations of 200 mg/kg Pb or Zn when compared with normal control; whereas (2) the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) varied to different extents. Specifically, SOD increased initially but decreased afterwards, and POD increased sustainably; whereas the activity of CAT could neither be detected under Zn stress nor effectively estimated under Pb stress. Subsequent correlation analyses suggested that the antioxidant enzymes have produced some protective effect in the tolerance reaction against Pb and Zn pollution, among which POD has plausibly played the central role.