龙葵叶片和根系抗氧化酶对镉胁迫的响应

针对日益严重的土壤镉污染,采用1/2 Hogland营养液研究100 μmol/L CdCl₂处理1~4 d时龙葵(Solanum nigrum L)叶片和根系的氧化损伤和抗氧化酶活性的变化.结果表明,叶片的MDA 和H₂O₂含量随着Cd胁迫时间的延长而上升,叶片MDA的上升幅度大于根系,根系H₂O₂的上升幅度大于叶片;叶片和根组织的SOD、CAT、APX和POD活性均随Cd处理时间的延长而升高.说明Cd胁迫诱导龙葵H₂O₂累积并导致氧化胁迫,抗氧化酶活性升高可能是Cd的解毒机制之一;龙葵叶片H₂O₂由CAT和APX共同作用清除,而根中H₂O₂主要由APX清除.

Response of antioxidant enzymes in leaves and roots of Solanum nigrum L to cadmium stress

Cadmium (Cd) is one of the most toxic environmental pollutants for soils. The seedlings of S. nigrum were exposed to half-strength Hogland solution with 100 μmol/L CdCl₂ for 1-4 days, and the activity of antioxidant enzyme in leaves and roots was investigated. The results show that the contents of MDA and H₂O₂ increase in leaves and roots and the increase of MDA in leaves is larger than that in roots while the increase of H₂O₂ in roots is larger than that in leaves. Also, the activities of SOD, CAT, APX, and POD in leaves and roots are enhanced with prolonged Cd treatment. It is suggested that the H₂O₂ accumulation induced by Cd stress leads to oxidative stress and the increase of the oxitioxidant enzyme activity may be one of the mechanisms of Cd detoxification in S. nigrum. H₂O₂ in leaves may be scavenged by both CAT and APX while the H₂O₂ in roots may be mainly scavenged by APX.