Effects of copper ion on antioxidant function of Vallisneria asiatica

Abstract

The objective of this research is to demonstrate the antioxdant ecological response of Vallisneria asiatica to the heavy metal Cu²⁺ pollution which is recently a serious problem in the lakes. Batch experiments with five different concentrations of Cu²⁺ (0, 5, 10, 20, 40, 80 mg· L^-1) were carried out. After the 12^th day, the roots and leaves of Vallisneria asiatica dipped in the solution with Cu²⁺ were removed and the physiological and biochemical indexes, chlorophyll, protein and malondialdehyde (MDA) content, superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activity were measured. After the experiment; the roots and leaves cultivated in the 0 mg·L^-1 of Cu²⁺ group showed chlorophyll and protein content reduced while the MDA content, POD and SOD activity were increased notoriously. Compared with the 0 mg·L^-1 of Cu²⁺ group, the 5 mg·L^-1 of Cu²⁺ group showed chlorophyll and protein content increase, SOD and POD activity showed also a slight increase, while MDA content decreased. However, for the 10 mg·L^-1 of Cu²⁺ group, the decrease of chlorophyll and protein content and the increase of MDA content were observed. Also a sharp increase of SOD and CAT activity compared with the 5 mg·L^-1 group were found; for over 10 mg·L^-1 of Cu²⁺ concentration, chlorophyll content and protein content fell off, whereas increase of MDA became considerable, CAT raised up steadily and POD showed a decrease trend. The results showed that, both insufficiency and overabundance of Cu²⁺ in water environment can affect the anti-oxidation function of Vallisneria asiatica which can be observed by the value of SOD, CAT and POD activity. Therefore, the measurement of anti-oxidation activity, protein content and MDA as a forecast and judgment indicator of Cu²⁺ contaminations in the water environment can be considered in the future.