Cadmium-induced biochemical responses of Vallisneria spiralis

The following study was carried out to investigate the cadmium (Cd) accumulating potential of Vallisneria. After subjecting plants to different concentrations of Cd, it was observed that plants are able to accumulate ample amount of metal in their roots (5,542 microg g(-1) dw) and leaves (4,368 microg g(-1) dw) in a concentration- and duration-dependent manner. Thus, it is evident that the accumulation in roots was 1.3 times higher than the shoots. It was also noted that with increasing Cd accumulation, roots of the plant appeared darker in color and harder in texture. In response to metal exposure, amount of low molecular weight antioxidants such as cysteine and nonprotein thiols (NP-SH) and activity of enzymes such as APX and GPX were significantly enhanced at lower concentrations of Cd, followed by decline at higher doses. It was also observed that in exposed plants, activity of APX enzyme was higher in roots (ca. 3 times) as compared to leaves. However, chlorophyll and protein content was found to decline significantly in a dose-dependent manner. Results suggested that due to its high accumulation potential, Vallisneria may be effectively grown in water bodies moderately contaminated with Cd.