Responses of ruderal verbascum olympicum boiss. (scrophulariaceae) growing under cadmium stress

Abstract

Variations in the nitrate assimilation, antioxidant system (superoxide dismutase, catalase, ascorbate peroxidase (SOD, CAT, and APX)), and lipid peroxidation (MDA) of Verbascum olympicum (Scrophulariaceae) exposed to cadmium (Cd) in Hoagland's nutrient medium were investigated. The accumulation of Cd and variations in the content of some trace elements (Cu, Mo, Mn, and Zn) and growth parameters as, e. g., the water content, biomass production and chlorophyll and soluble protein content were also studied. Cd treatment (0, 50, 100, and 250 mu M Cd) was applied for seven days to eight weeks old seedlings in a growth chamber. Cd accumulated predominantly in the roots of V. olympicum, and the contents of Zn and Cu in the leaves and roots increased with the increasing Cd concentration. We found that increasing the Cd dosage inhibited the activity of nitrate assimilation enzymes and reduced the protein content, water content, and biomass production in the roots and leaves and the chlorophyll content in the leaves. Oxidative stress was confirmed by an increasing level of MDA in the seedlings. We concluded that this species has a powerful antioxidative defence system against Cd stress since SOD, CAT, and APX activities were induced.