Cadmium-induced Stress and Antioxidative Responses in Different Brassica napus Cultivars

To estimate plant resistance to Cadmium Chloride (CdCl۲) stress for phytoremediation purposes, the effect of cadmium (Cd) phytotoxicity was assessed on total soluble protein, chlorophyll (Chl) content and antioxidant enzymes in the leaves of three different Brassica napus (B. napus) cultivars; Mohican, Reg.Cob and Okapi. Plants were exposed to three levels of CdCl۲ (۰.۷۵, ۱.۵ and ۲.۲۵ mM) in irrigation water. A reduction in protein and Chl content was noted for all treatments in the three cultivars. Generally, superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities were increased with ۰.۷۵ mM CdCl۲ and then decreased at higher concentrations. SOD activity was enhanced up to ۱.۵ mM CdCl۲ concentration in Mohican cultivar. Moreover, APX activity of Okapi cultivar was increased at a much higher rate of CdCl۲ levels compared to Mohican and Reg.Cob cultivars. Different concentrations of CdCl۲ induced a reduction in the catalase (CAT) activity of Mohican and Reg.Cob. However, this activity was increased with ۰.۷۵ mM CdCl۲ in Okapi and then decreased with higher concentrations. These results indicate that B. napus cultivars have different tolerances to CdCl۲ stress and in consequence, different phytoremediation efficiencies. Moreover, because Okapi possesses a higher antioxidant enzyme activity than the other two cultivars, it is suggested that it is probably the most tolerant cultivar to CdCl۲ stress.

Keywords:

Antioxidant enzymes , B. napus , Cadmium Chloride , Cultivars , stress