Toxic Effect of Cadmium and Catalase Activity in the Corms of Crocus sativus L.

Cadmium is a highly carcinogenic heavy metal and a known contaminant of today’s industrial world. In this research we report its effect on rooting and on the activity of catalase, a major antioxidant enzyme, in Crocus sativus L. corms cultivated for 3, 6 and 9 days in distilled water and in water supplemented with 0, 0.5, 2, 5, 20, 50 mg/l cadmium (Cd2+). Over 9 days cultivation, root elongation was unaffected in 0.1 mg/l Cd2+, moderately inhibited in 0.5 and 2 mg/l Cd2+ and drastically inhibited in 5-20 mg/l Cd2+; no root elongation was observed after one day cultivation in 50 mg/l Cd2+. However, exposure to Cd2+ triggered an increase in catalase activity after 3 days cultivation. In corms grown for 3 days in distilled water a 60 % increase in catalase activity compared to dormant corms was observed. This increase was brought to 130 % in corms cultivated in 0.1 mg/l Cd2+and to 110 %, 90 % and 65 % in corms cultivated in 0.5, 2-20 and 50 mg/l Cd2+, respectively. Thus, in up to 0.5 mg/l Cd2+, the increase in catalase activity doubled compared to the control in response to metal-induced oxidative stress; in higher Cd2+ concentrations, the catalase activity would itself be hampered by the metal, resulting in a more moderate increase. In contrast to corms grown for 3 days in the presence of increasing Cd2+ concentrations, in corms exposed for 6 days to Cd2+ catalase activity remained close to that found in corms grown in distilled water for 6 days. After 9 days cultivation, an increase in catalase activity compared to the control was again observed in the presence of Cd2+, but the activity remained lower than in dormant corms. Our investigation showed the importance of catalase in controlling Cd2+ toxicity in Crocus sativus L. corm.

کلیدواژه ها:

Antioxidant enzyme ، Heavy metals ، Root elongation ، ROS ، Saffron