Antioxidant enzymes in paraquat and cadmium resistant cell lines of horseradish

Abstract

Effect of paraquat (PQ) and cadmium on the activity and isoenzymatic pattern of antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (POX) and ascorbate peroxidase (APX), was investigated in non-stressed and PQor Cd-tolerant cells of horseradish (Armoracia rusticana Gaertn.). The activities of these enzymes were used as biochemical markers of the stress resistance capacity of the selected cells able to grow in suspension culture in the presence of 1 μM, 5 μM and 15 μM PQ or 50 μM, 100 μM and 200 μM Cd ions. Native polyacrylamide gel electrophoresis, followed by appropriate staining, showed that in herbicide-tolerant cells the most active enzyme was catalase, whereas in metal-tolerant cells the most important role was played by POX and APX. We regenerated plants from control cells and cells tolerant to 1 μM PQ. At 5 μM PQ, only early stages of plant formation from callus were observed. There were no signs of regeneration in callus derived from Cd-treated cells. In plants regenerated from cells tolerant to 1 μM PQ, the activity of POX was slightly higher than in control plants but the SOD activity remained unaffected.