Induction of antioxidant system in response to cadmium imparts tolerance to toxicity stress in Brassica

Effect of cadmium (Cd) toxicity stress on growth traits, photosynthetic pigments, cellular membrane damage, enzymatic and non-enzymatic antioxidant system, and Cd tolerance index was studied in two mustard cultivars (Brassica juncea L.) using four different doses of Cd incorporated as CdCl2. With increasing soil Cd content, a drastic decrease in leaf area, root length, plant height, and dry weight was observed while maximum reduction was recorded at highest dose (150 mg Cd kg−1 of soil) in both mustard cultivars (PCS 701 and Chamatkar). Cultivar ‘Chamatkar’ showed higher damage in terms of membrane lipid peroxidation and growth parameters than ‘PCS 701’. ‘Chamatkar’ cultivar also indicated lower induction in the activity of all antioxidant enzymes as compared with ‘PCS 701’ and considered as sensitive cultivar to Cd toxicity stress. In PCS 701, there was significant increase in all the antioxidant enzymes activity, which lowered the level of oxidative stress on cellular membrane and enhanced the Cd tolerance index. This cultivar was also found tolerant for growth response and showed lower reductions in plant height, leaf area and shoot biomass. This study concludes that among various traits antioxidant system plays significant role in reducing Cd toxicity.