Evaluation Activity of some Antioxidant Enzymes under Cadmium Toxicity in Two wheat Cultivars

Background and objectives: Wheat is one of the crops that have an important role especially in developing countries for feeding people. Therefore pay attention to the most minor issues with related to this crop strategy has a great importance role in ensuring food security and maintaining the independence of the country. First response of plants as soon as are exposed to high levels of heavy metals such as cadmium is production of reactive oxygen species (ROS). Effect of cadmium stress on superoxide dismutase (SOD) activity in different varieties of wheat showed a significant increase (31). Khan et al (2007) reported that under cadmium stress, ascorbate peroxidase (APX) enzyme activity in all varieties of the wheat had risen. Milone et al (2003) showed that about plants treated with cadmium, peroxidase (POX) activity increased. Catalase (CAT) enzyme activity in rice was increased under salt stress (33). According to importance of this issue, this study examined the uptake of cadmium and changes in activity of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase and peroxidase Guaiacol) three stage sampling was conducted at two Iranian bread wheat cultivars.
Materials and Methods: A factorial experiment in completely randomized has been designed and performed with three replications in the research greenhouse in Tehran University, Collage of Agriculture and Natural Resources. The treatments were consisted of four levels of Cd (0 (as control), 25, 50 and 100 mg Cd kg-1 soil), three times of sampling (30, 45 and 60 days after seed planting) and two cultivars of Iranian wheat (Alvand and Azadi), respectively.
Results and discussion: The results of this study has been showed with increasing of cadmium level in soil (Cd0to Cd50), SOD activity in two cultivars of wheat and three time of sampling was increased. On the other hand, in Cd100, SOD activity in two cultivars of wheat and three time of sampling was decreased. Level of decreasing in third time of sampling was clearer in compare to first and second time of sampling. For example Alvand and Azadi cultivars in Cd100 treatment showed 39 and 37 percent reduce. For two cultivars and in every three stage of sampling, CAT activity showed a decrease when level of cadmium was increased. Alvand cultivar showed the greatest decrease in third time of sampling with 73 percent, when level of cadmium was 100 mg/kg. Similar to SOD activity, POX activity was increased, when level of cadmium increased, but activity of POX was increased continuous. APX activity was increased when level of cadmium increased. Generally result of this research showed that efficiency of ant oxidative system in Alvand cultivar was more of Azadi cultivar.
Conclusion: Our results showed that Alvand cultivar compared with Azadi cultivar is more able to accumulate cadmium in its root and shoot that based on a botanical point view is an advantage and from the perspective of food security is a disadvantage.