Effects of Cadmium Stress on Antioxidant Enzymes in Vigna Radiata Roots

A brief study to analyze oxidative stress and antioxidant response of cadmium stress was carried out. The plant chosen Vigna radiata (var. SML-668) was hydroponically grown in 0, 50μM, 100μM and 150μM, cadmium chloride. The roots were taken from hydroponic culture at 6 days of growth for various enzymatic and metabolic estimations. Among the antioxidant enzymes, root catalase and ascorbate peroxidase decreased while guaiacol peroxidase and superoxide dismutase increased in response to cadmium. The lipid peroxidation and protein oxidation too increased probably due to production of active oxygen species by heavy metal stress which causes lipid peroxidation. So, Cd was definitely toxic to root system of V. radiata plants as indicated by consistent increase in peroxidation and protein oxidation. However, the plant was able to counter this partially by concomitant increase in SOD and guaiacol peroxidase. But, the other two antioxidant enzymes catalase and ascorbate peroxidase could not counter oxidative stress generated by Cd as they were decreased. INTRODUCTION: Cadmium is a heavy and nonessential element which is released into the environment by power stations, heating systems, metal-working industries or urban traffic. Its high toxicity and large solubility in water has made it an important pollutant. 1 Plant Cd concentrations are between 0.05-0.2ppm, 2 but can be much higher in plants growing in contaminated soils. Heavy metals are generally involved in generation of reactive oxygen species (ROS). 3 As an example, transition metals like Fe 3+ and Cu 2+ participate in the wellknown Haber-Weiss cycle, producing HO ·from O2 ·and H2O2 4 . QUICK RESPONSE CODE DOI: 10.13040/IJPSR.0975-8232.6(7).2882-85 Article can be accessed online on: www.ijpsr.com DOI link: http://dx.doi.org/10.13040/IJPSR.0975-8232.6(7).2882-85 Metals without redox capacity (such as Cd 2+ , Pb 2+ , and Hg 2+ ) can enhance the prooxidant status by reducing the antioxidant glutathione (GSH) pool, activating calcium-dependent systems and affecting iron-mediated processes. 1 These heavy metals can also disrupt the photosynthetic electron chain, leading to O2 ·and 1 O2 production 5 . So, hydroponic cultivation of Vigna radiata in 50/100/150 μM Cd stresses with lipid and protein peroxidation in cadmium stressed V. radiata roots were studied. MATERIALS AND METHODS: Collection of experimental material: The certified seeds of Vigna radiata (cv. SML 668) were purchased from local market. Growth and collection of plant material: Seeds of V. radiata were soaked overnight in minimum DW and surface sterilized next day in 0.1% HgCl2. The pre-soaked and sterilized seeds were then germinated hydroponically in nutrient