Micronutrient deficiency changes activities of superoxide dismutase and ascorbate peroxidase in tobacco plants

The effects of copper (Cu), zinc (Zn), and manganese (Mn) deficiencies on the activities of superoxide dismutase (SOD) and ascorbate peroxidase (APx) were investigated in seedlings of Nicotiana tabacum cv. Xanthin. After germinating in sand for 7 days, plants were transplanted to solution culture with all nutrients or without Cu, Zn, or Mn. Plants grown without Mn developed visual deficiency symptoms 15 days after transplanting (DAT), and those grown without Zn showed Zn deficiency symptoms 26 DAT. In contrast, plants grown without Cu showed only minor symptoms of Cu deficiency at 33 DAT. When harvested 41 DAT, -Mn plants suffered the largest, and -Cu the smallest reduction in shoot dry weight compared to plants supplied with all nutrients. Nutrient analysis in leaf tissue showed a considerable decrease in concentration of nutrients not supplied to plants. Total SOD, MnSOD+FeSOD, Cu/Zn SOD, and APx activities declined drastically in -Mn and -Zn plants, while total SOD, MnSOD+FeSOD and APx activities in -Cu plants remained significantly higher than those of control plants. It was concluded that micronutrient deficiencies (Cu, Zn, and Mn) can alter the activities of antioxidative enzymes in tobacco plants depending on the severity and the type of the deficiency stress.