Cerium under calcium deficiency-influence on the antioxidative defense system in spinach plants

The influence of calcium-deficiency and cerium addition on the antioxidative defense system in spinach leaves was investigated. It was found that spinach cultivated in calcium-deficiency media developed distinct calcium deficiency symptoms and the plant growth was significantly inhibited as expected. While cerium-treated spinach remained green and expanded, and plant growth was improved. Calcium deprivation in spinach also increased the permeability of plasma membrane, malondialdehyde as a degradation product of lipid peroxidation, reactive oxygen species such as superoxide radicals, hydrogen peoxide, and decreased activities of the antioxidant enzymes such as superoxide dismutase, catalase, ascorbate peroxidase, guaiacol peroxidase and glutathione content. However, cerium treatment cultivated in calcium-deficiency media decreased the permeability of plasma membrane, malondialdehyde and reactive oxygen species, and increased activities of the antioxidative defense system. This is viewed as evidence for cerium addition to calcium-deficiency media in the spinach plants could substitute calcium and enhance oxidative stress-resistance.