Protective Effect of Nitric Oxide on High Temperature Induced Oxidative Stress in Wheat (<i>Triticum aestivum</i>) Callus Culture

Abstract

High temperature (HT) stress is a major environmental factor that limits plant growth, metabolism and productivity worldwide. Plant growth and development involve numerous biochemical reactions that are sensitive to temperature. Plants’ responses to HT vary with the degree and duration of HT and the plants’ adaptability. The protective effect of exogenous nitric oxide in alleviating high temperature induced damages of wheat (Triticum aestivum) callus tissues was investigated. Heat treatment (35 and 40 °C) alone or in combination with 0.5 mM sodium nitroprusside (SNP; nitric oxide donor) was applied for 72 h to callus tissues cultured on MS medium. Heat stress significantly increased lipid peroxidation, hydrogen peroxide and superoxide anion radical levels, whereas ascorbate and total glutathione contents markedly decreased. In addition, heat stress increased the activities of antioxidant defense enzymes: superoxide distumase, ascorbate peroxidase and glutathione reductase. In contrast, the addition of SNP in the culture media prevented the callus from the heat-induced oxidative damage as indicated by the decrease of MDA, H2O2 and O2.− contents, and increased the activities of antioxidant enzymes and non-enzymatic antioxidant constituents. These results provided support for the hypothesis that the exogenous applications of NO confer tolerance to high temperature stress by reducing the oxidative damage in plants.