Alleviation of UV-B radiation damages by sodium hydrosulfide (H2S donor) pre-treatment in Borage seedlings

ABSTRACT Hydrogen sulfide (H2S) is a highly diffusible, gaseous molecule that has been proved to control a range of physiological responses in many plant stresses. Exposure to UV-B radiation leads to the generation of reactive oxygen species that cause oxidative damages. In this study, sodium hydrosulfide (NaHS) was used as a H2S donor for the alleviation of damage caused by UV-B in Borage plant. Lipid peroxidation, protein oxidation, and H2O2 content were increased in plant exposed to UV-B. Results showed that ascorbate peroxidase, guaiacol peroxidase, and catalase activities and reduced glutathione (GSH) did not change significantly in stressed plants when compared with control, but flavonoids concentration was increased considerably. Pre-treatment of plants with NaHS (120？μM), significantly decreased the Malondialdehyde content, carbonyl groups, and H2O2. Activities of ascorbate peroxidase and guaiacol peroxidase enzymes increased in plants which were pre-treated while catalase activity decreased. The reduced glutathione content increased in borage plant leaves. HPLC analysis of flavonoids demonstrated that pre-treatment with NaHS caused a decrease in flavonoid content. These findings suggest that H2S alleviates UV-B damages may occur through enhancement of antioxidative enzyme activities and GSH content in borage seedlings