OP012 The role of H2S in pepper leaves under salt stress conditions

• Published in: Nitric oxide 2013-09, Vol.31, p.S24-S24
• Main Authors: Lisjak, M., Teklic, T., Wilson, I., Wood, M.E., Whiteman, M., Špoljarević, M., Hancock, J.T.
• Format: Article
• Language: English
• ISSN: 1089-8603; 1089-8611
• DOI: 10.1016/j.niox.2013.06.042

In plants high concentrations of hydrogen sulfide (H2S) can inhibit enzymes such as cytochrome oxidase. Based on this, and its similar inhibitory effects, H2S has commonly been thought of as a phytotoxin. However, at lower concentrations, it may act in a more positive manner. Many plant species have been found to generate H2S suggesting that it may be an endogenous chemical and suitable to be considered as signalling molecule. There is a growing body of evidence to suggest that the presence of this gasotransmitter may impact on oxidative stress metabolism in plants. The treatment of plant cells with H2S affects both cysteine and glutathione metabolism but are there other plant physiological pathways which can be affected by H2S? The activity of stress-related enzymes and also the content of some specific metabolites are often used as physiological stress response parameters. In greenhouse growing, plants are often exposed to unfavorable growth conditions due the salt stress, while at the same time numerous H2S-based preparations are often used as fungicides. Thus, our study aimed to further explore the potential role of H2S in plant physiological pathways, with a particular focus on the possible protective role of H2S in salt stress conditions. Pepper plants grown in substrate under fully controlled conditions were pre-treated with H2S donors (NaHS, GYY4137) and exposed to the three different levels of salt stress. Significant differences between individual treatments and pre-treatments were observed. Total activity of catalase, glutathione reductase and guaiacol peroxidase were significantly increased at 100 and 200mM NaCl. The applied salt stress treatments increased lipid peroxidation rates as well as free proline and hydrogen peroxide content. In general, both H2S donors decreased lipid peroxidation levels in leaves, while NaHS reduced free proline and hydrogen peroxide content. Salt stressed plants pretreated with GYY4137 showed significantly higher free proline content. The results suggest that H2S may have a protective role in the case of salt stress, through increasing enzymatic activity and the accumulation of stress protective metabolites such as proline. Lowered lipid peroxidation in plants pre-treated with H2S donors implies that this gasotransmitter can protect cell membranes constituents from chain destruction, whether through direct involvement in ROS neutralization, or through the synthesis of important antioxidants such as glutathione.