Nitric oxide alleviates oxidative stress caused by salt in leaves of a mangrove species, Aegiceras corniculatum

The high availability of ammonium in mangrove sediments is favorable for the production of nitric oxide (NO). NO has been found to function in plant responses to various environmental stresses. The aim of this paper is to evaluate the role of NO in relieving salt-induced oxidative stress in a mangrove species, Aegiceras corniculatum. A. corniculatum seedlings were subjected to 350 mM NaCl treatment. Sodium nitroprusside (SNP), an exogenous NO donor, was used to investigate the effects of NO on the content of low-molecular weight antioxidants, as well as the activity of antioxidant enzymes in salt-treated A. corniculatum seedlings by biochemical and enzymological analysis. We found that NO alleviated the oxidative damage in leaves of A. corniculatum by reducing hydrogen peroxide content and lipid peroxidation, and increasing the content of reduced glutathione and polyphenols. NO could also enhance guaiacol peroxidase activity, while reduce polyphenol oxidase activity. Based on the above results, we conclude that NO plays an important role in enhancing the salt tolerance of A. corniculatum primarily through regulating the antioxidant system, thus supporting tolerance of this mangrove to a high salinity. (C) 2014 Elsevier B.V. All rights reserved.