Antioxidant defence mechanism operational in a mangrove - Acanthus ilicifolius L. subjected to NaCl stress.

Hydroponically grown Acanthus ilicifolius were exposed to different concentrations of NaCl (200, 400 and 600 mM) for 15d in order to characterize the potential of antioxidant system. In this study, our focus was to determine the NaCl tolerance potential of A. ilicifolius, on the basis of extend of lipid peroxidation, antioxidant enzyme activity and osmoregulation mechanism when subjected to high NaCl concentration. Antioxidant enzymes (SOD, CAT, GPX and APX) showed an enhanced activity in all the treatments and the increased activity was more significant in 400 mM treated plants. In 600 mM treated plants, a decrease in activity of antioxidant enzymes, accumulation of antioxidant molecules and malondialdehyde content was recorded upon increasing the treatment period. However, the PPO activity and ascorbate content showed reduction in all the treatments as compared to the control. These results indicates that A. ilicifolius exhibits efficient tolerance to NaCl upto a level of 400 mM, beyond which it turns to be intolerable. It can be concluded that, short term exposure to NaCl could trigger the stress tolerating mechanism of salt excreting mangrove A. ilicifolius.