Effect of sodium nitroprusside on arsenic-induced oxidative stress in wheat (Triticum aestivum L.) seedlings

In the present study, the possible regulatory role of sodium nitroprusside in mitigating oxidative stress in wheat seedlings exposed to arsenic (As) was investigated. 20-day-old seedlings were treated with As (0, 25 and 50 µM) and NO donor (0, 50 and 100 µM sodium nitroprusside) and hydroponically grown for 20 days. As treatment reduced the relative water content and chlorophyll content and increased proline content. Arsenic (50 µM) also increased the contents of malondialdehyde (173%), hydrogen peroxide (194%), reduced glutathione (GSH, 89%) and glutathione disulfide (GSSG, 138%), while decreased ascorbic acid (41%) and the ratio of GSH/GSSG (21%) compared to control. Increasing As concentrations enhanced the activity of ascorbate peroxidase, glutathione S-transferase and ascorbate peroxidase enzymes. Dehydro-azosporbate reductase and glyoxalase I activity decreased at both levels of arsenic, while glutathione peroxidase and glyoxalase II decreased only under 50 μm As. The activities of dehydroascorbate reductase and glyoxalase I decreased at any levels of As, while glutathione peroxidase and glyoxalase II activities decreased only upon 50 μm of As. The SNP treatment increased the RWC, chl and proline contents; AsA and GSH contents and the GSH/GSSG ratio as well as the activities of MDHAR, DHAR, GR, GPX, CAT, Gly I and Gly II in the seedlings subjected to As stress. These results suggest that the application of SNP rendered the plants more tolerant to As-induced oxidative damage by enhancing their antioxidant defense and glyoxalase system, which ultimately improved plant growth.