Effect of NaCl Stress on Antioxidant System in Kandelia candel Roots

Abstract:

In order to understand the response of antioxidant system in roots of Kandelia candel seedlings to salt stress, sixty-day-old mangrove Kandelia candel seedlings cultured in sand with Hoagland solution were treated with 0, 200, 400 and 600 mmol L^–1 NaCl for 1, 3, 5, and 7 days, respectively. The results showed that the contents of O₂^· and H₂O₂ remained low level treated with 200 and 400 mmol L^–1 NaCl for the same days, but increased significantly under 600 mmol L^–1 NaCl. MDA content remained stable under 200 and 400 mmol L^–1 NaCl compared to control (0 mmol L^–1 NaCl), while increased remarkably under 600 mmol L^–1 NaCl. The activities of SOD, POD, CAT, APX, and GR increased at first and then decreased with increment of NaCl concentration treated for the same days. The activities of these enzymes were significantly higher than those in control treated for 3 and 5 days, but they were significantly lower than those in control treated with 600 mmol L^–1 NaCl for 7 days. The contents of AsA and GSH were significantly higher than those in control. Therefore, it was suggested that Kandelia candel roots could improve the resistance to salt stress through strong antioxidant system to scavenging active oxygen.