Dynamic Changes in Antioxidative Systems in Roots of Tomato (Lycopersicom Esculentum Mill.) Seedling under Zinc Stress and Recovery

A solution culture experiment was carried out in greenhouse to study the dynamic changes in antioxidative systems in roots of tomato seedlings (Lycopersicom esculentum Mill.) under zinc stress and recovery. The results showed that under stress malonaldehyde (MDA) and protein contents increased, and the activities of superoxide dismutase (SOD, EC 1.15. 1.1), catlase (CAT, EC 1.11. 1.6) and glutathione peroxidase (GPX, PC 1.11. 1.9) increased, while guaiacol peroxidase (POD, EC 1.11. 1.7) activity declined. AsA-GSH cycle was affected. Ascorhate peroxidase (APX, EC 1.11. 1.11) activity rose in the first three days and decreased then, and glutathione reductase (CR, EC 1.6. 4.2) activity decreased in the first five days and increased then, the contents of ascrobate (AsA) and glutathione (GSH) increased as well. After recovery, MDA and protein contents declined to control level. The activities of POD and APX increased, while the activities of SOD, CAT and GR and GSH content increased in the beginning of recovery, and then decreased. GPX activity and AsA content in roots duratively declined. After recovery the activities and contents remained higher than those of controls. According to the results of the experiment, the role of AsA-CSH cycle during the stressed and recovering period was discussed in this paper. Fig 3, Ref 16