NO Involved In Ascorbate-glutathione Cycle Of Tomato Seedling Under Copper Stress

Tomato (Lycopersicon esculentum Mill.), cultivated in greenhouse, is an annual vegetable crop which is liked by the majority of the people. The large number of application of organic fertilizer contained heavy metal and chemical fertilizer, made the vegetable soil polluted by copper, cadmium and other heavy metal. And the polluted vegetable produce resulted in a series of physiological disorders. Therefore the investigation of toxicity and detoxification mechanism of tomato under copper stress is significant in theory and practice. This experiment, the tomato as the test material, cultured in nutrient solution, investigate the effect of exogenous NO on AsA-GSH cycle of roots of tomato seedling under copper and the metabolism of reactive oxygen and NO of tomato seedling.1. Exogenous NO increased the content of AsA, GSH and GSSG in the root of tomato seedlings. After adding100μmol·L-1BSO solution, the content of AsA in the root of tomato was increased by exogenous NO under copper stress, and the content of DHA, GSH, GSSG was reduced. After adding250μmol·L-1BSO solution, exogenous NO can increase the content of AsA, DHA, GSH, and alleviate the content of GSSG.2. Exogenous NO increased the ratio of AsA/DHA in the root, however the ratio of GSH/GSSG was not significantly changed. Added100μmol·L-1BSO, exogenous NO increased ratio of AsA/DHA, reduced the ratio of GSH/GSSG in the root under copper. Added250μmol·L-1BSO, exogenous NO increased ratio of AsA/DHA、GSH/GSSG. The exogenous NO regulation of the ratio of AsA/DHA, GSH/GSSG involve the concentration of BSO. The results suggested that exogenous NO affected the AsA-GSH cycle of tomato seedling roots under copper stress and alleviated oxidative stress by regulating AsA/DHA, GSH/GSSH in seedling roots of tomato under copper stress.3. The application of exogenous NO significantly increased the activity of DHAR and reduced the activities of APX, GR. With the addition of100μmol·L-1BSO, the exogenous NO increased the activities of DHAR, AAO of root under copper. With the addition of250μmol·L-1BSO, exogenous NO supply increased the activity of GR, alleviated the activities of DHAR, MDHAR, AAO in root of tomato seedling. Added a low concentration of BSO treatment, the application of exogenous NO involved the activities of enzyme related the ASA and DHA, increasing the ASA/DHA, alleviated the copper stress. Added a high concentration of BSO treatment, the exogenous NO affected the activities of enzyme related the AsA, DHA, GSH and GSSG to improve the ratios of AsA/DHA and GSH/GSSG.4. After applied exogenous NO, the variation of mineral elements in tomato seedlings under copper stress was associated with the concentration of BSO. Added100μmol·L-1BSO, the exogenous NO increased the content of Mg in leaves and Cu, Ca, Zn in roots, decreased the content of Cu, Zn, Mn, Fe in leaves. Added250μmol·L-1BSO, the application increased Zn and Fe content in leaves, alleviated Ca, Mn, Fe content in leaves and Cu, Fe content in roots, did not change significantly the content of Zn, Mn, Mg and Ca in roots. With the addition of100μmol·L-1BSO, exogenous NO maintain the mineral nutrition balance in cytoplasm to relieve the inhibitory effect on the growth of tomato plants under copper. However, after adding250μmol·L-1BSO, exogenous NO inhibited the absorption of mineral elements of tomato seedlings under copper stress.5. The copper treatment increased the production rate of O2-, and reduced the production amout of NO and the activities of NR, NOS in tomato seedling. The application of nitric oxide increased the production amout of NO and the activity of NOS in leaves and roots and activity of NR in leaves. The100μmol·L-1BSO treatment increased the production rate of O2-, and decreased the production amout of NO and activity of NR in leaves. The nitric oxide increased the production of NO in leaves and roots, activities of NR, NOS in leaves, alleviated the production rate of O2-in leaves and roots of tomato seedling.