外源NO对NaCl胁迫下黄瓜(Cucumis sativus L.)幼苗生长和谷胱甘肽抗氧化酶系统的影响

Effects of nitric oxide on the growth and glutathione dependent antioxidative system in cucumber (Cucumis sativus L.) seedlings under NaCl stress

采用营养液水培,研究了外源一氧化氮(NO)对黄瓜(Cucumis sativusL.)幼苗生长和叶片谷胱甘肽抗氧化酶系统的影响。结果表明,正常生长条件下添加NO能促进黄瓜幼苗生长,而添加NO信号传递途径关键酶鸟苷酸环化酶(cGC)抑制剂亚甲基蓝(MB-1)显著抑制了黄瓜幼苗的生长;添加NO显著缓解了盐胁迫对黄瓜幼苗生长的抑制,提高了叶片谷胱甘肽还原酶(GR)活性、脱氢抗坏血酸还原酶(DHAR)活性、抗坏血酸过氧化物酶(APX)及还原型谷胱甘肽(GSH)、抗坏血酸(ASA)含量,降低了氧化型谷胱甘肽(GSSG)含量,提高了GSH/GSSG,对单脱氢抗坏血酸还原酶(MDAR)活性无显著影响;NaCl胁迫下添加NO的同时添加MB-1抑制了GR活性的提高,GSH和ASA含量、GSH/GSSG均降低,GSSG含量提高,但对MDAR、APX和DHAR活性无显著影响,表明NaCl胁迫下NO对GR活性、GSH和ASA含量、GSH/GSSG的调节可能是通过cGC介导的,对MDAR无明显的调节作用,对DHAR、APX的调节还存在其它途径。

The object of the study was to investigate the effects of nitric oxide on the growth and glutathione dependent antioxidative system in cucumber （ Cucumis sativus L. cv. Jinchun 2） seedlings. The results showed that exogenous nitric oxide increased the growth of cucumber seedlings in normal growth conditions. But exogenous methylene blue, the inhibitor of the key enzyme cGC during signal transfer of nitric oxide, markedly decreased the growth of cucumber seedlings. Exogenous nitric oxide alleviated the injured cucumber seedlings under NaC1 stress. The activities of GR and DHAR, and the content of APX, GSH, ASA, GSH/GSSG was increased while the content of GSSG was decreased. The activity of MDAR was not affected under NaC1 stress. But methylene blue blocked some effects of exogenous nitric oxide under NaC1 stress, so the activity of GR and the content of GSH, ASA, GSH/GSSG was decreased. It was observed that the content of GSSG was increased, however, the activity of DHAR, MDAR and APX was not affected markedly under NaCl stress.Therefore nitric oxide was not adjusted the activity of GR, the content of GSH and ASA, GSH/GSSG through cGC. Nitric oxide couldn＇t affect on the activity of MDAR. And there were some other ways which adjusted the activity of DHAR and the content of APX.