外源苯丙烯酸对黄瓜叶片弱光胁迫下抗坏血酸-谷胱甘肽循环系统的影响

Effects of Exogenous Cinnamic Acid on Ascorbate-glutathione Cycle Metabolism in Cucumber leaves Under Low Light Stress

以"津春4号"黄瓜品种为材料,研究外源苯丙烯酸对弱光下黄瓜幼苗叶片抗坏血酸-谷胱甘肽(ASA-GSH)循环中抗氧化酶活性和非酶抗氧化物含量以及活性氧代谢的影响.研究结果表明,用50μmol苯丙烯酸(CA)处理2天后,MDA和H_2O_2含量降低,脱氢抗坏血酸还原酶(DHAR)、单脱氢抗坏血酸还原酶(MDHAR)、抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)活性提高,还原型抗坏血酸(AsA)和还原型谷胱甘肽(GSH)含量增加.8天后,弱光胁迫显著提高了MDA和H_2O_2含量,提高了DHAR,MDHAR,APX和GR的活性以及还原型抗坏血酸(AsA)和还原型谷胱甘肽(GSH)含量;CA预处理则降低了弱光胁迫下MDA和H_2O_2含量,提高了DHAR,MDHAR,APX和GR的活性以及AsA和GSH含量.外源CA预处理通过抗坏血酸-谷胱甘肽循环缓解了弱光下黄瓜叶片的膜脂过氧化损伤.

A cucumber variety（Cucumis sativus cv.Jinchun no.4）were used as experimental material.We investigate the effect of exogenous cinnamic acid（CA）on antioxidant enzyme activities and active oxygen metabolism of ascorbate-glutathione cycle in Cucumber leavers under low light stress.The results suggested that：at 2d,exogenous CA（50μmol）decreased levels of malonaldehyde（MDA）,superoxide radical（O2.-）and hydrogen peroxide（H2O2）,elevated the activities of antioxidant enzymes monodehydroascorbate reductase（MDHAR）,dehydroascorbate reductase（DHAR）,ascorbate peroxidase（APX）and glutathione reductase（GR）in cucumber leaves,and it also increased the contents of reduced glutathione（GSH）and ascorbate（AsA）.At 8d,compared with control,low light increased levels of O2.-,H2O2 and MDA,elevated the activities of antioxidant enzymes MDHAR,DHAR,APX and GR,enhanced the contents of GSH and AsA.The combination of CA pretreatment and low light decreased the contents of MDA,H2O2 and O2.- and enhanced the activities of DHAR,MDHAR,APX and GR and increased the levels of GSH and AsA in comparison to non-pretreated stressed plants.So exogenous CA is able to moderate ascorbate-glutathione cycle and decrease lipid peroxidation to some extent,thus reducing stress intensity at low light.