外源GSH对NaCl胁迫下番茄幼苗生长及AsA-GSH循环的影响

Effects of Exogenous GSH on the Growth and AsA-GSH Cycle in Tamato Seedlings under NaCl Stress

采用营养液栽培法,研究叶片喷施还原型谷胱甘肽(GSH)、氧化型谷胱甘肽(GSSG)和谷胱甘肽合成抑制剂(BSO)对NaCl胁迫下番茄幼苗植株生长、叶片丙二醛(MDA)和H2O2含量、抗坏血酸-谷胱甘肽(AsA-GSH)循环中抗氧化酶活性及氧化还原水平的影响。结果表明:外源喷施GSH通过显著提高NaCl胁迫下番茄幼苗还原力水平和叶片中超氧化物歧化酶(SOD)、AsA-GSH循环中抗坏血酸过氧化物酶(APX)、脱氢抗坏血酸还原酶(DAHR)、单脱氢抗坏血酸还原酶(MDHAR)和谷胱甘肽还原酶(GR)的活性,有效提高了活性氧清除能力,显著缓解了NaCl胁迫对番茄幼苗生长的抑制。外源喷施GSSG虽然降低了GSH/GSSG比值,但由于通过上调了AsA/DHA比值和SOD、AsA-GSH循环关键酶活性,一定程度缓解了NaCl胁迫对番茄幼苗生长的抑制作用。喷施BSO显著降低了NaCl胁迫下番茄幼苗叶片的还原力水平和SOD、GR、APX和MDHAR的活性,导致H2O2清除能力降低,从而进一步抑制了NaCl胁迫下番茄幼苗的生长。

Hydroponic experiments were conducted to investigate the effects of foliar spraying with reduced glutathione（GSH）,oxidized glutathione（GSSG） and glutathione synthesis inhibitor（BSO） on plant growth,as well as H2O2 and MDA contents and antioxidant enzymes activities in the ascorbate-glutathione cycle and redox states in leaves of tomato seedlings under NaCl stress.The results showed that the application of exogenous GSH significantly alleviated salt-induced growth inhibition and increased reactive oxygen species scavenging capacity in leaves of salt-stressed tomato seedlings by enhancing the levels of reducing power and activities of superoxidase dismutase（SOD）,ascorbate peroxidase（APX）,dehydroascorbate reductase（DHAR）,monodehydroascorbate reductase（MDHAR） and glutathione reductase（GR）.Although the application of exogenous GSSG decreased the ratio of GSH/GSSH,the salt-induced growth inhibition was alleviated in plants stressed by NaCl,which might attribute to the up-regulation of AsA/DHA ratio and the activities of SOD and enzymes related to ascorbate-glutathione cycle.Application of exogenous BSO significantly decreased reducing power levels,SOD,GR,APX and MDHAR activities in tomato leaves under NaCl stressed,which contributed to the lower H2O2 scavenging capacity, and resulted in aggravating the growth inhibition of salt-stressed tomato seedlings.