棉花幼苗AsA-GSH循环对低温胁迫的响应机制研究

为探究棉花幼苗营养器官抗坏血酸-谷胱甘肽(AsA-GSH)循环系统对低温胁迫的响应机制,以新陆早57号为试验材料,研究4℃低温胁迫不同时间(0、1和2 d)对根、茎和叶中抗氧化物质含量和酶活性的影响。结果表明,与对照(0 d)相比,随着低温胁迫时间延长,棉花幼苗根中还原型抗坏血酸(AsA)含量及单脱氢抗坏血酸还原酶(MDHAR)和谷胱甘肽还原酶(GR)活性呈上升趋势,氧化型抗坏血酸(DHA)含量先减少后增加,氧化型谷胱甘肽(GSSG)含量和脱氢抗坏血酸还原酶(DHAR)活性先升高后降低,谷胱甘肽氧化还原状态(GSH/GSSG比率)和抗坏血酸过氧化物酶(APX)活性总体呈下降趋势,抗坏血酸氧化还原状态(AsA/DHA比率)、还原型谷胱甘肽(GSH)含量和谷胱甘肽过氧化物酶(GPX)活性无显著性差异;茎和叶中AsA和GSH含量、AsA/DHA比率及APX、MDHAR和GR活性总体呈上升趋势,且茎中DHAR活性升高,DHA和GSSG含量先减少后增加,GSH/GSSG比率和GPX活性无显著性差异,而叶中DHA含量和GSH/GSSG比率先不变后增加,DHAR活性先升高后降低,GSSG含量和GPX活性无显著性差异。综合分析显示,棉花幼苗通过调节根、茎和叶中抗氧化物质含量和酶活性来清除活性氧,从而适应低温胁迫,减轻低温伤害。此外,低温对根中AsA-GSH循环影响最大。本研究结果为揭示低温胁迫对棉花幼苗AsA-GSH循环代谢机制提供了理论依据。

Study on the Response Mechanism of the AsA-GSH Cycle in Cotton Seedling Under Low Temperature Stress

In order to investigate the response mechanism of ascorbate-glutathione circulatory system in the vegetative organs of cotton seedlings subjected to low temperature stress,an indoor experiment was conducted to study the effects of low temperature stress(4℃)at different times(0 d,1 d and 2 d)on antioxidant contents and antioxidant enzyme activities in roots,stems and leaves of Xinluzao 57 cotton seedlings.The results showed that compared with the control treatment(0 d),as the low temperature stress time prolonged,in roots,the AsA content,MDHAR and GR activities in roots gradually increased.DHA content first decreased and then increased,GSSG content and DHAR activity first increased and then decreased,GSH/GSSG ratio and APX activity decreased,and no significant difference was observed in AsA/DHA ratio,GSH content and GPX activity.Low temperature stress treatment gradually increased the AsA,GSH contents,AsA/DHA ratio,APX,MDHAR,GR activities in stems and leaves.Moreover,DHAR activity increased,DHA and GSSG contents in stems first decreased and then increased,and no significant difference was observed in GSH/GSSG ratio and GPX activity;in leaves,DHA content and GSH/GSSG ratio first remained stable and then increased,DHAR activity first increased and then decreased,and no significant difference was observed in GSSG content and GPX activity.Comprehensive analysis showed that cotton seedlings could remove reactive oxygen species by regulating the antioxidant contents and antioxidant enzyme activities in roots,stems and leaves to adapt to low temperature stress and reduce the damage to cotton seedlings caused by low temperature stress.Besides,low temperature stress had the greatest effect on AsA-GSH cycle in roots.These results would provide a theoretical basis for revealing the mechanism of AsA-GSH cycle metabolism in cotton seedling subjected to low temperature stress.