外源24-表油菜素内酯对低氧胁迫下黄瓜幼苗氮代谢的影响  

Effect of exogenous 24-epibrassinolide on nitrogen assimilation of cucumber seedlings under hypoxia stress

作　　者：马月花[1] 郭世荣[1,2] 杜南山[1] 山溪 孙锦[1,2] 王磊[1] 王颖[1] 束胜[1] 

机构地区：[1]南京农业大学园艺学院/农业部南方蔬菜遗传改良重点开放实验室,江苏南京210095 [2]南京农业大学(宿迁)设施园艺研究院,江苏宿迁223800

出　　处：《南京农业大学学报》2015年第4期538-545,共8页Journal of Nanjing Agricultural University

基　　金：现代农业产业技术体系建设专项资助(CARS-25-C-03)

摘　　要：[目的]本文的目的是研究外源24-表油菜素内酯(EBR)对低氧胁迫植株氮代谢的影响。[方法]以低氧耐性较弱的‘中农6号’黄瓜品种为材料,采用营养液通N2形成低氧逆境的方法,深入探讨了EBR对低氧胁迫下植株叶片和根系中与氮代谢相关的酶活性的影响。[结果]低氧处理显著降低了植株叶片的总氮含量,EBR使胁迫植株叶片总氮积累恢复至对照水平。低氧处理后,硝态氮含量在叶片中增加而在根系中降低,铵态氮的变化趋势与硝态氮相反,而EBR显著促进了胁迫植株根系的铵态氮积累。低氧胁迫下,植株根系硝酸还原酶(NR)和谷氨酰胺合成酶(GS)活性升高,随后恢复至对照水平,而谷氨酸合成酶(GOGAT)活性显著低于对照。叶片NR活性受到低氧抑制,亚硝酸还原酶(NiR)、GOGAT、氧化型谷氨酸脱氢酶(NAD+-GDH)活性则先升高,随后降低;叶片还原型谷氨酸脱氢酶(NADH-GDH)活性也受到低氧促进,至处理末期时显著高于对照植株。EBR显著提高了胁迫植株根系的NR活性及叶片的NiR、NAD+-GDH活性。[结论]黄瓜植株通过增强硝酸还原,加强氮代谢缓解低氧胁迫伤害;EBR通过增强根系NR活性及叶片NAD+-GDH活性,提高了植株的低氧耐性。[ Objectives ] This paper was to investigate the effect of exogenous 24-epibrassinolide on nitrogen metabolism of cucumber seedlings under hypoxia stress. [ Methods] A hypoxia-sensitive cucumber genotype（ Cucumis sativus＇ Zhongnong 6＇ ）was used and we investigated the effect of EBR on activity of key enzymes involved in nitrogen assimilation of plants under hypoxia. [ Results ] Total N content of leaves was decreased remarkably under hypoxia while EBR restored it to the control level. NO3^- content was increased in leaf but reduced in root. The change of NH4 content was contrary to that of NO3^-. EBR improved NH4^＋ accumulation in root under hypoxia stress. The activity of root nitrate reductase（NR） and glutamine synthetase（GS） was increased at the beginning of the stress, but recovered to that of the control level after 9 d hypoxia. While glutamate synthase（GOGAT） activity was reduced significantly at the end of the stress. Under hypoxia, activity of leaf NR was inhibited greatly, while nitrite reductase （NiR） , GOGAT and oxidized glutamate dehydrogenase（NAD^＋-GDH） activity showed a trend of increasing-decreasing with the prolongation of the stress. After 9 d hypoxia stress, activity of leaf reduced glutamate dehydrogenase （NADH-GDH）was raised significantly. EBR greatly improved activity of root NR, leaf NiR and NAD^＋-GDH of the plants under hypoxia. [ Conclusions ] The cucumber plants acclimated to hypoxia by improving nitrate reduction and nitrogen metabolism. EBR protected the plants from oxygen limitation by accelerating activity of root NR and leaf NAD^＋-GDH.

关 键 词：黄瓜 低氧胁迫 24-表油菜素内酯 氮代谢 

分 类 号：S642.2[农业科学—蔬菜学]