绿狐尾藻耐铵态氮性能的研究

发布时间：2018-06-17 18:09

本文选题：铵态氮 + 绿狐尾藻　；参考：《郑州大学》2017年硕士论文

【摘要】：富营养化现象会产生很多不利于沉水植物生长的因素,而水体中铵态氮浓度的升高是沉水植物在富营养化湖泊中消亡的重要因素这一观点已成为共识。目前,国内外关于水体中铵态氮对沉水植物的毒性效应的研究主要集中于对铵态氮耐受度较低的沉水植物。本课题通过构建微型环境,对三种沉水植物在铵态氮胁迫下的生理响应进行了对比研究;然后以耐受物种绿狐尾藻为主要研究对象,考察绿狐尾藻在高浓度铵态氮胁迫下的毒性效应和过氧化损伤,分析各组织的毒性阈值;最后对绿狐尾藻在不同程度的铵态氮胁迫下的氮素代谢和调节酶活性差异进行研究,探讨耐受度较高的沉水植物在应对高浓度铵态氮胁迫时的解毒机制,帮助我们认识沉水植被在富营养化湖泊中的衰退机理以及恢复重建工作。试验结果表明:1.常见沉水植物如金鱼藻和狐尾藻在10 mg L-1铵态氮浓度下就会表现出生物量负增长和叶绿素水平显著降低的现象,而绿狐尾藻的相对生长速率和叶绿素含量随着铵态氮浓度从1到20 mg L-1的增长而增长。铵态氮的过量蓄积所产生的毒性效应往往导致沉水植物体内可溶性蛋白质和非结构性碳水化合物含量的下降,而绿狐尾藻对于铵态氮的高耐受度主要由于对C-N代谢的调节管制,这种调节管制有效避免了过量铵态氮可能造成的毒性损伤。2.绿狐尾藻在80 mg L-1的铵态氮浓度下出现生长速率下降和叶绿素含量降低,膜脂过氧化水平增长的现象。当铵态氮浓度升至120 mg L-1时,绿狐尾藻的生物量在实验后期出现负增长,根系组织开始表现损伤,抗氧化系统损伤加剧。绿狐尾藻的根系组织对铵态氮的耐受程度高于叶片组织,但在120 mg L-1的铵态氮浓度下根系组织也表现出显著的毒性效应。3.作为对铵态氮耐受程度较高的沉水植物,绿狐尾藻可以高效地利用氮素,这与绿狐尾藻体内氮素代谢的关键酶类密切相关。绿狐尾藻对于铵态氮的解毒恢复和应对氮素缺乏的代谢调节分别与其体内天冬酰胺酶和硝酸还原酶的高效表达密切相关。铵态氮浓度的增加对于绿狐尾藻组织内的氮素调节酶类有显著影响,当铵态氮浓度达到120 mg L-1时,随着实验的进行,绿狐尾藻的谷氨酰胺合成酶和天冬酰胺酶的活性显著下降。绿狐尾藻可以通过有效的代谢调节实现对于铵态氮的解毒,这与敏感物种的代谢机制有很大差别,而调节绿狐尾藻氮代谢的关键酶类在组织间表现出明显差异。
[Abstract]:The phenomenon of eutrophication will produce many unfavorable factors to the growth of submerged plants, and the increasing of ammonium nitrogen concentration in water is an important factor for the extinction of submerged plants in eutrophic lakes. At present, the toxicity of ammonium nitrogen to submerged plants is mainly focused on submerged plants with low tolerance to ammonium nitrogen. In this study, the physiological responses of three submerged plants under ammonium nitrogen stress were studied by constructing microenvironment, and then the tolerant species green foxtail algae was taken as the main research object. The toxic effects and peroxidation damage of P. virulent under high concentration of ammonium nitrogen stress were investigated, and the toxicity threshold of each tissue was analyzed. Finally, the difference of nitrogen metabolism and regulatory enzyme activity in different levels of ammonium nitrogen stress was studied. The detoxification mechanism of submerged plants with high tolerance to high concentration of ammonium nitrogen was discussed, which helps us to understand the decline mechanism of submerged vegetation in eutrophic lakes and the restoration and reconstruction of submerged vegetation. The test results show that 1: 1. Common submerged plants such as goldfish and foxtail showed negative biomass growth and significant decrease in chlorophyll level at the concentration of 10 mg L-1 ammonium nitrogen. The relative growth rate and chlorophyll content increased with the increase of ammonium nitrogen concentration from 1 to 20 mg L ~ (-1). The toxic effect of excessive accumulation of ammonium nitrogen often leads to the decrease of soluble protein and non-structural carbohydrate content in submerged plants, while the high tolerance to ammonium nitrogen is mainly due to the regulation of C-N metabolism. This regulatory regulation effectively avoids the toxic damage. 2. 2 that may be caused by excessive ammonium nitrogen. The growth rate and chlorophyll content decreased and the membrane lipid peroxidation level increased at the concentration of 80 mg 路L ~ (-1) ammonium nitrogen. When the concentration of ammonium nitrogen increased to 120 mg / L, the biomass of Phaeophyllum sp. increased negatively, the root tissue began to show damage, and the damage of antioxidant system was aggravated. The tolerance of root tissue to ammonium nitrogen was higher than that of leaf tissue, but the root tissue also showed significant toxicity at 120 mg 路L ~ (-1) of ammonium nitrogen. As a submerged plant with high tolerance to ammonium nitrogen, the algae can utilize nitrogen efficiently, which is closely related to the key enzymes of nitrogen metabolism. The detoxification of ammonium nitrogen and the metabolic regulation of nitrogen deficiency were closely related to the high expression of asparaginase and nitrate reductase respectively. When the concentration of ammonium nitrogen reached 120 mg 路L ~ (-1), the activities of glutamine synthetase and asparaginase decreased significantly. The detoxification of ammonium nitrogen can be achieved by effective metabolic regulation, which is very different from the metabolic mechanism of sensitive species, and the key enzymes regulating the nitrogen metabolism of green fox tail algae show significant differences among tissues.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X173;X52

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