环境因子对温带典型草原土壤中氨氧化菌和AM真菌群落的影响
文献类型：学位论文
| 作者 | 陈永亮 |
| 学位类别 | 博士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 陈保冬 |
| 关键词 | 氨氧化古菌 氨氧化细菌 丛枝菌根真菌 环境变化 人类活动 典型草原 ammonia oxidizing archaea ammonia oxidizing bacteria arbuscular mycorrhizal fungi Global change anthropogenic disturbance typical grassland ecosystem |
| 其他题名 | Responses of ammonia oxidizers and AM fungi to environmental changes in a typical temperate steppe |
| 学位专业 | 生态学 |
| 中文摘要 | 人类的干扰活动持续地影响着地球环境，导致了一系列环境变化事件的发生，比如氮沉降、极端降水和干旱、二氧化碳浓度升高和全球变暖。草原生态系统是对全球变化比较敏感的生态系统类型之一，然而关于全球变化对草原生态系统土壤中参加养分循环的微生物的研究还相对匮乏。在全球变化背景下，研究土壤微生物多样性及其参与的生态过程，认识关键土壤功能微生物类群的生态重要性，已成为生态学的前沿和热点领域。由氨氧化微生物控制的氨氧化过程是硝化作用的第一个反应步骤，也是限速步骤，是全球氮循环的中心环节，因此受到了特别的关注。同时，作为一链接生态系统地上和地下部分的桥梁，丛枝菌根真菌（arbuscular mycorrhizal fungi, AMF）在维护生态系统的平衡与稳定中也发挥着重要的作用，因此也受到了特别的关注。 本论文采用多种分子生态学研究方法，如聚合酶链式反应（PCR）、实时荧光定量PCR、末端限制性片段多态性分析（T-RFLP）、克隆文库、普通测序技术以及第二代高通量焦磷酸测序（Pyrosequencing）技术，深入地研究环境因子对温带典型草原土壤中氨氧化菌和AM真菌的影响以及微生物之间的相互作用。在野外试验中，利用了中国科学院植物研究所多伦站的两个长期定位试验平台，研究了施肥（氮肥、磷肥）、水分添加、割草对草原生态系统土壤中氨氧化古菌（ammonia oxidizing archaea, AOA）、氨氧化细菌（ammonia oxidizing bacteria, AOB）、AM真菌丰度和多样性的影响；在室内试验中，采用模拟盆栽的方法研究了氨氧化菌（AOA和AOB）与AM真菌之间的直接和间接作用。论文的主要研究内容和结果如下： （1）长期施加氮素、水分添加均显著提高氨氧化细菌（AOB）丰度，但是对氨氧化古菌（AOA）的丰度没有显著影响。T-RFLP结果显示，氮素添加和水分添加显著改变了AOB的群落结构，但对AOA的群落结构没有显著影响。氨氧化潜势（PNR）与AOB丰度呈现明显的正相关关系，表明在温带典型草原生态系统中，氨氧化过程可能主要由AOB来驱动。系统发育树分析显示，AOA全部属于soil and sediment，而AOB全部属于Nitrosospira。 （2）长期施肥（氮肥、磷肥）和割草对氨氧化微生物的丰度有显著的影响，但在不同季节之间存在差异。在五月份，氮肥显著降低了AOA的丰度但显著增加了AOB的丰度，割草均显著减低了AOA的丰度但显著增加了AOB的丰度；在八月份，氮肥、磷肥均显著增加了AOB丰度，割草显著降低了AOB丰度。PCA结果显示，氮肥在两个季节均显著改变了AOB的群落结构，割草在五月份对AOA的群落结构有一定的影响，而磷肥在两个季节对AOA、AOB群落结构均没有显著的影响。系统发育树显示所有的AOA克隆属于Nitrososphaera，而所有的AOB克隆属于Nitrosospira。 （3）氮肥、水分对土壤中丛枝菌根真菌的OTU数量，Chao1，物种多样性指数以及系统发育多样性指数均没有显著的影响。然而，氮肥和水分均显著改变了土壤中AM真菌的群落组成。RDA分析显示土壤pH值和铵态氮浓度是影响AM真菌群落分布的两个关键因素。该研究验证了全球变化对草原生态系统土壤中丛枝菌根真菌多样性的影响。 （4）长期施磷显著降低了菌根侵染率、丛枝丰度和菌丝密度，而长期施氮对这些指标没有显著影响。与对AM真菌丰度的影响不同，施氮显著改变了AM真菌的群落结构，而施磷对AM真菌的群落组成没有显著影响。此外，氮磷交互作用显著影响AM真菌的群落结构。这些结果说明，在温带典型草原生态系统中，施氮显著改变了AM真菌的群落结构，而施磷显著降低了AM真菌的丰度。 （5）通过模拟盆栽试验，发现接种AM真菌显著降低了菌根室中AOA、AOB丰度，并且显著影响了菌丝室AOA群落组成。这些结果说明AM真菌在调控土壤氨氧化过程方面起到非常重要的作用，不仅可以通过植物途径间接影响氨氧化微生物丰度，还可以通过根外菌丝途径直接影响氨氧化微生物丰度。 综上所述，本论文综合运用各种传统和现代分子生态学研究手段，从野外样地试验揭示了全球变化对温带典型草原土壤土壤中氨氧化微生物、AM真菌多样性的影响；通过室内模拟试验揭示了AM真菌与氨氧化微生物之间的相互作用。本研究对于全面认识全球变化的生态效应具有重要意义，可以为全球变化背景下草地资源和生态环境管理提供科学依据，有助于科学管理调控草原生态系统的养分地球化学循环过程。 |
| 英文摘要 | Human activities have been continuously influencing the global environment, leading to a series of extreme climate change events such as nitrogen deposition, extreme precipitation and drought, elevated CO2 and global warming. Grassland ecosystem is sensitive to the global change. However, less attention has been paid to the soil microbial communitiess involved in soil nutrient cycling in grassland ecosystems. There is a high need to study the diversity and ecological function of soil microbial organisms, which has been the frontier and hot study field in ecology. Ammonia oxidation has received special attention for its first and rate-limting role in soil nitrogen cycling. Meanwhile, as an important linkage between aboveground and belowground part of the ecosystem, arbuscular mycorrhizal fungi （AMF） also play an important role in sustaining the ecosystem stability and balance, and therefore also received much attention. In this study, we adopted a variety of research methods in molecular ecology, such as PCR, qPCR, T-RFLP, clone library, sanger sequencing technology and the second generation of high-throughput sequencing technology, deeply researched the effect of environmental factors on ammonia oxidizers and AM fungi, the interaction between ammonia oxidizers and AM fungi. In field trials, two long-term experiment platporms in Duolun Country belonging to the institute of botany, Chinese academy of sciences were adopted to study the effects of fertilizer regimes (nitrogen, phosphorus), artificial precipitation increment and mowing on the the abundance and diversity of soil AOA, AOB and AM fungi. In indoor studies, the direct and indirect influence of AM fungi on ammonia oxidizers was studied based on two-compartment microcosms. The research contents and main findings of this thesis are as follows: 1. Long term nitrogen fertilization and precipitation increment signigicantly increased AOB but not AOA abundance. The results of T-RFLP showed that nitrogen fertilization and precipitation increment had an obvious effect on AOB community structure, whereas AOA community structure remained stable among all treatments. There was a significant positive correlation between PNR and only AOB abundance, suggesting the ammonia oxidization was properbly driven by AOB in this temperate steppe. Phylogenetic analysis showed that all AOA clones were afficiated within soil and sediment lineage, while all AOB fell within Nitrosospira cluster. 2. Long term N fertilization changed AOB community composition and increased AOB abundance in both May and August, but significantly decreased AOA abundance in May. By contrast, P fertilization significantly influenced AOB abundance only in August. Mowing significantly decreased AOA abundance and had little effect on AOA community compositions in May, while significantly influenced AOB abundance in both May and August. Moreover, AOA and AOB community structures showed obvious seasonal variations between May and August. Phylogenetic analysis showed that all AOA sequences fell into the Nitrososphaera cluster, and the AOB community was dominated by Nitrosospira Cluster 3. All together, the results suggested that fertilization and mowing played important roles in affecting the abundance and community compositions of AOA and AOB. 3. Six-year N fertilization significantly altered the AMF communities in both soils and mixed roots but had no obvious influence on AMF abundance. However, P fertilization showed no significant influence on the AMF community structure, but induced a significant decrease in mycorrhizal colonization rate, arbuscule colonization and hyphal length density. Furthermore, N and P application showed significant interactions in affecting AMF species compositions in soils but not in roots. Generally the AMF diversity in the soil was higher than that in the roots. The study suggested that N fertilization predominantly altered AMF species composition, while P fertilization influenced AMF abundance in this steppe. 4. Seven-year N fertilization and precipitation increment showed no obvious effect on mycorrhizal colonization rate and arbuscule colonization. However, both N fertilization and precipitation increment significantly affected the AMF communities. Soil pH and soil ammonia concentration showed significant effect on determing AMF communities. 5. Inoculation with AM fungi significantly decreased the amoA gene copy numbers of AOA and AOB in the root compartment （RC） but not in the hyphal compartment （HC）. Moreover, AM fungi induced some changes in AOA community structure in HC and RC, while only marginal variations in AOA composition were detected in responding to N supply level in HC. There were no significant differences in AOB composition both in the RC and HC irrespective of experimental treatments. The experimental results suggested that AM fungi could directly shape the AOA composition, but more likely exerted indirect influences on AOA and AOB abundance via the plant pathway. In general, AM fungi may play an important role in mediating ammonia oxidizers, but the AOA community appeared to be more sensitive to AM fungi than AOB did. Taken together, traditional and cutting-edge molecular methods were employed in this thesis to decipher the effect of global change events on the diversity of ammonia oxidizers and arbuscular mycorrhizal fungi in filed conditions. In addition, the interaction of ammonia oxidizers and arbuscular mycorrhizal fungi was also studied in soil microcosm conditions. The study is of great significance for fully understanding the ecological effect of global change events, and can also provide scientific basis for the ecological environment management of this temperate steppe, and help us to formulate the corresponding ecological management strategy to control the nutrient cycling in this grassland ecosystem. |
| 公开日期 | 2015-06-16 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/13486]  |
| 专题 | 生态环境研究中心_城市与区域生态国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 陈永亮. 环境因子对温带典型草原土壤中氨氧化菌和AM真菌群落的影响[D]. 北京. 中国科学院研究生院. 2014. |
入库方式： OAI收割
来源：生态环境研究中心
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