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题名: 城市化对丛枝菌根真菌多样性、群落结构及与宿主植物共生关系的影响
作者: 陈云
学位类别: 硕士
答辩日期: 2015-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 马克明
关键词: 丛枝菌根真菌,城市生态系统,城市绿地,共生关系,高通量测序,网络分析,arbuscular mycorrhizal fungi, urban ecosystems, urban green space, symbiotic associations, high-throughput sequencing, network analysis
其他题名: Effects of Urbanization on Arbuscular Mycorrhizal Fungal Diversity, Community Composition and Symbiotic Associations with Host Plants
学位专业: 生态学
中文摘要: 城市化深刻影响了区域气候、生物地球化学循环及水文系统,是造成城市地区栖息地破碎化及斑块化的主要驱动因子之一,对城市生物多样性构成了严重威胁。丛枝菌根真菌(arbuscular mycorrhizal fungi, AMF)隶属于球囊菌门(Glomeromycota),是一类专性共生微生物,能够与80%以上的陆生维管植物形成互惠共生关系,具有改善宿主植物矿质营养、改良土壤结构、增强宿主植物对多种环境胁迫的耐受性及抗性等重要生态功能,是维持植物群落多样性与生产力的重要决定性因素。作为连接植物-土壤系统的重要组分,AM真菌的分布及多度格局同时受到宿主植物及土壤条件的双重制约。而城市化导致城市地区植被覆盖及土壤特性均发生了剧烈变化,对城市 AM真菌的着生状况起到了选择与过滤的作用,直接或间接地影响了 AM真菌多样性、群落组成及与宿主植物的共生关系,但相关研究长期以来并未得到足够重视。基于此,本研究采用二代高通量测序的分子方法,以北京市作为研究区,首次对城市生态系统中 AM真菌的多样性、群落结构及与宿主植物的共生关系进行了系统研究,以期为城市生态系统中微生物资源的保存及绿地系统的维持提供理论依据。本论文得到的主要研究结论如下:
(1)北京城市绿地AM真菌多样性及群落组成情况
城市绿地土壤中共检测到 79个  AM真菌  OTUs(operational taxonomic units, OTUs),72%的 OTUs属于  Glomeraceae科。AM真菌物种丰富度、Shannon多样性、Simpson多样性及均匀度与土壤 Cd含量均呈显著负相关关系,同时  Cd显著影响了  AM真菌群落结构。城市绿地草本植物物种丰富度与 AM真菌物种丰富度及  Shannon多样性指数之间呈现显著正相关关系,草本植物群落 β多样性显著影响了  AM真菌的群落组成。
   (2)城市化对宿主植物-AM真菌共生关系的影响
城区植物 AM真菌的 Shannon多样性、Simpson多样性及均匀度均显著高于郊区植物,但  PD指数无显著差异。城、郊植物    AM真菌各类群的相对多度明显不同,城区样品中Glomus GroupⅡ类群相对多度显著高于郊区样品,而 Diversispora Group类群的相对多度则
显著低于郊区样品。应用不同距离矩阵计算的城、郊样品 AM真菌群落组成差异结果并不一致。总体而言,城、郊环境差异可能对宿主植物所共生的 AM真菌群落结构并没有很大影响,可能受宿主植物种类或微栖息地的影响。
    植物样品水平,全部宿主植物、城区植物、郊区植物与 AM真菌的共生关系网络均存在显著嵌套性结构。植物物种水平,全部植物、郊区植物与 AM真菌的关系网络结构也表现出显著嵌套性,但城区样品嵌套性结构并不显著。城、郊宿主植物与 AM真菌共生关系特异性程度的不同可能是造成二者网络结构差异的主要原因。城区植物较郊区植物与  AM真菌之间的共生关系相对泛化,特异性较弱,共生伙伴更为丰富。此外,城、郊宿主植物与 AM真菌之间形成不同的种间关系模块,模块中植物与  AM真菌组合差异较大,二者作
用集合并非按照植物物种聚类。
英文摘要:     Urbanization   has   exerted   profound   effects   on   local   climate,   biogeochemistry,   and hydrological systems. It  is also one of the  primary drivers of habitat loss  and fragmentation. All these  modifications  and  alterations  threaten  the  biodiversity  in  urbanized  areas.  Arbuscular mycorrhizal (AM)  fungi, belonging to  the phylum Glomeromycota,  are obligate  symbionts and colonize the roots of more than 80% of vascular terrestrial plant species. AM fungi improve plant nutrition and  soil structure,  and enhance plant  tolerance or  resistance to various  environmental stresses, thus, they contribute a lot to the maintenance of plant biodiversity and productivity. As a main  component  of  plant-soil   system,  AM  fungal  distribution   and  abundance  patterns  are influenced by  host plants  and soil conditions  simultaneously. Within  cities, urbanization drives dramatic  changes in  vegetation  cover  and  soil  properties, which  is  a  powerful  selective and filtering force  that affects  AM fungal diversity,  community composition,  and associations with host plants  directly  and indirectly.  However, the  related  studies have  been longly  overlooked. Based on this  thoughtfulness, we examined  for the first time,  to our knowledge, the  AM fungal diversity and  community structure,  as well  as their mutualistic  associations with  host plants  in Beijing city  using high-throughput DNA sequencing.  We hope this  knowledge would provide a basis  for  microbial  resource  conservation  and  green-space  maintenance  in  cities.  Our  main results are as followed:
    (1) Diversity  and  community  composition  of AM  fungi  detected  in  green  space  soil in Beijing city.
    We detected 79 AM fungal operational  taxonomic units (OTUs) in green space soils,  72% of which were  assigned to Glomeraceae.  Across sites, AM  fungal species richness, Shannon’s diversity, Simpson’s  diversity, and evenness were  negatively correlated with  the concentration of Cd, which also significantly affected AM fungal  community structure. In addition, there was a significantly  positive correlation between  herbaceous species  richness and AM  fungal OTU richness, and Shannon’s  diversity. The plant  β diversity had  effects on AM fungal  community structure as well.
    (2)   Effects of urbanization on symbiotic associations between host plants and AM fungi.
    Urban  plants  hosted  significantly  greater  Shannon’s  diveristy,  Simpson’s  diversity,  and evenness of AM fungi than did the plants  in rural sites. However, no significant differences were observed in PD indexes. The  relative abundance of each AM fungal taxon  associated with urban and rural plants  were different. Urban plant  samples had a significant  higher relative abundance of Glomus  GroupⅡtaxa  than that  of  rural ones,  while a  lower  Diversispora Group  taxa. The results based on different distance  metrics were not consistent. In general, it  is host plant species or microhabitats rather than differences  in urban and rural habitats that may contribute  largely to AM fungal community structures.
    All host  plant samples-AMF  network, urban plant  samples-AMF network,  and rural  plant samples-AMF network  were significantly  more nested than  expected by  chance. Besides,  rural plant  species-AMF   network  and   all   plant  species-AMF   network  also   showed  significant nestedness,  while urban  plant  species-AMF network  did  not.  Different degrees  of  interaction specialization at urban and rural plant species with their fungal symbionts  may contribute mainly to these  distinct patterns. Associations between  urban plants and  AM fungi characterized  lower specialization compared with rural  communities, thus urban plants interacted with  a wider range of fungal partners. Besides, urban and rural  plants formed distinct interaction modulars with AM fungal symbionts, and these mutualistic hubs were not converged by plant species.




    
 
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/34355
Appears in Collections:城市与区域生态国家重点实验室_学位论文

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Recommended Citation:
陈云. 城市化对丛枝菌根真菌多样性、群落结构及与宿主植物共生关系的影响[D]. 北京. 中国科学院研究生院. 2015.
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