黄渤海海洋真菌及莱州湾滨海土壤丛枝菌根真菌的分子多样性与群落结构

	黄渤海海洋真菌及莱州湾滨海土壤丛枝菌根真菌的分子多样性与群落结构
	郭晓红
学位类型	博士
导师	龚骏
	2015-05-25
学位授予单位	中国科学院研究生院
学位授予地点	北京
关键词	丛枝菌根真菌、基因条形码、海岸带与河口、群落结构、分子多样性、系统发育、浮游真菌
摘要	真菌在土壤、淡水、海水等生境中广泛存在，在有机质降解、植物促生长、动植物病害等生态系统服务中发挥重要作用。然而，环境中相当一部分真菌还未成功培养，我们对环境中真菌多样性的认识仍然有限，对于海洋及滨海盐渍化环境更是如此。本工作利用分子生态学方法开展了海岸带盐渍化环境中植物根系的丛枝菌根真菌及我国黄渤海海洋真菌的多样性与分布的研究，以期为理解真菌在海岸带及海洋生态系统的分布及生态系统功能服务提供基础数据。研究结果总结如下： 1）滨海盐渍化土壤生态系统中菌根真菌的分布：对中国莱州湾南岸盐渍化土壤中18种植物的丛枝菌根真菌（AMF）进行了调查。基于18s rRNA基因构建的18个克隆文库，得到的所有22个AMF基因型均隶属于球囊菌门最大的类群球囊霉菌属，其中有9个基因型为国际上首次发现，可能代表新的AMF类群。系统发育分析表明，其中的18个属于Glomus A，而另外的4个属于Glomus B。含盐量较低的土壤中AMF多属于未培养球囊霉属，而高盐度环境中AMF则主要集中在已经过孢子鉴定的球囊霉属。AMF 基因型丰富度,香农指数和均匀度指数在盐生与非盐生植物、本土植物与入侵植物、一年生与多年生植物之间没有明显的区别。然而，AMF多样性在不同的盐度梯度或在不同的采样地点间有显著差异，但不同pH采样区域中的AMF多样性并没有显著差异。UniFrac检验表明, 宿主植物的性状(耐盐,或起源耐盐性、寿命和来源)和非生物因素（盐度、pH值或采样位置）对植物根系的AMF群落组成有显著的影响。冗余分析表明，土壤含盐量和pH值分别解释了丛枝菌根真菌群落结构变异的6.9%和4.3%,是最具影响力的非生物因素。研究表明, 宿主植物的耐盐性，寿命和来源等特征虽然对AMF的多样性无明显影响，却显著影响盐渍化生态系统中AMF的群落组成和结构。研究结果同时也强调了土壤盐度和pH值在影响植物和土壤中丛枝菌根真菌分布的重要性。 2）海水养殖系统中浮游及底栖真菌的多样性与群落动态：在三个采样时间点对海参养殖系统中浮游和底栖真菌取样。18S rRNA基因的4个克隆文库分析共检测到131个真菌分类操作单位（OTU），其中58%是未分类真菌。子囊菌在中沉积物所占的比例较高，而担子菌在水体中所占的比例较高。壶菌门、芽枝霉门和新丽鞭毛菌门只在沉积物中有发现，而隐真菌在水和沉积物样品中都可以被检测到。通过末端片段长度多态性分析发现，水体与沉积物中的真菌群落结构有显著差异。而且无论将水体与沉积物作为整体还是单独分析，时间变化都对其中真菌的群落结构有显著的影响。冗余分析表明，水体中可溶性硅的含量显著影响养殖水体中真菌的群落结构，而氮磷比是影响沉积物中真菌群落的首要因素。海水中可溶性硅酸盐的含量和沉积物孔隙水中的氮磷比（N:P）分别是影响浮游和底栖真菌群落最重要的非生物因子。这表明，即使是在浅海，真菌群落结构在浮游和底栖这两种不同栖息环境中也是显著不同的，而环境中营养物质的含量和化学计量比在决定真菌群落组成中起非常重要的作用。 3）黄渤海海水及沉积物中的真菌多样性：基于18S、ITS-28S及18S -ITS-28S rRNA基因对中国莱州湾河口、渤海、黄海海域中xx个站点的真菌群落进行了研究。共获得765条18S序列、702条ITS-28S序列、142条18S-ITS-28S序列。18S和ITS-28S克隆文库都显示海洋环境中子囊菌所占的比例较高，而河口环境中担子菌比例较高。真菌及真菌中的隐真菌的群落组成在海洋和河口中明显不同，隐真菌只出现在18S基因克隆文库中。无论将海洋与河口作为整体还是单独分析，真菌的群落结构都具有显著的空间分布模式。18S和ITS-28S在真菌阶元划分上的作用有明显的区别，18S基因能更全面的分析真菌的种类，确定未定种真菌的位置系统地位。18S和ITS-28S两种DNA条形码对海洋与河口中真菌的系统进化分析都显示，真菌有许多处于系统发育树基部的未被定义的类群。
其他摘要	Fungi are widespread in soil, freshwater and marine ecosystems. They act as important decomposers of organic matter, promotors for plankt growth, and pathogens of both plants and animals. However, our knowledge of fungi in environments is still insufficient. This is especially true for coastal and marine habitats. This study investigated the genetic diversity of arbuscular mycorrhizal fungi in a salt-stressed ecosystem and fungi in waters and sediments of Bohai and Yellow Sea using a range of molecular approaches, aiming to better understanding their distribution and potential ecological functioning in coastal and marine ecosystems. The results are summaried as follows: 1) Arbuscular mycorrhizal fungi (AMF) in roots of 18 host plant species in a salinized south coastal plain of Laizhou Bay, China, were investigated. From 18 clone libraries of 18S rRNA genes, all of the 22 AMF phylotypes were identified into Glomus, the largest clade within the Glomeromycota, of which 18 and 4 were classified in group A and B in the phylogenetic tree, respectively. The phylotypes related to morphologically defined Glomus species occurred generally in soil with higher salinity. AMF phylotype richness, Shannon index and evenness were not significantly different between samples of halophytes/non-halophytes, invader/natives, or annuals/perennials. However, AMF diversity estimates frequently differed along the saline gradient or among locations, but not among pH grades. However, UniFrac tests showed that the both plant traits (salt tolerance, life span or origin) and abiotic factors (salinity, pH, or location) significantly affected the community composition of AMF colonizers. Redundancy and variation partitioning analyses revealed that soil salinity and pH, which respectively explained 6.9% and 4.3% of the variation, were the most influential abiotic variables in shaping the AMF community structure. Our study indicates that the salt tolerance, life span and the origin traits of host species may not significantly affect the diversity, but do influence the community composition, of root-colonizing AMF in this salinized ecosystem. Our findings also highlight the importance of soil salinity and pH in driving the distribution of AMF in plant and soil systems. 2) The planktonic and benthic fungi in a sea cucumber farming system were simultaneously investigated on three sampling dates. Analyses of SSU rRNA gene libraries of four samples revealed 131 fungal operational taxonomic units, of which 58% were potentially novel. Chytridiomycota, Blastocladiomycota and Monoblepharidomycota were detected only from sediment whereas ascomycetes and basidiomycetes dominated in sediment and water, respectively. Cryptomycota phylotypes were detected from both water and sediment samples. Based on terminal-restriction fragment length polymorphisms, we found distinct succession and contrasting community structure between planktonic and benthic habitats. Redundancy analysis indicated that the concentration of dissolved silicate in surface water and N:P in porewater were the most significant abiotic variables shaping the planktonic and benthic communities, respectively. This study indicates that plankton and benthos are distinct habitats for fungal distribution in even shallow coastal systems, and nutrients and stoichiometric ratios play important roles in driving succession of fungal communities. 3) Fungal communities of 22 sampling sites in estuary of Laizhou bay and sea of northern China were studied based on 18S, ITS-28S and 18S-ITS-28S rRNA regions. Totally, 765, 702 and 142 sequences were obtained from 18S, ITS-28S and 18S-ITS-28S rDNA libraries, respectively。Clone libraries of 18S rRNA and ITS-28S rRNA showed that Ascomycetes in marine environment is higher than in estuaries, while higher percentage of Basidiomycete was found in estuarine environment. Marine and estuarine sites exhibted significantly different fungal community composition; Cryptomycota were only detected in 18S clone library. Significant different fungal community structure was found, regardless of the samples of marine and estuary possess analyzed as a whole or separately. 18S rRNA gene can determine the position of the unclassified fungi species more explicitly. Both 18S and ITS-28S indicate that many fungal phylotypes in marine and estuarine habitats have not been classified, and their ecological role has yet to be characterized.
语种	中文
文献类型	学位论文
条目标识符	http://ir.yic.ac.cn/handle/133337/7933
专题	中国科学院烟台海岸带研究所知识产出_学位论文
推荐引用方式 GB/T 7714	郭晓红. 黄渤海海洋真菌及莱州湾滨海土壤丛枝菌根真菌的分子多样性与群落结构[D]. 北京. 中国科学院研究生院,2015.

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