青藏高原东缘不同生境丛枝菌根真菌孢子群落的研究

发布时间：2018-03-04 00:22

本文选题：丛枝菌根真菌　切入点：生境　出处：《兰州大学》2017年硕士论文　论文类型：学位论文

【摘要】：丛枝菌根真菌是一类可以与大多数陆地植物形成共生关系的土壤微生物,它在生态系统的物质循环和能量流动等环节都发挥着功能,因而其多样性和种质资源研究具有重要的生态学意义。然而到目前为止丛枝菌根真菌的多样性研究大多集中在欧洲和北美,这限制了菌根学家对丛枝菌根真菌多样性和分布特征在地球生物圈的情况的认识。青藏高原占有中国国土面机的26%,其生境类型多样,且受到的人为干扰较少,具有重要的生态学研究价值。本文选取了青藏高原东缘四种不同的生境,包括农田、森林、草原和灌丛。每种生境各选取5个样点,通过观察孢子的形态学特征并结合单孢测序技术鉴定其AM真菌孢子群落,并采用多元线性回归及拟合环境因子的NMDS统计分析,探索影响AM真菌群落多样性和分布的因素。结果共鉴定到AM真菌6科13属31种。其中球囊霉科(Glomeraceae)、无梗囊霉科(Acaulosporaceae)和多孢囊霉科(Diversisporaceae)在所有的生境中均有较高的出现频度(frequency of occurrence)和相对多度(relative abundance)。在属的水平上,不同生境的AM真菌差异比较明显。农田生境的AM真菌群落与其它三个生境的差异最大,其AM真菌相对多度呈现两极分化的特点:相对多度较高的四个属(多孢囊霉属、管柄囊霉属、近明囊霉属和无梗囊霉属)占据了90%,其余的不足10%,另外其Shannon-Weiner多样性指数、根外菌丝长密度(extraradical hyphal length density)均最低。灌丛生境作为草原和森林的过渡类型,其AM真菌群落与草原和森林均有一定的交叉和重叠,说明植物群落特征与AM真菌群落的相匹配性。森林生境的优势属为无梗囊霉属(Acaulospora),草原的为管柄囊霉属(Funneliformis),此两属在灌丛生境的相对多度均较高,分别为18.38%和19.12%,这也印证了灌丛的过渡特性。指示物种分析发现农田、灌丛和草原均有其对应的指示物种,分别为柯氏无梗囊霉(Acaulospora koskei)、Funneliformis sp.和Dentiscutata erythropa,而森林生境没有。AM真菌群落的多样性、根外菌丝长密度与土壤磷含量、水稳性土壤团聚体、植物多样性显著相关。高磷环境减少AM真菌根外菌丝长密度,从而导致水稳性土壤微团聚体进一步聚集形成大团聚体的过程。影响AM真菌侵染率的环境因子较多,包括海拔、纬度、土壤含水量、有机碳、速效磷等,这说明AM共生体系的形成是一个高度环境敏感的过程,为了更深层次的了解其机理,需要更多的关于其侵染过程的研究。最后,通过比较青藏高原其它地区的AM真菌多样性研究成果,我们发现球囊霉科和多孢囊霉科具有较高的广谱分布特性,而巨孢囊霉科(Gigasporaceae)和无梗囊霉科的分布具有较大的空间特异性。
[Abstract]:Arbuscular mycorrhizal fungi (arbuscular mycorrhizal fungi) are a kind of soil microorganism that can form symbiotic relationship with most terrestrial plants. Therefore, the study of its diversity and germplasm resources is of great ecological significance. However, so far, most of the studies on the diversity of arbuscular mycorrhizal fungi have been concentrated in Europe and North America. This limits mycorrhizologists' understanding of the diversity and distribution of arbuscular mycorrhizal fungi in the Earth's biosphere. This paper selects four different habitats in the eastern margin of the Qinghai-Xizang Plateau, including farmland, forest, grassland and thickets. The spore community of AM fungi was identified by observing the morphological characteristics of the spores and combining with the monospore sequencing technique. The spore community of AM fungi was analyzed by multivariate linear regression and NMDS statistical analysis of fitting environmental factors. Results A total of 31 species belonging to 13 genera and 6 families of AM fungi were identified, among which Glomeraceaeae, Acaulosporaceaeae and Diversiaceaeae have high frequency of occurrence in all habitats. Frequency of current) and relative abundance. At the generic level, The difference of AM fungi in different habitats was obvious. The AM fungi community of farmland habitat had the biggest difference with the other three habitats, and the relative abundance of AM fungi showed the characteristics of polarization: four genera with higher relative abundance (Polysporocystis spp.). In addition, the Shannon-Weiner diversity index and extrinsic hyphal length density were the lowest. The shrub habitat was the transitional type of steppe and forest, and had the lowest Shannon-Weiner diversity index in the genus Cysticillium, the genus Cysticillium, and the genus Cystis Sinica, and the rest were less than 100.In addition, their Shannon-Weiner diversity index and extrinsic hyphal length densitywere the lowest, and thickets were the transitional types of steppe and forest. The AM fungi community overlaps and overlaps with grassland and forest to a certain extent. The results showed that the characteristics of plant communities and AM fungal communities were matched. The dominant species of forest habitats were Acaulospora, Acaulospora, and the steppe, Funneliformisus. The relative abundance of these two genera in shrub habitats was higher than that in grassland. It was 18.38% and 19.12, respectively, which confirmed the transition characteristics of thickets. The indicator species analysis showed that there were corresponding indicative species in farmland, shrub and grassland. Acaulospora koskei Funneliformis sp. and Dentiscutata erythropa.There was no diversity of mycorrhizal community in forest habitats. The long density of mycelium and phosphorus content in soil, water stable soil aggregates were found in forest habitats. Plant diversity was significantly correlated. High phosphorus environment reduced the long density of mycelium outside AM fungi, which led to the further aggregation of microaggregates into large aggregates in water-stable soil. There were many environmental factors affecting the infection rate of AM fungi, including altitude. Latitude, soil water content, organic carbon, available phosphorus, etc., which indicates that the formation of AM symbiotic system is a highly environmentally sensitive process. In order to understand its mechanism more deeply, more research on its infection process is needed. By comparing the diversity of AM fungi in other areas of Qinghai-Xizang Plateau, we found that the distribution of Balloonidae and Polysporocystis has a high broad-spectrum distribution, while the distribution of Gigasporaceaeand Cysporaceaeae has greater spatial specificity.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S154.3

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