中文摘要：

以盐边县代表性烟草种植区域的成熟期烟草根际及非根际土壤为研究对象,利用变性梯度凝胶电泳（DGGE）分析了真菌（18S基因）群落结构和多样性,结合之前研究所得土壤理化性质,应用多元回归树分析研究了土壤环境因子对真菌多样性的影响.免培养真菌群落结构和多样性的分析结果表明,系统的根际效应在成熟期烟草中没有体现.条带克隆测序结果表明,成熟期烟草根际和非根际免培养真菌优势种群差异显著,其中,以EF6-1为代表的不可培养真菌为非根际土壤中的特异真菌;以EF7-1为代表的不可培养真菌为根际土壤中的特异真菌.同时烟草成熟期根际土壤中优势免培养真菌为角担菌科（Ceratobasidiaceae）、伞菌纲（Agaricomycetes）、散囊菌纲（Eurotiomycetes）、马拉色菌属（Malassezia）、球囊霉属（Glomus）及部分不可培养真菌;而角担菌科（Ceratobasidiaceae）、伞菌纲（Agaricomycetes）及部分不可培养真菌为烟草成熟期非根际优势真菌.多元回归树分析结果表明,土壤环境因子中速效钾含量对真菌群落结构及多样性影响最大.

英文摘要：

The rhizosphere and bulk soil samples were collected from the representative sites of the tobacco-growing regions in Yanbian,Sichuan Province of China. The method of denaturing gradient gel electrophoresis（ DGGE） was used to study the community structure and diversity of culture independent fungi（18S gene）. The multiple regression tree analysis（ MRT） was used to explore the diversity of fungi in tobacco soils at the mature stage associated with environmental variables analyzed from our previous studies. The results of fungal diversity and community structure indicated that the systematical rhizosphere effect on soil microbial characteristics were not found though typical rhizosphere effect was evident in some of the samples and characteristics tested due to the accumulation of autotoxins in the tobacco rhizosphere. A total of 18 clones,belonging to Basidiomycota,Glomeromycota,Ascomycota and Unclassified Fungi,were identified. The results of sequencing indicated that the fungal species of rhizosphere soil samples showed a significant difference with that of bulk soil samples. The representative of clone EF7-1 was the specific fungal specie which only present in the rhizosphere soil samples,and the representative of EF6-1 was the specific fungal specie which only present in the bulk soil samples. The results also indicated that the dominant fungal groups of rhizosphere soil samples showed a significant difference with that of bulk soil samples. The dominant fungal groups in rhizosphere soil samples at the mature stage were Ceratobasidiaceae,Agaricomycetes,Eurotiomycetes,Malassezia,Glomus and some uncultured fungi while Ceratobasidiaceae,Agaricomycetes and some uncultured fungi were dominant in bulk soil samples at the same stage. The results of soil fungal diversity associated with environmental variables indicated that available potassium was the main environmental factors affecting the fungal diversity and community structure at the mature stage.