华北特有腐生型兰科植物北京无喙兰根际土壤微生物多样性研究

北京无喙兰(Holopogon pekinensis X. Y. Mu & Bing Liu)为华北地区特有珍稀腐生型兰科植物，分布在海拔约1100 m的杂木林内，生境与本区域内其他腐生型兰科植物(常在1600 m以上桦木林中生长)显著不同。本研究针对北京玉渡山和百花山两个北京无喙兰种群的根际土壤样品开展基于高通量测序技术的根际土壤微生物多样性分析，解析北京无喙兰根际土壤微生物群落组成及多样性。测序分析结果显示，共得到4973个细菌OTU(Operational taxonomic unit)，发现北京无喙兰根际土壤的优势细菌类群为变形菌门、放线菌门、拟杆菌门等7个门，优势属有MND1、硝化螺菌属(Nitrospira)和Haliangium等。1914个真菌OTU的分析结果表明，根际土壤优势真菌类群为子囊菌门、担子菌门、结合菌门等；优势属有Archaeorhizomyces、蜡壳耳属(Sebacina)和被孢霉属(Mortierella)等；优势真菌多为外生菌根真菌，可能是北京无喙兰潜在的菌根真菌。多样性指数分析显示，北京无喙兰玉渡山种群根际土壤中的真菌和细菌群落的丰富度和均匀度均高于百花山种群，各种群土壤微生物多样性与北京无喙兰所在种群的乔木种类多样性具有一定的相关性。

Study on rhizosphere microorganism diversity of a myco-heterotrophic orchid endemic to North China,Holopogon pekinensis X. Y. Mu & Bing Liu

Holopogon pekinensis X. Y. Mu & Bing Liu, a rare saprophytic orchid unique to North China, is distributed in mixed-wood forests at an altitude of about 1100 m with large habitat variety, which is significantly different from other saprophytic orchids (usually under birch forests above 1600 m) with large habitat differences. In this study, rhizosphere soil samples from two populations of H. pekinensis in the Beijing Yudu and Baihua mountains were collected to analyze microbial diversity using high-throughput sequencing. Based on the 4973 bacterial operational taxonomic units (OTUs) identified, the dominant bacterial groups consisted of seven phyla, including Proteobacteria, Actinobacteria, and Bacteroidetes, and the dominant genera included MND1, Nitrospira, and Haliangium. Based on the 1914 fungal OTUs identified, the dominant fungal groups were Ascomycota, Basidiomycota, and Zygomycota and the dominant genera were Archaeorhizomyces, Sebacina, and Mortierella. Most of them are ectomycorrhizal fungi and consistent with the existing reports of orchid mycorrhizal fungi, so they are most likely to be the potential mycorrhizal fungi of H. pekinensis. Diversity index analysis indicated that fungal and bacterial community richness and evenness in the rhizosphere soil were higher in the Yudu Mountain population than in the Baihua Mountain population. Soil microbial diversity showed a certain correlation with arbor species diversity in the two H. pekinensis populations.