神农架两种杓兰根际土壤及根内微生物的群落结构与多样性

Community structure and diversity of microorganisms from rhizosphere soil and root endosphere of two Cypripedium species in Shennongjia

关键词:  绿花杓兰, 扇脉杓兰, 根际微生物, 群落多样性, 高通量测序

Key words:   Cypripedium henryi, Cypripedium japonicum, rhizospheric microorganism, community diversity, high-throughput sequencing

摘要:

兰科植物生长发育与根际土壤及根内微生物密切相关,解析其微生物群落特征,对指导人工繁育、野外保护和潜在功能微生物资源挖掘具有重要意义。该研究以神农架地区的野生绿花杓兰(Cypripedium henryi)和扇脉杓兰(C. japonicum)为对象,采用高通量测序技术,分析其花期和果期根际土壤及根内真菌、细菌群落的组成、多样性及潜在功能。结果表明:(1)两种杓兰根际土壤与根内共检出真菌14门、细菌38门,真菌优势门为子囊菌门(Ascomycota)、担子菌门(Basidiomycota)和被孢霉门(Mortierellomycota),细菌优势门为变形菌门(Proteobacteria)、酸杆菌门(Acidobacteriota)和放线菌门(Actinobacteria)。(2)根际土壤真菌和细菌群落的丰富度及均匀度整体高于根内,其中根际土壤真菌丰富度由花期至果期显著升高,而根内细菌丰富度显著下降。(3)生态位对两种杓兰根际土壤与根内微生物群落结构差异具有较高解释度,对真菌和细菌群落变异的解释度分别为19.49%和60.20%。(4)发育阶段影响部分微生物类群的丰度变化及群落功能分化,从花期到果期,根际土壤真菌和根内细菌分别有13个属和20个属的相对丰度发生显著变化。(5)根际土壤与根内真菌群落功能组成差异明显,而细菌群落功能谱相对稳定,根际土壤微生物互作中竞争与协同并存,根内群落则以正相关关系为主。该文初步阐明了神农架两种杓兰根际土壤和根内真菌、细菌群落的组成特征及其与生态位、发育阶段和宿主种类的关系,结果可为杓兰属植物共生微生物筛选、人工繁育及种群保护提供基础数据参考。

Abstract:

The growth and development of orchids are closely associated with microorganisms in rhizosphere soil and root endosphere. Characterizing orchid-associated microbial communities is of great significance for guiding artificial propagation, field conservation, and the exploration of potential functional microbial resources. To clarify the microbial community characteristics of endangered Cypripedium species in Shennongjia, wild Cypripedium henryi and C. japonicum were used as experimental materials. High-throughput sequencing was used to analyze the composition, diversity, and potential functions of fungal and bacterial communities in rhizosphere soil and root endosphere at the flowering and fruiting stages. The results were as follows:(1)A total of 14 fungal phyla and 38 bacterial phyla were detected in rhizosphere soil and root endosphere of the two Cypripedium species. The dominant fungal phyla were Ascomycota, Basidiomycota, and Mortierellomycota, and the dominant bacterial phyla were Proteobacteria, Acidobacteriota, and Actinobacteria.(2)The richness and evenness of fungal and bacterial communities in rhizosphere soil were generally higher than those in root endosphere. Fungal richness in rhizosphere soil increased significantly from the flowering stage to the fruiting stage, whereas bacterial richness in root endosphere decreased significantly.(3)Ecological niche explained a relatively high proportion of the differences in microbial community structure between rhizosphere soil and root endosphere of the two Cypripedium species, accounting for 19.49% and 60.20% of the variation in fungal and bacterial communities, respectively.(4)Developmental stage affected the abundance changes of some microbial taxa and differentiation of community functions. From the flowering stage to the fruiting stage, the relative abundance of 13 fungal genera in rhizosphere soil and 20 bacterial genera in root endosphere changed significantly.(5)The functional composition of fungal communities differed markedly between rhizosphere soil and root endosphere, whereas the functional profiles of bacterial communities were relatively stable. Competitive and cooperative interactions coexisted in rhizosphere soil microbial communities, whereas positive correlations dominated in root-endosphere microbial communities. This study preliminarily clarifies the composition characteristics of fungal and bacterial communities in rhizosphere soil and root endosphere of two Cypripedium species in Shennongjia, as well as their associations with ecological niche, developmental stage, and host species. These findings provide foundational data for screening symbiotic microorganisms, artificial propagation, and population conservation of Cypripedium plants.