Hartvig Ida, Kosawang Chatchai, Rasmussen Hanne, Kjær Erik Dahl, Nielsen Lene Rostgaard
Forest and Landscape Ecology, Department of Geosciences and Natural Resource Management University of Copenhagen Copenhagen Denmark.
Center for Evolutionary Hologenomics, Globe Institute University of Copenhagen Copenhagen Denmark.
Ecol Evol. 2024 Jan 31;14(2):e10863. doi: 10.1002/ece3.10863. eCollection 2024 Feb.
Plant-fungal interactions are ubiquitous across ecosystems and contribute significantly to plant ecology and evolution. All orchids form obligate symbiotic relationships with specific fungi for germination and early growth, and the distribution of terrestrial orchid species has been linked to occurrence and abundance of specific orchid mycorrhizal fungi (OMF) in the soil. The availability of OMF can therefore be a habitat requirement that is relevant to consider when establishing management and conservation strategies for threatened orchid species, but knowledge on the spatial distribution of OMF in soil is limited. We here studied the mycorrhizal associations of three terrestrial orchid species (, and ) found in a local orchid diversity hotspot in eastern Denmark, and investigated the abundance of the identified mycorrhizal fungi in the surrounding soil. We applied ITS metabarcoding to samples of orchid roots, rhizosphere soil and bulk soil collected at three localities, supplemented with standard barcoding of root samples with OMF specific primers, and detected 22 Operational Taxonomic Units (OTUs) putatively identified as OMF. The three orchid species displayed different patterns of OMF associations, supporting the theory that association with specific fungi constitutes part of an orchid's ecological niche allowing co-occurrence of many species in orchid-rich habitats. The identified mycorrhizal partners in the basidiomycete families Tulasnellaceae and Ceratobasidiaceae (Cantharallales) were detected in low abundance in rhizosphere soil, and appeared almost absent from bulk soil at the localities. This finding highlights our limited knowledge of the ecology and trophic mode of OMF outside orchid tissues, as well as challenges in the detection of specific OMF with standard methods. Potential implications for management and conservation strategies are discussed.
植物与真菌的相互作用在生态系统中普遍存在，对植物生态和进化具有重要意义。所有兰花在萌发和早期生长阶段都与特定真菌形成专性共生关系，并且地生兰花物种的分布与土壤中特定兰花菌根真菌（OMF）的出现和丰度有关。因此，在为受威胁的兰花物种制定管理和保护策略时，OMF的可利用性可能是一个需要考虑的栖息地要求，但关于OMF在土壤中的空间分布的知识有限。我们在此研究了在丹麦东部一个当地兰花多样性热点地区发现的三种地生兰花物种（、和）的菌根关联，并调查了周围土壤中已鉴定的菌根真菌的丰度。我们将ITS元条形码技术应用于在三个地点采集的兰花根、根际土壤和大体积土壤样本，并使用OMF特异性引物对根样本进行标准条形码分析，检测到22个假定为OMF的操作分类单元（OTU）。这三种兰花物种表现出不同的OMF关联模式，支持了与特定真菌的关联构成兰花生态位一部分的理论，从而使得许多物种能够在兰花丰富的栖息地中共存。在担子菌科的丝核菌科和角担菌科（鸡油菌目）中鉴定出的菌根伙伴在根际土壤中的丰度较低，在这些地点的大体积土壤中几乎不存在。这一发现凸显了我们对兰花组织外OMF的生态和营养模式的了解有限，以及使用标准方法检测特定OMF的挑战。文中还讨论了对管理和保护策略的潜在影响。
