The environmental distribution of non-obligate orchid mycorrhizal (OM) symbionts belonging to the ‘rhizoctonia’ complex remains elusive. Some of these fungi, indeed, are undetectable in soil outside the host rhizosphere. A manipulation experiment was performed to assess the importance of neighbouring non-orchid plants and soil as possible reservoirs of OM fungi for Spiranthes spiralis, a widespread photosynthetic European terrestrial orchid species. Fungi of S. spiralis roots were identified by DNA metabarcoding before and 4 months after the removal of the surrounding vegetation and soil. Although such a treatment significantly affected fungal colonization of newly-formed orchid roots, most OM fungi were consistently associated with the host roots. Frequency patterns in differently aged roots suggest that these fungi colonize new orchid roots from either older roots or other parts of the same plant, which may thus represent an environmental source for the subsequent establishment of the OM symbiosis.

属于“丝核菌”复合体的非专性兰花菌根 (OM) 共生体的环境分布仍然难以捉摸。事实上，其中一些真菌在寄主根际以外的土壤中是检测不到的。进行了一项操作实验，以评估邻近的非兰花植物和土壤作为 OM 真菌对Spiranthes spinis（一种广泛的光合欧洲陆生兰花物种）可能的储库的重要性。真菌S.旋毛虫在去除周围植被和土壤之前和 4 个月后，通过 DNA 宏条形码鉴定根。尽管这种处理显着影响了新形成的兰花根的真菌定植，但大多数 OM 真菌始终与宿主根相关。不同年龄根的频率模式表明，这些真菌从旧根或同一植物的其他部分定殖新的兰花根，因此这可能代表随后建立 OM 共生的环境来源。