Abstract：
Despite being the second largest family of flowering plants, orchids represent community structure variation in plant-microbial associations, contributes to niche partitioning in metacommunity assemblages. Yet, mycorrhizal communities and interactions remain unknown for orchids that are highly specialized or even obligated in their associations with their mycorrhizal partners. In this study, we sought to compare orchid mycorrhizal fungal (OMF) communities of three co-occurring hemiepiphytic Vanilla species (V. hartii, V. pompona, and V. trigonocarpa) in tropical forests of Costa Rica by addressing the identity of their OMF communities across species, root types, and populations, using high-throughput sequencing. Sequencing the nuclear ribosomal internal transcribed spacer (nrITS) yielded 299 fungal Operational Taxonomic Units (OTUs) from 193 root samples. We showed distinct segregation in the putative OMF (pOMF) communities of the three coexisting Vanilla hosts. We also found that mycorrhizal communities associated with the rare V. hartii varied among populations. Furthermore, we identified Tulasnellaceae and Ceratobasidiaceae as dominant pOMF families in terrestrial roots of the three Vanilla species. In contrast, the epiphytic roots were mainly dominated by OTUs belonging to the Atractiellales and Serendipitaceae. Furthermore, the pOMF communities differed significantly across populations of the widespread V. trigonocarpa and showed patterns of distance decay in similarity. This is the first report of different pOMF communities detected in roots of wild co-occurring Vanilla species using high-throughput sequencing, which provides evidence that three coexisting Vanilla species and their root types exhibited pOMF niche partitioning, and that the rare and widespread Vanilla hosts displayed diverse mycorrhizal preferences.
摘要：
尽管是第二大开花植物家族，兰花代表植物-微生物关联中的群落结构变化，有助于元社区组合中的生态位划分。然而，对于高度专业化甚至与菌根伴侣有联系的兰花，菌根群落和相互作用仍然未知。在这项研究中,我们试图比较三种同时发生的半附生香草物种的兰花菌根真菌（OMF）群落（V。hartii,V.庞波纳,和V.trigonocarpa）在哥斯达黎加的热带森林中，通过解决其跨物种的OMF群落的身份，根类型,和人口，使用高通量测序。对核核糖体内部转录间隔区（nrITS）进行测序，从193个根样品中产生了299个真菌操作分类单位（OTU）。我们在三个共存的香草寄主的推定的OMF（pOMF）群落中显示出明显的隔离。我们还发现，与稀有V.hartii相关的菌根群落在人群中有所不同。此外，我们确定了Tulasnellaceae和Ceratobasidiaceae是三种香草物种陆地根中的优势pOMF家族。相比之下,附生根主要由属于无尾藻科和偶氮藻科的OTUs主导。此外，pOMF群落在广泛分布的三角果弧菌种群之间存在显着差异，并显示出相似的距离衰减模式。这是使用高通量测序在野生共生香草物种的根中检测到的不同pOMF群落的第一份报告，这提供了三个共存的香草物种及其根型表现出pOMF生态位分区的证据，稀有和广泛的香草寄主显示出不同的菌根偏好。
