Interactions with mycorrhizal fungi have been increasingly recognized as one of the most important ecological factors determining the distribution and local abundance of orchids. While some orchid species may interact with a variety of fungal associates, others are more specific in their choice of mycorrhizal partners. Moreover, orchids that co-occur at a given site, often associate with different partners, possibly to avoid competition and to allow stable coexistence. However, whether differences in mycorrhizal partners directly affect seed germination and subsequent protocorm formation remains largely unknown. In this research, we used in vitro germination experiments to investigate to what extent seed germination and protocorm formation of Gymnadenia conopsea was affected by the origin and identity of fungal associates. Fungi were isolated from G. conopsea and three other co-occurring orchid species (Dactylorhiza viridis (Coeloglossum viride), Herminium monorchis, and Platanthera chlorantha). In total, eight fungal associates, belonging to Tulasnellaceae, Ceratobasidiaceae, and Serendipitaceae, were successfully isolated and cultured. While all eight fungal strains were able to promote early germination of G. conopsea seeds, only fungal strain GS2, a member of the Ceratobasidiaceae isolated from G. conopsea itself, was able to promote protocorm formation and subsequent growth to a seedling. Two other fungal strains isolated from G. conopsea only supported seed germination until the protocorm formation stage. The other five fungal strains isolated from the co-occurring orchid species did not support seed germination beyond the protocorm stage. We conclude that, although G. conopsea is considered a mycorrhizal generalist that associates with a wide range of fungi during its adult life, it requires specific fungi to promote protocorm formation and growth to a seedling.

中文翻译：

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共生兰花的真菌同伴是否会促进广泛的兰花物种金冠藻的种子发芽？

与菌根真菌的相互作用已日益被认为是决定兰花的分布和局部丰富度的最重要的生态因素之一。虽然某些兰花物种可能会与各种真菌相关联相互作用，但其他兰花物种在选择菌根伴侣时却更具特异性。此外，在给定位置共生的兰花通常与不同的伙伴联系在一起，可能是为了避免竞争并允许稳定的共存。但是，菌根伴侣之间的差异是否直接影响种子的发芽和随后的原球茎形成仍然是未知的。在这项研究中，我们使用了体外发芽实验，以研究Gymnadenia conopsea的种子发芽和原球茎形成的程度。受真菌同伴的起源和身份的影响。从G. conopsea和其他三个同时存在的兰花物种（Dactylorhiza viridis（Coeloglossum viride），Herminium monorchis和Platanthera chlorantha）中分离出真菌。总共成功分离并培养了8个真菌伴生体，它们分别属于伞形科，杜鹃花科和蕨科。尽管所有八种真菌菌株均能促进圆锥角锥菌种子的早期萌发，但只有真菌菌株GS2（从圆锥形锥菌中分离出的藜科的一种）本身能够促进原球茎的形成以及随后的幼苗生长。从锥果肠球菌分离的另外两个真菌菌株仅支持种子发芽，直到原球茎形成阶段。从共生兰花物种中分离出的其他五种真菌菌株在原球茎阶段之后不支持种子发芽。我们得出的结论是，尽管G. conopsea被认为是在其成年后与多种真菌相关的菌根通才，但它需要特定的真菌来促进原球茎的形成和幼苗生长。