BACKGROUND Orchids maintain a symbiotic relationship with mycorrhizal fungi in the lifecycle. Previous reports indicated that diverse mycobionts may have different roles during orchid growth and development. Although various mycorrhizal fungi have been isolated from Dendrobium roots and protocorms, little is known about their specific effects on seed germination and seedling growth. To understand the specific role of isolated fungal strains (i.e., Tulasnella and Sebacina), we used symbiotic culture to compare the effect of 6 fungal strains on seed germination and seedling growth of Dendrobium officinale, an important Chinese medicinal orchid. RESULTS In symbiotic germination tests, 6 fungal strains (4 Tulasnella strains and 2 Sebacina strains) promoted seed germination with different efficiencies. Seeds inoculated with Tulasnella strains S6 and S7 conferred higher germination percentage and faster protocorm development than other fungal strains. In symbiotic cultures, seedlings inoculated with Sebacina strain S3 had optimal fresh and dry matter yield. Also, Tulasnella strains S6 and S7 promoted seedling growth with good fresh and dry matter yield. Sebacina strain S2 inoculation greatly enhanced root and tiller production and the content of total crude polysaccharides, although seedlings were smaller with less fresh and dry matter yield than other seedlings. CONCLUSIONS Tulasnella and Sebacina strains could promote seed germination and seedling growth of D. officinale with different efficiencies. Our results suggest a non-specific mycorrhizal association and development-dependent preference. Our data provide the basic knowledge for use of different fungal strains in conservation and/or production practices of D. officinale.

中文翻译：

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不同的真菌菌根对重要药用兰花石D的共生发芽和幼苗生长的影响。

背景技术兰花在生命周期中与菌根真菌保持共生关系。以前的报道表明，各种真菌菌在兰花的生长和发育过程中可能具有不同的作用。尽管已从石rob根和原球茎中分离出各种菌根真菌，但对它们对种子发芽和幼苗生长的特定作用知之甚少。为了了解分离的真菌菌株（例如，兔小球藻和Sebacina）的具体作用，我们使用共生培养法比较了6种真菌菌株对中药石end（Dendrobium officinale）种子发芽和幼苗生长的影响。结果在共生萌发测试中，有6种真菌菌株（4种Tulasnella菌株和2种Sebacina菌株）以不同的效率促进了种子的萌发。与其他真菌菌株相比，接种风铃草菌株S6和S7的种子具有更高的发芽率和更快的原球茎发育。在共生培养中，接种Sebacina S3菌株的幼苗具有最佳的新鲜和干物质产量。同样，杜氏藻菌株S6和S7促进了幼苗生长，并具有良好的新鲜和干物质产量。接种Sebacina菌株S2可以显着提高根和分production产量以及总粗多糖的含量，尽管幼苗比其他幼苗更小，鲜，干物质产量也更少。结论薄壳菌和Sebacina菌株可以不同效率促进D.officinale的种子发芽和幼苗生长。我们的结果表明非特异性菌根协会和发展依赖偏好。