Landcare Research, Gerald Street, Lincoln, 7608, New Zealand.
School of Biological Sciences, University of Aberdeen, Cruickshank Building, St. Machar Drive, Aberdeen, AB24 3UU, Scotland, UK.
Mycorrhiza. 2017 Nov;27(8):831-839. doi: 10.1007/s00572-017-0797-5. Epub 2017 Aug 25.
Typically, Mycena species are viewed as saprotrophic fungi. However, numerous detections of Mycena spp. in the roots of green plants suggest that a continuum from saprotrophy to biotrophy could exist. In particular, mycenoid species have repeatedly been found in Ericaceae plant roots. Our study asked whether (1) Mycena species are commonly found in the roots of green Ericaceae plants; (2) Mycena sequences are limited to a single group/lineage within the genus; and (3) a Mycena sp. can behave as a beneficial root associate with a typical ericoid mycorrhizal plant (Vaccinium corymbosum), regardless of how much external labile carbon is available. We detected Mycena sequences in roots of all sampled Ericaceae plants. Our Mycena sequences clustered in four different groups distributed across the Mycena genus. Only one group could be assigned with confidence to a named species (M. galopus). Our Mycena sequences clustered with other Mycena sequences detected in roots of ericoid mycorrhizal plant species collected throughout Europe, America, and Australia. An isolate of M. galopus promoted growth of V. corymbosum seedlings in vitro regardless of external carbon supply in the media. Seedlings inoculated with M. galopus grew as well as those inoculated with the ericoid mycorrhizal fungus Rhizoscyphus ericae. Surprisingly, this M. galopus isolate colonized Vaccinium roots and formed distinctive peg-like structures. Our results suggest that Mycena species might operate along a saprotroph-symbiotic continuum with a range of ericoid mycorrhizal plant species. We discuss our results in terms of fungal partner recruitment by Ericaceae plants.
通常情况下，杯伞属真菌被视为腐生真菌。然而，大量的杯伞属真菌在绿色植物根部的检测结果表明，它们可能存在从腐生到共生的连续过渡。特别是，在杜鹃花科植物的根部中，已经反复发现了类杯伞属真菌。我们的研究提出了以下三个问题：（1）杯伞属真菌是否普遍存在于绿色杜鹃花科植物的根部；（2）杯伞属真菌的序列是否仅限于该属内的一个单一群体/谱系；（3）一种杯伞属真菌能否与典型的杜鹃花类菌根植物（蔓越橘）形成有益的根伴生关系，而不论外部可利用的易位碳量如何。我们在所有采样的杜鹃花科植物根部都检测到了杯伞属真菌的序列。我们的杯伞属真菌序列聚类为四个不同的组，分布在整个杯伞属中。只有一个组可以被自信地分配到一个命名的种（M. galopus）。我们的杯伞属真菌序列与在欧洲、美洲和澳大利亚采集的杜鹃花类菌根植物根部中检测到的其他杯伞属真菌序列聚类在一起。M. galopus 的一个分离株在体外促进了蔓越橘幼苗的生长，而不论培养基中外部碳源的供应如何。接种 M. galopus 的幼苗的生长情况与接种杜鹃花类菌根真菌 Rhizoscyphus ericae 的幼苗一样好。令人惊讶的是，这种 M. galopus 分离株可以在蔓越橘根部定植，并形成独特的钉状结构。我们的研究结果表明，杯伞属真菌可能沿着腐生-共生的连续体与一系列杜鹃花类菌根植物物种相互作用。我们根据杜鹃花科植物对真菌伙伴的招募来讨论我们的研究结果。
