Uesugi Takashi, Nakano Miho, Selosse Marc-André, Obase Keisuke, Matsuda Yosuke
Laboratory of Forest Mycology, Graduate School of Bioresources, Mie University, Kurimamachiya 1577, Tsu, Mie, 514-8507, Japan.
Faculty of Bioresources, Mie University, Kurimamachiya 1577, Tsu, Mie, 514-8507, Japan.
Mycorrhiza. 2016 Nov;26(8):819-829. doi: 10.1007/s00572-016-0715-2. Epub 2016 Jun 21.
Mycorrhizal symbiosis often displays low specificity, except for mycoheterotrophic plants that obtain carbon from their mycorrhizal fungi and often have higher specificity to certain fungal taxa. Partially mycoheterotrophic (or mixotrophic, MX) plant species tend to have a larger diversity of fungal partners, e.g., in the genus Pyrola (Monotropoideae, Ericaceae). Preliminary evidence however showed that the Japanese Pyrola japonica has preference for russulacean fungi based on direct sequencing of the fungal internal transcribed spacer (ITS) region from a single site. The present study challenges this conclusion using (1) sampling of P. japonica in different Japanese regions and forest types and (2) fungal identification by ITS cloning. Plants were sampled from eight sites in three regions, in one of which the fungal community on tree ectomycorrhizal (ECM) tips surrounding P. japonica was also analyzed. In all, 1512 clone sequences were obtained successfully from 35 P. japonica plants and 137 sequences from ECM communities. These sequences were collectively divided into 74 molecular operational taxonomic units (MOTUs) (51 and 33 MOTUs, respectively). MOTUs from P. japonica involved 36 ECM taxa (96 % of all clones), and 17 of these were Russula spp. (76.2 % of all clones), which colonized 33 of the 35 sampled plants. The MOTU composition significantly differed between P. japonica and ECM tips, although shared species represented 26.3 % of the ECM tips community in abundance. This suggests that P. japonica has a preference for russulacean fungi.
菌根共生通常表现出较低的特异性，但菌根异养植物除外，这类植物从其菌根真菌中获取碳，并且通常对某些真菌类群具有较高的特异性。部分菌根异养（或兼养型，MX）植物物种往往有更多样化的真菌伙伴，例如鹿蹄草属（鹿蹄草科，水晶兰亚科）的植物。然而，初步证据表明，基于对单个地点真菌内部转录间隔区（ITS）区域的直接测序，日本鹿蹄草偏好红菇科真菌。本研究通过以下方法对这一结论提出质疑：（1）在日本不同地区和森林类型中采集日本鹿蹄草样本；（2）通过ITS克隆进行真菌鉴定。从三个地区的八个地点采集了植物样本，其中一个地点还分析了围绕日本鹿蹄草的树木外生菌根（ECM）根尖上的真菌群落。总共从35株日本鹿蹄草植物中成功获得了1512个克隆序列，从ECM群落中获得了137个序列。这些序列共分为74个分子操作分类单元（MOTU）（分别为51个和33个MOTU）。来自日本鹿蹄草的MOTU涉及36个ECM分类群（占所有克隆的96%），其中17个是红菇属（占所有克隆的76.2%），它们定殖在35株采样植物中的33株上。尽管共享物种在丰度上占ECM根尖群落的26.3%，但日本鹿蹄草和ECM根尖之间的MOTU组成存在显著差异。这表明日本鹿蹄草偏好红菇科真菌。
