Tedersoo Leho, Suvi Triin, Jairus Teele, Ostonen Ivika, Põlme Sergei
Institute of Ecology and Earth Sciences, University of Tartu, 40 Lai Street, 51005 Tartu, Estonia.
Natural History Museum of Tartu University, 46 Vanemuise Street, 51005 Tartu, Estonia.
New Phytol. 2009;182(3):727-735. doi: 10.1111/j.1469-8137.2009.02792.x. Epub 2009 Mar 6.
Actinorhizal plants, including those of the genus Alnus (alders; Betulaceae), and their nitrogen-fixing bacterial symbionts rely on mycorrhizal fungi for phosphorus and other mineral nutrients. To date, alders are known to associate with only 20-30 species of ectomycorrhizal fungi which are highly host-specific. This study aimed to determine the species richness and the relative importance of host species, soil and site variables on the community composition of Alnus-associated ectomycorrhizal fungi on root tips. Using rDNA internal transcribed spacer (ITS) and large subunit (LSU) sequence analysis, 40 species of putatively ectomycorrhizal fungi were identified from seven sites dominated by Alnus incana or Alnus glutinosa. Alnicola spp. and Tomentella aff. sublilacina were most prevalent in all sites. Species of the /pseudotomentella, /inocybe, /peziza michelii-peziza succosa, /genea-humaria, /pachyphloeus-amylascus, /helvella-tuber and /tarzetta-geopyxis lineages were recorded as natural symbionts of alders for the first time. All basidiomycetes were specific to Alnus, whereas four out of seven Pezizales spp. (ascomycetes) were nonspecific. The complex of soil variables and geographical (site) effect drives the community composition of ectomycorrhizal fungi in alder forests. Alder-associated fungi have independently evolved and subsequently radiated in several ectomycorrhizal lineages, indicating frequent and persistent host shifts after the divergence of Alnus and Betula.
放线菌根植物，包括桤木属（桤木；桦木科）的植物及其固氮细菌共生体，依靠菌根真菌获取磷和其他矿物质养分。迄今为止，已知桤木仅与20 - 30种外生菌根真菌相关联，这些真菌具有高度的宿主特异性。本研究旨在确定宿主物种、土壤和场地变量对桤木根尖相关外生菌根真菌群落组成的物种丰富度和相对重要性。通过核糖体DNA内转录间隔区（ITS）和大亚基（LSU）序列分析，从七个以灰桤木或欧洲桤木为主的场地中鉴定出40种推定的外生菌根真菌。Alnicola属和近似浅紫绒盖牛肝菌的绒盖牛肝菌在所有场地中最为普遍。假绒盖牛肝菌属、丝盖伞属、米氏盘菌 - 多汁盘菌、Genea - Humaria、厚皮盘菌 - 曲霉属、皱盖牛肝菌 - 块菌属和塔泽牛肝菌 - 地菇属谱系的物种首次被记录为桤木的天然共生体。所有担子菌都对桤木具有特异性，而七个盘菌目物种（子囊菌）中有四个是非特异性的。土壤变量和地理（场地）效应的复合体驱动了桤木林中外生菌根真菌的群落组成。桤木相关真菌在几个外生菌根谱系中独立进化并随后辐射，表明在桤木和桦木分化后宿主发生了频繁且持续的转变。
