Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, PO Box 5003, NO-1432 Ås, Norway.
Microbial Evolution Research Group (MERG), Department of Biology, University of Oslo, PO Box 1066 Blindern, NO-0316 Oslo, Norway.
New Phytol. 2012 Sep;195(4):844-856. doi: 10.1111/j.1469-8137.2012.04215.x. Epub 2012 Jul 3.
Bryophytes are a dominant vegetation component of the boreal forest, but little is known about their associated fungal communities, including seasonal variation within them. Seasonal variation in the fungal biomass and composition of fungal communities associated with three widespread boreal bryophytes was investigated using HPLC assays of ergosterol and amplicon pyrosequencing of the internal transcribed spacer 2 (ITS2) region of rDNA. The bryophyte phyllosphere community was dominated by Ascomycota. Fungal biomass did not decline appreciably in winter (P=0.272). Significant host-specific patterns in seasonal variation of biomass were detected (P=0.003). Although seasonal effects were not the primary factors structuring community composition, collection date significantly explained (P=0.001) variation not attributed to locality, host, and tissue. Community homogenization and a reduction in turnover occurred with the onset of frost events and subzero air and soil temperatures. Fluctuations in the relative abundance of particular fungal groups seem to reflect the nature of their association with mosses, although conclusions are drawn with caution because of potential methodological bias. The moss-associated fungal community is dynamic, exhibiting seasonal turnover in composition and relative abundance of different fungal groups, and significant fungal biomass is present year-round, suggesting a winter-active fungal community.
苔藓植物是北方森林的主要植被组成部分，但对于与它们相关的真菌群落，包括其中的季节性变化，人们知之甚少。本研究使用 HPLC 法测定麦角固醇和 rDNA 内转录间隔区 2（ITS2）区域的扩增子焦磷酸测序法，调查了与三种广泛分布的北方苔藓植物相关的真菌生物量和群落组成的季节性变化。苔藓植物叶际群落主要由子囊菌门组成。真菌生物量在冬季没有明显下降（P=0.272）。检测到生物量季节性变化的宿主特异性显著模式（P=0.003）。尽管季节效应不是群落组成结构的主要因素，但采集日期显著解释了（P=0.001）无法归因于地点、宿主和组织的变异。随着霜期和零下的空气和土壤温度的出现，群落同质化和周转率降低。特定真菌群的相对丰度的波动似乎反映了它们与苔藓植物的关联性质，但由于潜在的方法学偏差，结论应谨慎得出。苔藓植物相关真菌群落是动态的，表现出组成和不同真菌群相对丰度的季节性变化，并且全年都存在显著的真菌生物量，表明真菌群落具有冬季活性。
