Fungal colonization of shrub willow roots at the forefront of a receding glacier
Fungal colonization of shrub willow roots at the forefront of a receding glacier
复制标题
DOI：
10.1007/s00572-003-0264-3
复制
发表时间：
2004-10
期刊：
影响因子：
3.9
通讯作者：
Justin Trowbridge;A. Jumpponen
中科院分区：
文献类型：
--
作者：
Justin Trowbridge;A. Jumpponen
灌木柳树（Salixspp.）与丛枝菌根（AM）、外生菌根（EM）和暗隔内生真菌（DSE）形成关联。在美国华盛顿的莱曼冰川的冰川消融前沿，研究了这三种真菌在杨柳根部的定殖。根定殖率低，AM和DSE定殖率分别为根长的1%和25.6%。EM在25%的根尖和19.4%的根长上定殖。AM和DSE殖民地与距离目前的冰川终点或冠层覆盖。EM殖民增加的距离从冰川终点的网格线截取数据的基础上，但不是根尖频率数据。繁殖体在基板的可用性是低的，但繁殖体的数量增加，从冰川终点的距离。在BLAST分析中，EM群落以三种子囊菌为主，显示出与Sordariaceae的亲和性。冰川前沿的其他常见类群包括Cortinariaceae、Pezizaceae、Russulaceae、Thelephoraceae和Tricholomataceae。当个体分类群的出现被用作对冠层覆盖、距冰川终点的距离以及它们之间的相互作用的响应变量时，确定了四种不同的真菌类群：1）不响应这些环境变量的真菌; 2）主要发生在冠层间区域并且随着距冰川终点的距离而减少的真菌;（3）对林冠覆盖不敏感，但随距冰川终点距离的增加而增加的真菌;（4）主要发生在杨柳林冠下，并随距冰川终点距离的增加而增加的真菌。我们认为，真菌定植主要是有限的真菌繁殖体的可用性。环境条件也可能限制植物真菌协会的成功建立。我们建议，四个EM行业协会部分解释演替动态。初始EM群落包括耐受低有机质和氮环境的真菌（上述第一和第二公会）。在后来的群落发展中，这些真菌被那些受益于有机质和氮环境增加的真菌所取代（上面的第三和第四个公会）。
Shrub willows (Salixspp.) form associations with arbuscular mycorrhizal (AM), ectomycorrhizal (EM) and dark septate endophytic (DSE) fungi. Willow root colonization by these three types of fungi was studied on a deglaciated forefront of Lyman Glacier, Washington, USA. Root colonization was low; less than 1% of the root length was colonized by AM and 25.6% by DSE. EM colonized 25% of the root tips and 19.4% of the root length. AM and DSE colonization were not related to distance from the present glacier terminus or to canopy cover. EM colonization increased with distance from the glacier terminus based on gridline intercept data but not on root tip frequency data. Availability of propagules in the substrate was low, but numbers of propagules increased with distance from the glacier terminus. The EM communities were dominated by three ascomycetes showing affinity to Sordariaceae in BLAST analyses. Other frequent taxa on the glacier forefront included species of Cortinariaceae, Pezizaceae, Russulaceae, Thelephoraceae and Tricholomataceae. When occurrence of individual taxa was used as a response variable to canopy cover, distance from the glacier terminus, and their interaction, four different fungal guilds were identified: 1) fungi that did not respond to these environmental variables; 2) fungi that occurred mainly in intercanopy areas and decreased with distance from the glacier terminus; 3) fungi that were insensitive to canopy cover but increased with distance from the glacier terminus; 4) fungi that occurred mainly under willow canopies and increased with distance from the glacier terminus. We suggest that fungal colonization is mainly limited by fungal propagule availability. Environmental conditions may also limit successful establishment of plant-fungus associations. We propose that the four EM guilds partly explain successional dynamics. The initial EM community comprises fungi that tolerate low organic matter and nitrogen environment (first and second guilds above). During later community development, these fungi are replaced by those that benefit from an increased organic matter and nitrogen environment (third and fourth guilds above).