Microbial Genome Sequencing: Coupling Diversity with Function: Metagenomics of Boreal Forest Fungi

真菌在植物的分解和养分获取中起主导作用，从而影响土壤的净初级生产力、碳固存以及氮、磷等关键元素的生物地球化学循环。人们对特定真菌种类在这些过程中的作用知之甚少，部分原因是许多种类不能在纯培养中轻易分离出来。宏基因组方法为这种隔离偏差问题提供了解决方案。北方针叶林储量丰富，并且储存了大约30%的地球活性碳，因此在全球生物地球化学循环中发挥着核心作用。因此，北方森林真菌的多样性和功能是宏基因组研究的重要课题。该项目将对单一地理区域内的真菌多样性、遗传关系和底物特异性进行迄今为止最详细的研究。在第一步中，将对从土壤DNA提取物中扩增的真菌核糖体基因区域的PCR文库中的32,000个克隆进行测序。这些dna将从北部北方针叶林的三种森林类型中的每一种的关键土壤基质（如凋落叶、腐殖质、木材、根）中提取。预计会发现新的真菌和它们对底物的偏好。在第二步中，将在UAF真菌学植物标本室保存的4000个干子实体（如蘑菇）中对相同的核糖体区域进行测序。植物标本室标本序列将允许对地下和地上的多样性进行比较，将有助于识别未知的真菌，并将为识别来自各种相关生态研究的“群落指纹”中观察到的组成真菌提供强大的数据库。

Fungi play dominant roles in decomposition and plant nutrient acquisition, and thus influence net primary productivity, carbon sequestration in soil, and the biogeochemical cycling of key elements such as nitrogen and phosphorus. Little is known about the roles of particular fungal species in these processes, in part because many species cannot easily be isolated in pure culture. Metagenomic methods offer solutions to this isolation-bias problem. The boreal forest plays a central role in global biogeochemical cycling due to its abundance and because it stores approximately 30% of the earth's reactive carbon. Hence, fungal diversity and function in the boreal forest are compelling subjects for metagenomic scrutiny. This project will undertake the most detailed examination to date of fungal diversity, genetic relationships and substrate specificity within a single geographic region. In the first step, 32,000 clones from PCR libraries of fungal ribosomal gene-regions amplified from soil DNA extracts will be sequenced. The DNAs will be extracted from key soil substrates (e.g. leaf litter, humus, wood, roots) within each of three forest types that are important components of the northern boreal forest. Discovery of novel fungi and their substrate preferences are anticipated. In the second step, the same ribosomal region will be sequenced in 4000 dried fruitbodies (e.g. mushrooms) maintained within the UAF Mycological Herbarium. The herbarium specimen sequences will permit below-ground and above-ground views of diversity to be compared, will help identify unknown fungi, and will provide a powerful database for identification of the constituent fungi observed in 'community fingerprints' from a variety of related ecological studies.