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

真菌在分解和植物养分获取中起主导作用，从而影响净第一性生产力、土壤固碳和氮、磷等关键元素的生物地球化学循环。人们对特定真菌物种在这些过程中的作用知之甚少，部分原因是许多真菌物种在纯培养中不容易分离。元基因组学方法为这种隔离偏向问题提供了解决方案。北方森林因其丰富的储量和储存了地球上约30%的活性碳，在全球生物地球化学循环中发挥着核心作用。因此，北方森林中真菌的多样性和功能是元基因组研究的引人注目的主题。该项目将对单一地理区域内的真菌多样性、遗传关系和底物专一性进行迄今为止最详细的检查。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3.2万个克隆进行测序。DNA将从北部北方针叶林重要组成部分的三种森林类型中的每一种内的关键土壤基质(例如，叶凋落物、腐殖质、木材、根)中提取。新真菌的发现和它们的底物偏好是可预见的。在第二步中，将对UAF真菌标本馆内保存的4000个干子实体(例如蘑菇)进行相同的核糖体区域测序。标本馆的标本序列将允许比较地下和地上的多样性视图，将有助于识别未知的真菌，并将提供一个强大的数据库，用于从各种相关的生态学研究的“群落指纹”中观察到组成真菌的鉴定。

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.