The systematics of reduced, soil-inhabiting ascomycetes

关于真菌的系统发育关系和多样性的信息严重缺乏，特别是在子囊菌门内，这一组包括了大多数经济上重要的真菌。子囊菌已在许多生境中被列举和鉴定，但记录其多样性的研究受到分离方法的选择性和鉴定这些真菌的困难的限制。许多子囊菌不形成有性状态，是根据其无性孢子形态(无性体)来定义的。变形的子囊菌在解剖学上通常很简单，因此很难识别。在纯培养中不形成孢子阶段的子囊菌不能用基于显微镜的方法来鉴定。幸运的是，通过聚合酶链式反应(聚合酶链式反应)目的基因区域的扩增和所得到的扩增产物的DNA序列的比较，准确地识别变形子囊菌和非产孢子囊菌的问题在很大程度上已经解决了。序列数据对于推断系统发育也是有价值的，这使得能够识别单系类群并基于生态和形态特征评估假说。

Lack of information concerning the phylogenetic relationships and diversity of fungi is acute, particularly within the Ascomycota, a group that includes the majority of economically important fungi. Ascomycetes have been enumerated and identified in many habitats, but studies documenting their diversity are limited by the selective nature of isolation methods and the difficulty of identifying these fungi. Many ascomycetes do not form sexual states and are defined on the basis of their asexual spore forms (anamorphs). Anamorphic ascomycetes are typically simple anatomically and thus challenging to identify. Ascomycetes that form no spore stages in pure culture cannot be identified using microscopy-based methods. Fortunately, the problem of accurately identifying anamorphic and non-sporulating ascomycetes has been solved largely through the PCR (polymerase chain reaction)-amplification of target gene regions and the comparison of DNA sequences of the resulting amplicons. Sequence data are also valuable for inferring phylogenies that permit the recognition of monophyletic groups and the assessment of hypotheses based on ecological and morphological characters.