The systematics of reduced, soil-inhabiting ascomycetes

缺乏有关真菌的系统发育关系和多样性的信息是严重的，特别是在子囊菌门，一组，包括大多数经济上重要的真菌。 子囊菌在许多栖息地中已经被列举和鉴定，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，并根据它们的无性孢子形式（无性型）来定义。 无性型子囊菌通常在解剖学上是简单的，因此难以识别。 在纯培养中不形成孢子阶段的子囊菌不能使用基于显微镜的方法鉴定。 幸运的是，通过PCR（聚合酶链式反应）-扩增靶基因区域和比较所得扩增子的DNA序列，已经在很大程度上解决了准确鉴定变形和非孢子形成子囊菌的问题。 序列数据也是有价值的推断单系群，允许识别和评估基于生态和形态特征的假设。

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.