Reconstruction of the phylogeny of anaerobic chytridiomycetes (Neocallimasticales, Fungi) based on multigene-genealogie

厌氧肠道真菌在真菌王国中具有非凡的进化意义。肠道真菌的独特特性，特别是它们的厌氧性、拥有氢酶体而不是线粒体、多鞭毛和极低的基因组GC含量，使它们在壶菌类中分类相当困难。基于DNA分析的厌氧真菌现代系统学消除了肠道真菌随环境条件的广泛形态变化的问题。然而，由于核糖体DNA簇的重复性和异质性，基于核糖体DNA序列的分子数据并不能令人满意地回答有氧和厌氧壶菌之间的关系。多个蛋白质编码基因的分子分析克服了这些问题，并为研究厌氧真菌在其他真菌类群中的系统发育位置提供了强有力的策略。编码肌动蛋白、β -微管蛋白、翻译延伸因子1-ot的单拷贝蛋白编码基因或编码几丁质降解和能量代谢酶的基因经过强烈的选择，是植物重建的可靠标记。与其他真菌谱系的主要分支相比，目前的研究计划产生了壶菌所有分类群的五基因谱系。由于动物和真菌被认为是姐妹类群，鞭毛真菌被认为是真菌最基础的谱系，我们的项目将揭示动物和真菌之间分歧的古代进化史。

Anaerobic gut fungi are evolutionarily extraordinary in the fungal kingdom. Unique traits of gut fungi especially their anaerobiosis, possession of hydrogenosomes instead of mitochondria, multiple flagella and extremely low genomic GC content caused considerable difficulties with their classification within the class of the chytridiomycetes. Modern systematics of anaerobic fungi based on DNA analyses eliminates the problems with extensive morphological variation of gut fungi depending on environmental conditions. However molecular data based on ribosomal DNA sequences did not answered to satisfaction the relationship between aerobic and anaerobic chytrids because of the repetitive and heterogenous nature of the ribosomal DNA cluster. Molecular analyses of multiple protein-coding genes overcome these problems and offer a robust strategy to study the phylogenetic position of anaerobic fungi among other fungal groups. Single copy protein-coding genes encoding actin, ß- tubulin, translation elongation factor 1-ot or genes encoding enzymes involved in chitin degradation and energy metabolism undergo strong selection and are reliable markers for the reconstruction of phytogenies. The present research proposal results in the generation of a five-gene-genealogy from all taxonomic groups of the chytridiomycetes in comparison with major clades of other fungal lineages. Since animals and fungi are known to be sister groups and flagellate fungi are accepted to represent the most basal lineage of fungi our project will shed light on the ancient evolutionary history of divergence between animals and fungi.