Morphological and Ecological Diversification In the Homobasidiomycetes: A Molecular Phylogenetic Analysis

9903835 Hibbett和Donoghue Homobasidiomycetes包括形成蘑菇的真菌和它们的亲戚。目前已知的真菌约有13，500种，约占所有已知真菌的23%。同担子菌纲的子实体包括明显的、发育上完整的结构，如蘑菇和马勃菌，以及非常简单的形式，如“皮质类”真菌的壳状子实体。同担子菌在陆地生态系统的碳循环中起着重要作用;它们包括大多数木材腐烂真菌和外生菌根真菌（与树根有关）;它们还包括真菌寄生虫，昆虫共生体，地衣和凋落物分解者。虽然这些真菌的个别群体已被深入研究，其形态和生态进化的整体格局尚未确定，因为迄今为止，还没有广泛的支持系统发育框架的组。在过去的几年里，通过使用新的DNA序列特征，特别是编码核和线粒体核糖体RNA（rDNA）的基因，在理解同担子菌的遗传学方面取得了相当大的进展。该项目将扩大核和线粒体rDNA序列的数据库，并增加正在研究的蛋白质编码基因的新数据，如微管蛋白或RNA聚合酶。分类群采样将针对有问题的群体，如多孔菌，hymenochaetoid，和真菌类，其关系仍然弱支持现有的分子数据。将采用系统发育分析的常规方案，此外，研究人员将探索使用“超级树”结合或整理独立的系统发育树与重叠的类群，以构建一个复合系统发育假说。这些树将用于构建系统发育分类，并研究选定的形态和生态特征的历史演变模式。具体的字符进行调查，包括：corticioid与直立子实体;棕色腐烂与白色腐烂模式的木材腐烂;和外生菌根与腐营养和致病模式的营养。一个广泛的框架homobasidiomycetes的系统发育将有助于，例如通过确定姐妹群和最近的外群，更深入的分析这些真菌的形态和生理变化。

9903835Hibbett and Donoghue Homobasidiomycetes include the mushroom-forming fungi and their relatives. About 13,500 species have been described, which is about 23% of all known species of fungi. The fruiting bodies of homobasidiomycetes include conspicuous, developmentally integrated structures such as mushrooms and puffballs, as well as very simple forms such as the crust-like fruiting bodies of "corticioid" fungi. Homobasidiomycetes play major roles in carbon cycling in terrestrial ecosystems; they comprise the majority of wood-decay fungi and ectomycorrhizal fungi (associated with tree roots); and they also include mycoparasites, insect symbionts, lichens, and litter decomposers. Although individual groups of these fungi have been studied intensively, their overall pattern of morphological and ecological evolution has not been determined because to date there has existed no broad well-supported phylogenetic framework for the group. Over the last few years, considerable progress has been made in understanding homobasidiomycete phylogeny through the use of new DNA sequence characters, particularly the genes encoding nuclear and mitochondrial ribosomal RNA (rDNA). This project will expand the database of nuclear and mitochondrial rDNA sequences and add new data from protein-coding genes under study, such as the tubulins or RNA polymerases. Taxon sampling will target problematic groups such as the polyporoid, hymenochaetoid, and cantharelloid groups of fungi, whose relationships remain weakly supported by the existing molecular data. Conventional protocols for phylogenetic analyses will be employed, and in addition the investigators will explore the use of "supertrees" for combining or collating independent phylogenetic trees with overlapping sets of taxa in order to construct a composite phylogenetic hypothesis. The trees will be used to construct phylogenetic classifications and to study historical patterns of evolution in selected morphological and ecological characters. Specific characters to be investigated include: corticioid versus erect fruiting bodies; brown rot versus white rot modes of wood decay; and ectomycorrhizal versus saprotrophic and pathogenic modes of nutrition. A broad framework phylogeny for the homobasidiomycetes will facilitate, for example by identifying sister groups and nearest outgroups, more intensive analyses of morphological and physiological changes in these fungi.