Molecular Systematics and Evolution of Fungi in the Russuloid Lineage

9974018 Miller红菇属（Russula）和乳菇属（Lactarius）的种类是温带森林和北极高山生态系统中显著丰富的成分，并且越来越被认为是世界热带地区的重要成分。它们为真菌生物量做出了重大贡献，是啮齿动物和昆虫的重要饮食元素，世界各地的许多物种都被收获供人类消费。红菇属作为与林木的根共生体（外生菌根），在温带和热带森林中占菌根植物群的近四分之一。尽管这两个属的物种具有明显的世界性，但它们很难识别和描述。该类群的分类学依赖于已知表现出表型可塑性的特征（例如，渐变的颜色变化和渐变的孢子形状）或怀疑在物种群中平行出现的特征（例如，子实体的形状）。此外，对热带分类群的研究大大改变了早期的分类学观念，这些观念主要基于对北方温带地区真菌的有限取样。现在描述的物种数量很大，但所有主要的分类都是区域性的，并且不能提供全世界范围内的属的全面概述。核核糖体基因的DNA测序的新的分子证据表明，产生的数据有用的构建一个系统发育框架之间的物种群的红菇属和乳菇属和众多的盟友在担子菌的进化关系的承诺。怀俄明州大学的史蒂文米勒博士正在与几个国家的合作者组成的令人印象深刻的网络合作，收集这些真菌的样本，分析它们的核核糖体基因中的DNA序列多样性，并将这些数据与新的和传统的形态学研究相结合。特别是，南美洲，非洲和澳大拉西亚的联系人和同事将允许急需的热带代表属的采样，以平衡温带样本，在分子和形态学研究。初步研究已经完成。80个分类群的目的Russulales，证明了该项目的可行性和有希望的解决方案从DNA数据。从分子系统发育分析中得到支持的谱系将成为深入的形态学研究的重点，以描述物种鉴定的可靠特征。新开发的分类和基因序列数据的另一个直接结果是，即使在没有子实体生产的情况下，也能够从分子上识别单个菌根根上的这些真菌，从而促进温带和热带生态系统的生态研究。

9974018Miller Species in the mushroom genera Russula and Lactarius are conspicuous abundant elements of temperate zone forests and arctic alpine ecosystems, and increasingly are known as important elements in tropical regions of the world. They contribute significantly to fungal biomass, are important dietary elements for rodents and insects, and many species are harvested worldwide for human consumption. As root symbionts (ectomycorrhizae) with forest trees, species of Russula may constitute nearly a quarter of the total mycorrhizal flora in various temperate and tropical forests. Despite their conspicuous and cosmopolitan nature, species in both genera have been difficult to identify and to characterize. Taxonomy of the group has relied on features that are known to exhibit phenotypic plasticity (intergrading color variation, for example, and intergrading spore shape) or suspected of arising in parallel in species groups (shape of the fruiting body, for example). In addition, the study of tropical taxa has considerably altered earlier taxonomic ideas that were principally based on a restricted sampling of fungi from temperate zones of the northern hemisphere. The number of described species is now large, but all major classifications are regional in nature, and fail to provide a comprehensive overview of the genera on a worldwide basis. New molecular evidence from DNA sequencing of nuclear ribosomal genes shows promise of yielding data useful for constructing a phylogenetic framework of evolutionary relationships among the species groups of Russula and Lactarius and numerous allies in the basidiomycetes. Dr. Steven Miller of the University of Wyoming is working with an impressive network of collaborators in several countries to collect samples of these fungi and analyze them for DNA sequence diversity in the nuclear ribosomal genes, and to integrate these data with new and traditional morphological investigations. In particular, contacts and colleagues in South America, in Africa, and in Australasia will allow much-needed sampling of tropical representatives of the genera to balance temperate-zone exemplars, in the molecular and morphological studies. Preliminary studies have been accomplished on ca. 80 taxa from the order Russulales, demonstrating feasibility of the project and promising resolution from the DNA data. Well supported lineages emerging from the molecular-phylogenetic analyses will become the focus of intensive morphological studies to characterize reliable features for species identification. Another direct result of the newly developed classification and gene sequence data will be the capability molecularly to identify these fungi on individual mycorrhizal roots even in the absence of fruit-body production, thus facilitating ecological research in temperate and tropical ecosystems.