Understanding the Phylogeny, Evolution and Host Specificity of the Exobasidiales (Ustilaginomycotina)

植物寄生虫是真菌中最大的生态类群之一。当陆地植物覆盖地球时，辐射的两个主要谱系包含了几个完全是植物寄生的群体。尽管子囊菌门和担子菌门是在与其宿主的直接相互作用中进化的，但目前的数据表明，植物寄生的生活方式已经出现过几次。如果我们考虑到宿主特有的寄生虫，如白粉病、锈病或黑穗病，这一点尤其正确。这些寄主特有的植物寄生虫不仅是进化的重要驱动因素，而且也是对我们主要作物的最大威胁。例如，所有谷物都受到这三种宿主特有真菌谱系的威胁，这些真菌每年造成巨大的经济损失。对乌氏菌属毒力因子的认识作出了重要贡献。马氏黑穗病菌是第一个已完成基因组测序的真菌寄生虫。与许多其他真菌植物寄生虫相比，它可以很容易地在无性系条件下生长，并可用于许多遗传工具。Ustilaginomycotina共有1700多种，其中大多数具有高度的寄主特异性，同时对少数几种进行了较详细的研究。比较基因组学和反向遗传学研究表明，所谓的核心效应物是对植物感染至关重要的毒力因子。然而，对更远的亲缘物种的分析未能确定与宿主特异性相关的因素。因此，我们建议以Exobasidiales （Ustilaginomycotina）目为研究对象，识别和研究与宿主特异性相关的因素。与黑穗病菌（Ustilago maydis）的近缘种相比，黑穗病菌（Exobasidium）很常见，而且容易被发现和分离。在中国和欧洲进行补充取样，可以比较两个近亲物种的谱系。因此，比较基因组学将超越核心效应物的识别，因为更详细的分析，如合成研究、选择分析甚至转录组学，将允许更多的信息方法。因此，基于40-50个额外的基因组，我们将提供一个外黑猴的系统发育，以分析各自谱系之间和内部的性状进化。我们将特别关注分泌组的分析，但我们将包括基因组的所有信息方面。此外，我们计划使用电子显微镜来研究相互作用装置的超微结构，因为这可能是宿主特异性的另一个特征。通过这些不同的方法，我们希望分析1)不同谱系的营养模式，2)性位点和潜在性染色体的进化，3)各自谱系和物种的效应池的进化，4)形态学特征，将这些数据整合到Ustilaginomycotina的基因组进化中。

Plant parasites constitute one of the largest ecological groups of fungi. The two major lineages that radiated once land plants were covering the planet, harbour several groups, which are exclusively plant parasitic. Although the Ascomycota and Basidiomycota evolved in direct interaction with their hosts, present data suggest, that the plant parasitic life-style has emerged several times. This is especially true, if we consider host-specific parasites like powdery mildews, rust or smut fungi. These host specific plant parasites are not only relevant as important drivers of evolution, but they represent also the largest threat to our major crop plants. E.g. all cereals are threatened by these three host specific fungal lineages and these fungi are responsible for a large economic loss each year.Major contributions have been made to the general understanding of virulence factors of Ustilaginomycotina. Ustilago maydis was the first fungal parasite, of which the genome has been fully sequenced. And in contrast to many other fungal plant parasites it can be easily grown in axenic conditions and is available for many genetic tools. The Ustilaginomycotina in total comprise more than 1700 species, most of which are highly host specific and in the meanwhile a few species have been studied in more detail. Comparative genomics and revers genetics have revealed, that so-called core effectors are important virulence factors being essential for the infection of the plant. However, the analyses of more distantly related species failed to identify factors relevant for host specificity. Therefore, we propose to use the order of Exobasidiales (Ustilaginomycotina) as a study case to identify and study factors relevant for host specificity. In contrast to the relatives of Ustilago maydis, the species of Exobasidium are very common and easy to find and isolated. A complementary sampling in China and Europe would allow to compare two lineages of closely related species. Thus, comparative genomics will go beyond the identification of core effectors, as more detailed analyses like studies of synteny, selection analyses or even transcriptomics will allow much more informative approaches. Therefore, based on 40-50 additional genomes, we will provide a phylogeny of the Exobasidiales to analyse trait evolution among and within the respective lineages. We would pay special attention to the analysis of the secretome, but we will include all informative aspects of the genomes. Additionally, we plan to use electron microscopy to study the ultrastructure of the interaction apparatus, as this might be an additional trait for host specificity. By applying these various approaches we want to analyse 1) the nutrition mode of various lineages, 2) the evolution of the sex-loci and potential sex chromosomes, 3) the evolution of effector pools of respective lineages and species, 4) morphological traits to integrate these data in the genome evolution in Ustilaginomycotina.