How do plant pathogens adapt to novel host groups? Divergent genome evolution after a host jump in the plant parasitic oomycete Hyaloperonospora crispula and its sister species Hyaloperonospora arabidopsidis.

植物病原体如何适应新的宿主群体？

• 批准号: 270159645
• 负责人: Dr. Ronny Kellner
• 金额: --
• 依托单位: Max-Planck-Institut für Pflanzenzüchtungsforschung
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/270159645?language=en
• 关键词: How; do; plant; pathogens; adapt

Highly specialized plant-biotrophic microbes can infect non-host species at some frequency. Occasionally, this gives rise to adaptation and novel pathogen lineages. In many pathogen groups, including severe crop pathogens, specialization to distant host groups is frequent. Facing host jump-related risks for devastating pandemics we still lack profound knowledge of gateways and borders for host jumps and the following adaptive processes. The oomycete Hyaloperonospora crispula (Hpc) is an ideal candidate to analyze molecular mechanisms of adaptation to distant host groups. It is the only species in the Hyaloperonospora genus that adapted to non-crucifer hosts of the genus Reseda. I hypothesize that after the host jump, Hpc underwent fundamental changes in gene content and gene regulation and that these changes largely reflect adaptive traits towards the novel host group. During the proposed fellowship I aim to identify molecular requirements and consequences of host specificity of Hpc to this novel host group. I will analyze the genome and transcriptome of Hpc in comparison to its crucifer-infecting sister species H. arabidopsidis (Hpa), a well-established model parasite of the model plant Arabidopsis thaliana. Data of 5 distantly related Phytophthora species will serve as an outgroup. The genome of Hpc will be surveyed for gene gain and loss, gene family rise and fall, non-coding genomic features and signatures of selection. Besides the set of conserved virulence-related genes this approach will potentially disclose novel effector classes that represent promising candidate genes of host specialization. To analyze rates of polymorphisms and substitutions I will sample populations of Hpc on Reseda from East England. To further survey host plant-specific gene expression in Hpc, RNAseq will be performed on infected plant material using Illumina HiSeq2000. Finally, I will analyse ~10 host specialization candidate genes for their effect on virulence in A. thaliana versus R. luteola using the bacterial type-three secretion system of Pseudomonas syringae. This includes genes with accelerated evolutionary rates, absence/presence polymorphisms, differential transcription between host plants, and expanded/retracted gene families. In summary, this project aims to understand mechanisms of adaptive evolution that are involved in host specialization of a parasite following a host jump. It studies genomic, transcriptional and molecular features of the obligate biotrophic oomycete Hpc in comparison to its sister species Hpa. It establishes a wild type collection of Hpc populations. Thereby, it highlights fundamental insights into changes of genome structure and gene expression after adaption to a novel host group and could become a key resource for scientists to advance our plant defense strategies in agro-ecosystems. Finally, it will bring new tools and perspectives to the extensive immunity and pathology research taking place on the Hpa-Arabidopsis pathosystem.

高度专门化的植物生物营养微生物可以在一定频率上感染非寄主物种。偶尔，这会导致适应和新的病原体谱系。在许多病原菌群中，包括严重的作物病原菌，对远距离寄主群的专化性很常见。面对与宿主跳跃相关的破坏性大流行风险，我们仍然缺乏对宿主跳跃的网关和边界以及随后的适应性过程的深刻了解。皱纹卵菌(HPC)是分析远距离寄主适应分子机制的理想候选者。它是透明孢属中唯一适应于Reseda属的非十字花科寄主的物种。我推测，在寄主跳跃之后，HPC在基因含量和基因调控方面经历了根本的变化，这些变化在很大程度上反映了对新寄主群体的适应特性。在建议的研究期间，我的目标是确定HPC对这一新的宿主群的分子要求和宿主专一性的后果。我将分析HPC的基因组和转录组，并将其与其感染十字花科植物的姊妹种阿拉比多比迪斯(HPA)进行比较，HPA是模式植物拟南芥的模式寄生虫。近缘疫霉属5个种的数据将作为外类群。HPC的基因组将被调查基因的得失，基因家族的兴衰，非编码的基因组特征和选择的签名。除了一组保守的毒力相关基因外，这种方法还可能揭示代表寄主专化性的有希望的候选基因的新的效应器类别。为了分析多态和替换率，我将对来自英格兰东部的Reseda上的HPC种群进行采样。为了进一步研究寄主植物特异性基因在HPC中的表达，将使用Illumina HiSeq2000对受感染的植物材料进行RNAseq。最后，我将利用丁香假单胞菌的3型分泌系统，分析~10个寄主专化候选基因对海棠对黄曲霉致病力的影响。这包括进化速度加快的基因，缺失/存在多态，寄主植物之间的差异转录，以及扩大/收回的基因家族。综上所述，该项目旨在了解寄生虫在宿主跳跃后的宿主专门化所涉及的适应性进化机制。它研究了专性生物营养卵菌HPC与其姊妹种HPA的基因组、转录和分子特征。它建立了一个野生型的HPC种群集合。因此，它突出了对适应新宿主群后基因组结构和基因表达变化的基本见解，并可能成为科学家在农业生态系统中推进植物防御战略的关键资源。最后，它将为HPA-拟南芥病理系统的广泛免疫和病理学研究带来新的工具和前景。