Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland.
Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
mBio. 2020 Oct 6;11(5):e02343-20. doi: 10.1128/mBio.02343-20.
Dynamic changes in transcription profiles are key for the success of pathogens in colonizing their hosts. In many pathogens, genes associated with virulence, such as effector genes, are located in regions of the genome that are rich in transposable elements and heterochromatin. The contribution of chromatin modifications to gene expression in pathogens remains largely unknown. Using a combination of a reporter gene-based approach and chromatin immunoprecipitation, we show that the heterochromatic environment of effector genes in the fungal plant pathogen is a key regulator of their specific spatiotemporal expression patterns. Enrichment in trimethylated lysine 27 of histone H3 dictates the repression of effector genes in the absence of the host. Chromatin decondensation during host colonization, featuring a reduction in this repressive modification, indicates a major role for epigenetics in effector gene induction. Our results illustrate that chromatin modifications triggered during host colonization determine the specific expression profile of effector genes at the cellular level and, hence, provide new insights into the regulation of virulence in fungal plant pathogens. Fungal plant pathogens possess a large repertoire of genes encoding putative effectors, which are crucial for infection. Many of these genes are expressed at low levels in the absence of the host but are strongly induced at specific stages of the infection. The mechanisms underlying this transcriptional reprogramming remain largely unknown. We investigated the role of the genomic environment and associated chromatin modifications of effector genes in controlling their expression pattern in the fungal wheat pathogen Depending on their genomic location, effector genes are epigenetically repressed in the absence of the host and during the initial stages of infection. Derepression of effector genes occurs mainly during and after penetration of plant leaves and is associated with changes in histone modifications. Our work demonstrates the role of chromatin in shaping the expression of virulence components and, thereby, the interaction between fungal pathogens and their plant hosts.
转录谱的动态变化是病原体成功定殖宿主的关键。在许多病原体中，与毒力相关的基因，如效应基因，位于富含转座元件和异染色质的基因组区域。染色质修饰对病原体中基因表达的贡献在很大程度上仍是未知的。我们使用基于报告基因的方法和染色质免疫沉淀相结合的方法，证明了真菌植物病原体中效应基因的异染色质环境是其特定时空表达模式的关键调节剂。组蛋白 H3 赖氨酸 27 三甲基化的富集决定了在没有宿主的情况下效应基因的抑制。在宿主定殖过程中染色质解凝聚，这种抑制性修饰减少，表明表观遗传在效应基因诱导中起主要作用。我们的结果表明，宿主定殖过程中触发的染色质修饰决定了效应基因在细胞水平上的特定表达谱，从而为真菌植物病原体毒力的调控提供了新的见解。真菌植物病原体拥有大量编码假定效应物的基因，这些基因对于感染至关重要。许多这些基因在没有宿主的情况下表达水平较低，但在感染的特定阶段强烈诱导。这种转录重编程的机制在很大程度上仍是未知的。我们研究了效应基因的基因组环境和相关染色质修饰在控制其在真菌小麦病原体中的表达模式中的作用。根据它们的基因组位置，效应基因在没有宿主和感染的初始阶段在表观遗传上受到抑制。效应基因的去抑制主要发生在植物叶片穿透期间和之后，与组蛋白修饰的变化相关。我们的工作证明了染色质在塑造毒力成分表达方面的作用，从而塑造了真菌病原体与其植物宿主之间的相互作用。
