Kellner Ronny, Bhattacharyya Amitava, Poppe Stephan, Hsu Tiffany Y, Brem Rachel B, Stukenbrock Eva H
Max Planck Institute for Terrestrial Microbiology, Max Planck Research Group, Fungal Biodiversity, Marburg, Germany
Max Planck Institute for Terrestrial Microbiology, Max Planck Research Group, Fungal Biodiversity, Marburg, Germany.
Genome Biol Evol. 2014 May 14;6(6):1353-65. doi: 10.1093/gbe/evu101.
Host specialization by pathogens requires a repertoire of virulence factors as well as fine-tuned regulation of gene expression. The fungal wheat pathogen Zymoseptoria tritici (synonym Mycosphaerella graminicola) is a powerful model system for the discovery of genetic elements that underlie virulence and host specialization. We transcriptionally profiled the early stages of Z. tritici infection of a compatible host (wheat) and a noncompatible host (Brachypodium distachyon). The results revealed infection regulatory programs common to both hosts and genes with striking wheat-specific expression, with many of the latter showing sequence signatures of positive selection along the Z. tritici lineage. Genes specifically regulated during infection of wheat populated two large clusters of coregulated genes that may represent candidate pathogenicity islands. On evolutionarily labile, repeat-rich accessory chromosomes (ACs), we identified hundreds of highly expressed genes with signatures of evolutionary constraint and putative biological function. Phylogenetic analyses suggested that gene duplication events on these ACs were rare and largely preceded the diversification of Zymoseptoria species. Together, our data highlight the likely relevance for fungal growth and virulence of hundreds of Z. tritici genes, deepening the annotation and functional inference of the genes of this model pathogen.
病原体的宿主特异性需要一系列毒力因子以及基因表达的精细调控。真菌小麦病原体小麦黄斑叶枯病菌（学名Zymoseptoria tritici，同义词为Mycosphaerella graminicola）是用于发现毒力和宿主特异性潜在遗传元件的强大模型系统。我们对小麦黄斑叶枯病菌在亲和宿主（小麦）和非亲和宿主（短柄草）上感染的早期阶段进行了转录谱分析。结果揭示了两个宿主共有的感染调控程序以及具有显著小麦特异性表达的基因，其中许多后者沿着小麦黄斑叶枯病菌谱系显示出正选择的序列特征。在小麦感染过程中特异性调控的基因聚集在两个共调控基因的大簇中，这可能代表候选致病岛。在进化上不稳定、富含重复序列的辅助染色体（ACs）上，我们鉴定出数百个具有进化限制特征和推定生物学功能的高表达基因。系统发育分析表明，这些ACs上的基因复制事件很少见，并且大多发生在小麦黄斑叶枯病菌物种分化之前。总之，我们的数据突出了数百个小麦黄斑叶枯病菌基因对真菌生长和毒力的潜在相关性，深化了对这种模式病原体基因的注释和功能推断。
