Plant Pathology, Institute of Integrative Biology, ETH Zürich, 8092 Zürich, Switzerland.
UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France.
Annu Rev Phytopathol. 2018 Aug 25;56:21-40. doi: 10.1146/annurev-phyto-080516-035303. Epub 2018 May 16.
Filamentous pathogens, including fungi and oomycetes, pose major threats to global food security. Crop pathogens cause damage by secreting effectors that manipulate the host to the pathogen's advantage. Genes encoding such effectors are among the most rapidly evolving genes in pathogen genomes. Here, we review how the major characteristics of the emergence, function, and regulation of effector genes are tightly linked to the genomic compartments where these genes are located in pathogen genomes. The presence of repetitive elements in these compartments is associated with elevated rates of point mutations and sequence rearrangements with a major impact on effector diversification. The expression of many effectors converges on an epigenetic control mediated by the presence of repetitive elements. Population genomics analyses showed that rapidly evolving pathogens show high rates of turnover at effector loci and display a mosaic in effector presence-absence polymorphism among strains. We conclude that effective pathogen containment strategies require a thorough understanding of the effector genome biology and the pathogen's potential for rapid adaptation.
丝状病原体，包括真菌和卵菌，对全球粮食安全构成重大威胁。作物病原体通过分泌效应子来损害宿主，从而使病原体受益。编码这些效应子的基因是病原体基因组中进化最快的基因之一。在这里，我们回顾了效应子基因的出现、功能和调控的主要特征如何与这些基因在病原体基因组中所处的基因组区室紧密联系在一起。这些区室中重复元件的存在与点突变和序列重排的频率升高有关，这对效应子多样化有重大影响。许多效应子的表达集中在由重复元件介导的表观遗传控制上。群体基因组学分析表明，快速进化的病原体在效应子基因座上表现出高的替换率，并在菌株间表现出效应子存在缺失多态性的镶嵌现象。我们的结论是，有效的病原体遏制策略需要对效应子基因组生物学和病原体的快速适应潜力有一个透彻的了解。
