Gene Flow between Divergent Cereal- and Grass-Specific Lineages of the Rice Blast Fungus Magnaporthe oryzae.
Gene Flow between Divergent Cereal- and Grass-Specific Lineages of the Rice Blast Fungus Magnaporthe oryzae.
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DOI：
10.1128/mbio.01219-17
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发表时间：
2018-02-27
期刊：
影响因子：
6.4
通讯作者：
Fournier E
中科院分区：
文献类型：
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作者：
Gladieux P;Condon B;Ravel S;Soanes D;Maciel JLN;Nhani A Jr;Chen L;Terauchi R;Lebrun MH;Tharreau D;Mitchell T;Pedley KF;Valent B;Talbot NJ;Farman M;Fournier E
描绘真菌植物病原体的物种和流行谱系对于我们了解疾病的出现和真菌生物多样性的结构至关重要，也为国际监管决策提供信息。稻瘟病菌（同义词 Magnaporthe oryzae）是一种多宿主病原体，可感染多种草和谷物，是最具破坏性的水稻病害（稻瘟病）的罪魁祸首，并且由于最近从南美洲传入孟加拉国的麦瘟病而受到越来越多的关注。然而，米霉的遗传结构和进化历史，包括可能存在的神秘系统发育物种，仍然不清楚。在这里，我们使用从 12 个禾本科属和谷类属中采样的 76 个米霉分离株的全基因组序列信息来推断米霉的种群结构，并重新评估感染小麦的真菌种群的物种状态。基于家谱一致性的物种识别，使用已发表的数据或从基因组组装中提取以前使用的基因座，未能确认小麦瘟疫分离株先前归属于新物种（小麦瘟疫菌）。种群细分的推断揭示了米霉内部存在多个不同的谱系，每个谱系优先与一个宿主属相关，这表明宿主转移或宿主范围扩展后的早期物种形成。考虑到谱系分选不完整的可能性，对基因流的分析表明，基因交换有助于米霉内多个谱系的构成。这些发现使人们更好地了解米霉多样化背后的生态进化因素，并强调了基因组数据在这种重要的多宿主病原体流行病学监测中的实用性。新宿主的感染是病原微生物发生疾病的主要途径。因此，了解多宿主病原体的进化史对于更好地预测新疾病可能的传播和出现非常重要。稻瘟病是一种多宿主真菌，可引起严重的谷物病害，包括毁灭性的稻瘟病和麦瘟病，由于其最近从南美洲传播到亚洲而引起越来越多的关注。通过对来自不同宿主的 76 种真菌菌株进行全基因组分析，我们记录了米霉分化为多个谱系，每个谱系感染有限数量的宿主物种。我们的分析提供的证据表明，谱系间基因流对同一物种内多个米曲霉谱系的基因构成做出了贡献。因此，有必要进行植物健康监测，以防止多种真菌谱系相互接触的地区出现疾病。
Delineating species and epidemic lineages in fungal plant pathogens is critical to our understanding of disease emergence and the structure of fungal biodiversity and also informs international regulatory decisions. Pyricularia oryzae (syn. Magnaporthe oryzae) is a multihost pathogen that infects multiple grasses and cereals, is responsible for the most damaging rice disease (rice blast), and is of growing concern due to the recent introduction of wheat blast to Bangladesh from South America. However, the genetic structure and evolutionary history of M. oryzae, including the possible existence of cryptic phylogenetic species, remain poorly defined. Here, we use whole-genome sequence information for 76 M. oryzae isolates sampled from 12 grass and cereal genera to infer the population structure of M. oryzae and to reassess the species status of wheat-infecting populations of the fungus. Species recognition based on genealogical concordance, using published data or extracting previously used loci from genome assemblies, failed to confirm a prior assignment of wheat blast isolates to a new species (Pyricularia graminis-tritici). Inference of population subdivisions revealed multiple divergent lineages within M. oryzae, each preferentially associated with one host genus, suggesting incipient speciation following host shift or host range expansion. Analyses of gene flow, taking into account the possibility of incomplete lineage sorting, revealed that genetic exchanges have contributed to the makeup of multiple lineages within M. oryzae. These findings provide greater understanding of the ecoevolutionary factors that underlie the diversification of M. oryzae and highlight the practicality of genomic data for epidemiological surveillance in this important multihost pathogen. Infection of novel hosts is a major route for disease emergence by pathogenic microorganisms. Understanding the evolutionary history of multihost pathogens is therefore important to better predict the likely spread and emergence of new diseases. Magnaporthe oryzae is a multihost fungus that causes serious cereal diseases, including the devastating rice blast disease and wheat blast, a cause of growing concern due to its recent spread from South America to Asia. Using whole-genome analysis of 76 fungal strains from different hosts, we have documented the divergence of M. oryzae into numerous lineages, each infecting a limited number of host species. Our analyses provide evidence that interlineage gene flow has contributed to the genetic makeup of multiple M. oryzae lineages within the same species. Plant health surveillance is therefore warranted to safeguard against disease emergence in regions where multiple lineages of the fungus are in contact with one another.