Deciphering Genome Content and Evolutionary Relationships of Isolates from the Fungus Magnaporthe oryzae Attacking Different Host Plants.
Deciphering Genome Content and Evolutionary Relationships of Isolates from the Fungus Magnaporthe oryzae Attacking Different Host Plants.
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DOI：
10.1093/gbe/evv187
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发表时间：
2015-10-09
影响因子：
3.3
通讯作者：
Fournier E
中科院分区：
文献类型：
--
作者：
Chiapello H;Mallet L;Guérin C;Aguileta G;Amselem J;Kroj T;Ortega-Abboud E;Lebrun MH;Henrissat B;Gendrault A;Rodolphe F;Tharreau D;Fournier E
破译病原体适应宿主的遗传基础是生态学和进化中的一个关键问题。为了了解真菌稻瘟病菌如何适应不同的植物，我们对宿主特异性不同（水稻、谷子、小麦和牛草）的八种米瘟菌分离株和一种马唐特异性的稻瘟病菌菌株进行了测序。 Magnaporthe 基因组分析显示，分离株之间的基因组大小 (39–43 Mb) 和基因内容（12,283–14,781 个基因）存在微小差异。整套 Magnaporthe 基因由 14,966 个共享家族组成，其中 63% 包含所有九个米霉基因组中存在的基因。使用 6,878 个单拷贝直向同源物推断 Magnaporthe 分离株之间的进化关系。由此产生的谱系主要在不同的宿主特异性谱系之间分裂，但在水稻谱系内部呈网状。我们在水稻参考 70-15 基因组中检测到非水稻基因组渗入的痕迹。在米霉分离株和宿主特异性谱系中，就推定涉及致病性的基因（效应子、次生代谢、cazome）频率而言，基因组组成是保守的。然而，仅在非水稻谱系中发现了 529 个共享家族，而水稻谱系则拥有非水稻基因组中不存在的 86 个特定家族。我们的结果证实，米霉分离株的宿主特异性与没有主要基因流的谱系之间的分歧有关，并且尽管谱系之间的基因家族具有很强的保守性，但对不同宿主（尤其是水稻）的适应与少数特定基因家族的存在有关。所有信息均收集在公共数据库中（http://genome.jouy.inra.fr/gemo）。
Deciphering the genetic bases of pathogen adaptation to its host is a key question in ecology and evolution. To understand how the fungus Magnaporthe oryzae adapts to different plants, we sequenced eight M. oryzae isolates differing in host specificity (rice, foxtail millet, wheat, and goosegrass), and one Magnaporthe grisea isolate specific of crabgrass. Analysis of Magnaporthe genomes revealed small variation in genome sizes (39–43 Mb) and gene content (12,283–14,781 genes) between isolates. The whole set of Magnaporthe genes comprised 14,966 shared families, 63% of which included genes present in all the nine M. oryzae genomes. The evolutionary relationships among Magnaporthe isolates were inferred using 6,878 single-copy orthologs. The resulting genealogy was mostly bifurcating among the different host-specific lineages, but was reticulate inside the rice lineage. We detected traces of introgression from a nonrice genome in the rice reference 70-15 genome. Among M. oryzae isolates and host-specific lineages, the genome composition in terms of frequencies of genes putatively involved in pathogenicity (effectors, secondary metabolism, cazome) was conserved. However, 529 shared families were found only in nonrice lineages, whereas the rice lineage possessed 86 specific families absent from the nonrice genomes. Our results confirmed that the host specificity of M. oryzae isolates was associated with a divergence between lineages without major gene flow and that, despite the strong conservation of gene families between lineages, adaptation to different hosts, especially to rice, was associated with the presence of a small number of specific gene families. All information was gathered in a public database (http://genome.jouy.inra.fr/gemo).