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The evolution of inter-genomic variation in arbuscular mycorrhizal fungi.

机译：丛枝菌根真菌基因组间变异的演变。

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摘要

Background: Arbuscular mycorrhizal fungi (AMF) are root-inhabiting fungi whose hyphal networks form symbioses with plants. Previous studies have revealed extremely high levels of genetic variation for some loci, which has lead to the proposition that AMF contain thousands of genetically divergent nuclei that share the same cytoplasm, i.e. they are heterokaryotic coenocytes. No reproductive stage has as yet been observed in AMF, yet evidence is accumulating that the observed high levels of diversity could be maintained by the exchange of nuclei between hyphal systems and (meiotic) recombination. AMF spores contain varying fractions of this heterogeneous population of nuclei, which migrate directly from the parent mycelium. To our knowledge, AMF are the only organisms that never pass through a single nucleus stage in their life cycle, which allows nuclei to diverge into genetically distinct nuclei within the same cytoplasm. Thus, estimating genetic diversity in arbuscular mycorrhizal fungi (AMF) is a major challenge, not only for ecologists in the field but also for molecular biologists in the lab. It is unclear what the extent of polymorphism is in AMF genomes. The present thesis investigates different aspects of this peculiar genome organization.;Results: The second chapter in this thesis confirms the extensive intra-isolate polymorphism that was previously observed for large subunit rDNA (in G. irregulare DAOM-197198) and the polymerase1-like gene, PLS (in G. etunicatum), and shows that this polymorphism is transcribed. In the third chapter I report the presence of a bottleneck of genetic variation at sporulation for the PLS locus, in G. etunicatum. Analyses in the fourth chapter, based on a conservative network-based clustering approach and five novel single copy genomic markers, reveal extensive genome-wide patterns of diversity in two different AMF species (G. irregulare and G. diaphanum ).;Conclusions: The results from this thesis provide additional evidence in favor of genome differentiation between nuclei in the same isolate for AMF. Thus, at least three members of the Glomus genus, G. irregulare, G. diaphanum and G. etunicatum appear to be organisms whose genome organization cannot be described by a single genome sequence: genetically differentiated nuclei in AMF form a pangenome.;Keywords: Glomus, arbuscular mycorrhizal fungi, intra-organismal genetic heterogeneity, transcriptome variation, rDNA variation, nuclear variation, genetic bottleneck, heterokaryosis, anastomosis, polymerase1-like sequence.
机译：背景：丛枝菌根真菌（AMF）是根生真菌，其菌丝网络与植物共生。先前的研究已经揭示了某些基因座的遗传变异水平极高，这导致了这样的主张，即AMF包含成千上万个具有相同细胞质的遗传散布的核，即它们是异核共生细胞。在AMF中尚未观察到生殖阶段，但是越来越多的证据表明，观察到的高水平多样性可以通过菌丝系统之间的核交换和（减数分裂）重组来维持。 AMF孢子包含这种异质细胞核的不同部分，这些部分直接从母体菌丝体迁移。据我们所知，AMF是唯一在其生命周期中从未经过单个核阶段的生物，这使核能够在同一细胞质内分化成遗传上不同的核。因此，估计丛枝菌根真菌（AMF）的遗传多样性是一项重大挑战，这不仅对于该领域的生态学家而言，而且对于实验室中的分子生物学家而言都是如此。尚不清楚AMF基因组中多态性的程度。本论文研究了这种独特的基因组结构的不同方面。结果：本论文的第二章证实了以前在大亚基rDNA（在不规则G. DAOM-197198中）和聚合酶1样中观察到的广泛的分离内多态性。基因PLS（在G.etunicatum中），并表明该多态性已被转录。在第三章中，我报告了在牛毛草中PLS基因座形成孢子时存在遗传变异的瓶颈。第四章中的分析基于保守的基于网络的聚类方法和五个新颖的单拷贝基因组标记，揭示了两种不同AMF物种（G.normale和G.diaphanum）的广泛的全基因组多样性模式。该论文的结果为AMF同一分离株中的核之间的基因组分化提供了更多证据。因此，至少有3个Glomus属的成员，不规则G.，diaphanum和g。etunicatum似乎是其基因组组织无法用单一基因组序列描述的生物：AMF中的遗传分化核形成了一个泛基因组。 Glomus，丛枝菌根真菌，生物体内遗传异质性，转录组变异，rDNA变异，核变异，遗传瓶颈，异核，吻合，聚合酶1序列。

著录项

  • 作者

    Boon, Eva.;

  • 作者单位

    Universite de Montreal (Canada).;

  • 授予单位 Universite de Montreal (Canada).;
  • 学科 Biology Microbiology.;Biology Evolution and Development.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 180 p.
  • 总页数 180
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 肿瘤学;
  • 关键词

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