Mitotic recombination between homologous chromosomes drives genomic diversity in diatoms
2021
Bulankova, Petra | Sekulić, Mirna | Jallet, Denis | Nef, Charlotte | van Oosterhout, Cock | Delmont, Tom | Vercauteren, Ilse | Osuna-Cruz, Cristina Maria | Vancaester, Emmelien | Mock, Thomas | Sabbe, Koen | Daboussi, Fayza | Bowler, Chris | Vyverman, Wim | Vandepoele, Klaas | de Veylder, Lieven | Center for Plant Systems Biology (PSB Center) ; Vlaams Instituut voor Biotechnologie [Ghent, Belgique] (VIB) | Universiteit Gent = Ghent University = Université de Gand (UGENT) | Toulouse Biotechnology Institute (TBI) ; Institut National des Sciences Appliquées - Toulouse (INSA Toulouse) ; Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | Institut de biologie de l'ENS Paris (IBENS) ; Département de Biologie - ENS-PSL (IBENS) ; École normale supérieure - Paris (ENS-PSL) ; Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL) ; Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS) | University of East Anglia [Norwich] (UEA) | Global Oceans Systems Ecology & Evolution - Tara Oceans (GOSEE) ; Université de Perpignan Via Domitia (UPVD)-École Pratique des Hautes Études (EPHE) ; Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Aix Marseille Université (AMU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université d'Évry-Val-d'Essonne (UEVE)-Université de Toulon (UTLN)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche pour le Développement (IRD [Ile-de-France])-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay)-European Molecular Biology Laboratory (EMBL)-NANTES UNIVERSITÉ - École Centrale de Nantes (Nantes Univ - ECN) ; Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Université australe du Chili | Génomique métabolique (UMR 8030) ; Genoscope - Centre national de séquençage [Evry] (GENOSCOPE) ; Université Paris-Saclay-Direction de Recherche Fondamentale (CEA) (DRF (CEA)) ; Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Direction de Recherche Fondamentale (CEA) (DRF (CEA)) ; Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université d'Évry-Val-d'Essonne (UEVE)-Centre National de la Recherche Scientifique (CNRS) | The Wellcome Trust Sanger Institute [Cambridge] | Gordon and Betty Moore Foundation GBMF 4966 | Region Occitanie 15058490 | French National Research Agency (ANR) ANR-16-CE05-000601 | 3BCAR Carnot Institute | ANR-16-CE05-0006,SynDia,Conception d'une plateforme d'ingénierie génomique pour les microalgues(2016) | European Project: 835067,H2020-EU.1.1. - EXCELLENT SCIENCE - European Research Council (ERC),10.3030/835067,DIATOMIC(2019)
International audience
Show more [+] Less [-]English. Diatoms, an evolutionarily successful group of microalgae, display high levels of intraspecific genetic variability in natural populations. However, the contribution of various mechanisms generating such diversity is unknown. Here we estimated the genetic micro-diversity within a natural diatom population and mapped the genomic changes arising within clonally propagated diatom cell cultures. Through quantification of haplotype diversity by next-generation sequencing and amplicon re-sequencing of selected loci, we documented a rapid accumulation of multiple haplotypes accompanied by the appearance of novel protein variants in cell cultures initiated from a single founder cell. Comparison of the genomic changes between mother and daughter cells revealed copy number variation and copy-neutral loss of heterozygosity leading to the fixation of alleles within individual daughter cells. The loss of heterozygosity can be accomplished by recombination between homologous chromosomes. To test this hypothesis, we established an endogenous readout system and estimated that the frequency of interhomolog mitotic recombination was under standard growth conditions 4.2 events per 100 cell divisions. This frequency is increased under environmental stress conditions, including treatment with hydrogen peroxide and cadmium. These data demonstrate that copy number variation and mitotic recombination between homologous chromosomes underlie clonal variability in diatom populations. We discuss the potential adaptive evolutionary benefits of the plastic response in the interhomolog mitotic recombination rate, and we propose that this may have contributed to the ecological success of diatoms.
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