Mitotic recombination between homologous chromosomes drives genomic diversity in diatoms

Bulankova, Petra, Sekulić, Mirna, Jallet, Denis, Nef, Charlotte, Van Oosterhout, Cock, Delmont, Tom O., Vercauteren, Ilse, Osuna-Cruz, Cristina Maria, Vancaester, Emmelien, Mock, Thomas, Sabbe, Koen, Daboussi, Fayza, Bowler, Chris, Vyverman, Wim, Vandepoele, Klaas and De Veylder, Lieven (2021) Mitotic recombination between homologous chromosomes drives genomic diversity in diatoms. Current Biology, 31 (15). 3221-3232.e9. ISSN 0960-9822

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Abstract

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.

Item Type: Article
Uncontrolled Keywords: copy number variation,diatom,genetic variability,haplotypes diversity,loss of heterozygosity,recombination,neuroscience(all),biochemistry, genetics and molecular biology(all),agricultural and biological sciences(all) ,/dk/atira/pure/subjectarea/asjc/2800
Faculty \ School: Faculty of Science > School of Environmental Sciences
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Depositing User: LivePure Connector
Date Deposited: 15 Jun 2021 00:08
Last Modified: 25 Aug 2021 09:52
URI: https://ueaeprints.uea.ac.uk/id/eprint/80271
DOI: 10.1016/j.cub.2021.05.013

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