Nature Communications (Sep 2023)

Dynamics of transposable element accumulation in the non-recombining regions of mating-type chromosomes in anther-smut fungi

  • Marine Duhamel,
  • Michael E. Hood,
  • Ricardo C. Rodríguez de la Vega,
  • Tatiana Giraud

DOI
https://doi.org/10.1038/s41467-023-41413-4
Journal volume & issue
Vol. 14, no. 1
pp. 1 – 18

Abstract

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Abstract In the absence of recombination, the number of transposable elements (TEs) increases due to less efficient selection, but the dynamics of such TE accumulations are not well characterized. Leveraging a dataset of 21 independent events of recombination cessation of different ages in mating-type chromosomes of Microbotryum fungi, we show that TEs rapidly accumulated in regions lacking recombination, but that TE content reached a plateau at ca. 50% of occupied base pairs by 1.5 million years following recombination suppression. The same TE superfamilies have expanded in independently evolved non-recombining regions, in particular rolling-circle replication elements (Helitrons). Long-terminal repeat (LTR) retrotransposons of the Copia and Ty3 superfamilies also expanded, through transposition bursts (distinguished from gene conversion based on LTR divergence), with both non-recombining regions and autosomes affected, suggesting that non-recombining regions constitute TE reservoirs. This study improves our knowledge of genome evolution by showing that TEs can accumulate through bursts, following non-linear decelerating dynamics.