Thomas Badet

@tbadet.bsky.social

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Junior researcher at the university of Neuchâtel - fungi enthousiast

Evolution of major eukaryotic genome defense systems. The figure is organized along two axes representing core mechanistic features (homology recognition, small interfering RNA, and heterochromatin assembly) and their lineage-specific elaborations. We hypothesize that a recombination-independent DNA homology recognition system present in the eukaryotic common ancestor facilitated the emergence of both heterochromatin assembly and small RNA-based repeat silencing. From this conserved ancestral core, lineage-specific gene neofunctionalizations gave rise to distinct defense pathways: the RdDM pathway in plants; the piRNA and KRAB–ZFP pathways in vertebrates; and the repeat-induced point mutation (RIP), methylation induced premeiotically (MIP), MSUD, and tandem repeat-induced sexual silencing (TRISS) systems in filamentous ascomycete fungi. Question marks indicate steps for which the molecular mechanisms remain unknown.