Genome-Wide A-to-I RNA Editing During Sexual Reproduction in Filamentous Ascomycetes

Like plants, fungi lack the Adenosine Deaminase that Acts on RNA (ADAR) enzymes that are unique to animals for A-to-I mRNA editing. However, genome-wide RNA editing has been reported to occur specifically during sexual reproduction in a number of filamentous ascomycetes. Unlike ADAR-mediated editing, fungal editing events have a strong preference for U at the −1 position and hairpin loops. Furthermore, majority of editing events in fungi are in the open reading frame and nonsynonymous. For PUK1 and other 70 genes with premature stop codons, mRNA editing is essential for their functions in ascosporogenesis. For conserved nonsynonymous editing sites, editing provides heterozygous advantages with both edited and unedited transcripts. Furthermore, recent studies have showed that genome-wide mRNA editing is mediated by adenosine deaminases acting on tRNA (ADATs) and stage-specific cofactors during sexual reproduction in Fusarium graminearum.