Fig. 1.

A-to-I mRNA editing expands proteome complexity to drive fungal development and provide an adaptive advantage. (A) Sordariomycete fungi grow vegetatively as mycelia or differentiate to produce multicellular structures during sexual development (protoperithecia and perithecia). A-to-I mRNA editing operates exclusively during sexual development. (B) Genetic studies of two conserved missense editing (CME) genes in F. graminearum demonstrate that A-to-I editing provides an adaptive advantage. Recoding of CME5 mRNA by A-to-I editing replaces the ancestral, genome-encoded arginine (R) with a glycine (G) to generate a stage-specific protein variant required for normal development of perithecia. In addition, expression of both edited and unedited CME11 transcripts is required for normal perithecial development, suggesting that editing confers a heterozygous advantage.