Chloroplast C-to-U RNA editing in vascular plants is adaptive due to its restorative effect: testing the restorative hypothesis

C-to-U RNA editing restores canonical start codon AUG. (A) Barplot showing the fraction of C-to-U editing on start codon or other codons. P-value was calculated by Fisher's exact test. (***) P < 0.001. (B) Heatmap showing the presence or absence of C-to-U editing on start codons. Each column is an orthologous gene across 21 species. (C) C-to-U editing restores start codon AUG in two fern species, whereas in other species the DNA encodes ATG. (D) Explanation for the prevalence of restorative C-to-U editing in start codons. PPR proteins are responsible for both RNA splicing and editing.