RNA editing in plants

Abstract

Higher plant mitochondrial RNAs undergo predetermined modifications which involve differences of splicing and trimming of the primary transcripts. These post‐transcriptional modifications are specific C‐to‐U changes occurring mostly in the coding regions of mRNAs without changing the reading frame. Editing of mRNAs can lead to the formation or initiation of stop codons. Plant mitochondrial proteins issued from edited mRNAs are more similar to non‐plant homologous proteins suggesting that this process is involved in the production of functional polypeptides. RNA editing in non‐coding regions are also observed and may represent a new mechanism for modulating gene expression. Three possible biochemical mechanisms can account for RNA editing in plant mitochondria: nucleotide replacement, base exchange and deamination. Although some evidence shows that RNA editing proceeds by a deamination mechanism, several questions remain to be solved: What are the signals recognised by the biochemical machinery for such a specific process? What are the reasons that make an additional process acquired by land plant mitochondria for faithful gene expression?