Tissue- and stage-specific RNA editing of rps14 transcripts in moss (Physcomitrella patens) chloroplasts

The C to U editing event that converts an ACG codon to an AUG translation initiation codon in the chloroplast rps14 transcript is unique to the moss Physcomitrella patens and has not been found in other species. The efficiency of RNA editing was 80 percnt; in the young protonemata and decreased to approximately 20 percnt; in old protonemata and fully developed leafy shoots. This indicates that RNA editing of this site is regulated in a tissue- and stage-specific manner. In this study, a novel C to U RNA editing site has been identified at the -1 position relative to the AUG. Because the editing site is localized in the mRNA 5′ untranslated region, it may affect the efficiency of rps14 mRNA translation.