Heterologous, splicing-dependent RNA editing in chloroplasts: allotetraploidy provides trans-factors

• Published in: The EMBO journal Vol. 20; no. 17; pp. 4874 - 4883
• Main Authors: Schmitz-Linneweber, Christian, Tillich, Michael, Herrmann, Reinhold G., Maier, Rainer M.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 03-09-2001; Blackwell Publishing Ltd; Oxford University Press
• Subjects: allotetraploidy; Base Sequence; Biolistics; chloroplast; Chloroplasts - genetics; Chloroplasts - metabolism; Chromosome Mapping; evolution; Exons; Introns; Molecular Sequence Data; NADH Dehydrogenase - genetics; ndhA gene; Nicotiana - enzymology; Nicotiana - genetics; Nicotiana sylvestris; Nicotiana tabacum; Nicotiana tomentosiformis; Plants, Toxic; Plastids - genetics; Polyploidy; RNA Editing; RNA Splicing; Sequence Alignment; Sequence Homology, Nucleic Acid; Speciation; Spinacea oleracea; Spinacia oleracea - enzymology; Spinacia oleracea - genetics
• ISSN: 0261-4189; 1460-2075; 1460-2075
• DOI: 10.1093/emboj/20.17.4874

RNA editing is unique among post‐transcriptional processes in plastids, as it exhibits extraordinary phylogenetic dynamics leading to species‐specific editing site patterns. The evolutionary loss of a site is considered to entail the loss of the corresponding nuclear‐encoded site‐specific factor, which prevents the editing of foreign, i.e. heterologous, sites. We investigated the editing of short ‘spliced’ and ‘unspliced’ ndhA gene fragments from spinach in Nicotiana tabacum (tobacco) in vivo using biolistic transformation. Surprisingly, it turned out that the spinach site is edited in the heterologous nuclear background. Furthermore, only exon–exon fusions were edited, whereas intron‐containing messages remained unprocessed. A homologue of the spinach site was found to be present and edited in Nicotiana tomentosiformis, representing the paternal parent, but absent from Nicotiana sylvestris, representing the maternal parent of tobacco. Our data show that: (i) the cis‐determinants for ndhA editing are split by an intron; (ii) the editing capacity cannot be deduced from editing sites; and (iii) allopolyploidization can increase the editing capacity, which implies that it can influence speciation processes in evolution.