RNA editing in higher plant plastids: oligoribonucleotide SSCP analysis allows the proof of base conversion directly at the RNA level

Plastid RNA editing of a number of transcripts at specific sites changes ge nomically encoded cytidines to nucleosides, which act like uridines in RT-P CR analyses. To study plastid-editing directly at the RNA level, we establi shed a single-strand conformational polymorphism, assay for the discriminat ion of small RNA molecules. The electrophoretic mobility of a oligoribonucl eotide resulting from a RNase TI-digested and edited plastid mRNA was shown to be identical with a control RNA molecule containing a uridine at the ed iting, site, whereas the unedited RNA behaved like a RNA molecule containin g a cytidine at the respective position.