THE WHEAT MITOCHONDRIAL RPS13 GENE - RNA EDITING AND CO-TRANSCRIPTIONWITH THE ATP6 GENE

Northern analyses and reverse transcription-polymerase chain-reaction (RT-PCR) experiments, followed by PCR amplification product sequencing , were performed on total mitochondrial (mt) RNAs from wheat seedlings and tissue cultures. It was shown that the rps13 gene, which encodes ribosomal protein S13, and the atp6 gene, which encodes subunit 6 of t he ATP synthase complex, were co-transcribed. However, rps13 transcrip ts were virtually undetectable in seedlings under conditions where atp 6 transcripts appeared abundant. In addition, markedly higher steady s tate transcript levels were observed in tissue culture. Expression of the mitochondrial rps13 gene was confirmed by showing that its transcr ipts were edited. Slight differences between editing patterns of tissu e-culture and whole-plant transcripts were found. Taken together, thes e results suggest that in vitro culture could disturb the post-transcr iptional regulation of gene expression.