TRANSCRIPTION OF PLASTID DERIVED TRANSFER-RNA GENES IN RICE MITOCHONDRIA

Previous investigations located nine of the genes for rice tRNAs on pl astid (pt)-derived sequences in mitochondrial DNA. In the present stud y, we examined whether these genes were also transcribed in rice mitoc hondria. Northern-blot hybridization revealed that seven of these gene s (trnC, trnF, trnH, trnM, trnN, trnS and trnW) are transcribed and an precisely processed to mature tRNAs. One of the other two genes (trnP ) is transcribed but cannot be processed efficiently, while the other (trnR), which has 100% identity to the original plastid tRNA(Arg) gene , is not transcribed in rice mitochondria. These results suggest that seven of the nine pt-derived tRNAs may be utilized for the biosynthesi s of protein in plant mitochondria.