Sequence and transcription analysis of mitochondrial plasmids isolated from cytoplasmic male-sterile lines of Vicia faba.

Three mitochondrial plasmids (1704, 1695 and 1478 bp) were isolated from sterile cytoplasms of Vicia faba L. and cloned into a bacterial plasmid vector. Their nucleotide sequence was found to be 99 to 100% homologous to their counterparts isolated from a fertile cytoplasm (J.A. Wahleithner and D.R. Wolstenholme, Curr Genet 12 (1987) 55-76). Several overlapping transcripts were localized in the region which is unique to each of the three plasmids. S1 nuclease mapping indicated for all of them several 3' termini but a unique 5' boundary which was located downstream of the consensus sequence CNTAAGTGANNNNNGAA also found at the transcript 5' boundary of other plant mitochondrial plasmids. Southern blot hybridization with nuclear DNA indicated the presence of nuclear sequences homologous to each plasmid.