title: The nucleotide sequence and transcription of minicircular mitochondrial DNA's associated with male-fertile and cytoplasmic male-sterile lines of sugarbeet.
abstract: Male-fertile (MF) and cytoplasmic male-sterile (CMS) lines of sugarbeet possess characteristic low molecular weight minicircular mitochondrial DNA's, and Southern hybridizations revealed sequence homologies between them. The complete nucleotide sequences of minicircle a present in MF and CMS lines, and minicircle d present in some MF lines have been determined and compared to minicircle c present in all MF lines. Computer analysis revealed sequences common to all three DNA's: these may be essential to their maintenance in sugarbeet mitochondria. Analysis of the extent and arrangement of homologous sequences in minicircle a and minicircle d suggests the latter may have arisen from an intramolecular recombination event in minicircle a. The G+C contents of the minicircles differ and their possible origins are discussed. All three DNA's are transcribed. Minicircle c and minicircle d transcripts are exclusive to MF mitochondria, but are unlikely to encode protein products. Two transcripts of sufficient size and the predicted polarity to encompass a short open reading frame on minicircle a are common to both MF and CMS mitochondria.
mesh_terms: D001482:Base Composition; D001483:Base Sequence; D003001:Cloning, Molecular; D004270:DNA, Circular / Q000032:analysis* / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000032:analysis* / Q000378:metabolism; D010944:Plants / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
chemical_list: D004270:DNA, Circular; D004272:DNA, Mitochondrial