Organization of mitochondrial DNA in normal and texas male sterile cytoplasms of maize

Homology between mitochondrial DNA of Agaricus bisporus and an internal portion of a linear mitochondrial plasmid of Agaricus bitorquis

Agaricus bisporus, the cultivated mushroom, contains a mitochondrial fragment (50H) which was previously demonstrated by Southern hybridization to have sequence similarity to an internal region of pEM, a linear mitochondrial plasmid of Agaricus bitorquis. The nucleotide sequence of 50H was determined and compared to the sequence of the corresponding pEM fragment. The region of sequence homology on pEM is contained within an open reading frame (ORF) that may encode an RNA polymerase, but 50H is neither an intact nor a complete copy of the ORF. pEM also contains an ORF with characteristics of genes for virus-encoded DNA polymerases. pEM appears to be very similar to other linear mitochondrial plasmids (in fungi and higher plants) reported to contain ORFs that may encode the same types of polymerases. The potential functionality of the pEM sequence suggests that it has diverged less than the mitochondrial fragment from a common ancestor.

Intraspecific diversity of sugar beet (Beta vulgaris) mitochondrial DNA

Mitochondrial (mt) DNA, isolated from different sugar beet populations, was analyzed using BamHI and EcoRI restriction enzymes. It was shown that plants possessing the new mtDNA types are revealed among O-type fertilizers quite frequently. Among cytoplasmic male sterile (cms) plants, which evolved during cultivation of O-type fertilizers, plants with altered mt genome were found.

Characterization of inverted repeats from plasmid-like DNAs and the maize mitochondrial genome

Integrated inverted repeat (IR) sequences similar to those of the S plasmids have been isolated from the genomes of the normal and S type male-sterile cytoplasms of maize mitochondria. The nucleotide sequences of both the IRs and their flanking regions have distinguished and characterized several different types of repeats. The repeats may be involved in the recombinational process that occurs continuously in the mitochondrial genome. One cloned fragment, derived from a fertile revertant and containing sequences similar to S-2, does not appear to act as a typical transposable element during reversion. Several of the flanking regions examined contain a small repeat of 34 base pairs, in which a nonanucleotide segment is found with similarity to the yeast mitochondrial promoter.