Homologous recombination involving cox2 is responsible for a mutation in the cmS-specific mitochondrial locus of Petunia.
We have characterized the only mutation detected so far in S-Pcf, the mitochondrial cytoplasmic male sterility (CMS)-specific locus of petunia. This locus consists of three open reading frames (ORFs): the first contains part of atp9, an intron-less cox2 pseudogene (which does not contain the original cox2 ATG) and the unidentified reading frame urf-s; the second and third ORFs correspond to the only copies of nad3 and rps12 genes in the genome, respectively. In the cell line R13-138, which was generated from a male-sterile somatic hybrid (line SH13-138), a change in the first ORF of the S-Pcf locus has been characterized: the atp9 sequence has been lost, while exonl of the normal copy of the cox2 gene (including the original ATG sequence) and the adjacent 5' sequence of the petunia recombination repeat, have been introduced. The data suggest that this reorganization of mtDNA is the consequence of a homologous recombination event involving part of the cox2 coding region, and that the cox2 coding region may serve as an active site for inter- or intra-mtDNA homologous recombination. The results further suggest that in line SH13-138 (or during its maintenance in tissue culture), segregation of the S-Pcf-containing mtDNA molecules has occurred, and the mutant mtDNA is now predominant in the population.
Yesodi
V
V
Department of Plant Genetics, Volcani Center, Bet Dagan, Israel.
Izhar
S
S
Hauschner
H
H
Tabib
Y
Y
Firon
N
N
D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins; D001483:Base Sequence; D002460:Cell Line; D004272:DNA, Mitochondrial / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000235:genetics*; D017343:Genes, Plant; D006822:Hybrid Cells; D008928:Mitochondria / Q000235:genetics; D025261:Mitochondrial Proton-Translocating ATPases; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D018521:Plant Physiological Phenomena; D010940:Plant Proteins; D010944:Plants / Q000201:enzymology / Q000235:genetics*; D011510:Proteolipids / Q000235:genetics; D006180:Proton-Translocating ATPases / Q000235:genetics; D011544:Pseudogenes; D011995:Recombination, Genetic
C063668:ATP9 protein, Arabidopsis; D029681:Arabidopsis Proteins; D004272:DNA, Mitochondrial; D010940:Plant Proteins; D011510:Proteolipids; D003576:Electron Transport Complex IV; D025261:Mitochondrial Proton-Translocating ATPases; D006180:Proton-Translocating ATPases