title: Identification of a novel mitochondrial genome type and development of molecular markers for cytoplasm classification in radish (Raphanus sativus L.).
abstract: Plant mitochondrial genomes have complex configurations resulting from the multipartite structures and highly rearranged substoichiometric molecules created by repetitive sequences. To expedite the reliable classification of the diverse radish (Raphanus sativus L.) cytoplasmic types, we have developed consistent molecular markers within their complex mitochondrial genomes. orf138, a gene responsible for Ogura male-sterility, was detected in normal cultivars in the form of low-copy-number substoichiometric molecules. In addition to the dominant orf138-atp8 Ogura mitochondrial DNA (mtDNA) organization, three novel substoichiometric organizations linked to the atp8 gene were identified in this study. PCR amplification profiles of seven atp8- and atp6-linked sequences were divided into three groups. Interestingly, the normal cytoplasm type, which had previously been considered a single group, showed two patterns by PCR amplification. The most prominent difference between the two normal mtDNAs was size variation within four short-repeat sequences linked to the atp6 gene. This variation appeared to be the result of a double crossover, mediated by these homologous, short-repeat sequences. Specific PCR amplification profiles reflecting the stoichiometry of different mtDNA fragments were conserved within cultivars and across generations. Therefore, the specific sequences detected in these profiles were used as molecular markers for the classification of diverse radish germplasm. Using this classification system, a total of 90 radish cultivars, or accessions, were successfully assigned to three different mitotypes.
authors.affiliation: Biotech Research Center, Dongbu Advanced Research Institute, Dongbu HiTek Co., Ltd, Daejeon 305-708, South Korea.
authors.forename: Sunggil
authors.initials: S
authors.lastname: Kim
authors.forename: Heerae
authors.initials: H
authors.lastname: Lim
authors.forename: Suhyung
authors.initials: S
authors.lastname: Park
authors.forename: Kang-Hee
authors.initials: KH
authors.lastname: Cho
authors.forename: Soon-Kee
authors.initials: SK
authors.lastname: Sung
authors.forename: Dae-Geun
authors.initials: DG
authors.lastname: Oh
authors.forename: Ki-Taek
authors.initials: KT
authors.lastname: Kim
mesh_terms: D001483:Base Sequence; D003593:Cytoplasm / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics; D015321:Gene Rearrangement; D005819:Genetic Markers; D054629:Genome, Mitochondrial; D024101:Mitochondrial Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics; D031224:Raphanus / Q000145:classification* / Q000235:genetics*