Identification of a mitochondrial protein associated with cytoplasmic male sterility in petunia.

The petunia fused gene (pcf), which is associated with cytoplasmic male sterility (CMS), is composed of sequences derived from atp9, coxII, and an unidentified reading frame termed urfS. To determine whether the pcf gene is expressed at the protein level, we produced antibodies to synthetic peptides specified by the coxII and urfS portions of the pcf gene. Anti-COXII peptide antibodies recognized petunia COXII but no other mitochondrial proteins. Anti-URF-S peptide antibodies recognized a 20-kilodalton protein present in both cytoplasmic male sterile and fertile lines and a protein with an apparent molecular mass of 25 kilodaltons present only in cytoplasmic male sterile lines. The 25-kilodalton protein was found to be synthesized by isolated mitochondria and to fractionate into both the soluble and membrane portions of disrupted mitochondria, whereas the 20-kilodalton protein was found only in the membrane fraction. The abundance of the 25-kilodalton protein was much lower in fertile plants carrying the cytoplasmic male sterile cytoplasm and a single dominant nuclear fertility restorer gene, Rf. Thus, the pcf gene is correlated with cytoplasmic male sterility not only by its co-segregation with the phenotype in somatic hybrids, but also by the modification of its expression at the protein level through the action of a nuclear gene that confers fertility.     

Comparative analysis of mitochondrial genomes provides insights into the mechanisms underlying an S-type cytoplasmic male sterility (CMS) system in wheat (Triticum aestivum L.)

Functional & Integrative Genomics - Cytoplasmic male sterility (CMS) has been widely used in crop cross breeding. There has been much research on wheat CMS. However, the correlation between...     

High-rate spontaneous reversion to cytoplasmic male sterility in sugar beet: a characterization of the mitochondrial genomes

Summary Among the fertile sugar beet lines with nuclear sterility maintenance genes, rf, in a homozygous recessive state, sublines capable of reverting spontaneously at a high rate to sterility were identified. Of 24 related fertile sublines studied, 6 were found to spontaneously revert to sterility with a frequency of about 19%. Genetic analysis confirmed the cytoplasmic nature of spontaneously arising sterility. Reversion to sterility in these sublines was accompanied by alterations in the mitochondrial genome structure: loss of the autonomously replicating minicircle c (1.3 kb) and changes in the restriction patterns of high-molecular-weight mitochondrial DNA (mtDNA). Southern hybridixation analysis with cloned minicircle c as a probe revealed no integration of this DNA molecule into the main mitochondrial and nuclear genomes of the revertants. Comparative BamHI and EcoRI restriction analysis of the mtDNA from the sterile revertants and fertile parental subline showed that the spontaneous reversion is accompanied by extensive genomic rearrangement. Southern blot analysis with cloned -subunit of F₁-ATPase (atpA) and cytochrome c oxidase subunit II (COX II) genes as probes indicated that the changes in mtDNA accompanying spontaneous reversion to sterility involved these regions. The mitochondrial genomes of the spontaneous revertants and the sterile analogue were shown to be identical.     

Mitochondrial DNA modifications associated with cytoplasmic male sterility in rice

Summary Mitochondrial DNA was isolated from fertile and cytoplasmic male sterile lines of rice. Restriction analysis showed specific modifications in the male sterile cytoplasm. In addition to the major mitochondrial DNA, three small plasmid-like DNA molecules were detected by agarose gel electrophoresis in both cytoplasms. An additional molecule was specifically found in the sterile cytoplasm. These mitochondrial DNA modifications support the hypothesis of the mitochondrial inheritance of the cytoplasmic male sterility in rice.     

ORF355 confers enhanced salinity stress adaptability to S-type cytoplasmic male sterility maize by modulating the mitochondrial metabolic homeostasis

Moderate stimuli in mitochondria improve wideranging stress adaptability in animals, but whether mitochondria play similar roles in plants is largely unknown. Here, we report the enhanced stress adaptability of S-type cytoplasmic male sterility(CMS-S) maize and its association with mild expression of sterilizing gene ORF355. A CMS-S maize line exhibited superior growth potential and higher yield than those of the near-isogenic N-type line in saline fields. Moderate expression of ORF355 induced t...     

Molecular-genetic analysis of maize mitochondrion regions associated with cytoplasmic male sterility

Molecular-genetic polymorphism of 86 world and Ukrainian breeding maize lines with S-, C- and T-types of cytoplasmic male sterility (CMS) and with normal wild type mitochondrion has been researched via mitochondrion regions PCR-analysis. Molecular marker system allowed to detect and identify definite type of CMS within maize lines, as well as to differentiate lines with definite CMS type either from lines with another CMS type or from normal wild type cytoplasm lines.     

TheBrassica mitochondrial DNA plasmid and large RNAs are not exclusively associated with cytoplasmic male sterility

Summary More than 100 differentBrassica nucleo-cytoplasmic combinations were analysed for the presence or absence of the 11.3 kb mitochondrial plasmid. Contrary to some previous reports, no close association exists between the presence of the plasmid and cytoplasmic male sterility. Some novel abundant RNAs which copurified withBrassica mitochondria are described.     

A unique cytoplasmic male sterility (CMS) determinant is present in three Phaseolus species characterized by different mitochondrial genomes

Previous results have shown that cytoplasmic male sterility (CMS) in lines from Phaseolus coccineus and Phaseolus vulgaris contain the same CMS-specific sequence, raising the question of whether this sequence rearrangement arose before divergence of the two species or afterward with subsequent transfer by introgression. Hybridization patterns of total DNA from eight P. vulgaris lines with cytoplasm from P. coccineus and three P. vulgaris lines were examined in order to analyze the mitochondrial DNA (mtDNA) diversity within each species and to determine differences between CMS lines derived from the two species. Three restriction enzymes and 17 heterologous mtDNA sequences were used. The analysis of the different hybridization patterns revealed a considerable diversity in mtDNA organization particularly within P. coccineus. We obtained distinctive hybridization patterns for the five CMS lines tested. The resulting classification showed that mitochondrial genomes from P. coccineus CMS lines group with those of fertile P. coccineus but not with CMS lines from P. vulgaris. The groupings concur with the taxonomic classification of these lines. The results support the hypothesis of a single ancient origin of the CMS determinant and exclude the transfer of cytoplasm by introgression from P. vulgaris to P. coccineus and P. coccineus ssp polyanthus.     

Nucleoli and cytoplasmic male sterility

Summary The paper describes the relation of cytoplasmic male sterility and the differentiation of nucleoli. Defects in the formation of nucleoli of pollen grains of maize with cytoplasmic male sterility were observed whereas the nuclei of control, i.e. fertile maize contained always only a single nucleole. In the nuclei of sterile pollen grains nucleoli of various sizes and numbers are formed.With 8 Figures in the Text