BACKGROUND: Silene vulgaris (bladder campion) is a gynodioecious species existing as two genders - male-sterile females and hermaphrodites. Cytoplasmic male sterility (CMS) is generally encoded by mitochondrial genes, which interact with nuclear fertility restorer genes. Mitochondrial genomes of this species vary in DNA sequence, gene order and gene content. Multiple CMS genes are expected to exist in S. vulgaris, but little is known about their molecular identity. RESULTS: We assembled the complete mitochondrial genome from the haplotype KRA of S. vulgaris. It consists of five chromosomes, two of which recombine with each other. Two small non-recombining chromosomes exist in linear, supercoiled and relaxed circle forms. We compared the mitochondrial transcriptomes from females and hermaphrodites and confirmed the differentially expressed chimeric gene bobt as the strongest CMS candidate gene in S. vulgaris KRA. The chimeric gene bobt is co-transcribed with the Cytochrome b (cob) gene in some genomic configurations. The co-transcription of a CMS factor with an essential gene may constrain transcription inhibition as a mechanism for fertility restoration because of the need to maintain appropriate production of the necessary protein. Homologous recombination places the gene cob outside the control of bobt, which allows for the suppression of the CMS gene by the fertility restorer genes. We found the loss of three editing sites in the KRA mitochondrial genome and identified four sites with highly distinct editing rates between KRA and another S. vulgaris haplotypes (KOV). Three of these highly differentially edited sites were located in the transport membrane protein B (mttB) gene. They resulted in differences in MttB protein sequences between haplotypes. CONCLUSIONS: Frequent homologous recombination events that are widespread in plant mitochondrial genomes may change chromosomal configurations and also the control of gene transcription including CMS gene expression. Posttranscriptional processes, e.g. RNA editing shall be evaluated in evolutionary and co-evolutionary studies of mitochondrial genes, because they may change protein composition despite the sequence identity of the respective genes. The investigation of natural populations of wild species such as S. vulgaris are necessary to reveal important aspects of CMS missed in domesticated crops, the traditional focus of the CMS studies.

• MeSH
• cytochromy b genetika   metabolismus   MeSH
• editace RNA MeSH
• genom mitochondriální * MeSH
• haplotypy MeSH
• homologní rekombinace * MeSH
• membránové glykoproteiny genetika   MeSH
• mitochondriální protonové ATPasy genetika   MeSH
• mitochondrie genetika   MeSH
• neplodnost rostlin genetika   MeSH
• otevřené čtecí rámce genetika   MeSH
• rostlinné proteiny genetika   MeSH
• Silene genetika   MeSH
• transkriptom MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cytochromy b MeSH
• membránové glykoproteiny MeSH
• mitochondriální protonové ATPasy MeSH
• rostlinné proteiny MeSH

The interactions between mitochondria and nucleus substantially influence plant development, stress response and morphological features. The prominent example of a mitochondrial-nuclear interaction is cytoplasmic male sterility (CMS), when plants produce aborted anthers or inviable pollen. The genes responsible for CMS are located in mitochondrial genome, but their expression is controlled by nuclear genes, called fertility restorers. Recent explosion of high-throughput sequencing methods enabled to study transcriptomic alterations in the level of non-coding RNAs under CMS biogenesis. We summarize current knowledge of the role of nucleus encoded regulatory non-coding RNAs (long non-coding RNA, microRNA as well as small interfering RNA) in CMS. We also focus on the emerging data of non-coding RNAs encoded by mitochondrial genome and their possible involvement in mitochondrial-nuclear interactions and CMS development.

• Klíčová slova
• cytoplasmic male sterility, gene expression, global transcriptome, non-coding RNA, pollen development,
• MeSH
• autoinkompatibilita krytosemenných rostlin genetika   MeSH
• Magnoliopsida fyziologie   MeSH
• mitochondriální geny MeSH
• nekódující RNA genetika   metabolismus   MeSH
• neplodnost rostlin genetika   MeSH
• pyl genetika   fyziologie   MeSH
• rostlinné geny MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• nekódující RNA MeSH

Cytoplasmic male sterility (CMS) is a widespread phenomenon in flowering plants caused by mitochondrial (mt) genes. CMS genes typically encode novel proteins that interfere with mt functions and can be silenced by nuclear fertility-restorer genes. Although the molecular basis of CMS is well established in a number of crop systems, our understanding of it in natural populations is far more limited. To identify CMS genes in a gynodioecious plant, Silene vulgaris, we constructed mt transcriptomes and compared transcript levels and RNA editing patterns in floral bud tissue from female and hermaphrodite full siblings. The transcriptomes from female and hermaphrodite individuals were very similar overall with respect to variation in levels of transcript abundance across the genome, the extent of RNA editing, and the order in which RNA editing and intron splicing events occurred. We found only a single genomic region that was highly overexpressed and differentially edited in females relative to hermaphrodites. This region is not located near any other transcribed elements and lacks an open-reading frame (ORF) of even moderate size. To our knowledge, this transcript would represent the first non-coding mt RNA associated with CMS in plants and is, therefore, an important target for future functional validation studies.

• Klíčová slova
• Cytoplasmic male sterility, Silene vulgaris, editing, mitochondrion, non-coding RNA, splicing, transcriptome.,
• MeSH
• editace RNA MeSH
• květy genetika   růst a vývoj   MeSH
• mitochondriální geny * MeSH
• nekódující RNA * MeSH
• neplodnost rostlin * MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• Silene genetika   fyziologie   MeSH
• transkriptom * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• nekódující RNA * MeSH
• rostlinné proteiny MeSH

Chimeric genes are significant sources of evolutionary innovation that are normally created when portions of two or more protein coding regions fuse to form a new open reading frame. In plant mitochondria astonishingly high numbers of different novel chimeric genes have been reported, where they are generated through processes of rearrangement and recombination. Nonetheless, because most studies do not find or report nucleotide variation within the same chimeric gene, evolution after the origination of these chimeric genes remains unstudied. Here we identify two alleles of a complex chimera in Silene vulgaris that are divergent in nucleotide sequence, genomic position relative to other mitochondrial genes, and expression patterns. Structural patterns suggest a history partially influenced by gene conversion between the chimeric gene and functional copies of subunit 1 of the mitochondrial ATP synthase gene (atp1). We identified small repeat structures within the chimeras that are likely recombination sites allowing generation of the chimera. These results establish the potential for chimeric gene divergence in different plant mitochondrial lineages within the same species. This result contrasts with the absence of diversity within mitochondrial chimeras found in crop species.

• MeSH
• alely MeSH
• DNA primery genetika   MeSH
• druhová specificita MeSH
• fylogeneze MeSH
• genetická transkripce MeSH
• genetická variace MeSH
• genom rostlinný MeSH
• kodon MeSH
• křížení genetické MeSH
• messenger RNA metabolismus   MeSH
• mitochondriální geny * MeSH
• modely genetické MeSH
• molekulární evoluce MeSH
• mozaicismus MeSH
• polymerázová řetězová reakce MeSH
• pravděpodobnostní funkce MeSH
• proteiny huseníčku genetika   MeSH
• protonové ATPasy genetika   MeSH
• regulace genové exprese MeSH
• rekombinace genetická MeSH
• rostlinné geny MeSH
• Silene genetika   MeSH
• Southernův blotting MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• ATP1 protein, Arabidopsis MeSH Prohlížeč
• DNA primery MeSH
• kodon MeSH
• messenger RNA MeSH
• proteiny huseníčku MeSH
• protonové ATPasy MeSH