Cytoplasmic male sterility (CMS), encoded by the interacting mitochondrial and nuclear genes, causes pollen abortion or non-viability. CMS is widely used in agriculture and extensively studied in crops. Much less is known about CMS in wild species. We performed a comparative transcriptomic analysis of male sterile and fertile individuals of Silene vulgaris, a model plant for the study of gynodioecy, to reveal the genes responsible for pollen abortion in this species. We used RNA-seq datasets previously employed for the analysis of mitochondrial and plastid transcriptomes of female and hermaphrodite flower buds, making it possible to compare the transcriptomes derived from three genomes in the same RNA specimen. We assembled de novo transcriptomes for two haplotypes of S. vulgaris and identified differentially expressed genes between the females and hermaphrodites, associated with stress response or pollen development. The gene for alternative oxidase was downregulated in females. The genetic pathways controlling CMS in S. vulgaris are similar to those in crops. The high number of the differentially expressed nuclear genes contrasts with the uniformity of organellar transcriptomes across genders, which suggests these pathways are evolutionarily conserved and that selective mechanisms may shield organellar transcription against changes in the cytoplasmic transcriptome.

• Klíčová slova
• Silene vulgaris, cytoplasmic male sterility, differential gene expression,
• MeSH
• anotace sekvence MeSH
• buněčné jádro genetika   MeSH
• down regulace genetika   MeSH
• genová ontologie MeSH
• haplotypy genetika   MeSH
• messenger RNA genetika   metabolismus   MeSH
• mitochondriální proteiny genetika   metabolismus   MeSH
• neplodnost rostlin genetika   MeSH
• oxidační stres genetika   MeSH
• oxidoreduktasy genetika   metabolismus   MeSH
• pyl genetika   MeSH
• regulace genové exprese u rostlin * MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• Silene genetika   fyziologie   MeSH
• stanovení celkové genové exprese * MeSH
• transkriptom genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alternative oxidase MeSH Prohlížeč
• messenger RNA MeSH
• mitochondriální proteiny MeSH
• oxidoreduktasy MeSH
• rostlinné proteiny MeSH

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