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Mandáková T, Krumpolcová A, Matyášek R, Volkov R, Lysak MA, Kovařík A. Uniparental silencing of 5S rRNA genes in plant allopolyploids - insights from Cardamine (Brassicaceae). THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024. [PMID: 38838061 DOI: 10.1111/tpj.16850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 04/30/2024] [Accepted: 05/14/2024] [Indexed: 06/07/2024]
Abstract
While the phenomenon of uniparental silencing of 35S rDNA in interspecific hybrids and allopolyploids is well documented, there is a notable absence of information regarding whether such silencing extends to the 5S RNA component of ribosomes. To address this gap in knowledge, we analyzed the 5S and 35S rDNA expression in Cardamine (Brassicaceae) allopolyploids, namely C. × insueta (2n = 3x = 24, genome composition RRA), C. flexuosa (2n = 4x = 32, AAHH), and C. scutata (2n = 4x = 32, PPAA) which share a common diploid ancestor (AA). We employed high-throughput sequencing of transcriptomes and genomes and phylogenetic analyses of 5S rRNA variants. The genomic organization of rDNA was further scrutinized through clustering and fluorescence in situ hybridization. In the C. × insueta allotriploid, we observed uniparental dominant expression of 5S and 35S rDNA loci. In the C. flexuosa and C. scutata allotetraploids, the expression pattern differed, with the 35S rDNA being expressed from the A subgenome, whereas the 5S rDNA was expressed from the partner subgenome. Both C. flexuosa and C. scutata but not C. × insueta showed copy and locus number changes. We conclude that in stabilized allopolyploids, transcription of ribosomal RNA components occurs from different subgenomes. This phenomenon appears to result in the formation of chimeric ribosomes comprising rRNA molecules derived from distinct parental origins. We speculate that the interplay of epigenetic silencing and rDNA rearrangements introduces an additional layer of variation in multimolecule ribosomal complexes, potentially contributing to the evolutionary success of allopolyploids.
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Affiliation(s)
- Terezie Mandáková
- Central European Institute of Technology (CEITEC), Masaryk University, 625 00, Brno, Czech Republic
- Department of Experimental Biology, Faculty of Science, Masaryk University, 611 37, Brno, Czech Republic
| | - Alice Krumpolcová
- Department of Experimental Biology, Faculty of Science, Masaryk University, 611 37, Brno, Czech Republic
- Department of Molecular Epigenetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, 612 00, Brno, Czech Republic
| | - Roman Matyášek
- Department of Molecular Epigenetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, 612 00, Brno, Czech Republic
| | - Roman Volkov
- Department of Molecular Genetics and Biotechnology, Yuriy Fedkovych Chernivtsi National University, 58012, Chernivtsi, Ukraine
| | - Martin A Lysak
- Central European Institute of Technology (CEITEC), Masaryk University, 625 00, Brno, Czech Republic
- Faculty of Science, National Centre for Biomolecular Research, Masaryk University, 625 00, Brno, Czech Republic
| | - Ales Kovařík
- Department of Molecular Epigenetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, 612 00, Brno, Czech Republic
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Garcia S, Pascual-Díaz JP, Krumpolcová A, Kovarík A. Analysis of 5S rDNA Genomic Organization Through the RepeatExplorer2 Pipeline: A Simplified Protocol. Methods Mol Biol 2023; 2672:501-512. [PMID: 37335496 DOI: 10.1007/978-1-0716-3226-0_30] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2023]
Abstract
The ribosomal RNA genes (rDNA) are universal genome components with a housekeeping function, given the crucial role of ribosomal RNA in the synthesis of ribosomes and thus for life-on-Earth. Therefore, their genomic organization is of considerable interest for biologists, in general. Ribosomal RNA genes have also been largely used to establish phylogenetic relationships, and to identify allopolyploid or homoploid hybridization.Here, we demonstrate how high-throughput sequencing data, through graph clustering implemented in RepeatExplorer2 pipeline ( https://repeatexplorer-elixir.cerit-sc.cz/galaxy/ ), can be helpful to decipher the genomic organization of 5S rRNA genes. We show that the linear shapes of cluster graphs are reminiscent to the linked organization of 5S and 35S rDNA (L-type arrangement) while the circular graphs correspond to their separate arrangement (S-type). We further present a simplified protocol based on the paper by (Garcia et al., Front Plant Sci 11:41, 2020) about the use of graph clustering of 5S rDNA homoeologs (S-type) to identify hybridization events in the species history. We found that the graph complexity (i.e., graph circularity in this case) is related to ploidy and genome complexity, with diploids typically showing circular-shaped graphs while allopolyploids and other interspecific hybrids display more complex graphs, with usually two or more interconnected loops representing intergenic spacers. When a three-genomic comparative clustering analysis from a given hybrid (homoploid/allopolyploid) and its putative progenitor species (diploids) is performed, it is possible to identify the corresponding homoeologous 5S rRNA gene families, and to elucidate the contribution of each putative parental genome to the 5S rDNA pool of the hybrid. Thus, the analysis of 5S rDNA cluster graphs by RepeatExplorer, together with information coming from other sources (e.g., morphology, cytogenetics) is a complementary approach for the determination of allopolyploid or homoploid hybridization and even ancient introgression events.
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Affiliation(s)
- Sònia Garcia
- Institut Botànic de Barcelona (CSIC - Ajuntament de Barcelona), Barcelona, Spain
| | | | - Alice Krumpolcová
- Department of Molecular Epigenetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czech Republic
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Ales Kovarík
- Department of Molecular Epigenetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
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Peng H, Mirouze M, Bucher E. Extrachromosomal circular DNA: A neglected nucleic acid molecule in plants. CURRENT OPINION IN PLANT BIOLOGY 2022; 69:102263. [PMID: 35872391 DOI: 10.1016/j.pbi.2022.102263] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 06/15/2022] [Accepted: 06/19/2022] [Indexed: 06/15/2023]
Abstract
Throughout the years, most plant genomic studies were focused on nuclear chromosomes. Extrachromosomal circular DNA (eccDNA) has largely been neglected for decades since its discovery in 1965. While initial research showed that eccDNAs can originate from highly repetitive sequences, recent findings show that many regions of the genome can contribute to the eccDNA pool. Currently, the biological functions of eccDNAs, if any, are a mystery but recent studies have indicated that they can be regulated by different genomic loci and contribute to stress response and adaptation. In this review, we outline current relevant technological developments facilitating eccDNA identification and the latest discoveries about eccDNAs in plants. Finally, we explore the probable functions and future research directions that could be undertaken with respect to different eccDNA sources.
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Affiliation(s)
- Haoran Peng
- Crop Genome Dynamics Group, Agroscope Changins, 1260, Nyon, Switzerland; Department of Botany and Plant Biology, Section of Biology, Faculty of Science, University of Geneva, 1211, Geneva, Switzerland
| | - Marie Mirouze
- Institut de Recherche pour le Développement (IRD), EMR269 MANGO, Université de Perpignan, 66860 Perpignan, France; Laboratory of Plant Genome and Development, Université de Perpignan, 66860, Perpignan, France.
| | - Etienne Bucher
- Crop Genome Dynamics Group, Agroscope Changins, 1260, Nyon, Switzerland.
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Tulpová Z, Kovařík A, Toegelová H, Navrátilová P, Kapustová V, Hřibová E, Vrána J, Macas J, Doležel J, Šimková H. Fine structure and transcription dynamics of bread wheat ribosomal DNA loci deciphered by a multi-omics approach. THE PLANT GENOME 2022; 15:e20191. [PMID: 35092350 DOI: 10.1002/tpg2.20191] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 12/16/2021] [Indexed: 06/14/2023]
Abstract
Three out of four RNA components of ribosomes are encoded by 45S ribosomal DNA (rDNA) loci, which are organized as long head-to-tail tandem arrays of nearly identical units, spanning several megabases of sequence. Due to this structure, the rDNA loci are the major sources of gaps in genome assemblies, and gene copy number, sequence composition, and expression status of particular arrays remain elusive, especially in complex genomes harboring multiple loci. Here we conducted a multi-omics study to decipher the 45S rDNA loci in hexaploid bread wheat. Coupling chromosomal genomics with optical mapping, we reconstructed individual rDNA arrays, enabling locus-specific analyses of transcription activity and methylation status from RNA- and bisulfite-sequencing data. We estimated a total of 6,650 rDNA units in the bread wheat genome, with approximately 2,321, 3,910, 253, and 50 gene copies located in short arms of chromosomes 1B, 6B, 5D, and 1A, respectively. Only 1B and 6B loci contributed substantially to rRNA transcription at a roughly 2:1 ratio. The ratio varied among five tissues analyzed (embryo, coleoptile, root tip, primary leaf, mature leaf), being the highest (2.64:1) in mature leaf and lowest (1.72:1) in coleoptile. Cytosine methylation was considerably higher in CHG context in the silenced 5D locus as compared with the active 1B and 6B loci. In conclusion, a fine genomic organization and tissue-specific expression of rDNA loci were deciphered, for the first time, in a complex polyploid species. The results are discussed in the context of wheat evolution and transcription regulation.
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Affiliation(s)
- Zuzana Tulpová
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Aleš Kovařík
- Institute of Biophysics, Czech Academy of Sciences, Brno, Czech Republic
| | - Helena Toegelová
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Pavla Navrátilová
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Veronika Kapustová
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Eva Hřibová
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Jan Vrána
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Jiří Macas
- Biology Centre, Institute of Plant Molecular Biology, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Jaroslav Doležel
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Hana Šimková
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
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Yu F, Zhao X, Chai J, Ding X, Li X, Huang Y, Wang X, Wu J, Zhang M, Yang Q, Deng Z, Jiang J. Chromosome-specific painting unveils chromosomal fusions and distinct allopolyploid species in the Saccharum complex. THE NEW PHYTOLOGIST 2022; 233:1953-1965. [PMID: 34874076 DOI: 10.1111/nph.17905] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 11/29/2021] [Indexed: 06/13/2023]
Abstract
Karyotypes provide key cytogenetic information on the phylogenetic relationships and evolutionary origins in related eukaryotic species. Despite our knowledge of the chromosome numbers of sugarcane and its wild relatives, the chromosome composition and evolution among the species in the Saccharum complex have been elusive owing to the complex polyploidy and the large numbers of chromosomes of these species. Oligonucleotide-based chromosome painting has become a powerful tool of cytogenetic studies especially for plant species with large numbers of chromosomes. We developed oligo-based chromosome painting probes for all 10 chromosomes in Saccharum officinarum (2n = 8x = 80). The 10 painting probes generated robust fluorescence in situ hybridization signals in all plant species within the Saccharum complex, including species in the genera Saccharum, Miscanthus, Narenga and Erianthus. We conducted comparative chromosome analysis using the same set of probes among species from four different genera within the Saccharum complex. Excitingly, we discovered several novel cytotypes and chromosome rearrangements in these species. We discovered that fusion from two different chromosomes is a common type of chromosome rearrangement associated with the species in the Saccharum complex. Such fusion events changed the basic chromosome number and resulted in distinct allopolyploids in the Saccharum complex.
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Affiliation(s)
- Fan Yu
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
- State Key Laboratory for Protection and Utilization of Subtropical Agro-bioresources, Guangxi University, Nanning, 530004, China
| | - Xinwang Zhao
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Jin Chai
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Xueer Ding
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Xueting Li
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Yongji Huang
- Marine and Agricultural Biotechnology Laboratory, Fuzhou Institute of Oceanography, Minjiang University, Fuzhou, 350108, China
| | - Xianhong Wang
- College of Agriculture, Yunnan Agricultural University, Kunming, 650201, Yunnan, China
| | - Jiayun Wu
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
- Institute of Nanfan & Seed Industry, Guangdong Academy of Sciences, Guangzhou, 510316, China
| | - Muqing Zhang
- State Key Laboratory for Protection and Utilization of Subtropical Agro-bioresources, Guangxi University, Nanning, 530004, China
| | - Qinghui Yang
- College of Agriculture, Yunnan Agricultural University, Kunming, 650201, Yunnan, China
| | - Zuhu Deng
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
- State Key Laboratory for Protection and Utilization of Subtropical Agro-bioresources, Guangxi University, Nanning, 530004, China
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Jiming Jiang
- Department of Plant Biology, Department of Horticulture, MSU AgBioResearch, Michigan State University, East Lansing, MI, 48824, USA
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Hemleben V, Grierson D, Borisjuk N, Volkov RA, Kovarik A. Personal Perspectives on Plant Ribosomal RNA Genes Research: From Precursor-rRNA to Molecular Evolution. FRONTIERS IN PLANT SCIENCE 2021; 12:797348. [PMID: 34992624 PMCID: PMC8724763 DOI: 10.3389/fpls.2021.797348] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 11/26/2021] [Indexed: 06/13/2023]
Abstract
The history of rDNA research started almost 90 years ago when the geneticist, Barbara McClintock observed that in interphase nuclei of maize the nucleolus was formed in association with a specific region normally located near the end of a chromosome, which she called the nucleolar organizer region (NOR). Cytologists in the twentieth century recognized the nucleolus as a common structure in all eukaryotic cells, using both light and electron microscopy and biochemical and genetic studies identified ribosomes as the subcellular sites of protein synthesis. In the mid- to late 1960s, the synthesis of nuclear-encoded rRNA was the only system in multicellular organisms where transcripts of known function could be isolated, and their synthesis and processing could be studied. Cytogenetic observations of NOR regions with altered structure in plant interspecific hybrids and detailed knowledge of structure and function of rDNA were prerequisites for studies of nucleolar dominance, epistatic interactions of rDNA loci, and epigenetic silencing. In this article, we focus on the early rDNA research in plants, performed mainly at the dawn of molecular biology in the 60 to 80-ties of the last century which presented a prequel to the modern genomic era. We discuss - from a personal view - the topics such as synthesis of rRNA precursor (35S pre-rRNA in plants), processing, and the organization of 35S and 5S rDNA. Cloning and sequencing led to the observation that the transcribed and processed regions of the rRNA genes vary enormously, even between populations and species, in comparison with the more conserved regions coding for the mature rRNAs. Epigenetic phenomena and the impact of hybridization and allopolyploidy on rDNA expression and homogenization are discussed. This historical view of scientific progress and achievements sets the scene for the other articles highlighting the immense progress in rDNA research published in this special issue of Frontiers in Plant Science on "Molecular organization, evolution, and function of ribosomal DNA."
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Affiliation(s)
- Vera Hemleben
- Center of Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
| | - Donald Grierson
- Plant and Crop Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
| | - Nikolai Borisjuk
- School of Life Sciences, Huaiyin Normal University, Huai'an, China
| | - Roman A. Volkov
- Department of Molecular Genetics and Biotechnology, Yuriy Fedkovych Chernivtsi National University, Chernivtsi, Ukraine
| | - Ales Kovarik
- Laboratory of Molecular Epigenetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czechia
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7
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Kolter A, Gemeinholzer B. Internal transcribed spacer primer evaluation for vascular plant metabarcoding. METABARCODING AND METAGENOMICS 2021. [DOI: 10.3897/mbmg.5.68155] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The unprecedented ongoing biodiversity decline necessitates scalable means of monitoring in order to fully understand the underlying causes. DNA metabarcoding has the potential to provide a powerful tool for accurate and rapid biodiversity monitoring. Unfortunately, in many cases, a lack of universal standards undermines the widespread application of metabarcoding. One of the most important considerations in metabarcoding of plants, aside from selecting a potent barcode marker, is primer choice. Our study evaluates published ITS primers in silico and in vitro, through mock communities and presents newly designed primers. We were able to show that a large proportion of previously available ITS primers have unfavourable attributes. Our combined results support the recommendation of the introduced primers ITS-3p62plF1 and ITS-4unR1 as the best current universal plant specific ITS2 primer combination. We also found that PCR optimisation, such as the addition of 5% DMSO, is essential to obtain meaningful results in ITS2 metabarcoding. Finally, we conclude that continuous quality assurance is indispensable for reliable metabarcoding results.
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Provazníková I, Hejníčková M, Visser S, Dalíková M, Carabajal Paladino LZ, Zrzavá M, Voleníková A, Marec F, Nguyen P. Large-scale comparative analysis of cytogenetic markers across Lepidoptera. Sci Rep 2021; 11:12214. [PMID: 34108567 PMCID: PMC8190105 DOI: 10.1038/s41598-021-91665-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/24/2021] [Indexed: 11/25/2022] Open
Abstract
Fluorescence in situ hybridization (FISH) allows identification of particular chromosomes and their rearrangements. Using FISH with signal enhancement via antibody amplification and enzymatically catalysed reporter deposition, we evaluated applicability of universal cytogenetic markers, namely 18S and 5S rDNA genes, U1 and U2 snRNA genes, and histone H3 genes, in the study of the karyotype evolution in moths and butterflies. Major rDNA underwent rather erratic evolution, which does not always reflect chromosomal changes. In contrast, the hybridization pattern of histone H3 genes was well conserved, reflecting the stable organisation of lepidopteran genomes. Unlike 5S rDNA and U1 and U2 snRNA genes which we failed to detect, except for 5S rDNA in a few representatives of early diverging lepidopteran lineages. To explain the negative FISH results, we used quantitative PCR and Southern hybridization to estimate the copy number and organization of the studied genes in selected species. The results suggested that their detection was hampered by long spacers between the genes and/or their scattered distribution. Our results question homology of 5S rDNA and U1 and U2 snRNA loci in comparative studies. We recommend the use of histone H3 in studies of karyotype evolution.
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Affiliation(s)
- Irena Provazníková
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Institute of Entomology, Biology Centre CAS, České Budějovice, Czech Republic
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Martina Hejníčková
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Institute of Entomology, Biology Centre CAS, České Budějovice, Czech Republic
| | - Sander Visser
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Institute of Entomology, Biology Centre CAS, České Budějovice, Czech Republic
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Martina Dalíková
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Institute of Entomology, Biology Centre CAS, České Budějovice, Czech Republic
| | | | - Magda Zrzavá
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Institute of Entomology, Biology Centre CAS, České Budějovice, Czech Republic
| | - Anna Voleníková
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Institute of Entomology, Biology Centre CAS, České Budějovice, Czech Republic
| | - František Marec
- Institute of Entomology, Biology Centre CAS, České Budějovice, Czech Republic
| | - Petr Nguyen
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.
- Institute of Entomology, Biology Centre CAS, České Budějovice, Czech Republic.
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Krak K, Caklová P, Kopecký D, Blattner FR, Mahelka V. Horizontally Acquired nrDNAs Persist in Low Amounts in Host Hordeum Genomes and Evolve Independently of Native nrDNA. FRONTIERS IN PLANT SCIENCE 2021; 12:672879. [PMID: 34079572 PMCID: PMC8165317 DOI: 10.3389/fpls.2021.672879] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/22/2021] [Indexed: 06/12/2023]
Abstract
Nuclear ribosomal DNA (nrDNA) has displayed extraordinary dynamics during the evolution of plant species. However, the patterns and evolutionary significance of nrDNA array expansion or contraction are still relatively unknown. Moreover, only little is known of the fate of minority nrDNA copies acquired between species via horizontal transfer. The barley genus Hordeum (Poaceae) represents a good model for such a study, as species of section Stenostachys acquired nrDNA via horizontal transfer from at least five different panicoid genera, causing long-term co-existence of native (Hordeum-like) and non-native (panicoid) nrDNAs. Using quantitative PCR, we investigated copy number variation (CNV) of nrDNA in the diploid representatives of the genus Hordeum. We estimated the copy number of the foreign, as well as of the native ITS types (ribotypes), and followed the pattern of their CNV in relation to the genus' phylogeny, species' genomes size and the number of nrDNA loci. For the native ribotype, we encountered an almost 19-fold variation in the mean copy number among the taxa analysed, ranging from 1689 copies (per 2C content) in H. patagonicum subsp. mustersii to 31342 copies in H. murinum subsp. glaucum. The copy numbers did not correlate with any of the genus' phylogeny, the species' genome size or the number of nrDNA loci. The CNV was high within the recognised groups (up to 13.2 × in the American I-genome species) as well as between accessions of the same species (up to 4×). Foreign ribotypes represent only a small fraction of the total number of nrDNA copies. Their copy numbers ranged from single units to tens and rarely hundreds of copies. They amounted, on average, to between 0.1% (Setaria ribotype) and 1.9% (Euclasta ribotype) of total nrDNA. None of the foreign ribotypes showed significant differences with respect to phylogenetic groups recognised within the sect. Stenostachys. Overall, no correlation was found between copy numbers of native and foreign nrDNAs suggesting the sequestration and independent evolution of native and non-native nrDNA arrays. Therefore, foreign nrDNA in Hordeum likely poses a dead-end by-product of horizontal gene transfer events.
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Affiliation(s)
- Karol Krak
- Czech Academy of Sciences, Institute of Botany, Prùhonice, Czechia
- Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Prague 6, Czechia
| | - Petra Caklová
- Czech Academy of Sciences, Institute of Botany, Prùhonice, Czechia
| | - David Kopecký
- Czech Academy of Sciences, Institute of Experimental Botany, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czechia
| | - Frank R. Blattner
- Experimental Taxonomy, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
- German Centre of Integrative Biodiversity Research (iDiv) Halle–Jena–Leipzig, Leipzig, Germany
| | - Václav Mahelka
- Czech Academy of Sciences, Institute of Botany, Prùhonice, Czechia
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10
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Methylation of 45S Ribosomal DNA (rDNA) Is Associated with Cancer and Aging in Humans. Int J Genomics 2021; 2021:8818007. [PMID: 33575316 PMCID: PMC7861956 DOI: 10.1155/2021/8818007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 12/14/2020] [Accepted: 01/19/2021] [Indexed: 01/01/2023] Open
Abstract
Cancer and aging, two distinct processes of cell development, are two major problems threatening our human health and life in current days. Epigenetic studies, especially DNA methylation, have been intensively investigated on them over the years, though a lot of unanswered issues remain. In the human genome, rDNA is a highly conserved tandem repeat family playing critical roles in protein synthesis, genome stability and integrity, etc. More importantly, rDNA is the significant target of DNA methylation, and a potential association between rDNA methylation and cancer and aging has emerged recently. However, whether there is a general trend that rDNA methylation is associated with cancer and aging remains an open issue. In this study, the involvement of rDNA methylation in a series of records of cancer and aging was investigated and summarized, upon which perspectives about rDNA methylation in cancer and aging were proposed. The results showed that rDNA methylation in most cancer cases displayed a consistent pattern with hypermethylation in the coding region but with hypomethylation in the promoter region, which likely facilitates the proliferation and metastasis of cancerous cells. Distinctively, both the coding and promoter regions of rDNA become increasingly methylated during the process of aging, indicating the decline of rDNA activity. The finding of rDNA methylation also implies its potential application as an epigenetic biomarker in the diagnosis of cancer and aging. This work will shed light on our understanding of the pathogenesis, diagnosis, and treatment of cancer and aging from the perspective of rDNA methylation.
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Zhang M, Tang YW, Xu Y, Yonezawa T, Shao Y, Wang YG, Song ZP, Yang J, Zhang WJ. Concerted and birth-and-death evolution of 26S ribosomal DNA in Camellia L. ANNALS OF BOTANY 2021; 127:63-73. [PMID: 32939535 PMCID: PMC7750723 DOI: 10.1093/aob/mcaa169] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/15/2020] [Indexed: 05/05/2023]
Abstract
BACKGROUND AND AIMS The ribosomal DNA (rDNA) gene family, encoding ribosomal RNA (rRNA), has long been regarded as an archetypal example illustrating the model of concerted evolution. However, controversy is arising, as rDNA in many eukaryotic species has been proved to be polymorphic. Here, a metagenomic strategy was applied to detect the intragenomic polymorphism as well as the evolutionary patterns of 26S rDNA across the genus Camellia. METHODS Degenerate primer pairs were designed to amplify the 26S rDNA fragments from different Camellia species. The amplicons were then paired-end sequenced on the Illumina MiSeq platform. KEY RESULTS An extremely high level of rDNA polymorphism existed universally in Camellia. However, functional rDNA was still the major component of the family, and was relatively conserved among different Camellia species. Sequence variations mainly came from rRNA pseudogenes and favoured regions that are rich in GC. Specifically, some rRNA pseudogenes have existed in the genome for a long time, and have even experienced several expansion events, which has greatly enriched the abundance of rDNA polymorphism. CONCLUSIONS Camellia represents a group in which rDNA is subjected to a mixture of concerted and birth-and-death evolution. Some rRNA pseudogenes may still have potential functions. Conversely, when released from selection constraint, they can evolve in the direction of decreasing GC content and structural stability through a methylation-induced process, and finally be eliminated from the genome.
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Affiliation(s)
- Min Zhang
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, China
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Yi-Wei Tang
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Ying Xu
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
- Shanghai Railway Entry-Exit Inspection and Quarantine Bureau, Shanghai, China
| | - Takahiro Yonezawa
- Faculty of Agriculture, Tokyo University of Agriculture, Funako, Atsugi, Kanagawa, Japan
| | - Yang Shao
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Yu-Guo Wang
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Zhi-Ping Song
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Ji Yang
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
| | - Wen-Ju Zhang
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, China
- For correspondence. E-mail
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Garcia S, Wendel JF, Borowska-Zuchowska N, Aïnouche M, Kuderova A, Kovarik A. The Utility of Graph Clustering of 5S Ribosomal DNA Homoeologs in Plant Allopolyploids, Homoploid Hybrids, and Cryptic Introgressants. FRONTIERS IN PLANT SCIENCE 2020; 11:41. [PMID: 32117380 PMCID: PMC7025596 DOI: 10.3389/fpls.2020.00041] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 01/13/2020] [Indexed: 05/18/2023]
Abstract
INTRODUCTION Ribosomal DNA (rDNA) loci have been widely used for identification of allopolyploids and hybrids, although few of these studies employed high-throughput sequencing data. Here we use graph clustering implemented in the RepeatExplorer (RE) pipeline to analyze homoeologous 5S rDNA arrays at the genomic level searching for hybridogenic origin of species. Data were obtained from more than 80 plant species, including several well-defined allopolyploids and homoploid hybrids of different evolutionary ages and from widely dispersed taxonomic groups. RESULTS (i) Diploids show simple circular-shaped graphs of their 5S rDNA clusters. In contrast, most allopolyploids and other interspecific hybrids exhibit more complex graphs composed of two or more interconnected loops representing intergenic spacers (IGS). (ii) There was a relationship between graph complexity and locus numbers. (iii) The sequences and lengths of the 5S rDNA units reconstituted in silico from k-mers were congruent with those experimentally determined. (iv) Three-genomic comparative cluster analysis of reads from allopolyploids and progenitor diploids allowed identification of homoeologous 5S rRNA gene families even in relatively ancient (c. 1 Myr) Gossypium and Brachypodium allopolyploids which already exhibit uniparental partial loss of rDNA repeats. (v) Finally, species harboring introgressed genomes exhibit exceptionally complex graph structures. CONCLUSION We found that the cluster graph shapes and graph parameters (k-mer coverage scores and connected component index) well-reflect the organization and intragenomic homogeneity of 5S rDNA repeats. We propose that the analysis of 5S rDNA cluster graphs computed by the RE pipeline together with the cytogenetic analysis might be a reliable approach for the determination of the hybrid or allopolyploid plant species parentage and may also be useful for detecting historical introgression events.
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Affiliation(s)
- Sònia Garcia
- Institut Botànic de Barcelona (IBB, CSIC - Ajuntament de Barcelona), Barcelona, Spain
- Department of Molecular Epigenetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czechia
| | - Jonathan F. Wendel
- Department of Ecology, Evolution & Organismal Biology, Iowa State University, Ames, IA, United States
| | - Natalia Borowska-Zuchowska
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, Katowice, Poland
| | - Malika Aïnouche
- UMR CNRS 6553 ECOBIO, Université de Rennes 1, Rennes, France
| | - Alena Kuderova
- Department of Molecular Epigenetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czechia
| | - Ales Kovarik
- Department of Molecular Epigenetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czechia
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de Souza TB, Gaeta ML, Martins C, Vanzela ALL. IGS sequences in Cestrum present AT- and GC-rich conserved domains, with strong regulatory potential for 5S rDNA. Mol Biol Rep 2019; 47:55-66. [PMID: 31571109 DOI: 10.1007/s11033-019-05104-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 09/24/2019] [Indexed: 11/28/2022]
Abstract
The 35S and 5S ribosomal DNA (rDNA) organized in thousands of copies in genomes, have been widely used in numerous comparative cytogenetic studies. Nevertheless, several questions related to the diversity and organization of regulatory motifs in 5S rDNA remain to be addressed. The 5S rDNA unit is composed of a conserved 120 bp length coding region and an intergenic spacer (IGS) containing potential regulatory motifs (Poly-T, AT-rich and GC-rich) differing in number, redundancy and position along the IGS. The Cestrum species (Solanaceae) have large genomes (about 10 pg/1C) and conserved 2n = 16 karyotypes. Strikingly, these genomes show high diversity of heterochromatin distribution, variability in 35S rDNA loci and the occurrence of B chromosomes. However, the 5S rDNA loci are highly conserved in the proximal region of chromosome 8. Comparison of seventy-one IGS sequences in plants revealed several conserved motifs with potential regulatory function. The AT- and GC-rich domains appeared highly conserved in Cestrum chromosomes. The 5S genic and the GC-rich IGS probe produced FISH signals in both A (pair 8) and B chromosomes. The GC-rich domain presented a strong potential for regulation because it may be associated with CpG islands organization, as well as to hairpin and loop organization. Another interesting aspect was the ability of AT- and GC-rich motifs to produce non-heterochromatic CMA/DAPI signals. While the length of the 5S rDNA IGS region varied in size between the Cestrum species, the individual sequence motifs seem to be conserved suggesting their regulatory function. The most striking feature was the conserved GC-rich domain in Cestrum, which is recognized as a signature trait of the proximal region of chromosome pair 8.
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Affiliation(s)
- Thaíssa Boldieri de Souza
- Laboratório de Citogenética e Diversidade Vegetal, Departamento de Biologia Geral, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, Paraná, 86057-970, Brazil
| | - Marcos Letaif Gaeta
- Laboratório de Citogenética e Diversidade Vegetal, Departamento de Biologia Geral, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, Paraná, 86057-970, Brazil
| | - Cesar Martins
- Departamento de Morfologia, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Botucatu, SP, CEP 18618689, Brazil
| | - André Luís Laforga Vanzela
- Laboratório de Citogenética e Diversidade Vegetal, Departamento de Biologia Geral, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, Paraná, 86057-970, Brazil.
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Renner S, Sousa dos Santos A. The organization of nuclear ribosomal DNA in gnetophytes - physically separate and physically linked arrangements of 35S and 5S genes. A commentary on: 'Remarkable variation of ribosomal DNA organization and copy number in gnetophytes, a distinct lineage of gymnosperms'. ANNALS OF BOTANY 2019; 123:vi-vii. [PMID: 31106810 PMCID: PMC6526311 DOI: 10.1093/aob/mcz056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
This article comments on: Wencai Wang, Tao Wan, Hannes Becher, Alena Kuderova, Ilia J. Leitch, Sonia Garcia, Andrew R. Leitch and Aleš Kovařík. 2019. Remarkable variation of ribosomal DNA organization and copy number in gnetophytes, a distinct lineage of gymnosperms. Annals of Botany 123(5): 767–781.
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Affiliation(s)
- Susanne Renner
- University of Munich (LMU), Systematic Botany and Mycology, Munich, Germany
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Bughio F, Maggert KA. The peculiar genetics of the ribosomal DNA blurs the boundaries of transgenerational epigenetic inheritance. Chromosome Res 2018; 27:19-30. [PMID: 30511202 DOI: 10.1007/s10577-018-9591-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 10/31/2018] [Accepted: 11/07/2018] [Indexed: 12/20/2022]
Abstract
Our goal is to draw a line-hypothetical in its totality but experimentally supported at each individual step-connecting the ribosomal DNA and the phenomenon of transgenerational epigenetic inheritance of induced phenotypes. The reasonableness of this hypothesis is offset by its implication, that many (or most) (or all) of the cases of induced-and-inherited phenotypes that are seen to persist for generations are instead unmapped induced polymorphisms in the ribosomal DNA, and thus are the consequence of the peculiar and enduringly fascinating genetics of the highly transcribed repeat DNA structure at that locus.
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Affiliation(s)
- Farah Bughio
- Department of Cellular and Molecular Medicine, College of Medicine, University of Arizona, Tucson, AZ, USA
- University of Arizona Cancer Center, University of Arizona College of Medicine, Tucson, AZ, USA
| | - Keith A Maggert
- Department of Cellular and Molecular Medicine, College of Medicine, University of Arizona, Tucson, AZ, USA.
- University of Arizona Cancer Center, University of Arizona College of Medicine, Tucson, AZ, USA.
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