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Chen G, Stepanenko A, Borisjuk N. Contrasting patterns of 5S rDNA repeats in European and Asian ecotypes of greater duckweed, Spirodela polyrhiza (Lemnaceae). FRONTIERS IN PLANT SCIENCE 2024; 15:1378683. [PMID: 38711607 PMCID: PMC11070557 DOI: 10.3389/fpls.2024.1378683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 04/09/2024] [Indexed: 05/08/2024]
Abstract
Ribosomal DNA (rDNA) contains highly conserved, specifically organized sequences encoding ribosomal RNAs (rRNAs) separated by variable non-transcribed intergenic spacers (NTSs) and is abundant in eukaryotic genomes. These characteristics make the rDNA an informative molecular target to study genome organization, molecular evolution, and phylogenetics. In this study, we characterized the 5S rDNA repeats in the greater duckweed Spiroldela polyrhiza, a species known for its small size, rapid growth, highly conserved genome organization, and low mutation rate. Sequence analysis of at least 12 individually cloned PCR fragments containing the 5S rDNA units for each of six ecotypes that originated from Europe (Ukraine) and Asia (China) revealed two distinct types of 5S rDNA repeats containing NTSs of different lengths and nucleotide compositions. The shorter 5S rDNA repeat units had a highly homogeneous 400-bp NTS, with few ecotype- or region-specific single-nucleotide polymorphisms (SNPs). The longer 5S rDNA units had NTSs of 1056-1084 bp with characteristic intra- and inter-genomic variants due to specific SNPs and insertions/deletions of 4-15-bp DNA elements. We also detected significant variability in the ratio of short/long 5S rDNA variants between ecotypes of S. polyrhiza. The contrasting dynamics of the two types of 5S rDNA units, combined with the unusually low repeat copy number (for plants) in S. polyrhiza (46-220 copies per genome), shows that this species could serve as an excellent model for examining the mechanisms of concerted evolution and functional significance of rDNA variability.
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Affiliation(s)
- Guimin Chen
- School of Life Sciences, Huaiyin Normal University, Huai’an, China
| | - Anton Stepanenko
- School of Life Sciences, Huaiyin Normal University, Huai’an, China
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
- Department of Molecular Genetics, Institute of Cell Biology and Genetic Engineering, Kyiv, Ukraine
| | - Nikolai Borisjuk
- School of Life Sciences, Huaiyin Normal University, Huai’an, China
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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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Czech L, Stamatakis A, Dunthorn M, Barbera P. Metagenomic Analysis Using Phylogenetic Placement-A Review of the First Decade. FRONTIERS IN BIOINFORMATICS 2022; 2:871393. [PMID: 36304302 PMCID: PMC9580882 DOI: 10.3389/fbinf.2022.871393] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 04/11/2022] [Indexed: 12/20/2022] Open
Abstract
Phylogenetic placement refers to a family of tools and methods to analyze, visualize, and interpret the tsunami of metagenomic sequencing data generated by high-throughput sequencing. Compared to alternative (e. g., similarity-based) methods, it puts metabarcoding sequences into a phylogenetic context using a set of known reference sequences and taking evolutionary history into account. Thereby, one can increase the accuracy of metagenomic surveys and eliminate the requirement for having exact or close matches with existing sequence databases. Phylogenetic placement constitutes a valuable analysis tool per se, but also entails a plethora of downstream tools to interpret its results. A common use case is to analyze species communities obtained from metagenomic sequencing, for example via taxonomic assignment, diversity quantification, sample comparison, and identification of correlations with environmental variables. In this review, we provide an overview over the methods developed during the first 10 years. In particular, the goals of this review are 1) to motivate the usage of phylogenetic placement and illustrate some of its use cases, 2) to outline the full workflow, from raw sequences to publishable figures, including best practices, 3) to introduce the most common tools and methods and their capabilities, 4) to point out common placement pitfalls and misconceptions, 5) to showcase typical placement-based analyses, and how they can help to analyze, visualize, and interpret phylogenetic placement data.
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Affiliation(s)
- Lucas Czech
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, United States
| | - Alexandros Stamatakis
- Computational Molecular Evolution Group, Heidelberg Institute for Theoretical Studies, Heidelberg, Germany
- Institute for Theoretical Informatics, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Micah Dunthorn
- Natural History Museum, University of Oslo, Oslo, Norway
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Scoppola A, Cardoni S, Marcussen T, Simeone MC. Complex Scenarios of Reticulation, Polyploidization, and Species Diversity within Annual Pansies of Subsect. Bracteolatae (Viola Sect. Melanium, Violaceae) in Italy: Insights from 5S-IGS High-Throughput Sequencing and Plastid DNA Variation. PLANTS 2022; 11:plants11101294. [PMID: 35631718 PMCID: PMC9147628 DOI: 10.3390/plants11101294] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 04/02/2022] [Accepted: 05/11/2022] [Indexed: 01/02/2023]
Abstract
Viola sect. Melanium, the so-called pansy, is an allopolyploid morphologically well-defined lineage of ca. 110 perennial and annual species in the northern hemisphere, characterized by markedly complex genomic configurations. Five annual pansies occur in Italy, four of which are morphologically very similar and belong to the informal ‘V. tricolor species complex’: V. arvensis (2n = 34), V. hymettia (2n = 16), V. kitaibeliana (2n = 16), and V. tricolor (2n = 26). Their field recognition is difficult and reflects a long-debated taxonomy often resulting in doubtful records in field inventories and across European herbaria. The current lack of comprehensive intra- and interspecific comparative studies and a relative scarcity of appropriate genetic markers coupled with unambiguous cytological descriptions are hindering clear taxa circumscription and phylogenetic inferences within this group. In this work, we tested DNA sequence variation of three highly variable plastid markers and High-Throughput Sequencing (HTS) of the nuclear ribosomal 5S-IGS region in an attempt to decipher species identity within the V. tricolor species complex and to obtain an insight on their genome organization and evolution. Our results document the close relationships within this species group, a reliable molecular resolution for V. tricolor, and the common ancestry of V. arvensis and the poorly differentiated V. kitaibeliana and V. hymettia. Evidence of an important inter-population geographical divergence was recorded in V. tricolor and V. arvensis, pointing at the existence of different eco-cytotypes within these entities. Overall diversity patterns and the occurrence of two to four differently diverging 5S-IGS lineages are discussed in the light of the acknowledged taxonomy and genomic evolutive trajectories of sect. Melanium.
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Affiliation(s)
- Anna Scoppola
- Department of Agricultural and Forestry Sciences (DAFNE), Tuscia University, Via S. Camillo de Lellis, 01100 Viterbo, Italy; (A.S.); (M.C.S.)
| | - Simone Cardoni
- Department of Agricultural and Forestry Sciences (DAFNE), Tuscia University, Via S. Camillo de Lellis, 01100 Viterbo, Italy; (A.S.); (M.C.S.)
- Correspondence:
| | - Thomas Marcussen
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis (CEES), University of Oslo, P.O. Box 1066, NO-0316 Oslo, Norway;
| | - Marco Cosimo Simeone
- Department of Agricultural and Forestry Sciences (DAFNE), Tuscia University, Via S. Camillo de Lellis, 01100 Viterbo, Italy; (A.S.); (M.C.S.)
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Cardoni S, Piredda R, Denk T, Grimm GW, Papageorgiou AC, Schulze E, Scoppola A, Salehi Shanjani P, Suyama Y, Tomaru N, Worth JRP, Cosimo Simeone M. 5S-IGS rDNA in wind-pollinated trees (Fagus L.) encapsulates 55 million years of reticulate evolution and hybrid origins of modern species. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 109:909-926. [PMID: 34808015 PMCID: PMC9299691 DOI: 10.1111/tpj.15601] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 11/02/2021] [Accepted: 11/18/2021] [Indexed: 05/31/2023]
Abstract
Standard models of plant speciation assume strictly dichotomous genealogies in which a species, the ancestor, is replaced by two offspring species. The reality in wind-pollinated trees with long evolutionary histories is more complex: species evolve from other species through isolation when genetic drift exceeds gene flow; lineage mixing can give rise to new species (hybrid taxa such as nothospecies and allopolyploids). The multi-copy, potentially multi-locus 5S rDNA is one of few gene regions conserving signal from dichotomous and reticulate evolutionary processes down to the level of intra-genomic recombination. Therefore, it can provide unique insights into the dynamic speciation processes of lineages that diversified tens of millions of years ago. Here, we provide the first high-throughput sequencing (HTS) of the 5S intergenic spacers (5S-IGS) for a lineage of wind-pollinated subtropical to temperate trees, the Fagus crenata - F. sylvatica s.l. lineage, and its distant relative F. japonica. The observed 4963 unique 5S-IGS variants reflect a complex history of hybrid origins, lineage sorting, mixing via secondary gene flow, and intra-genomic competition between two or more paralogous-homoeologous 5S rDNA lineages. We show that modern species are genetic mosaics and represent a striking case of ongoing reticulate evolution during the past 55 million years.
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Affiliation(s)
- Simone Cardoni
- Department of Agricultural and Forestry Science (DAFNE)Università degli studi della TusciaViterbo01100Italy
| | - Roberta Piredda
- Department of Veterinary MedicineUniversity of Bari ‘Aldo Moro’Valenzano70010Italy
| | - Thomas Denk
- Swedish Museum of Natural HistoryStockholm10405Sweden
| | | | | | | | - Anna Scoppola
- Department of Agricultural and Forestry Science (DAFNE)Università degli studi della TusciaViterbo01100Italy
| | - Parvin Salehi Shanjani
- Natural Resources Gene Bank, Research Institute of Forests and RangelandsAgricultural Research, Education and Extension OrganizationTehranIran
| | - Yoshihisa Suyama
- Graduate School of Agricultural ScienceTohoku UniversityOsakiMiyagi989‐6711Japan
| | - Nobuhiro Tomaru
- Graduate School of Bioagricultural SciencesNagoya UniversityNagoyaAichi464‐8601Japan
| | - James R. P. Worth
- Ecological Genetics LaboratoryForestry and Forest Products Research Institute (FFPRI)TsukubaIbaraki305‐8687Japan
| | - Marco Cosimo Simeone
- Department of Agricultural and Forestry Science (DAFNE)Università degli studi della TusciaViterbo01100Italy
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