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Volarić M, Despot-Slade E, Veseljak D, Pavlek M, Vojvoda Zeljko T, Mravinac B, Meštrović N. The Genome Organization of 5S rRNA Genes in the Model Organism Tribolium castaneum and Its Sibling Species Tribolium freemani. Genes (Basel) 2024; 15:776. [PMID: 38927712 PMCID: PMC11202950 DOI: 10.3390/genes15060776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 06/07/2024] [Accepted: 06/11/2024] [Indexed: 06/28/2024] Open
Abstract
5S ribosomal DNAs (rDNAs) are arranged in tandem and are often under-represented in genome assemblies. In the present study, we performed a global and in-depth analysis of the 5S rDNAs in the model insect Tribolium castaneum and its closely related species Tribolium freemani. To accomplish this goal, we used our recently published genome assemblies based on Nanopore and PacBio long-read sequencing. Although these closely related species share the 5S rRNA gene sequence with high homology, they show a different organization of the 5S rDNA locus. Analysis of 5S rDNA arrays in T. castaneum revealed a typical tandemly repeated organization characterized by repeat units consisting of the 121 bp long 5S rRNA gene and the 71 bp long nontranscribed spacer (NTS). In contrast, T. freemani showed a much more complex organization of 5S rDNA arrays characterized by two patterns. The first is based on the association of 5S rRNA gene with arrays of a satellite DNA, representing the NTS sequence of the 5S rDNA genes in T. freemani. The second, more complex type is characterized by a somewhat less frequent occurrence of the 5S rRNA gene and its association with longer satellite DNA arrays that are regularly interrupted by Jockey-like retrotransposons. This organization, in which the ribosomal gene is associated with two completely different repetitive elements such as satellite DNAs and retrotransposons, suggests that the 5S rRNA gene, regardless of its crucial function in the genome, could be a subject of extremely dynamic genomic rearrangements.
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Affiliation(s)
| | | | | | | | | | | | - Nevenka Meštrović
- Ruđer Bošković Institute, Bijenička Cesta 54, 10000 Zagreb, Croatia; (M.V.); (E.D.-S.); (D.V.); (M.P.); (T.V.Z.); (B.M.)
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2
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Dias S, Souza RC, Vasconcelos EV, Vasconcelos S, da Silva Oliveira AR, do Vale Martins L, de Oliveira Bustamante F, da Costa VA, Souza G, da Costa AF, Benko-Iseppon AM, Knytl M, Brasileiro-Vidal AC. Cytomolecular diversity among Vigna Savi (Leguminosae) subgenera. PROTOPLASMA 2024:10.1007/s00709-024-01944-z. [PMID: 38467939 DOI: 10.1007/s00709-024-01944-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 03/04/2024] [Indexed: 03/13/2024]
Abstract
The genus Vigna (Leguminosae) comprises about 150 species grouped into five subgenera. The present study aimed to improve the understanding of karyotype diversity and evolution in Vigna, using new and previously published data through different cytogenetic and DNA content approaches. In the Vigna subgenera, we observed a random distribution of rDNA patterns. The 35S rDNA varied in position, from terminal to proximal, and in number, ranging from one (V. aconitifolia, V. subg. Ceratotropis) to seven pairs (V. unguiculata subsp. unguiculata, V. subg. Vigna). On the other hand, the number of 5S rDNA was conserved (one or two pairs), except for V. radiata (V. subg. Ceratotropis), which had three pairs. Genome size was relatively conserved within the genus, ranging from 1C = 0.43 to 0.70 pg in V. oblongifolia and V. unguiculata subsp. unguiculata, respectively, both belonging to V. subg. Vigna. However, we observed a positive correlation between DNA content and the number of 35S rDNA sites. In addition, data from chromosome-specific BAC-FISH suggest that the ancestral 35S rDNA locus is conserved on chromosome 6 within Vigna. Considering the rapid diversification in the number and position of rDNA sites, such conservation is surprising and suggests that additional sites may have spread out from this ancestral locus.
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Affiliation(s)
- Sibelle Dias
- Departamento de Genética, Centro de Biociências, Universidade Federal de Pernambuco, Recife, PE, Brazil
| | - Rosilda Cintra Souza
- Departamento de Genética, Centro de Biociências, Universidade Federal de Pernambuco, Recife, PE, Brazil
- Laboratório de Imunopatologia Keizo Asami, Universidade Federal de Pernambuco, Recife, PE, Brazil
| | | | | | | | - Lívia do Vale Martins
- Departamento de Genética, Centro de Biociências, Universidade Federal de Pernambuco, Recife, PE, Brazil
- Campus Amilcar Ferreira Sobral, Universidade Federal Do Piauí, Floriano, PI, Brazil
| | - Fernanda de Oliveira Bustamante
- Departamento de Genética, Centro de Biociências, Universidade Federal de Pernambuco, Recife, PE, Brazil
- Universidade Do Estado de Minas Gerais - Unidade Divinópolis, Divinópolis, MG, Brazil
| | - Victor Alves da Costa
- Departamento de Genética, Centro de Biociências, Universidade Federal de Pernambuco, Recife, PE, Brazil
| | - Gustavo Souza
- Departamento de Botânica, Centro de Biociências, Universidade Federal de Pernambuco, Recife, PE, Brazil
| | | | - Ana Maria Benko-Iseppon
- Departamento de Genética, Centro de Biociências, Universidade Federal de Pernambuco, Recife, PE, Brazil
| | - Martin Knytl
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, L8S4K1, Canada
- Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, Prague, 12843, Czech Republic
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Garcia S, Kovarik A, Maiwald S, Mann L, Schmidt N, Pascual-Díaz JP, Vitales D, Weber B, Heitkam T. The Dynamic Interplay Between Ribosomal DNA and Transposable Elements: A Perspective From Genomics and Cytogenetics. Mol Biol Evol 2024; 41:msae025. [PMID: 38306580 PMCID: PMC10946416 DOI: 10.1093/molbev/msae025] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 12/06/2023] [Accepted: 01/29/2024] [Indexed: 02/04/2024] Open
Abstract
Although both are salient features of genomes, at first glance ribosomal DNAs and transposable elements are genetic elements with not much in common: whereas ribosomal DNAs are mainly viewed as housekeeping genes that uphold all prime genome functions, transposable elements are generally portrayed as selfish and disruptive. These opposing characteristics are also mirrored in other attributes: organization in tandem (ribosomal DNAs) versus organization in a dispersed manner (transposable elements); evolution in a concerted manner (ribosomal DNAs) versus evolution by diversification (transposable elements); and activity that prolongs genomic stability (ribosomal DNAs) versus activity that shortens it (transposable elements). Re-visiting relevant instances in which ribosomal DNA-transposable element interactions have been reported, we note that both repeat types share at least four structural and functional hallmarks: (1) they are repetitive DNAs that shape genomes in evolutionary timescales, (2) they exchange structural motifs and can enter co-evolution processes, (3) they are tightly controlled genomic stress sensors playing key roles in senescence/aging, and (4) they share common epigenetic marks such as DNA methylation and histone modification. Here, we give an overview of the structural, functional, and evolutionary characteristics of both ribosomal DNAs and transposable elements, discuss their roles and interactions, and highlight trends and future directions as we move forward in understanding ribosomal DNA-transposable element associations.
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Affiliation(s)
- Sònia Garcia
- Institut Botànic de Barcelona (IBB), CSIC-CMCNB, 08038 Barcelona, Catalonia, Spain
| | - Ales Kovarik
- Institute of Biophysics, Academy of Sciences of the Czech Republic, 61265 Brno, Czech Republic
| | - Sophie Maiwald
- Faculty of Biology, Technische Universität Dresden, D-01069 Dresden, Germany
| | - Ludwig Mann
- Faculty of Biology, Technische Universität Dresden, D-01069 Dresden, Germany
| | - Nicola Schmidt
- Faculty of Biology, Technische Universität Dresden, D-01069 Dresden, Germany
| | | | - Daniel Vitales
- Institut Botànic de Barcelona (IBB), CSIC-CMCNB, 08038 Barcelona, Catalonia, Spain
- Laboratori de Botànica–Unitat Associada CSIC, Facultat de Farmàcia i Ciències de l’Alimentació, Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain
| | - Beatrice Weber
- Faculty of Biology, Technische Universität Dresden, D-01069 Dresden, Germany
| | - Tony Heitkam
- Faculty of Biology, Technische Universität Dresden, D-01069 Dresden, Germany
- Institute of Biology, NAWI Graz, Karl-Franzens-Universität, A-8010 Graz, Austria
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Kojima KK. Helenus and Ajax, Two Groups of Non-Autonomous LTR Retrotransposons, Represent a New Type of Small RNA Gene-Derived Mobile Elements. BIOLOGY 2024; 13:119. [PMID: 38392337 PMCID: PMC10886601 DOI: 10.3390/biology13020119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 02/06/2024] [Accepted: 02/10/2024] [Indexed: 02/24/2024]
Abstract
Terminal repeat retrotransposons in miniature (TRIMs) are short non-autonomous long terminal repeat (LTR) retrotransposons found from various eukaryotes. Cassandra is a unique TRIM lineage which contains a 5S rRNA-derived sequence in its LTRs. Here, two new groups of TRIMs, designated Helenus and Ajax, are reported based on bioinformatics analysis and the usage of Repbase. Helenus is found from fungi, animals, and plants, and its LTRs contain a tRNA-like sequence. It includes two LTRs and between them, a primer-binding site (PBS) and polypurine tract (PPT) exist. Fungal and plant Helenus generate 5 bp target site duplications (TSDs) upon integration, while animal Helenus generates 4 bp TSDs. Ajax includes a 5S rRNA-derived sequence in its LTR and is found from two nemertean genomes. Ajax generates 5 bp TSDs upon integration. These results suggest that despite their unique promoters, Helenus and Ajax are TRIMs whose transposition is dependent on autonomous LTR retrotransposon. These TRIMs can originate through an insertion of SINE in an LTR of TRIM. The discovery of Helenus and Ajax suggests the presence of TRIMs with a promoter for RNA polymerase III derived from a small RNA gene, which is here collectively termed TRIMp3.
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Affiliation(s)
- Kenji K Kojima
- Genetic Information Research Institute, Cupertino, CA 95014, USA
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Maiwald S, Mann L, Garcia S, Heitkam T. Evolving Together: Cassandra Retrotransposons Gradually Mirror Promoter Mutations of the 5S rRNA Genes. Mol Biol Evol 2024; 41:msae010. [PMID: 38262464 PMCID: PMC10853983 DOI: 10.1093/molbev/msae010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 10/26/2023] [Accepted: 12/11/2023] [Indexed: 01/25/2024] Open
Abstract
The 5S rRNA genes are among the most conserved nucleotide sequences across all species. Similar to the 5S preservation we observe the occurrence of 5S-related nonautonomous retrotransposons, so-called Cassandras. Cassandras harbor highly conserved 5S rDNA-related sequences within their long terminal repeats, advantageously providing them with the 5S internal promoter. However, the dynamics of Cassandra retrotransposon evolution in the context of 5S rRNA gene sequence information and structural arrangement are still unclear, especially: (1) do we observe repeated or gradual domestication of the highly conserved 5S promoter by Cassandras and (2) do changes in 5S organization such as in the linked 35S-5S rDNA arrangements impact Cassandra evolution? Here, we show evidence for gradual co-evolution of Cassandra sequences with their corresponding 5S rDNAs. To follow the impact of 5S rDNA variability on Cassandra TEs, we investigate the Asteraceae family where highly variable 5S rDNAs, including 5S promoter shifts and both linked and separated 35S-5S rDNA arrangements have been reported. Cassandras within the Asteraceae mirror 5S rDNA promoter mutations of their host genome, likely as an adaptation to the host's specific 5S transcription factors and hence compensating for evolutionary changes in the 5S rDNA sequence. Changes in the 5S rDNA sequence and in Cassandras seem uncorrelated with linked/separated rDNA arrangements. We place all these observations into the context of angiosperm 5S rDNA-Cassandra evolution, discuss Cassandra's origin hypotheses (single or multiple) and Cassandra's possible impact on rDNA and plant genome organization, giving new insights into the interplay of ribosomal genes and transposable elements.
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Affiliation(s)
- Sophie Maiwald
- Faculty of Biology, Technische Universität Dresden, 01069 Dresden, Germany
| | - Ludwig Mann
- Faculty of Biology, Technische Universität Dresden, 01069 Dresden, Germany
| | - Sònia Garcia
- Institut Botànic de Barcelona, IBB (CSIC-MCNB), 08038 Barcelona, Catalonia, Spain
| | - Tony Heitkam
- Faculty of Biology, Technische Universität Dresden, 01069 Dresden, Germany
- Institute of Biology, NAWI Graz, Karl-Franzens-Universität, 8010 Graz, Austria
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Gao D. Introduction of Plant Transposon Annotation for Beginners. BIOLOGY 2023; 12:1468. [PMID: 38132293 PMCID: PMC10741241 DOI: 10.3390/biology12121468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 11/21/2023] [Accepted: 11/23/2023] [Indexed: 12/23/2023]
Abstract
Transposons are mobile DNA sequences that contribute large fractions of many plant genomes. They provide exclusive resources for tracking gene and genome evolution and for developing molecular tools for basic and applied research. Despite extensive efforts, it is still challenging to accurately annotate transposons, especially for beginners, as transposon prediction requires necessary expertise in both transposon biology and bioinformatics. Moreover, the complexity of plant genomes and the dynamic evolution of transposons also bring difficulties for genome-wide transposon discovery. This review summarizes the three major strategies for transposon detection including repeat-based, structure-based, and homology-based annotation, and introduces the transposon superfamilies identified in plants thus far, and some related bioinformatics resources for detecting plant transposons. Furthermore, it describes transposon classification and explains why the terms 'autonomous' and 'non-autonomous' cannot be used to classify the superfamilies of transposons. Lastly, this review also discusses how to identify misannotated transposons and improve the quality of the transposon database. This review provides helpful information about plant transposons and a beginner's guide on annotating these repetitive sequences.
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Affiliation(s)
- Dongying Gao
- Small Grains and Potato Germplasm Research Unit, USDA-ARS, Aberdeen, ID 83210, USA
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7
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Kalendar R, Karlov GI. Editorial: Mobile elements and plant genome evolution, comparative analyses and computational tools, volume II. FRONTIERS IN PLANT SCIENCE 2023; 14:1308536. [PMID: 38023887 PMCID: PMC10676221 DOI: 10.3389/fpls.2023.1308536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 11/07/2023] [Indexed: 12/01/2023]
Affiliation(s)
- Ruslan Kalendar
- Institute of Biotechnology, Helsinki Institute of Life Science (HiLIFE), University of Helsinki, Helsinki, Finland
- National Laboratory Astana, Nazarbayev University, Astana, Kazakhstan
| | - Gennady I. Karlov
- All-Russia Research Institute of Agricultural Biotechnology, Russian Academy of Sciences, Moscow, Russia
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8
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Arvas YE, Marakli S, Kaya Y, Kalendar R. The power of retrotransposons in high-throughput genotyping and sequencing. FRONTIERS IN PLANT SCIENCE 2023; 14:1174339. [PMID: 37180380 PMCID: PMC10167742 DOI: 10.3389/fpls.2023.1174339] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Accepted: 04/11/2023] [Indexed: 05/16/2023]
Abstract
The use of molecular markers has become an essential part of molecular genetics through their application in numerous fields, which includes identification of genes associated with targeted traits, operation of backcrossing programs, modern plant breeding, genetic characterization, and marker-assisted selection. Transposable elements are a core component of all eukaryotic genomes, making them suitable as molecular markers. Most of the large plant genomes consist primarily of transposable elements; variations in their abundance contribute to most of the variation in genome size. Retrotransposons are widely present throughout plant genomes, and replicative transposition enables them to insert into the genome without removing the original elements. Various applications of molecular markers have been developed that exploit the fact that these genetic elements are present everywhere and their ability to stably integrate into dispersed chromosomal localities that are polymorphic within a species. The ongoing development of molecular marker technologies is directly related to the deployment of high-throughput genotype sequencing platforms, and this research is of considerable significance. In this review, the practical application to molecular markers, which is a use of technology of interspersed repeats in the plant genome were examined using genomic sources from the past to the present. Prospects and possibilities are also presented.
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Affiliation(s)
- Yunus Emre Arvas
- Department of Biology, Faculty of Sciences, Karadeniz Technical University, Trabzon, Türkiye
| | - Sevgi Marakli
- Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Yildiz Technical University, Istanbul, Türkiye
| | - Yılmaz Kaya
- Agricultural Biotechnology Department, Faculty of Agriculture, Ondokuz Mayıs University, Samsun, Türkiye
- Department of Biology, Faculty of Science, Kyrgyz-Turkish Manas University, Bishkek, Kyrgyzstan
| | - Ruslan Kalendar
- Center for Life Sciences, National Laboratory Astana, Nazarbayev University, Astana, Kazakhstan
- Institute of Biotechnology, Helsinki Institute of Life Science (HiLIFE), University of Helsinki, Helsinki, Finland
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Papolu PK, Ramakrishnan M, Mullasseri S, Kalendar R, Wei Q, Zou L, Ahmad Z, Vinod KK, Yang P, Zhou M. Retrotransposons: How the continuous evolutionary front shapes plant genomes for response to heat stress. FRONTIERS IN PLANT SCIENCE 2022; 13:1064847. [PMID: 36570931 PMCID: PMC9780303 DOI: 10.3389/fpls.2022.1064847] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Accepted: 11/21/2022] [Indexed: 05/28/2023]
Abstract
Long terminal repeat retrotransposons (LTR retrotransposons) are the most abundant group of mobile genetic elements in eukaryotic genomes and are essential in organizing genomic architecture and phenotypic variations. The diverse families of retrotransposons are related to retroviruses. As retrotransposable elements are dispersed and ubiquitous, their "copy-out and paste-in" life cycle of replicative transposition leads to new genome insertions without the excision of the original element. The overall structure of retrotransposons and the domains responsible for the various phases of their replication is highly conserved in all eukaryotes. The two major superfamilies of LTR retrotransposons, Ty1/Copia and Ty3/Gypsy, are distinguished and dispersed across the chromosomes of higher plants. Members of these superfamilies can increase in copy number and are often activated by various biotic and abiotic stresses due to retrotransposition bursts. LTR retrotransposons are important drivers of species diversity and exhibit great variety in structure, size, and mechanisms of transposition, making them important putative actors in genome evolution. Additionally, LTR retrotransposons influence the gene expression patterns of adjacent genes by modulating potential small interfering RNA (siRNA) and RNA-directed DNA methylation (RdDM) pathways. Furthermore, comparative and evolutionary analysis of the most important crop genome sequences and advanced technologies have elucidated the epigenetics and structural and functional modifications driven by LTR retrotransposon during speciation. However, mechanistic insights into LTR retrotransposons remain obscure in plant development due to a lack of advancement in high throughput technologies. In this review, we focus on the key role of LTR retrotransposons response in plants during heat stress, the role of centromeric LTR retrotransposons, and the role of LTR retrotransposon markers in genome expression and evolution.
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Affiliation(s)
- Pradeep K. Papolu
- State Key Laboratory of Subtropical Silviculture, Bamboo Industry Institute, Zhejiang A&F University, Hangzhou, Zhejiang, China
| | - Muthusamy Ramakrishnan
- State Key Laboratory of Subtropical Silviculture, Bamboo Industry Institute, Zhejiang A&F University, Hangzhou, Zhejiang, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Bamboo Research Institute, Key Laboratory of National Forestry and Grassland Administration on Subtropical Forest Biodiversity Conservation, College of Biology and the Environment, Nanjing Forestry University, Nanjing, Jiangsu, China
| | - Sileesh Mullasseri
- Department of Zoology, St. Albert’s College (Autonomous), Kochi, Kerala, India
| | - Ruslan Kalendar
- Helsinki Institute of Life Science HiLIFE, Biocenter 3, University of Helsinki, Helsinki, Finland
- National Laboratory Astana, Nazarbayev University, Astana, Kazakhstan
| | - Qiang Wei
- Co-Innovation Center for Sustainable Forestry in Southern China, Bamboo Research Institute, Key Laboratory of National Forestry and Grassland Administration on Subtropical Forest Biodiversity Conservation, College of Biology and the Environment, Nanjing Forestry University, Nanjing, Jiangsu, China
| | - Long−Hai Zou
- State Key Laboratory of Subtropical Silviculture, Bamboo Industry Institute, Zhejiang A&F University, Hangzhou, Zhejiang, China
| | - Zishan Ahmad
- Co-Innovation Center for Sustainable Forestry in Southern China, Bamboo Research Institute, Key Laboratory of National Forestry and Grassland Administration on Subtropical Forest Biodiversity Conservation, College of Biology and the Environment, Nanjing Forestry University, Nanjing, Jiangsu, China
| | | | - Ping Yang
- State Key Laboratory of Subtropical Silviculture, Bamboo Industry Institute, Zhejiang A&F University, Hangzhou, Zhejiang, China
- Zhejiang Provincial Collaborative Innovation Center for Bamboo Resources and High-Efficiency Utilization, Zhejiang A&F University, Hangzhou, Zhejiang, China
| | - Mingbing Zhou
- State Key Laboratory of Subtropical Silviculture, Bamboo Industry Institute, Zhejiang A&F University, Hangzhou, Zhejiang, China
- Zhejiang Provincial Collaborative Innovation Center for Bamboo Resources and High-Efficiency Utilization, Zhejiang A&F University, Hangzhou, Zhejiang, China
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Transposable Elements in the Revealing of Polymorphism-Based Differences in the Seeds of Flax Varieties Grown in Remediated Chernobyl Area. PLANTS 2022; 11:plants11192567. [PMID: 36235434 PMCID: PMC9571286 DOI: 10.3390/plants11192567] [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: 07/14/2022] [Revised: 09/20/2022] [Accepted: 09/21/2022] [Indexed: 11/16/2022]
Abstract
The nuclear reactor accident in Chernobyl, Ukraine, resulted in effects both locally and farther away. Most of the contaminated areas were the agricultural fields and forests. Experimental fields were established near Chernobyl—radioactively contaminated fields localized 5 km from Chernobyl Nuclear Power Plant as well as the remediated soil that is localized directly in the Chernobyl town. Two flax varieties growing under chronic exposition to ionizing radiation were used for this study—the local Ukrainian variety Kyivskyi and a commercial variety Bethune. The screening of the length polymorphism generated by transposable elements insertions were performed. All known types of common flax transposon, retrotransposons and iPBS approach were used. In the iPBS multiplex analyze, for the Kyivskyi variety, a unique addition was found in the seeds from the radioactive contaminated field and for the Bethune variety, a total of five amplicon additions were obtained and one deletion. For the TRIM Cassandra fingerprints, two amplicon additions were generated in the seeds from radioactive contaminated fields for the Bethune variety. In summary, the obtained data represent the genetic diversity between control and irradiated subgroups of flax seeds from Chernobyl area and the presence of activated transposable elements due to the irradiation stress.
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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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12
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Haig D. Concerted evolution of ribosomal DNA: Somatic peace amid germinal strife: Intranuclear and cellular selection maintain the quality of rRNA. Bioessays 2021; 43:e2100179. [PMID: 34704616 DOI: 10.1002/bies.202100179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 10/12/2021] [Indexed: 11/10/2022]
Abstract
Most eukaryotes possess many copies of rDNA. Organismal selection alone cannot maintain rRNA function because the effects of mutations in one rDNA are diluted by the presence of many other rDNAs. rRNA quality is maintained by processes that increase homogeneity of rRNA within, and heterogeneity among, germ cells thereby increasing the effectiveness of cellular selection on ribosomal function. A successful rDNA repeat will possess adaptations for spreading within tandem arrays by intranuclear selection. These adaptations reside in the non-coding regions of rDNA. Single-copy genes are predicted to manage processes of intranuclear and cellular selection in the germline to maintain the quality of rRNA expressed in somatic cells of future generations.
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Affiliation(s)
- David Haig
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
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The Dynamism of Transposon Methylation for Plant Development and Stress Adaptation. Int J Mol Sci 2021; 22:ijms222111387. [PMID: 34768817 PMCID: PMC8583499 DOI: 10.3390/ijms222111387] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 10/13/2021] [Accepted: 10/19/2021] [Indexed: 02/06/2023] Open
Abstract
Plant development processes are regulated by epigenetic alterations that shape nuclear structure, gene expression, and phenotypic plasticity; these alterations can provide the plant with protection from environmental stresses. During plant growth and development, these processes play a significant role in regulating gene expression to remodel chromatin structure. These epigenetic alterations are mainly regulated by transposable elements (TEs) whose abundance in plant genomes results in their interaction with genomes. Thus, TEs are the main source of epigenetic changes and form a substantial part of the plant genome. Furthermore, TEs can be activated under stress conditions, and activated elements cause mutagenic effects and substantial genetic variability. This introduces novel gene functions and structural variation in the insertion sites and primarily contributes to epigenetic modifications. Altogether, these modifications indirectly or directly provide the ability to withstand environmental stresses. In recent years, many studies have shown that TE methylation plays a major role in the evolution of the plant genome through epigenetic process that regulate gene imprinting, thereby upholding genome stability. The induced genetic rearrangements and insertions of mobile genetic elements in regions of active euchromatin contribute to genome alteration, leading to genomic stress. These TE-mediated epigenetic modifications lead to phenotypic diversity, genetic variation, and environmental stress tolerance. Thus, TE methylation is essential for plant evolution and stress adaptation, and TEs hold a relevant military position in the plant genome. High-throughput techniques have greatly advanced the understanding of TE-mediated gene expression and its associations with genome methylation and suggest that controlled mobilization of TEs could be used for crop breeding. However, development application in this area has been limited, and an integrated view of TE function and subsequent processes is lacking. In this review, we explore the enormous diversity and likely functions of the TE repertoire in adaptive evolution and discuss some recent examples of how TEs impact gene expression in plant development and stress adaptation.
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Orłowska R, Pachota KA, Dynkowska WM, Niedziela A, Bednarek PT. Androgenic-Induced Transposable Elements Dependent Sequence Variation in Barley. Int J Mol Sci 2021; 22:ijms22136783. [PMID: 34202586 PMCID: PMC8268840 DOI: 10.3390/ijms22136783] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/14/2021] [Accepted: 06/22/2021] [Indexed: 01/10/2023] Open
Abstract
A plant genome usually encompasses different families of transposable elements (TEs) that may constitute up to 85% of nuclear DNA. Under stressful conditions, some of them may activate, leading to sequence variation. In vitro plant regeneration may induce either phenotypic or genetic and epigenetic changes. While DNA methylation alternations might be related, i.e., to the Yang cycle problems, DNA pattern changes, especially DNA demethylation, may activate TEs that could result in point mutations in DNA sequence changes. Thus, TEs have the highest input into sequence variation (SV). A set of barley regenerants were derived via in vitro anther culture. High Performance Liquid Chromatography (RP-HPLC), used to study the global DNA methylation of donor plants and their regenerants, showed that the level of DNA methylation increased in regenerants by 1.45% compared to the donors. The Methyl-Sensitive Transposon Display (MSTD) based on methylation-sensitive Amplified Fragment Length Polymorphism (metAFLP) approach demonstrated that, depending on the selected elements belonging to the TEs family analyzed, varying levels of sequence variation were evaluated. DNA sequence contexts may have a different impact on SV generated by distinct mobile elements belonged to various TE families. Based on the presented study, some of the selected mobile elements contribute differently to TE-related SV. The surrounding context of the TEs DNA sequence is possibly important here, and the study explained some part of SV related to those contexts.
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Retrotransposable Elements: DNA Fingerprinting and the Assessment of Genetic Diversity. Methods Mol Biol 2021; 2222:263-286. [PMID: 33301099 DOI: 10.1007/978-1-0716-0997-2_15] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Retrotransposable elements (RTEs) are highly common mobile genetic elements that are composed of several classes and make up the majority of eukaryotic genomes. The "copy-out and paste-in" life cycle of replicative transposition in these dispersive and ubiquitous RTEs leads to new genome insertions without excision of the original element. RTEs are important drivers of species diversity; they exhibit great variety in structure, size, and mechanisms of transposition, making them important putative components in genome evolution. Accordingly, various applications have been developed to explore the polymorphisms in RTE insertion patterns. These applications include conventional or anchored polymerase chain reaction (PCR) and quantitative or digital PCR with primers designed for the 5' or 3' junction. Marker systems exploiting these PCR methods can be easily developed and are inexpensively used in the absence of extensive genome sequence data. The main inter-repeat amplification polymorphism techniques include inter-retrotransposon amplified polymorphism (IRAP), retrotransposon microsatellite amplified polymorphism (REMAP), and Inter-Primer Binding Site (iPBS) for PCR amplification with a single or two primers.
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Mahelka V, Krak K, Fehrer J, Caklová P, Nagy Nejedlá M, Čegan R, Kopecký D, Šafář J. A Panicum-derived chromosomal segment captured by Hordeum a few million years ago preserves a set of stress-related genes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 105:1141-1164. [PMID: 33484020 DOI: 10.1111/tpj.15167] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/15/2021] [Accepted: 01/19/2021] [Indexed: 06/12/2023]
Abstract
Intra-specific variability is a cornerstone of evolutionary success of species. Acquiring genetic material from distant sources is an important adaptive mechanism in bacteria, but it can also play a role in eukaryotes. In this paper, we investigate the nature and evolution of a chromosomal segment of panicoid (Poaceae, Panicoideae) origin occurring in the nuclear genomes of species of the barley genus Hordeum (Pooideae). The segment, spanning over 440 kb in the Asian Hordeum bogdanii and 219 kb in the South American Hordeum pubiflorum, resides on a pair of nucleolar organizer region (NOR)-bearing chromosomes. Conserved synteny and micro-collinearity of the segment in both species indicate a common origin of the segment, which was acquired before the split of the respective barley lineages 5-1.7 million years ago. A major part of the foreign DNA consists of several approximately 68 kb long repeated blocks containing five stress-related protein-coding genes and transposable elements (TEs). Whereas outside these repeats, the locus was invaded by multiple TEs from the host genome, the repeated blocks are rather intact and appear to be preserved. The protein-coding genes remained partly functional, as indicated by conserved reading frames, a low amount of non-synonymous mutations, and expression of mRNA. A screen across Hordeum species targeting the panicoid protein-coding genes revealed the presence of the genes in all species of the section Stenostachys. In summary, our study shows that grass genomes can contain large genomic segments obtained from distantly related species. These segments usually remain undetected, but they may play an important role in the evolution and adaptation of species.
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Affiliation(s)
- Václav Mahelka
- Institute of Botany, Czech Academy of Sciences, Průhonice, 25243, Czech Republic
| | - Karol Krak
- Institute of Botany, Czech Academy of Sciences, Průhonice, 25243, Czech Republic
- Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Prague 6, 16500, Czech Republic
| | - Judith Fehrer
- Institute of Botany, Czech Academy of Sciences, Průhonice, 25243, Czech Republic
| | - Petra Caklová
- Institute of Botany, Czech Academy of Sciences, Průhonice, 25243, Czech Republic
| | | | - Radim Čegan
- Institute of Biophysics, Czech Academy of Sciences, Brno, 61265, Czech Republic
| | - David Kopecký
- Institute of Experimental Botany, Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Šlechtitelů 31, Olomouc, 77900, Czech Republic
| | - Jan Šafář
- Institute of Experimental Botany, Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Šlechtitelů 31, Olomouc, 77900, Czech Republic
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Maiwald S, Weber B, Seibt KM, Schmidt T, Heitkam T. The Cassandra retrotransposon landscape in sugar beet (Beta vulgaris) and related Amaranthaceae: recombination and re-shuffling lead to a high structural variability. ANNALS OF BOTANY 2021; 127:91-109. [PMID: 33009553 PMCID: PMC7750724 DOI: 10.1093/aob/mcaa176] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 09/28/2020] [Indexed: 05/26/2023]
Abstract
BACKGROUND AND AIMS Plant genomes contain many retrotransposons and their derivatives, which are subject to rapid sequence turnover. As non-autonomous retrotransposons do not encode any proteins, they experience reduced selective constraints leading to their diversification into multiple families, usually limited to a few closely related species. In contrast, the non-coding Cassandra terminal repeat retrotransposons in miniature (TRIMs) are widespread in many plants. Their hallmark is a conserved 5S rDNA-derived promoter in their long terminal repeats (LTRs). As sugar beet (Beta vulgaris) has a well-described LTR retrotransposon landscape, we aim to characterize TRIMs in beet and related genomes. METHODS We identified Cassandra retrotransposons in the sugar beet reference genome and characterized their structural relationships. Genomic organization, chromosomal localization, and distribution of Cassandra-TRIMs across the Amaranthaceae were verified by Southern and fluorescent in situ hybridization. KEY RESULTS All 638 Cassandra sequences in the sugar beet genome contain conserved LTRs and thus constitute a single family. Nevertheless, variable internal regions required a subdivision into two Cassandra subfamilies within B. vulgaris. The related Chenopodium quinoa harbours a third subfamily. These subfamilies vary in their distribution within Amaranthaceae genomes, their insertion times and the degree of silencing by small RNAs. Cassandra retrotransposons gave rise to many structural variants, such as solo LTRs or tandemly arranged Cassandra retrotransposons. These Cassandra derivatives point to an interplay of template switch and recombination processes - mechanisms that likely caused Cassandra's subfamily formation and diversification. CONCLUSIONS We traced the evolution of Cassandra in the Amaranthaceae and detected a considerable variability within the short internal regions, whereas the LTRs are strongly conserved in sequence and length. Presumably these hallmarks make Cassandra a prime target for unequal recombination, resulting in the observed structural diversity, an example of the impact of LTR-mediated evolutionary mechanisms on the host genome.
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Affiliation(s)
- Sophie Maiwald
- Institute of Botany, Technische Universität Dresden, Dresden, Germany
| | - Beatrice Weber
- Institute of Botany, Technische Universität Dresden, Dresden, Germany
| | - Kathrin M Seibt
- Institute of Botany, Technische Universität Dresden, Dresden, Germany
| | - Thomas Schmidt
- Institute of Botany, Technische Universität Dresden, Dresden, Germany
| | - Tony Heitkam
- Institute of Botany, Technische Universität Dresden, Dresden, Germany
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The unusual dRemp retrotransposon is abundant, highly mutagenic, and mobilized only in the second pollen mitosis of some maize lines. Proc Natl Acad Sci U S A 2020; 117:18091-18098. [PMID: 32661148 DOI: 10.1073/pnas.2010234117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The frequent mutations recovered recently from the pollen of select maize lines resulted from the meiotic mobilization of specific low-copy number long-terminal repeat (LTR) retrotransposons, which differ among lines. Mutations that arise at male meiosis produce kernels with concordant mutant phenotypes in both endosperm and embryo because the two sperms that participate in double fertilization are genetically identical. Those are in a majority. However, a small minority of kernels with a mutant endosperm carry a nonconcordant normal embryo, pointing to a postmeiotic or microgametophytic origin. In this study, we have identified the basis for those nonconcordant mutations. We find that all are produced by transposition of a defective LTR retrotransposon that we have termed dRemp (defective retroelement mobile in pollen). This element has several unique properties. Unlike the mutagenic LTR retrotransposons identified previously, dRemp is present in hundreds of copies in all sequenced lines. It seems to transpose only at the second pollen mitosis because all dRemp insertion mutants are nonconcordant yet recoverable in either the endosperm or the embryo. Although it does not move in most lines, dRemp is highly mobile in the Corn Belt inbred M14, identified earlier by breeders as being highly unstable. Lastly, it can be recovered in an array of structures, ranging from solo LTRs to tandem dRemp repeats containing several internal LTRs, suggestive of extensive recombination during retrotransposition. These results shed further light on the spontaneous mutation process and on the possible basis for inbred instability in maize.
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Breaks of macrosynteny and collinearity among moth bean (Vigna aconitifolia), cowpea (V. unguiculata), and common bean (Phaseolus vulgaris). Chromosome Res 2020; 28:293-306. [PMID: 32654079 DOI: 10.1007/s10577-020-09635-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 06/29/2020] [Accepted: 07/01/2020] [Indexed: 10/23/2022]
Abstract
Comparative cytogenetic mapping is a powerful approach to gain insights into genome organization of orphan crops, lacking a whole sequenced genome. To investigate the cytogenomic evolution of important Vigna and Phaseolus beans, we built a BAC-FISH (fluorescent in situ hybridization of bacterial artificial chromosome) map of Vigna aconitifolia (Vac, subgenus Ceratotropis), species with no sequenced genome, and compared with V. unguiculata (Vu, subgenus Vigna) and Phaseolus vulgaris (Pv) maps. Seventeen Pv BACs, eight Vu BACs, and 5S and 35S rDNA probes were hybridized in situ on the 11 Vac chromosome pairs. Five Vac chromosomes (Vac6, Vac7, Vac9, Vac10, and Vac11) showed conserved macrosynteny and collinearity between V. unguiculata and P. vulgaris. On the other hand, we observed collinearity breaks, identified by pericentric inversions involving Vac2 (Vu2), Vac4 (Vu4), and Vac3 (Pv3). We also detected macrosynteny breaks of translocation type involving chromosomes 1 and 8 of V. aconitifolia and P. vulgaris; 2 and 3 of V. aconitifolia and P. vulgaris; and 1 and 5 of V. aconitifolia and V. unguiculata. Considering our data and previous BAC-FISH studies, six chromosomes (1, 2, 3, 4, 5, and 8) are involved in major karyotype divergences between genera and five (1, 2, 3, 4, and 5) between Vigna subgenera, including mechanisms such as duplications, inversions, and translocations. Macrosynteny breaks between Vigna and Phaseolus suggest that the major chromosomal rearrangements have occurred within the Vigna clade. Our cytogenomic comparisons bring new light on the degree of shared macrosynteny and mechanisms of karyotype diversification during Vigna and Phaseolus evolution.
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Turzhanova A, Khapilina ON, Tumenbayeva A, Shevtsov V, Raiser O, Kalendar R. Genetic diversity of Alternaria species associated with black point in wheat grains. PeerJ 2020; 8:e9097. [PMID: 32411537 PMCID: PMC7207207 DOI: 10.7717/peerj.9097] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 04/09/2020] [Indexed: 12/12/2022] Open
Abstract
The genus Alternaria is a widely distributed major plant pathogen that can act as a saprophyte in plant debris. Fungi of this genus frequently infect cereal crops and cause such diseases as black point and wheat leaf blight, which decrease the yield and quality of cereal products. A total of 25 Alternaria sp. isolates were collected from germ grains of various wheat cultivars from different geographic regions in Kazakhstan. We investigated the genetic relationships of the main Alternaria species related to black point disease of wheat in Kazakhstan, using the inter-primer binding site (iPBS) DNA profiling technique. We used 25 retrotransposon-based iPBS primers to identify the differences among and within Alternaria species populations, and analyzed the variation using clustering (UPGMA) and statistical approaches (AMOVA). Isolates of Alternaria species clustered into two main genetic groups, with species of A.alternata and A.tennuissima forming one cluster, and isolates of A. infectoria forming another. The genetic diversity found using retrotransposon profiles was strongly correlated with geographic data. Overall, the iPBS fingerprinting technique is highly informative and useful for the evaluation of genetic diversity and relationships of Alternaria species.
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Affiliation(s)
| | | | | | | | - Olesya Raiser
- National Center for Biotechnology, Nur-Sultan, Kazakhstan
| | - Ruslan Kalendar
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Uusimaa, Finland
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21
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Kalendar R, Raskina O, Belyayev A, Schulman AH. Long Tandem Arrays of Cassandra Retroelements and Their Role in Genome Dynamics in Plants. Int J Mol Sci 2020; 21:ijms21082931. [PMID: 32331257 PMCID: PMC7215508 DOI: 10.3390/ijms21082931] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 04/15/2020] [Accepted: 04/17/2020] [Indexed: 02/07/2023] Open
Abstract
Retrotransposable elements are widely distributed and diverse in eukaryotes. Their copy number increases through reverse-transcription-mediated propagation, while they can be lost through recombinational processes, generating genomic rearrangements. We previously identified extensive structurally uniform retrotransposon groups in which no member contains the gag, pol, or env internal domains. Because of the lack of protein-coding capacity, these groups are non-autonomous in replication, even if transcriptionally active. The Cassandra element belongs to the non-autonomous group called terminal-repeat retrotransposons in miniature (TRIM). It carries 5S RNA sequences with conserved RNA polymerase (pol) III promoters and terminators in its long terminal repeats (LTRs). Here, we identified multiple extended tandem arrays of Cassandra retrotransposons within different plant species, including ferns. At least 12 copies of repeated LTRs (as the tandem unit) and internal domain (as a spacer), giving a pattern that resembles the cellular 5S rRNA genes, were identified. A cytogenetic analysis revealed the specific chromosomal pattern of the Cassandra retrotransposon with prominent clustering at and around 5S rDNA loci. The secondary structure of the Cassandra retroelement RNA is predicted to form super-loops, in which the two LTRs are complementary to each other and can initiate local recombination, leading to the tandem arrays of Cassandra elements. The array structures are conserved for Cassandra retroelements of different species. We speculate that recombination events similar to those of 5S rRNA genes may explain the wide variation in Cassandra copy number. Likewise, the organization of 5S rRNA gene sequences is very variable in flowering plants; part of what is taken for 5S gene copy variation may be variation in Cassandra number. The role of the Cassandra 5S sequences remains to be established.
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Affiliation(s)
- Ruslan Kalendar
- Department of Agricultural Sciences, University of Helsinki, P.O. Box 27 (Latokartanonkaari 5), FI-00014 Helsinki, Finland
- RSE “National Center for Biotechnology”, Korgalzhyn Highway 13/5, Nur-Sultan 010000, Kazakhstan
- Correspondence: (R.K.); (A.H.S.)
| | - Olga Raskina
- Institute of Evolution, University of Haifa, Mount Carmel, Haifa 31905, Israel;
| | - Alexander Belyayev
- Laboratory of Molecular Cytogenetics and Karyology, Institute of Botany of the ASCR, Zámek 1, CZ-252 43 Průhonice, Czech Republic;
| | - Alan H. Schulman
- Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland
- Institute of Biotechnology and Viikki Plant Science Centre, University of Helsinki, P.O. Box 65, FI-00014 Helsinki, Finland
- Correspondence: (R.K.); (A.H.S.)
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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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High-throughput retrotransposon-based genetic diversity of maize germplasm assessment and analysis. Mol Biol Rep 2020; 47:1589-1603. [PMID: 31919750 DOI: 10.1007/s11033-020-05246-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 01/03/2020] [Indexed: 01/08/2023]
Abstract
Maize is one of the world's most important crops and a model for grass genome research. Long terminal repeat (LTR) retrotransposons comprise most of the maize genome; their ability to produce new copies makes them efficient high-throughput genetic markers. Inter-retrotransposon-amplified polymorphisms (IRAPs) were used to study the genetic diversity of maize germplasm. Five LTR retrotransposons (Huck, Tekay, Opie, Ji, and Grande) were chosen, based on their large number of copies in the maize genome, whereas polymerase chain reaction primers were designed based on consensus LTR sequences. The LTR primers showed high quality and reproducible DNA fingerprints, with a total of 677 bands including 392 polymorphic bands showing 58% polymorphism between maize hybrid lines. These markers were used to identify genetic similarities among all lines of maize. Analysis of genetic similarity was carried out based on polymorphic amplicon profiles and genetic similarity phylogeny analysis. This diversity was expected to display ecogeographical patterns of variation and local adaptation. The clustering method showed that the varieties were grouped into three clusters differing in ecogeographical origin. Each of these clusters comprised divergent hybrids with convergent characters. The clusters reflected the differences among maize hybrids and were in accordance with their pedigree. The IRAP technique is an efficient high-throughput genetic marker-generating method.
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Kojima KK. Structural and sequence diversity of eukaryotic transposable elements. Genes Genet Syst 2019; 94:233-252. [DOI: 10.1266/ggs.18-00024] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Kenji K. Kojima
- Genetic Information Research Institute
- Department of Life Sciences, National Cheng Kung University
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Karyotype heterogeneity in Philodendron s.l. (Araceae) revealed by chromosome mapping of rDNA loci. PLoS One 2018; 13:e0207318. [PMID: 30440003 PMCID: PMC6237374 DOI: 10.1371/journal.pone.0207318] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 10/29/2018] [Indexed: 12/18/2022] Open
Abstract
Philodendron s.l. (Araceae) has been recently focus of taxonomic and phylogenetic studies, but karyotypic data are limited to chromosome numbers and a few published genome sizes. In this work, karyotypes of 34 species of Philodendron s.l. (29 species of Philodendron and five of Thaumatophyllum), ranging from 2n = 28 to 36 chromosomes, were analyzed by fluorescence in situ hybridization (FISH) with rDNA and telomeric probes, aiming to understand the evolution of the karyotype diversity of the group. Philodendron presented a high number variation of 35S rDNA, ranging from two to 16 sites, which were mostly in the terminal region of the short arms, with nine species presenting heteromorphisms. In the case of Thaumatophyllum species, we observed a considerably lower variation, which ranged from two to four terminal sites. The distribution of the 5S rDNA clusters was more conserved, with two sites for most species, being preferably located interstitially in the long chromosome arms. For the telomeric probe, while exclusively terminal sites were observed for P. giganteum (2n = 30) chromosomes, P. callosum (2n = 28) presented an interstitial distribution associated with satellite DNA. rDNA sites of the analyzed species of Philodendron s.l. species were randomly distributed considering the phylogenetic context, probably due to rapid evolution and great diversity of these genomes. The observed heteromorphisms suggest the accumulation of repetitive DNA in the genomes of some species and the occurrence of chromosomal rearrangements along the karyotype evolution of the group.
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Marakli S. Transferability of Barley Retrotransposons (Sukkula and Nikita) to Investigate Genetic Structure of Pimpinella anisum L. ACTA ACUST UNITED AC 2018. [DOI: 10.7240/marufbd.395068] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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28
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Joachimiak AJ, Hasterok R, Sliwinska E, Musiał K, Grabowska-Joachimiak A. FISH-aimed karyotype analysis in Aconitum subgen. Aconitum reveals excessive rDNA sites in tetraploid taxa. PROTOPLASMA 2018; 255. [PMID: 29541843 PMCID: PMC6133112 DOI: 10.1007/s00709-018-1238-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The location of 5S and 35S rDNA sequences in chromosomes of four Aconitum subsp. Aconitum species was analyzed after fluorescence in situ hybridization (FISH). Both in diploids (2n = 2x = 16; Aconitum variegatum, A. degenii) and tetraploids (2n = 4× = 32; A. firmum, A. plicatum), rDNA repeats were localized exclusively on the shorter arms of chromosomes, in subterminal or pericentromeric sites. All analyzed species showed similar basal genome size (Cx = 5.31-5.71 pg). The most striking features of tetraploid karyotypes were the conservation of diploid rDNA loci and emergence of many additional 5S rDNA clusters. Chromosomal distribution of excessive ribosomal sites suggests their role in the secondary diploidization of tetraploid karyotypes.
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Affiliation(s)
- Andrzej J Joachimiak
- Department of Plant Cytology and Embryology, Institute of Botany, Jagiellonian University, Gronostajowa 9, PL-30-387, Kraków, Poland.
| | - Robert Hasterok
- Department of Plant Anatomy and Cytology, University of Silesia in Katowice, Jagiellonska 28, 40-032, Katowice, Poland
| | - Elwira Sliwinska
- Laboratory of Molecular Biology and Cytometry, Department of Plant Genetics and Biotechnology, University of Technology and Life Sciences in Bydgoszcz, Kaliskiego 7, 85-789, Bydgoszcz, Poland
| | - Krystyna Musiał
- Department of Plant Cytology and Embryology, Institute of Botany, Jagiellonian University, Gronostajowa 9, PL-30-387, Kraków, Poland
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Tamayo-Ordóñez YJ, Narváez-Zapata JA, Tamayo-Ordóñez MC, Sánchez-Teyer LF. Retroelements and DNA Methylation Could Contribute to Diversity of 5S rDNA in Agave L. J Mol Evol 2018; 86:404-423. [DOI: 10.1007/s00239-018-9856-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 07/03/2018] [Indexed: 01/21/2023]
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Circular RNAs Biogenesis in Eukaryotes Through Self-Cleaving Hammerhead Ribozymes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1087:53-63. [PMID: 30259357 DOI: 10.1007/978-981-13-1426-1_5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Circular DNAs are frequent genomic molecules, especially among the simplest life beings, whereas circular RNAs have been regarded as weird nucleic acids in biology. Now we know that eukaryotes are able to express circRNAs, mostly derived from backsplicing mechanisms, and playing different biological roles such as regulation of RNA splicing and transcription, among others. However, a second natural and highly efficient pathway for the expression in vivo of circRNAs has been recently reported, which allows the accumulation of abundant small (100-1000 nt) non-coding RNA circles through the participation of small self-cleaving RNAs or ribozymes called hammerhead ribozymes. These genome-encoded circRNAs with ribozymes seem to be a new family of small and nonautonomous retrotransposable elements of plants and animals (so-called retrozymes), which will offer functional clues to the biology and evolution of circular RNA molecules as well as new biotechnological tools in this emerging field.
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Kalendar R, Amenov A, Daniyarov A. Use of retrotransposon-derived genetic markers to analyse genomic variability in plants. FUNCTIONAL PLANT BIOLOGY : FPB 2018; 46:15-29. [PMID: 30939255 DOI: 10.1071/fp18098] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 08/23/2018] [Indexed: 06/09/2023]
Abstract
Transposable elements (TEs) are common mobile genetic elements comprising several classes and making up the majority of eukaryotic genomes. The movement and accumulation of TEs has been a major force shaping the genes and genomes of most organisms. Most eukaryotic genomes are dominated by retrotransposons and minimal DNA transposon accumulation. The 'copy and paste' lifecycle of replicative transposition produces new genome insertions without excising the original element. Horizontal TE transfer among lineages is rare. TEs represent a reservoir of potential genomic instability and RNA-level toxicity. Many TEs appear static and nonfunctional, but some are capable of replicating and mobilising to new positions, and somatic transposition events have been observed. The overall structure of retrotransposons and the domains responsible for the phases of their replication are highly conserved in all eukaryotes. TEs are important drivers of species diversity and exhibit great variety in their structure, size and transposition mechanisms, making them important putative actors in evolution. Because TEs are abundant in plant genomes, various applications have been developed to exploit polymorphisms in TE insertion patterns, including conventional or anchored PCR, and quantitative or digital PCR with primers for the 5' or 3' junction. Alternatively, the retrotransposon junction can be mapped using high-throughput next-generation sequencing and bioinformatics. With these applications, TE insertions can be rapidly, easily and accurately identified, or new TE insertions can be found. This review provides an overview of the TE-based applications developed for plant species and assesses the contributions of TEs to the analysis of plants' genetic diversity.
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Affiliation(s)
- Ruslan Kalendar
- Department of Agricultural Sciences, PO Box 27 (Latokartanonkaari 5), FI-00014 University of Helsinki, Helsinki, Finland
| | - Asset Amenov
- RSE 'National Center for Biotechnology', 13/5 Kurgalzhynskoye Road, Astana, 010000, Kazakhstan
| | - Asset Daniyarov
- RSE 'National Center for Biotechnology', 13/5 Kurgalzhynskoye Road, Astana, 010000, Kazakhstan
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32
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Sergeeva EM, Shcherban AB, Adonina IG, Nesterov MA, Beletsky AV, Rakitin AL, Mardanov AV, Ravin NV, Salina EA. Fine organization of genomic regions tagged to the 5S rDNA locus of the bread wheat 5B chromosome. BMC PLANT BIOLOGY 2017; 17:183. [PMID: 29143604 PMCID: PMC5688495 DOI: 10.1186/s12870-017-1120-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
BACKGROUND The multigene family encoding the 5S rRNA, one of the most important structurally-functional part of the large ribosomal subunit, is an obligate component of all eukaryotic genomes. 5S rDNA has long been a favored target for cytological and phylogenetic studies due to the inherent peculiarities of its structural organization, such as the tandem arrays of repetitive units and their high interspecific divergence. The complex polyploid nature of the genome of bread wheat, Triticum aestivum, and the technically difficult task of sequencing clusters of tandem repeats mean that the detailed organization of extended genomic regions containing 5S rRNA genes remains unclear. This is despite the recent progress made in wheat genomic sequencing. Using pyrosequencing of BAC clones, in this work we studied the organization of two distinct 5S rDNA-tagged regions of the 5BS chromosome of bread wheat. RESULTS Three BAC-clones containing 5S rDNA were identified in the 5BS chromosome-specific BAC-library of Triticum aestivum. Using the results of pyrosequencing and assembling, we obtained six 5S rDNA- containing contigs with a total length of 140,417 bp, and two sets (pools) of individual 5S rDNA sequences belonging to separate, but closely located genomic regions on the 5BS chromosome. Both regions are characterized by the presence of approximately 70-80 copies of 5S rDNA, however, they are completely different in their structural organization. The first region contained highly diverged short-type 5S rDNA units that were disrupted by multiple insertions of transposable elements. The second region contained the more conserved long-type 5S rDNA, organized as a single tandem array. FISH using probes specific to both 5S rDNA unit types showed differences in the distribution and intensity of signals on the chromosomes of polyploid wheat species and their diploid progenitors. CONCLUSION A detailed structural organization of two closely located 5S rDNA-tagged genomic regions on the 5BS chromosome of bread wheat has been established. These two regions differ in the organization of both 5S rDNA and the neighboring sequences comprised of transposable elements, implying different modes of evolution for these regions.
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Affiliation(s)
- Ekaterina M Sergeeva
- The Federal Research Center "Institute of Cytology and Genetics SB RAS", Novosibirsk, Russia
| | - Andrey B Shcherban
- The Federal Research Center "Institute of Cytology and Genetics SB RAS", Novosibirsk, Russia.
| | - Irina G Adonina
- The Federal Research Center "Institute of Cytology and Genetics SB RAS", Novosibirsk, Russia
| | - Michail A Nesterov
- The Federal Research Center "Institute of Cytology and Genetics SB RAS", Novosibirsk, Russia
| | - Alexey V Beletsky
- The Federal Research Center "Fundamentals of Biotechnology RAS", Moscow, Russia
| | - Andrey L Rakitin
- The Federal Research Center "Fundamentals of Biotechnology RAS", Moscow, Russia
| | - Andrey V Mardanov
- The Federal Research Center "Fundamentals of Biotechnology RAS", Moscow, Russia
| | - Nikolai V Ravin
- The Federal Research Center "Fundamentals of Biotechnology RAS", Moscow, Russia
- Faculty of Biology, Moscow State University, Moscow, Russia
| | - Elena A Salina
- The Federal Research Center "Institute of Cytology and Genetics SB RAS", Novosibirsk, Russia
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Mascagni F, Cavallini A, Giordani T, Natali L. Different histories of two highly variable LTR retrotransposons in sunflower species. Gene 2017; 634:5-14. [PMID: 28867564 DOI: 10.1016/j.gene.2017.08.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 07/15/2017] [Accepted: 08/23/2017] [Indexed: 11/20/2022]
Abstract
In the Helianthus genus, very large intra- and interspecific variability related to two specific retrotransposons of Helianthus annuus (Helicopia and SURE) exists. When comparing these two sequences to sunflower sequence databases recently produced by our lab, the Helicopia family was shown to belong to the Maximus/SIRE lineage of the Sirevirus genus of the Copia superfamily, whereas the SURE element (whose superfamily was not even previously identified) was classified as a Gypsy element of the Ogre/Tat lineage of the Metavirus genus. Bioinformatic analysis of the two retrotransposon families revealed their genomic abundance and relative proliferation timing. The genomic abundance of these families differed significantly among 12 Helianthus species. The ratio between the abundance of long terminal repeats and their reverse transcriptases suggested that the SURE family has relatively more solo long terminal repeats than does Helicopia. Pairwise comparisons of Illumina reads encoding the reverse transcriptase domain indicated that SURE amplification may have occurred more recently than that of Helicopia. Finally, the analysis of population structure based on the SURE and Helicopia polymorphisms of 32 Helianthus species evidenced two subpopulations, which roughly corresponded to species of the Helianthus and Divaricati/Ciliares sections. However, a number of species showed an admixed structure, confirming the importance of interspecific hybridisation in the evolution of this genus. In general, these two retrotransposon families differentially contributed to interspecific variability, emphasising the need to refer to specific families when studying genome evolution.
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Affiliation(s)
- Flavia Mascagni
- Dept. of Agriculture, Food, and Environment, University of Pisa, Via delBorghetto 80, I-56124 Pisa, Italy
| | - Andrea Cavallini
- Dept. of Agriculture, Food, and Environment, University of Pisa, Via delBorghetto 80, I-56124 Pisa, Italy
| | - Tommaso Giordani
- Dept. of Agriculture, Food, and Environment, University of Pisa, Via delBorghetto 80, I-56124 Pisa, Italy
| | - Lucia Natali
- Dept. of Agriculture, Food, and Environment, University of Pisa, Via delBorghetto 80, I-56124 Pisa, Italy.
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Delgado A, Carvalho A, Martín AC, Martín A, Lima-Brito J. Genomic restructuring in F1 Hordeum chilense × durum wheat hybrids and corresponding hexaploid tritordeum lines revealed by DNA fingerprinting analyses. J Genet 2017; 96:e13-e23. [PMID: 28674217 DOI: 10.1007/s12041-017-0772-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Andreia Delgado
- University of Tras-os-Montes and Alto Douro, 5001-801Vila Real, Portugal.
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35
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Higher-order organisation of extremely amplified, potentially functional and massively methylated 5S rDNA in European pikes (Esox sp.). BMC Genomics 2017; 18:391. [PMID: 28521734 PMCID: PMC5437419 DOI: 10.1186/s12864-017-3774-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 05/09/2017] [Indexed: 12/16/2022] Open
Abstract
Background Pikes represent an important genus (Esox) harbouring a pre-duplication karyotype (2n = 2x = 50) of economically important salmonid pseudopolyploids. Here, we have characterized the 5S ribosomal RNA genes (rDNA) in Esox lucius and its closely related E. cisalpinus using cytogenetic, molecular and genomic approaches. Intragenomic homogeneity and copy number estimation was carried out using Illumina reads. The higher-order structure of rDNA arrays was investigated by the analysis of long PacBio reads. Position of loci on chromosomes was determined by FISH. DNA methylation was analysed by methylation-sensitive restriction enzymes. Results The 5S rDNA loci occupy exclusively (peri)centromeric regions on 30–38 acrocentric chromosomes in both E. lucius and E. cisalpinus. The large number of loci is accompanied by extreme amplification of genes (>20,000 copies), which is to the best of our knowledge one of the highest copy number of rRNA genes in animals ever reported. Conserved secondary structures of predicted 5S rRNAs indicate that most of the amplified genes are potentially functional. Only few SNPs were found in genic regions indicating their high homogeneity while intergenic spacers were more heterogeneous and several families were identified. Analysis of 10–30 kb-long molecules sequenced by the PacBio technology (containing about 40% of total 5S rDNA) revealed that the vast majority (96%) of genes are organised in large several kilobase-long blocks. Dispersed genes or short tandems were less common (4%). The adjacent 5S blocks were directly linked, separated by intervening DNA and even inverted. The 5S units differing in the intergenic spacers formed both homogeneous and heterogeneous (mixed) blocks indicating variable degree of homogenisation between the loci. Both E. lucius and E. cisalpinus 5S rDNA was heavily methylated at CG dinucleotides. Conclusions Extreme amplification of 5S rRNA genes in the Esox genome occurred in the absence of significant pseudogenisation suggesting its recent origin and/or intensive homogenisation processes. The dense methylation of units indicates that powerful epigenetic mechanisms have evolved in this group of fish to silence amplified genes. We discuss how the higher-order repeat structures impact on homogenisation of 5S rDNA in the genome. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3774-7) contains supplementary material, which is available to authorized users.
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FastPCR: An in silico tool for fast primer and probe design and advanced sequence analysis. Genomics 2017; 109:312-319. [PMID: 28502701 DOI: 10.1016/j.ygeno.2017.05.005] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 05/09/2017] [Accepted: 05/11/2017] [Indexed: 01/16/2023]
Abstract
Polymerase chain reaction (PCR) is one of the most important laboratory techniques used in molecular biology, genetics and molecular diagnostics. The success of a PCR-based method largely depends on the correct nucleic acid sequence analysis in silico prior to a wet-bench experiment. Here, we report the development of an online Java-based software for virtual PCR on linear or circular DNA templates and multiple primer or probe search from large or small databases. Primer or probe sensitivity and specificity are predicted by searching a database to find sequences with an optimal number of mismatches, similarity and stability. The software determines primer location, orientation, efficiency of binding and calculates primer melting temperatures for standard and degenerate oligonucleotides. The software is suitable for batch file processing, which is essential for automation when working with large amounts of data. The online Java software is available for download at http://primerdigital.com/tools/pcr.html. Accession numbers for the sequences resulting from this study: EU140956 EU177767 EU867815 EU882730 FJ975775-FJ975780 HM481419 HM481420 KC686837-KC686839 KM262797.
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Moraes AP, Koehler S, Cabral JS, Gomes SSL, Viccini LF, Barros F, Felix LP, Guerra M, Forni-Martins ER. Karyotype diversity and genome size variation in Neotropical Maxillariinae orchids. PLANT BIOLOGY (STUTTGART, GERMANY) 2017; 19:298-308. [PMID: 27917576 DOI: 10.1111/plb.12527] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 11/28/2016] [Indexed: 06/06/2023]
Abstract
Orchidaceae is a widely distributed plant family with very diverse vegetative and floral morphology, and such variability is also reflected in their karyotypes. However, since only a low proportion of Orchidaceae has been analysed for chromosome data, greater diversity may await to be unveiled. Here we analyse both genome size (GS) and karyotype in two subtribes recently included in the broadened Maxillariinea to detect how much chromosome and GS variation there is in these groups and to evaluate which genome rearrangements are involved in the species evolution. To do so, the GS (14 species), the karyotype - based on chromosome number, heterochromatic banding and 5S and 45S rDNA localisation (18 species) - was characterised and analysed along with published data using phylogenetic approaches. The GS presented a high phylogenetic correlation and it was related to morphological groups in Bifrenaria (larger plants - higher GS). The two largest GS found among genera were caused by different mechanisms: polyploidy in Bifrenaria tyrianthina and accumulation of repetitive DNA in Scuticaria hadwenii. The chromosome number variability was caused mainly through descending dysploidy, and x=20 was estimated as the base chromosome number. Combining GS and karyotype data with molecular phylogeny, our data provide a more complete scenario of the karyotype evolution in Maxillariinae orchids, allowing us to suggest, besides dysploidy, that inversions and transposable elements as two mechanisms involved in the karyotype evolution. Such karyotype modifications could be associated with niche changes that occurred during species evolution.
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Affiliation(s)
- A P Moraes
- Departamento de Biologia Vegetal, Instituto de Biociências, Universidade Estadual de Campinas, Campinas, Brazil
- Departamento de Genética, Instituto de Biociências, Universidade Estadual Paulista Julio de Mesquita Filho, Botucatu, Brazil
- Instituto de Ciências e Tecnologia, Universidade Federal de São Paulo, São José dos Campos, Brazil
| | - S Koehler
- Departamento de Biologia Vegetal, Instituto de Biociências, Universidade Estadual de Campinas, Campinas, Brazil
| | - J S Cabral
- Departamento de Botânica, Centro de Ciências Biológicas, Cidade Universitária, Universidade Federal de Pernambuco, Recife, Brazil
- Synthesis Centre, German Centre for Integrative Biodiversity Research, Leipzig, Germany
- Center for Computational and Theoretical Biology, Ecosystem Modeling, University of Würzburg, Würzburg, Germany
| | - S S L Gomes
- Departamento de Biologia, Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora, Juiz de Fora, Brazil
| | - L F Viccini
- Departamento de Biologia, Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora, Juiz de Fora, Brazil
| | - F Barros
- Instituto de Botânica, Núcleo de Pesquisa Orquidário do Estado de São Paulo, São Paulo, Brazil
| | - L P Felix
- Departamento de Ciências Biológicas, Centro de Ciências Agrárias, Universidade Federal da Paraíba, Rodovia, Areias, Brazil
| | - M Guerra
- Departamento de Botânica, Centro de Ciências Biológicas, Cidade Universitária, Universidade Federal de Pernambuco, Recife, Brazil
| | - E R Forni-Martins
- Departamento de Biologia Vegetal, Instituto de Biociências, Universidade Estadual de Campinas, Campinas, Brazil
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Yu S, Lemos B. A Portrait of Ribosomal DNA Contacts with Hi-C Reveals 5S and 45S rDNA Anchoring Points in the Folded Human Genome. Genome Biol Evol 2016; 8:3545-3558. [PMID: 27797956 PMCID: PMC5203791 DOI: 10.1093/gbe/evw257] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Ribosomal RNAs (rRNAs) account for >60% of all RNAs in eukaryotic cells and are encoded in the ribosomal DNA (rDNA) arrays. The rRNAs are produced from two sets of loci: the 5S rDNA array resides exclusively on human chromosome 1, whereas the 45S rDNA array resides on the short arm of five human acrocentric chromosomes. The 45S rDNA gives origin to the nucleolus, the nuclear organelle that is the site of ribosome biogenesis. Intriguingly, 5S and 45S rDNA arrays exhibit correlated copy number variation in lymphoblastoid cells (LCLs). Here we examined the genomic architecture and repeat content of the 5S and 45S rDNA arrays in multiple human genome assemblies (including PacBio MHAP assembly) and ascertained contacts between the rDNA arrays and the rest of the genome using Hi-C datasets from two human cell lines (erythroleukemia K562 and lymphoblastoid cells). Our analyses revealed that 5S and 45S arrays each have thousands of contacts in the folded genome, with rDNA-associated regions and genes dispersed across all chromosomes. The rDNA contact map displayed conserved and disparate features between two cell lines, and pointed to specific chromosomes, genomic regions, and genes with evidence of spatial proximity to the rDNA arrays; the data also showed a lack of direct physical interaction between the 5S and 45S rDNA arrays. Finally, the analysis identified an intriguing organization in the 5S array with Alu and 5S elements adjacent to one another and organized in opposite orientation along the array. Portraits of genome folding centered on the ribosomal DNA array could help understand the emergence of concerted variation, the control of 5S and 45S expression, as well as provide insights into an organelle that contributes to the spatial localization of human chromosomes during interphase.
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Affiliation(s)
- Shoukai Yu
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
| | - Bernardo Lemos
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
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39
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Mahjoob B, Zarini HN, Hashemi SH, Shamasbi FV. Comparison of ISSR, IRAP and REMAP markers for assessing genetic diversity in different species of Brassica sp. RUSS J GENET+ 2016. [DOI: 10.1134/s1022795416120073] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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40
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Fawcett JA, Innan H. High Similarity between Distantly Related Species of a Plant SINE Family Is Consistent with a Scenario of Vertical Transmission without Horizontal Transfers. Mol Biol Evol 2016; 33:2593-604. [PMID: 27436006 DOI: 10.1093/molbev/msw130] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Many transposable element (TE) families show surprisingly high levels of similarity between distantly related species. This high similarity, coupled with a "patchy" phylogenetic distribution, has often been attributed to frequent horizontal transfers of TEs between species, even though the mechanistic basis tends to be speculative. Here, we studied the evolution of the Au SINE (Short INterspersed Element) family, in which high similarity between distantly related plant species has been reported. We were able to identify several copies present in orthologous regions of various species, including species that diverged ∼90 Ma, thereby confirming the presence of Au SINE at multiple evolutionary time points. We also found that the Au SINE has been degenerating and is en route to disappearing in many species, indicating that the loss of Au SINE is common. Our results suggest that the evolution of the Au SINE can be readily explained by a scenario of vertical transmission without having to invoke hypothetical scenarios of rampant horizontal transfers. The Au SINE was likely present in the common ancestor of all angiosperms and was retained in some lineages while lost from others. The high level of conservation is probably because the sequences were important for ensuring their transpositional activity. This model of TE evolution should provide a basic framework for understanding the evolution of TEs in general.
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Affiliation(s)
- Jeffrey A Fawcett
- SOKENDAI (The Graduate University for Advanced Studies), Hayama, Kanagawa, Japan
| | - Hideki Innan
- SOKENDAI (The Graduate University for Advanced Studies), Hayama, Kanagawa, Japan
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41
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Gao D, Li Y, Kim KD, Abernathy B, Jackson SA. Landscape and evolutionary dynamics of terminal repeat retrotransposons in miniature in plant genomes. Genome Biol 2016; 17:7. [PMID: 26781660 PMCID: PMC4717578 DOI: 10.1186/s13059-015-0867-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 12/29/2015] [Indexed: 12/05/2022] Open
Abstract
Background Terminal repeat retrotransposons in miniature (TRIMs) are a unique group of small long terminal repeat retrotransposons that are difficult to identify. Thus far, only a few TRIMs have been characterized in the euphyllophytes, and their evolutionary and biological significance as well as their transposition mechanisms are poorly understood. Results Using a combination of de novo and homology-based methods, we annotate TRIMs in 48 plant genome sequences, spanning land plants to algae. The TRIMs are grouped into 156 families including 145 that were previously undefined. Notably, we identify the first TRIMs in a lycophyte and non-vascular plants. The majority of the TRIM families are highly conserved and shared within and between plant families. Unlike other long terminal repeat retrotransposons, TRIMs are enriched in or near genes; they are also targeted by sRNAs between 21 and 24 nucleotides in length, and are frequently found in CG body-methylated genes. Importantly, we also identify putative autonomous retrotransposons and very recent transpositions of a TRIM element in Oryza sativa. Conclusions We perform the most comprehensive analysis of TRIM transposons thus far and report that TRIMs are ubiquitous across plant genomes. Our results show that TRIMs are more frequently associated with large and CG body-methylated genes that have undergone strong purifying selection. Our findings also indicate that TRIMs are likely derived from internal deletions of large long terminal repeat retrotransposons. Finally, our data and methodology are important resources for the characterization and evolutionary and genomic studies of long terminal repeat retrotransposons in other genomes. Electronic supplementary material The online version of this article (doi:10.1186/s13059-015-0867-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dongying Gao
- Center for Applied Genetic Technologies, University of Georgia, 111 Riverbend Road, Athens, GA, 30602, USA.
| | - Yupeng Li
- Center for Applied Genetic Technologies, University of Georgia, 111 Riverbend Road, Athens, GA, 30602, USA.
| | - Kyung Do Kim
- Center for Applied Genetic Technologies, University of Georgia, 111 Riverbend Road, Athens, GA, 30602, USA.
| | - Brian Abernathy
- Center for Applied Genetic Technologies, University of Georgia, 111 Riverbend Road, Athens, GA, 30602, USA.
| | - Scott A Jackson
- Center for Applied Genetic Technologies, University of Georgia, 111 Riverbend Road, Athens, GA, 30602, USA.
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Šurbanovski N, Brilli M, Moser M, Si-Ammour A. A highly specific microRNA-mediated mechanism silences LTR retrotransposons of strawberry. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 85:70-82. [PMID: 26611654 DOI: 10.1111/tpj.13090] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 11/06/2015] [Accepted: 11/20/2015] [Indexed: 06/05/2023]
Abstract
Small RNAs are involved in a plethora of functions in plant genomes. In general, transcriptional gene silencing is mediated by 24-nucleotide siRNAs and is required for maintaining transposable elements in a silenced state. However, microRNAs are not commonly associated with transposon silencing. In this study, we performed small RNA transcriptome and degradome analyses of the Rosaceae model plant Fragaria vesca (the woodland strawberry) at the genome-wide level, and identified miRNA families and their targets. We report a highly specific mechanism of LTR retrotransposon silencing mediated by an abundant, ubiquitously expressed miRNA (fve-miR1511) generated from a single locus. This miRNA specifically targets LTR retroelements, silencing them post-transcriptionally by perfectly pairing to the highly conserved primer binding site for methionyl initiator tRNA that is essential for reverse transcription. We investigated the possible origins of this miRNA, and present evidence that the pre-miR1511 hairpin structure probably derived from a locus coding for tRNA(iM) (et) through a single microinversion event. Our study shows that this miRNA targets retrotransposons specifically and constitutively, and contributes to features such as genome stability, size and architecture in a far more direct way than previously thought.
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Affiliation(s)
- Nada Šurbanovski
- Functional Genomics, Department of Genomics and Biology of Fruit Crops, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, San Michele all' Adige, 38010, Italy
| | - Matteo Brilli
- Functional Genomics, Department of Genomics and Biology of Fruit Crops, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, San Michele all' Adige, 38010, Italy
| | - Mirko Moser
- Functional Genomics, Department of Genomics and Biology of Fruit Crops, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, San Michele all' Adige, 38010, Italy
| | - Azeddine Si-Ammour
- Functional Genomics, Department of Genomics and Biology of Fruit Crops, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, San Michele all' Adige, 38010, Italy
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Zhao D, Ferguson AA, Jiang N. What makes up plant genomes: The vanishing line between transposable elements and genes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1859:366-80. [PMID: 26709091 DOI: 10.1016/j.bbagrm.2015.12.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 12/09/2015] [Accepted: 12/11/2015] [Indexed: 02/07/2023]
Abstract
The ultimate source of evolution is mutation. As the largest component in plant genomes, transposable elements (TEs) create numerous types of mutations that cannot be mimicked by other genetic mechanisms. When TEs insert into genomic sequences, they influence the expression of nearby genes as well as genes unlinked to the insertion. TEs can duplicate, mobilize, and recombine normal genes or gene fragments, with the potential to generate new genes or modify the structure of existing genes. TEs also donate their transposase coding regions for cellular functions in a process called TE domestication. Despite the host defense against TE activity, a subset of TEs survived and thrived through discreet selection of transposition activity, target site, element size, and the internal sequence. Finally, TEs have established strategies to reduce the efficacy of host defense system by increasing the cost of silencing TEs. This review discusses the recent progress in the area of plant TEs with a focus on the interaction between TEs and genes.
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Affiliation(s)
- Dongyan Zhao
- Department of Horticulture, Michigan State University, 1066 Bogue Street, East Lansing, MI 48824, USA
| | - Ann A Ferguson
- Department of Horticulture, Michigan State University, 1066 Bogue Street, East Lansing, MI 48824, USA
| | - Ning Jiang
- Department of Horticulture, Michigan State University, 1066 Bogue Street, East Lansing, MI 48824, USA.
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Yin H, Du J, Wu J, Wei S, Xu Y, Tao S, Wu J, Zhang S. Genome-wide Annotation and Comparative Analysis of Long Terminal Repeat Retrotransposons between Pear Species of P. bretschneideri and P. Communis. Sci Rep 2015; 5:17644. [PMID: 26631625 PMCID: PMC4668562 DOI: 10.1038/srep17644] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 11/03/2015] [Indexed: 12/02/2022] Open
Abstract
Recent sequencing of the Oriental pear (P. bretschneideri Rehd.) genome and the availability of the draft genome sequence of Occidental pear (P. communis L.), has provided a good opportunity to characterize the abundance, distribution, timing, and evolution of long terminal repeat retrotransposons (LTR-RTs) in these two important fruit plants. Here, a total of 7247 LTR-RTs, which can be classified into 148 families, have been identified in the assembled Oriental pear genome. Unlike in other plant genomes, approximately 90% of these elements were found to be randomly distributed along the pear chromosomes. Further analysis revealed that the amplification timeframe of elements varies dramatically in different families, super-families and lineages, and the Copia-like elements have highest activity in the recent 0.5 million years (Mys). The data also showed that two genomes evolved with similar evolutionary rates after their split from the common ancestor ~0.77–1.66 million years ago (Mya). Overall, the data provided here will be a valuable resource for further investigating the impact of transposable elements on gene structure, expression, and epigenetic modification in the pear genomes.
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Affiliation(s)
- Hao Yin
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China
| | - Jianchang Du
- Institute of Biotechnology, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, Jiangsu, China
| | - Jun Wu
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China
| | - Shuwei Wei
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China
| | - Yingxiu Xu
- Institute of Biotechnology, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, Jiangsu, China
| | - Shutian Tao
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China
| | - Juyou Wu
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China
| | - Shaoling Zhang
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China
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Roa F, Guerra M. Non-Random Distribution of 5S rDNA Sites and Its Association with 45S rDNA in Plant Chromosomes. Cytogenet Genome Res 2015; 146:243-9. [PMID: 26489031 DOI: 10.1159/000440930] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2015] [Indexed: 11/19/2022] Open
Abstract
5S and 45S rDNA sites are the best mapped chromosome regions in eukaryotic chromosomes. In this work, a database was built gathering information about the position and number of 5S rDNA sites in 784 plant species, aiming to identify patterns of distribution along the chromosomes and its correlation with the position of 45S rDNA sites. Data revealed that in most karyotypes (54.5%, including polyploids) two 5S rDNA sites (a single pair) are present, with 58.7% of all sites occurring in the short arm, mainly in the proximal region. In karyotypes of angiosperms with only 1 pair of sites (single sites) they are mostly found in the proximal region (52.0%), whereas in karyotypes with multiple sites the location varies according to the average chromosome size. Karyotypes with multiple sites and small chromosomes (<3 µm) often display proximal sites, while medium-sized (between 3 and 6 µm) and large chromosomes (>6 µm) more commonly show terminal or interstitial sites. In species with holokinetic chromosomes, the modal value of sites per karyotype was also 2, but they were found mainly in a terminal position. Adjacent 5S and 45S rDNA sites were often found in the short arm, reflecting the preferential distribution of both sites in this arm. The high frequency of genera with at least 1 species with adjacent 5S and 45S sites reveals that this association appeared several times during angiosperm evolution, but it has been maintained only rarely as the dominant array in plant genera.
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Koziol U, Radio S, Smircich P, Zarowiecki M, Fernández C, Brehm K. A Novel Terminal-Repeat Retrotransposon in Miniature (TRIM) Is Massively Expressed in Echinococcus multilocularis Stem Cells. Genome Biol Evol 2015; 7:2136-53. [PMID: 26133390 PMCID: PMC4558846 DOI: 10.1093/gbe/evv126] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2015] [Indexed: 12/14/2022] Open
Abstract
Taeniid cestodes (including the human parasites Echinococcus spp. and Taenia solium) have very few mobile genetic elements (MGEs) in their genome, despite lacking a canonical PIWI pathway. The MGEs of these parasites are virtually unexplored, and nothing is known about their expression and silencing. In this work, we report the discovery of a novel family of small nonautonomous long terminal repeat retrotransposons (also known as terminal-repeat retrotransposons in miniature, TRIMs) which we have named ta-TRIM (taeniid TRIM). ta-TRIMs are only the second family of TRIM elements discovered in animals, and are likely the result of convergent reductive evolution in different taxonomic groups. These elements originated at the base of the taeniid tree and have expanded during taeniid diversification, including after the divergence of closely related species such as Echinococcus multilocularis and Echinococcus granulosus. They are massively expressed in larval stages, from a small proportion of full-length copies and from isolated terminal repeats that show transcriptional read-through into downstream regions, generating novel noncoding RNAs and transcriptional fusions to coding genes. In E. multilocularis, ta-TRIMs are specifically expressed in the germinative cells (the somatic stem cells) during asexual reproduction of metacestode larvae. This would provide a developmental mechanism for insertion of ta-TRIMs into cells that will eventually generate the adult germ line. Future studies of active and inactive ta-TRIM elements could give the first clues on MGE silencing mechanisms in cestodes.
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Affiliation(s)
- Uriel Koziol
- Institute of Hygiene and Microbiology, University of Würzburg, Germany Sección Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Santiago Radio
- Laboratorio de Interacciones Moleculares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay Departamento de Genética, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Pablo Smircich
- Laboratorio de Interacciones Moleculares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay Departamento de Genética, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Magdalena Zarowiecki
- Parasite Genomics, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Cecilia Fernández
- Cátedra de Inmunología, Facultad de Química, Universidad de la República, Montevideo, Uruguay
| | - Klaus Brehm
- Institute of Hygiene and Microbiology, University of Würzburg, Germany
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The Wukong Terminal-Repeat Retrotransposon in Miniature (TRIM) Elements in Diverse Maize Germplasm. G3-GENES GENOMES GENETICS 2015; 5:1585-92. [PMID: 26019188 PMCID: PMC4528315 DOI: 10.1534/g3.115.018317] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
TRIMs (terminal-repeat retrotransposons in miniature), which are characterized by their small size, have been discovered in all investigated vascular plants and even in animals. Here, we identified a highly conservative TRIM family referred to as Wukong elements in the maize genome. The Wukong family shows a distinct pattern of tandem arrangement in the maize genome suggesting a high rate of unequal crossing over. Estimation of insertion times implies a burst of retrotransposition activity of the Wukong family after the allotetraploidization of maize. Using next-generation sequencing data, we detected 87 new Wukong insertions in parents of the maize NAM population relative to the B73 reference genome and found abundant insertion polymorphism of Wukong elements in 75 re-sequenced maize lines, including teosinte, landraces, and improved lines. These results suggest that Wukong elements possessed a persistent retrotransposition activity throughout maize evolution. Moreover, the phylogenetic relationships among 76 maize inbreds and their relatives based on insertion polymorphisms of Wukong elements should provide us with reliable molecular markers for biodiversity and genetics studies.
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48
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Zuccolo A, Scofield DG, De Paoli E, Morgante M. The Ty1-copia LTR retroelement family PARTC is highly conserved in conifers over 200 MY of evolution. Gene 2015; 568:89-99. [PMID: 25982862 DOI: 10.1016/j.gene.2015.05.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 04/06/2015] [Accepted: 05/11/2015] [Indexed: 11/26/2022]
Abstract
Long Terminal Repeat retroelements (LTR-RTs) are a major component of many plant genomes. Although well studied and described in angiosperms, their features and dynamics are poorly understood in gymnosperms. Representative complete copies of a Ty1-copia element isolate in Picea abies and named PARTC were identified in six other conifer species (Picea glauca, Pinus sylvestris, Pinus taeda, Abies sibirica, Taxus baccata and Juniperus communis) covering more than 200 million years of evolution. Here we characterized the structure of this element, assessed its abundance across conifers, studied the modes and timing of its amplification, and evaluated the degree of conservation of its extant copies at nucleotide level over distant species. We demonstrated that the element is ancient, abundant, widespread and its paralogous copies are present in the genera Picea, Pinus and Abies as an LTR-RT family. The amplification leading to the extant copies of PARTC occurred over long evolutionary times spanning 10s of MY and mostly took place after the speciation of the conifers analyzed. The level of conservation of PARTC is striking and may be explained by low substitution rates and limited removal mechanisms for LTR-RTs. These PARTC features and dynamics are representative of a more general scenario for LTR-RTs in gymnosperms quite different from that characterizing the vast majority of LTR-RT elements in angiosperms.
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Affiliation(s)
- Andrea Zuccolo
- Institute of Life Sciences, Scuola Superiore Sant'Anna, 56127 Pisa, Italy; Istituto di Genomica Applicata, Via J. Linussio 51, 33100 Udine, Italy.
| | - Douglas G Scofield
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, SE-75236 Uppsala, Sweden
| | - Emanuele De Paoli
- Università degli Studi di Udine, Via delle Scienze 208, 33100 Udine, Italy
| | - Michele Morgante
- Istituto di Genomica Applicata, Via J. Linussio 51, 33100 Udine, Italy; Università degli Studi di Udine, Via delle Scienze 208, 33100 Udine, Italy
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Ozheredova IP, Parnikoza IY, Poronnik OO, Kozeretska IA, Demidov SV, Kunakh VA. Mechanisms of antarctic vascular plant adaptation to abiotic environmental factors. CYTOL GENET+ 2015. [DOI: 10.3103/s0095452715020085] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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50
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Chaparro C, Gayraud T, de Souza RF, Domingues DS, Akaffou S, Laforga Vanzela AL, Kochko AD, Rigoreau M, Crouzillat D, Hamon S, Hamon P, Guyot R. Terminal-repeat retrotransposons with GAG domain in plant genomes: a new testimony on the complex world of transposable elements. Genome Biol Evol 2015; 7:493-504. [PMID: 25573958 PMCID: PMC4350172 DOI: 10.1093/gbe/evv001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
A novel structure of nonautonomous long terminal repeat (LTR) retrotransposons called terminal repeat with GAG domain (TR-GAG) has been described in plants, both in monocotyledonous, dicotyledonous and basal angiosperm genomes. TR-GAGs are relatively short elements in length (<4 kb) showing the typical features of LTR-retrotransposons. However, they carry only one open reading frame coding for the GAG precursor protein involved for instance in transposition, the assembly, and the packaging of the element into the virus-like particle. GAG precursors show similarities with both Copia and Gypsy GAG proteins, suggesting evolutionary relationships of TR-GAG elements with both families. Despite the lack of the enzymatic machinery required for their mobility, strong evidences suggest that TR-GAGs are still active. TR-GAGs represent ubiquitous nonautonomous structures that could be involved in the molecular diversities of plant genomes.
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Affiliation(s)
- Cristian Chaparro
- 2EI UMR5244 Université de Perpignan Via Domitia, UMR 5244 CNRS Ecologie et Evolution des Interactions (2EI), Perpignan, France
| | - Thomas Gayraud
- Institut de Recherche pour le Développement (IRD), UMR DIADE (CIRAD, IRD, UM2), Montpellier, France
| | | | - Douglas Silva Domingues
- Departamento de Botanica, Instituto de Biociencias, Univ Estadual Paulista, UNESP, Rio Claro, SP, Brazil
| | | | | | - Alexandre de Kochko
- Institut de Recherche pour le Développement (IRD), UMR DIADE (CIRAD, IRD, UM2), Montpellier, France
| | | | | | - Serge Hamon
- Institut de Recherche pour le Développement (IRD), UMR DIADE (CIRAD, IRD, UM2), Montpellier, France
| | - Perla Hamon
- Institut de Recherche pour le Développement (IRD), UMR DIADE (CIRAD, IRD, UM2), Montpellier, France
| | - Romain Guyot
- Institut de Recherche pour le Développement (IRD), UMR IPME, Montpellier, France
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