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Annotation of Siberian Larch (Larix sibirica Ledeb.) Nuclear Genome—One of the Most Cold-Resistant Tree Species in the Only Deciduous GENUS in Pinaceae. PLANTS 2022; 11:plants11152062. [PMID: 35956540 PMCID: PMC9370799 DOI: 10.3390/plants11152062] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 07/22/2022] [Accepted: 07/26/2022] [Indexed: 11/17/2022]
Abstract
The recent release of the nuclear, chloroplast and mitochondrial genome assemblies of Siberian larch (Larix sibirica Ledeb.), one of the most cold-resistant tree species in the only deciduous genus of Pinaceae, with seasonal senescence and a rot-resistant valuable timber widely used in construction, greatly contributed to the development of genomic resources for the larch genus. Here, we present an extensive repeatome analysis and the first annotation of the draft nuclear Siberian larch genome assembly. About 66% of the larch genome consists of highly repetitive elements (REs), with the likely wave of retrotransposons insertions into the larch genome estimated to occur 4–5 MYA. In total, 39,370 gene models were predicted, with 87% of them having homology to the Arabidopsis-annotated proteins and 78% having at least one GO term assignment. The current state of the genome annotations allows for the exploration of the gymnosperm and angiosperm species for relative gene abundance in different functional categories. Comparative analysis of functional gene categories across different angiosperm and gymnosperm species finds that the Siberian larch genome has an overabundance of genes associated with programmed cell death (PCD), autophagy, stress hormone biosynthesis and regulatory pathways; genes that may play important roles in seasonal senescence and stress response to extreme cold in larch. Despite being incomplete, the draft assemblies and annotations of the conifer genomes are at a point of development where they now represent a valuable source for further genomic, genetic and population studies.
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2
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Sattler MC, de Oliveira SC, Mendonça MAC, Clarindo WR. Coffea cytogenetics: from the first karyotypes to the meeting with genomics. PLANTA 2022; 255:112. [PMID: 35501619 DOI: 10.1007/s00425-022-03898-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 04/11/2022] [Indexed: 06/14/2023]
Abstract
Coffea karyotype organization and evolution has been uncovered by classical cytogenetics and cytogenomics. We revisit these discoveries and present new karyotype data. Coffea possesses ~ 124 species, including C. arabica and C. canephora responsible for commercial coffee production. We reviewed the Coffea cytogenetics, from the first chromosome counting, encompassing the karyotype characterization, chromosome DNA content, and mapping of chromosome portions and DNA sequences, until the integration with genomics. We also showed new data about Coffea karyotype. The 2n chromosome number evidenced the diploidy of almost all Coffea, and the C. arabica tetraploidy, as well as the polyploidy of other hybrids. Since then, other genomic similarities and divergences among the Coffea have been shown by karyotype morphology, nuclear and chromosomal C-value, AT and GC rich chromosome portions, and repetitive sequence and gene mapping. These cytogenomic data allowed us to know and understand the phylogenetic relations in Coffea, as well as their ploidy level and genomic origin, highlighting the relatively recent allopolyploidy. In addition to the euploidy, the role of the mobile elements in Coffea diversification is increasingly more evident, and the comparative analysis of their structure and distribution on the genome of different species is in the spotlight for future research. An integrative look at all these data is fundamental for a deeper understanding of Coffea karyotype evolution, including the key role of polyploidy in C. arabica origin. The 'Híbrido de Timor', a recent natural allotriploid, is also in the spotlight for its potential as a source of resistance genes and model for plant polyploidy research. Considering this, we also present some unprecedented results about the exciting evolutionary history of these polyploid Coffea.
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Affiliation(s)
- Mariana Cansian Sattler
- Laboratório de Citogenética e Citometria, Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa, MG, ZIP 36.570-900, Brazil.
| | - Stéfanie Cristina de Oliveira
- Laboratório de Citogenética e Cultura de Tecidos Vegetais, Campus de Alegre, Universidade Federal Do Espírito Santo, Alegre, ES, ZIP 29.500-000, Brazil
| | | | - Wellington Ronildo Clarindo
- Laboratório de Citogenética e Citometria, Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa, MG, ZIP 36.570-900, Brazil
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Oberlin S, Rajeswaran R, Trasser M, Barragán-Borrero V, Schon MA, Plotnikova A, Loncsek L, Nodine MD, Marí-Ordóñez A, Voinnet O. Innate, translation-dependent silencing of an invasive transposon in Arabidopsis. EMBO Rep 2021; 23:e53400. [PMID: 34931432 PMCID: PMC8892269 DOI: 10.15252/embr.202153400] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 12/05/2021] [Accepted: 12/06/2021] [Indexed: 11/25/2022] Open
Abstract
Co‐evolution between hosts’ and parasites’ genomes shapes diverse pathways of acquired immunity based on silencing small (s)RNAs. In plants, sRNAs cause heterochromatinization, sequence degeneration, and, ultimately, loss of autonomy of most transposable elements (TEs). Recognition of newly invasive plant TEs, by contrast, involves an innate antiviral‐like silencing response. To investigate this response’s activation, we studied the single‐copy element EVADÉ (EVD), one of few representatives of the large Ty1/Copia family able to proliferate in Arabidopsis when epigenetically reactivated. In Ty1/Copia elements, a short subgenomic mRNA (shGAG) provides the necessary excess of structural GAG protein over the catalytic components encoded by the full‐length genomic flGAG‐POL. We show here that the predominant cytosolic distribution of shGAG strongly favors its translation over mostly nuclear flGAG‐POL. During this process, an unusually intense ribosomal stalling event coincides with mRNA breakage yielding unconventional 5’OH RNA fragments that evade RNA quality control. The starting point of sRNA production by RNA‐DEPENDENT‐RNA‐POLYMERASE‐6 (RDR6), exclusively on shGAG, occurs precisely at this breakage point. This hitherto‐unrecognized “translation‐dependent silencing” (TdS) is independent of codon usage or GC content and is not observed on TE remnants populating the Arabidopsis genome, consistent with their poor association, if any, with polysomes. We propose that TdS forms a primal defense against EVD de novo invasions that underlies its associated sRNA pattern.
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Affiliation(s)
- Stefan Oberlin
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
| | - Rajendran Rajeswaran
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
| | - Marieke Trasser
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria.,Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Verónica Barragán-Borrero
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.,Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Michael A Schon
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Alexandra Plotnikova
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Lukas Loncsek
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Michael D Nodine
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria.,Laboratory of Molecular Biology, Wageningen University, Wageningen, The Netherlands
| | - Arturo Marí-Ordóñez
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.,Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Olivier Voinnet
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
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4
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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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Malaviya DR, Roy AK, Kaushal P, Pathak S, Kalendar R. Phenotype study of multifoliolate leaf formation in Trifolium alexandrinum L. PeerJ 2021; 9:e10874. [PMID: 33717683 PMCID: PMC7936568 DOI: 10.7717/peerj.10874] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 01/11/2021] [Indexed: 12/02/2022] Open
Abstract
Background The genus Trifolium is characterized by typical trifoliolate leaves. Alterations in leaf formats from trifoliolate to multifoliolate, i.e., individual plants bearing trifoliolate, quadrifoliolate, pentafoliolate or more leaflets, were previously reported among many species of the genus. The study is an attempt to develop pure pentafoliolate plants of T. alexandrinum and to understand its genetic control. Methods The experimental material consisted of two populations of T. alexandrinum with multifoliolate leaf expression, i.e.,interspecific hybrid progenies of T. alexandrinum with T. apertum, and T. alexandrinum genotype Penta-1. Penetrance of the multifoliolate trait was observed among multifoliolate and trifoliolate plant progenies. In vitro culture and regeneration of plantlets from the axillary buds from different plant sources was also attempted. Results The inheritance among a large number of plant progenies together with in vitro micro-propagation results did not establish a definite pattern. The multifoliolate leaf formation was of chimeric nature, i.e., more than one leaf format appearing on individual branches. Reversal to normal trifoliolate from multifoliolate was also quite common. Penetrance and expression of multifoliolate leaf formation was higher among the plants raised from multifoliolate plants. Multifoliolate and pure pentafoliolate plants were observed in the progenies of pure trifoliolate plants and vice-versa. There was an apparent increase in the pentafoliolate leaf formation frequency over the years due to targeted selection. A few progenies of the complete pentafoliolate plants in the first year were true breeding in the second year. Frequency of plantlets with multifoliolate leaf formation was also higher in in vitro axillary bud multiplication when the explant bud was excised from the multifoliolate leaf node. Conclusion Number of leaflets being a discrete variable, occurrence of multifoliolate leaves on individual branches, reversal of leaf formats on branches and developing true breeding pentafoliolates were the factors leading to a hypothesis beyond normal Mendelian inheritance. Transposable elements (TEs) involved in leaf development in combination with epigenetics were probably responsible for alterations in the expression of leaflet number. Putative TE’s movement owing to chromosomal rearrangements possibly resulted in homozygous pentafoliolate trait with evolutionary significance. The hypothesis provides a new insight into understanding the genetic control of this trait in T. alexandrinum and may also be useful in other Trifolium species where such observations are reported.
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Affiliation(s)
- Devendra Ram Malaviya
- ICAR - Indian Institute of Sugarcane Research, Lucknow, India.,ICAR - Indian Grassland and Fodder Research Institute, Jhansi, India
| | - Ajoy Kumar Roy
- ICAR - Indian Grassland and Fodder Research Institute, Jhansi, India
| | - Pankaj Kaushal
- ICAR - Indian Grassland and Fodder Research Institute, Jhansi, India.,ICAR - National Institute of Biotic Stress Management, Raipur, India
| | - Shalini Pathak
- ICAR - Indian Grassland and Fodder Research Institute, Jhansi, India
| | - Ruslan Kalendar
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Uusimaa, Finland.,National Laboratory Astana, Nazarbayev University, Nur-Sultan, Aqmola, Kazakhstan
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6
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Giraud D, Lima O, Huteau V, Coriton O, Boutte J, Kovarik A, Leitch AR, Leitch IJ, Aïnouche M, Salmon A. Evolutionary dynamics of transposable elements and satellite DNAs in polyploid Spartina species. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 302:110671. [PMID: 33288000 DOI: 10.1016/j.plantsci.2020.110671] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 07/31/2020] [Accepted: 09/06/2020] [Indexed: 06/12/2023]
Abstract
Repeated sequences and polyploidy play a central role in plant genome dynamics. Here, we analyze the evolutionary dynamics of repeats in tetraploid and hexaploid Spartina species that diverged during the last 10 million years within the Chloridoideae, one of the poorest investigated grass lineages. From high-throughput genome sequencing, we annotated Spartina repeats and determined what sequence types account for the genome size variation among species. We examined whether differential genome size evolution correlated with ploidy levels and phylogenetic relationships. We also examined the tempo of repeat sequence dynamics associated with allopatric speciation over the last 3-6 million years between hexaploid species that diverged on the American and European Atlantic coasts and tetraploid species from North and South America. The tetraploid S. spartinae, whose phylogenetic placement has been debated, exhibits a similar repeat content as hexaploid species, suggesting common ancestry. Genome expansion or contraction resulting from repeat dynamics seems to be explained mostly by the contrasting divergence times between species, rather than by genome changes triggered by ploidy level change per se. One 370 bp satellite may be exhibiting 'meiotic drive' and driving chromosome evolution in S. alterniflora. Our results provide crucial insights for investigating the genetic and epigenetic consequences of such differential repeat dynamics on the ecology and distribution of the meso- and neopolyploid Spartina species.
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Affiliation(s)
- Delphine Giraud
- UMR CNRS 6553 ECOBIO, Université de Rennes 1, F-35042, Rennes Cedex, France.
| | - Oscar Lima
- UMR CNRS 6553 ECOBIO, Université de Rennes 1, F-35042, Rennes Cedex, France.
| | - Virginie Huteau
- Plateforme de cytogénétique moléculaire végétale, INRAE, Université de Rennes 1, Agrocampus Ouest, IGEPP, F-35650, Le Rheu, France; INRAE, Université de Rennes 1, Agrocampus Ouest, IGEPP, F-35650, Le Rheu, France.
| | - Olivier Coriton
- Plateforme de cytogénétique moléculaire végétale, INRAE, Université de Rennes 1, Agrocampus Ouest, IGEPP, F-35650, Le Rheu, France; INRAE, Université de Rennes 1, Agrocampus Ouest, IGEPP, F-35650, Le Rheu, France.
| | - Julien Boutte
- UMR CNRS 6553 ECOBIO, Université de Rennes 1, F-35042, Rennes Cedex, France; INRAE, Université de Rennes 1, Agrocampus Ouest, IGEPP, F-35650, Le Rheu, France.
| | - Ales Kovarik
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, CZ-61265, Czech Republic.
| | - Andrew R Leitch
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK.
| | - Ilia J Leitch
- Department of Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, TW9 3DS, UK.
| | - Malika Aïnouche
- UMR CNRS 6553 ECOBIO, Université de Rennes 1, F-35042, Rennes Cedex, France.
| | - Armel Salmon
- UMR CNRS 6553 ECOBIO, Université de Rennes 1, F-35042, Rennes Cedex, France.
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7
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Choi IY, Kwon EC, Kim NS. The C- and G-value paradox with polyploidy, repeatomes, introns, phenomes and cell economy. Genes Genomics 2020; 42:699-714. [DOI: 10.1007/s13258-020-00941-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 05/12/2020] [Indexed: 12/14/2022]
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8
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da Costa ZP, Cauz-Santos LA, Ragagnin GT, Van Sluys MA, Dornelas MC, Berges H, de Mello Varani A, Vieira MLC. Transposable element discovery and characterization of LTR-retrotransposon evolutionary lineages in the tropical fruit species Passiflora edulis. Mol Biol Rep 2019; 46:6117-6133. [DOI: 10.1007/s11033-019-05047-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 08/28/2019] [Indexed: 12/23/2022]
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9
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Shaping Plant Adaptability, Genome Structure and Gene Expression through Transposable Element Epigenetic Control: Focus on Methylation. AGRONOMY-BASEL 2018. [DOI: 10.3390/agronomy8090180] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
In plants, transposable elements (TEs) represent a large fraction of the genome, with potential to alter gene expression and produce genomic rearrangements. Epigenetic control of TEs is often used to stop unrestricted movement of TEs that would result in detrimental effects due to insertion in essential genes. The current review focuses on the effects of methylation on TEs and their genomic context, and how this type of epigenetic control affects plant adaptability when plants are faced with different stresses and changes. TEs mobilize in response to stress elicitors, including biotic and abiotic cues, but also developmental transitions and ‘genome shock’ events like polyploidization. These events transitionally lift TE repression, allowing TEs to move to new genomic locations. When TEs fall close to genes, silencing through methylation can spread to nearby genes, resulting in lower gene expression. The presence of TEs in gene promoter regions can also confer stress inducibility modulated through alternative methylation and demethylation of the TE. Bursts of transposition triggered by events of genomic shock can increase genome size and account for differences seen during polyploidization or species divergence. Finally, TEs have evolved several mechanisms to suppress their own repression, including the use of microRNAs to control genes that promote methylation. The interplay between silencing, transient TE activation, and purifying selection allows the genome to use TEs as a reservoir of potential beneficial modifications but also keeps TEs under control to stop uncontrolled detrimental transposition.
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11
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Migicovsky Z, Kovalchuk I. Transgenerational inheritance of epigenetic response to cold in Arabidopsis thaliana. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2015. [DOI: 10.1016/j.bcab.2014.09.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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12
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Wegrzyn JL, Liechty JD, Stevens KA, Wu LS, Loopstra CA, Vasquez-Gross HA, Dougherty WM, Lin BY, Zieve JJ, Martínez-García PJ, Holt C, Yandell M, Zimin AV, Yorke JA, Crepeau MW, Puiu D, Salzberg SL, de Jong PJ, Mockaitis K, Main D, Langley CH, Neale DB. Unique features of the loblolly pine (Pinus taeda L.) megagenome revealed through sequence annotation. Genetics 2014; 196:891-909. [PMID: 24653211 PMCID: PMC3948814 DOI: 10.1534/genetics.113.159996] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 12/13/2013] [Indexed: 01/08/2023] Open
Abstract
The largest genus in the conifer family Pinaceae is Pinus, with over 100 species. The size and complexity of their genomes (∼20-40 Gb, 2n = 24) have delayed the arrival of a well-annotated reference sequence. In this study, we present the annotation of the first whole-genome shotgun assembly of loblolly pine (Pinus taeda L.), which comprises 20.1 Gb of sequence. The MAKER-P annotation pipeline combined evidence-based alignments and ab initio predictions to generate 50,172 gene models, of which 15,653 are classified as high confidence. Clustering these gene models with 13 other plant species resulted in 20,646 gene families, of which 1554 are predicted to be unique to conifers. Among the conifer gene families, 159 are composed exclusively of loblolly pine members. The gene models for loblolly pine have the highest median and mean intron lengths of 24 fully sequenced plant genomes. Conifer genomes are full of repetitive DNA, with the most significant contributions from long-terminal-repeat retrotransposons. In depth analysis of the tandem and interspersed repetitive content yielded a combined estimate of 82%.
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Affiliation(s)
- Jill L. Wegrzyn
- Department of Plant Sciences, University of California, Davis, California 95616
| | - John D. Liechty
- Department of Plant Sciences, University of California, Davis, California 95616
| | - Kristian A. Stevens
- Department of Evolution and Ecology, University of California, Davis, California 95616
| | - Le-Shin Wu
- National Center for Genome Analysis Support, Indiana University, Bloomington, Indiana 47405
| | - Carol A. Loopstra
- Department of Ecosystem Science and Management, Texas A&M University, College Station, Texas 77843
| | | | - William M. Dougherty
- Department of Evolution and Ecology, University of California, Davis, California 95616
| | - Brian Y. Lin
- Department of Plant Sciences, University of California, Davis, California 95616
| | - Jacob J. Zieve
- Department of Plant Sciences, University of California, Davis, California 95616
| | | | - Carson Holt
- Department of Human Genetics, University of Utah, Salt Lake City, Utah 84112
| | - Mark Yandell
- Department of Human Genetics, University of Utah, Salt Lake City, Utah 84112
| | - Aleksey V. Zimin
- Institute for Physical Sciences and Technology, University of Maryland, College Park, Maryland 20742
| | - James A. Yorke
- Institute for Physical Sciences and Technology, University of Maryland, College Park, Maryland 20742
- Departments of Mathematics and Physics, University of Maryland, College Park, Maryland 20742
| | - Marc W. Crepeau
- Department of Evolution and Ecology, University of California, Davis, California 95616
| | - Daniela Puiu
- Center for Computational Biology, McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University, Baltimore, Maryland 21205
| | - Steven L. Salzberg
- Center for Computational Biology, McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University, Baltimore, Maryland 21205
| | - Pieter J. de Jong
- Children’s Hospital Oakland Research Institute, Oakland, California 94609
| | | | - Doreen Main
- Department of Horticulture, Washington State University, Pullman, Washington 99163
| | - Charles H. Langley
- Department of Evolution and Ecology, University of California, Davis, California 95616
| | - David B. Neale
- Department of Plant Sciences, University of California, Davis, California 95616
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Wegrzyn JL, Lin BY, Zieve JJ, Dougherty WM, Martínez-García PJ, Koriabine M, Holtz-Morris A, deJong P, Crepeau M, Langley CH, Puiu D, Salzberg SL, Neale DB, Stevens KA. Insights into the loblolly pine genome: characterization of BAC and fosmid sequences. PLoS One 2013; 8:e72439. [PMID: 24023741 PMCID: PMC3762812 DOI: 10.1371/journal.pone.0072439] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 07/10/2013] [Indexed: 12/22/2022] Open
Abstract
Despite their prevalence and importance, the genome sequences of loblolly pine, Norway spruce, and white spruce, three ecologically and economically important conifer species, are just becoming available to the research community. Following the completion of these large assemblies, annotation efforts will be undertaken to characterize the reference sequences. Accurate annotation of these ancient genomes would be aided by a comprehensive repeat library; however, few studies have generated enough sequence to fully evaluate and catalog their non-genic content. In this paper, two sets of loblolly pine genomic sequence, 103 previously assembled BACs and 90,954 newly sequenced and assembled fosmid scaffolds, were analyzed. Together, this sequence represents 280 Mbp (roughly 1% of the loblolly pine genome) and one of the most comprehensive studies of repetitive elements and genes in a gymnosperm species. A combination of homology and de novo methodologies were applied to identify both conserved and novel repeats. Similarity analysis estimated a repetitive content of 27% that included both full and partial elements. When combined with the de novo investigation, the estimate increased to almost 86%. Over 60% of the repetitive sequence consists of full or partial LTR (long terminal repeat) retrotransposons. Through de novo approaches, 6,270 novel, full-length transposable element families and 9,415 sub-families were identified. Among those 6,270 families, 82% were annotated as single-copy. Several of the novel, high-copy families are described here, with the largest, PtPiedmont, comprising 133 full-length copies. In addition to repeats, analysis of the coding region reported 23 full-length eukaryotic orthologous proteins (KOGS) and another 29 novel or orthologous genes. These discoveries, along with other genomic resources, will be used to annotate conifer genomes and address long-standing questions about gymnosperm evolution.
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Affiliation(s)
- Jill L. Wegrzyn
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
- * E-mail: (JLW); (KAS)
| | - Brian Y. Lin
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
| | - Jacob J. Zieve
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
| | - William M. Dougherty
- Department of Evolution and Ecology, University of California Davis, Davis, California, United States of America
| | - Pedro J. Martínez-García
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
| | - Maxim Koriabine
- Children's Hospital Oakland Research Institute, Oakland, California, United States of America
| | - Ann Holtz-Morris
- Children's Hospital Oakland Research Institute, Oakland, California, United States of America
| | - Pieter deJong
- Children's Hospital Oakland Research Institute, Oakland, California, United States of America
| | - Marc Crepeau
- Department of Evolution and Ecology, University of California Davis, Davis, California, United States of America
| | - Charles H. Langley
- Department of Evolution and Ecology, University of California Davis, Davis, California, United States of America
| | - Daniela Puiu
- Center for Computational Biology, McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Steven L. Salzberg
- Center for Computational Biology, McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - David B. Neale
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
| | - Kristian A. Stevens
- Department of Evolution and Ecology, University of California Davis, Davis, California, United States of America
- * E-mail: (JLW); (KAS)
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González LG, Deyholos MK. Identification, characterization and distribution of transposable elements in the flax (Linum usitatissimum L.) genome. BMC Genomics 2012; 13:644. [PMID: 23171245 PMCID: PMC3544724 DOI: 10.1186/1471-2164-13-644] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Accepted: 11/15/2012] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Flax (Linum usitatissimum L.) is an important crop for the production of bioproducts derived from its seed and stem fiber. Transposable elements (TEs) are widespread in plant genomes and are a key component of their evolution. The availability of a genome assembly of flax (Linum usitatissimum) affords new opportunities to explore the diversity of TEs and their relationship to genes and gene expression. RESULTS Four de novo repeat identification algorithms (PILER, RepeatScout, LTR_finder and LTR_STRUC) were applied to the flax genome assembly. The resulting library of flax repeats was combined with the RepBase Viridiplantae division and used with RepeatMasker to identify TEs coverage in the genome. LTR retrotransposons were the most abundant TEs (17.2% genome coverage), followed by Long Interspersed Nuclear Element (LINE) retrotransposons (2.10%) and Mutator DNA transposons (1.99%). Comparison of putative flax TEs to flax transcript databases indicated that TEs are not highly expressed in flax. However, the presence of recent insertions, defined by 100% intra-element LTR similarity, provided evidence for recent TE activity. Spatial analysis showed TE-rich regions, gene-rich regions as well as regions with similar genes and TE density. Monte Carlo simulations for the 71 largest scaffolds (≥ 1 Mb each) did not show any regional differences in the frequency of TE overlap with gene coding sequences. However, differences between TE superfamilies were found in their proximity to genes. Genes within TE-rich regions also appeared to have lower transcript expression, based on EST abundance. When LTR elements were compared, Copia showed more diversity, recent insertions and conserved domains than the Gypsy, demonstrating their importance in genome evolution. CONCLUSIONS The calculated 23.06% TE coverage of the flax WGS assembly is at the low end of the range of TE coverages reported in other eudicots, although this estimate does not include TEs likely found in unassembled repetitive regions of the genome. Since enrichment for TEs in genomic regions was associated with reduced expression of neighbouring genes, and many members of the Copia LTR superfamily are inserted close to coding regions, we suggest Copia elements have a greater influence on recent flax genome evolution while Gypsy elements have become residual and highly mutated.
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C. elegans germ cells show temperature and age-dependent expression of Cer1, a Gypsy/Ty3-related retrotransposon. PLoS Pathog 2012; 8:e1002591. [PMID: 22479180 PMCID: PMC3315495 DOI: 10.1371/journal.ppat.1002591] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 01/30/2012] [Indexed: 11/19/2022] Open
Abstract
Virus-like particles (VLPs) have not been observed in Caenorhabditis germ cells, although nematode genomes contain low numbers of retrotransposon and retroviral sequences. We used electron microscopy to search for VLPs in various wild strains of Caenorhabditis, and observed very rare candidate VLPs in some strains, including the standard laboratory strain of C. elegans, N2. We identified the N2 VLPs as capsids produced by Cer1, a retrotransposon in the Gypsy/Ty3 family of retroviruses/retrotransposons. Cer1 expression is age and temperature dependent, with abundant expression at 15°C and no detectable expression at 25°C, explaining how VLPs escaped detection in previous studies. Similar age and temperature-dependent expression of Cer1 retrotransposons was observed for several other wild strains, indicating that these properties are common, if not integral, features of this retroelement. Retrotransposons, in contrast to DNA transposons, have a cytoplasmic stage in replication, and those that infect non-dividing cells must pass their genomic material through nuclear pores. In most C. elegans germ cells, nuclear pores are largely covered by germline-specific organelles called P granules. Our results suggest that Cer1 capsids target meiotic germ cells exiting pachytene, when free nuclear pores are added to the nuclear envelope and existing P granules begin to be removed. In pachytene germ cells, Cer1 capsids concentrate away from nuclei on a subset of microtubules that are exceptionally resistant to microtubule inhibitors; the capsids can aggregate these stable microtubules in older adults, which exhibit a temperature-dependent decrease in egg viability. When germ cells exit pachytene, the stable microtubules disappear and capsids redistribute close to nuclei that have P granule-free nuclear pores. This redistribution is microtubule dependent, suggesting that capsids that are released from stable microtubules transfer onto new, dynamic microtubules to track toward nuclei. These studies introduce C. elegans as a model to study the interplay between retroelements and germ cell biology. Retrotransposons and retroviruses pose enormous threats to animal and plants because of their ability to insert into host genes. Retroelements that replicate in germ cells can, if left unchecked, expand exponentially in the host genome. C. elegans has proven to be an exceptional model system for studying many facets of cell and molecular biology, and the genome contains both retrotransposon and retroviral sequences. However, no virus-like particles have been observed in C. elegans germ cells. We show here that Cer1, an endogenous Gypsy/Ty3 class retrotransposon, is expressed at very high levels in C. elegans germ cells, but escaped detection in previous studies because its expression is both temperature and age dependent. These studies reveal new aspects of microtubule regulation in C. elegans that the retroelement appears to exploit to navigate the germ cell cytoplasm, and demonstrate the power of C. elegans for studying host/pathogen interactions in germ cell biology.
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