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Li Z, Gilbert C, Peng H, Pollet N. Discovery of numerous novel Helitron-like elements in eukaryote genomes using HELIANO. Nucleic Acids Res 2024; 52:e79. [PMID: 39119924 PMCID: PMC11417382 DOI: 10.1093/nar/gkae679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Revised: 07/19/2024] [Accepted: 07/25/2024] [Indexed: 08/10/2024] Open
Abstract
Helitron-like elements (HLEs) are widespread eukaryotic DNA transposons employing a rolling-circle transposition mechanism. Despite their prevalence in fungi, animals, and plant genomes, identifying Helitrons remains a formidable challenge. We introduce HELIANO, a software for annotating and classifying autonomous and non-autonomous HLE sequences from whole genomes. HELIANO overcomes several limitations of existing tools in speed and accuracy, demonstrated through benchmarking and its application to the complex genomes of frogs (Xenopus tropicalis and Xenopus laevis) and rice (Oryza sativa), where it uncovered numerous previously unidentified HLEs. In an extensive analysis of 404 eukaryote genomes, we found HLEs widely distributed across phyla, with exceptions in specific taxa. HELIANO's application led to the discovery of numerous new HLEs in land plants and identified 20 protein domains captured by certain autonomous HLE families. A comprehensive phylogenetic analysis further classified HLEs into two primary clades, HLE1 and HLE2, and revealed nine subgroups, some of which are enriched within specific taxa. The future use of HELIANO promises to improve the global analysis of HLEs across genomes, significantly advancing our understanding of this fascinating transposon superfamily.
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Affiliation(s)
- Zhen Li
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
| | - Clément Gilbert
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
| | - Haoran Peng
- Crop Genome Dynamics Group, Agroscope, 1260 Nyon, Switzerland
| | - Nicolas Pollet
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
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2
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Urquhart A, Vogan AA, Gluck-Thaler E. Starships: a new frontier for fungal biology. Trends Genet 2024:S0168-9525(24)00183-5. [PMID: 39299886 DOI: 10.1016/j.tig.2024.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2024] [Revised: 08/20/2024] [Accepted: 08/20/2024] [Indexed: 09/22/2024]
Abstract
Transposable elements (TEs) are semiautonomous genetic entities that proliferate in genomes. We recently discovered the Starships, a previously hidden superfamily of giant TEs found in a diverse subphylum of filamentous fungi, the Pezizomycotina. Starships are unlike other eukaryotic TEs because they have evolved mechanisms for both mobilizing entire genes, including those encoding conditionally beneficial phenotypes, and for horizontally transferring between individuals. We argue that Starships have unrivaled capacity to engage their fungal hosts as genetic parasites and mutualists, revealing unexplored terrain for investigating the ecoevolutionary dynamics of TE-eukaryote interactions. We build on existing models of fungal genome evolution by conceptualizing Starships as a distinct genomic compartment whose dynamics profoundly shape fungal biology.
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Affiliation(s)
- Andrew Urquhart
- Systematic Biology, Department of Organismal Biology, Uppsala University, Uppsala, 752 36, Sweden
| | - Aaron A Vogan
- Systematic Biology, Department of Organismal Biology, Uppsala University, Uppsala, 752 36, Sweden
| | - Emile Gluck-Thaler
- Department of Plant Pathology, University of Wisconsin - Madison, Madison, WI 53706, USA; Wisconsin Institute for Discovery, Madison, WI 53706, USA.
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3
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Gluck-Thaler E, Vogan A. Systematic identification of cargo-mobilizing genetic elements reveals new dimensions of eukaryotic diversity. Nucleic Acids Res 2024; 52:5496-5513. [PMID: 38686785 PMCID: PMC11162782 DOI: 10.1093/nar/gkae327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 03/12/2024] [Accepted: 04/15/2024] [Indexed: 05/02/2024] Open
Abstract
Cargo-mobilizing mobile elements (CMEs) are genetic entities that faithfully transpose diverse protein coding sequences. Although common in bacteria, we know little about eukaryotic CMEs because no appropriate tools exist for their annotation. For example, Starships are giant fungal CMEs whose functions are largely unknown because they require time-intensive manual curation. To address this knowledge gap, we developed starfish, a computational workflow for high-throughput eukaryotic CME annotation. We applied starfish to 2 899 genomes of 1 649 fungal species and found that starfish recovers known Starships with 95% combined precision and recall while expanding the number of annotated elements ten-fold. Extant Starship diversity is partitioned into 11 families that differ in their enrichment patterns across fungal classes. Starship cargo changes rapidly such that elements from the same family differ substantially in their functional repertoires, which are predicted to contribute to diverse biological processes such as metabolism. Many elements have convergently evolved to insert into 5S rDNA and AT-rich sequence while others integrate into random locations, revealing both specialist and generalist strategies for persistence. Our work establishes a framework for advancing mobile element biology and provides the means to investigate an emerging dimension of eukaryotic genetic diversity, that of genomes within genomes.
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Affiliation(s)
- Emile Gluck-Thaler
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Neuchâtel 2000, Switzerland
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA
- Wisconsin Institute for Discovery, Madison, WI 53706, USA
| | - Aaron A Vogan
- Systematic Biology, Department of Organismal Biology, Uppsala University, Uppsala, 752 36, Sweden
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4
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Barro-Trastoy D, Köhler C. Helitrons: genomic parasites that generate developmental novelties. Trends Genet 2024; 40:437-448. [PMID: 38429198 DOI: 10.1016/j.tig.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 02/03/2024] [Accepted: 02/05/2024] [Indexed: 03/03/2024]
Abstract
Helitrons, classified as DNA transposons, employ rolling-circle intermediates for transposition. Distinguishing themselves from other DNA transposons, they leave the original template element unaltered during transposition, which has led to their characterization as 'peel-and-paste elements'. Helitrons possess the ability to capture and mobilize host genome fragments, with enormous consequences for host genomes. This review discusses the current understanding of Helitrons, exploring their origins, transposition mechanism, and the extensive repercussions of their activity on genome structure and function. We also explore the evolutionary conflicts stemming from Helitron-transposed gene fragments and elucidate their domestication for regulating responses to environmental challenges. Looking ahead, further research in this evolving field promises to bring interesting discoveries on the role of Helitrons in shaping genomic landscapes.
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Affiliation(s)
- Daniela Barro-Trastoy
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Claudia Köhler
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany; Department of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala 75007, Sweden.
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5
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Ma H, Wang M, Zhang YE, Tan S. The power of "controllers": Transposon-mediated duplicated genes evolve towards neofunctionalization. J Genet Genomics 2023; 50:462-472. [PMID: 37068629 DOI: 10.1016/j.jgg.2023.04.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 04/04/2023] [Accepted: 04/05/2023] [Indexed: 04/19/2023]
Abstract
Since the discovery of the first transposon by Dr. Barbara McClintock, the prevalence and diversity of transposable elements (TEs) have been gradually recognized. As fundamental genetic components, TEs drive organismal evolution not only by contributing functional sequences (e.g., regulatory elements or "controllers" as phrased by Dr. McClintock) but also by shuffling genomic sequences. In the latter respect, TE-mediated gene duplications have contributed to the origination of new genes and attracted extensive interest. In response to the development of this field, we herein attempt to provide an overview of TE-mediated duplication by focusing on common rules emerging across duplications generated by different TE types. Specifically, despite the huge divergence of transposition machinery across TEs, we identify three common features of various TE-mediated duplication mechanisms, including end bypass, template switching, and recurrent transposition. These three features lead to one common functional outcome, namely, TE-mediated duplicates tend to be subjected to exon shuffling and neofunctionalization. Therefore, the intrinsic properties of the mutational mechanism constrain the evolutionary trajectories of these duplicates. We finally discuss the future of this field including an in-depth characterization of both the duplication mechanisms and functions of TE-mediated duplicates.
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Affiliation(s)
- Huijing Ma
- Key Laboratory of Zoological Systematics and Evolution & State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Mengxia Wang
- Key Laboratory of Zoological Systematics and Evolution & State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yong E Zhang
- Key Laboratory of Zoological Systematics and Evolution & State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; CAS Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, Yunnan 650223, China; Chinese Institute for Brain Research, Beijing 102206, China.
| | - Shengjun Tan
- Key Laboratory of Zoological Systematics and Evolution & State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
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6
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Yim WC, Swain ML, Ma D, An H, Bird KA, Curdie DD, Wang S, Ham HD, Luzuriaga-Neira A, Kirkwood JS, Hur M, Solomon JKQ, Harper JF, Kosma DK, Alvarez-Ponce D, Cushman JC, Edger PP, Mason AS, Pires JC, Tang H, Zhang X. The final piece of the Triangle of U: Evolution of the tetraploid Brassica carinata genome. THE PLANT CELL 2022; 34:4143-4172. [PMID: 35961044 PMCID: PMC9614464 DOI: 10.1093/plcell/koac249] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 06/24/2022] [Indexed: 05/05/2023]
Abstract
Ethiopian mustard (Brassica carinata) is an ancient crop with remarkable stress resilience and a desirable seed fatty acid profile for biofuel uses. Brassica carinata is one of six Brassica species that share three major genomes from three diploid species (AA, BB, and CC) that spontaneously hybridized in a pairwise manner to form three allotetraploid species (AABB, AACC, and BBCC). Of the genomes of these species, that of B. carinata is the least understood. Here, we report a chromosome scale 1.31-Gbp genome assembly with 156.9-fold sequencing coverage for B. carinata, completing the reference genomes comprising the classic Triangle of U, a classical theory of the evolutionary relationships among these six species. Our assembly provides insights into the hybridization event that led to the current B. carinata genome and the genomic features that gave rise to the superior agronomic traits of B. carinata. Notably, we identified an expansion of transcription factor networks and agronomically important gene families. Completion of the Triangle of U comparative genomics platform has allowed us to examine the dynamics of polyploid evolution and the role of subgenome dominance in the domestication and continuing agronomic improvement of B. carinata and other Brassica species.
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Affiliation(s)
| | | | - Dongna Ma
- Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Hong An
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65201, USA
| | - Kevin A Bird
- Department of Horticulture, Michigan State University, East Lansing, Michigan 48824, USA
| | - David D Curdie
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada 89557, USA
| | - Samuel Wang
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada 89557, USA
| | - Hyun Don Ham
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada 89557, USA
| | | | - Jay S Kirkwood
- Metabolomics Core Facility, Institute for Integrative Genome Biology, University of California, Riverside, California 92521, USA
| | - Manhoi Hur
- Metabolomics Core Facility, Institute for Integrative Genome Biology, University of California, Riverside, California 92521, USA
| | - Juan K Q Solomon
- Department of Agriculture, Veterinary & Rangeland Sciences, University of Nevada, Reno, Nevada 89557, USA
| | - Jeffrey F Harper
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada 89557, USA
| | - Dylan K Kosma
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada 89557, USA
| | | | - John C Cushman
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada 89557, USA
| | - Patrick P Edger
- Department of Horticulture, Michigan State University, East Lansing, Michigan 48824, USA
| | - Annaliese S Mason
- Plant Breeding Department, INRES, The University of Bonn, Bonn 53115, Germany
| | - J Chris Pires
- Division of Biological Sciences, Bond Life Sciences Center, , University of Missouri, Columbia, Missouri 65211, USA
| | - Haibao Tang
- Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Xingtan Zhang
- Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization, Fujian Agriculture and Forestry University, Fuzhou, China
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7
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Birchler JA, Yang H. The multiple fates of gene duplications: Deletion, hypofunctionalization, subfunctionalization, neofunctionalization, dosage balance constraints, and neutral variation. THE PLANT CELL 2022; 34:2466-2474. [PMID: 35253876 PMCID: PMC9252495 DOI: 10.1093/plcell/koac076] [Citation(s) in RCA: 84] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 02/17/2022] [Indexed: 05/13/2023]
Abstract
Gene duplications have long been recognized as a contributor to the evolution of genes with new functions. Multiple copies of genes can result from tandem duplication, from transposition to new chromosomes, or from whole-genome duplication (polyploidy). The most common fate is that one member of the pair is deleted to return the gene to the singleton state. Other paths involve the reduced expression of both copies (hypofunctionalization) that are held in duplicate to maintain sufficient quantity of function. The two copies can split functions (subfunctionalization) or can diverge to generate a new function (neofunctionalization). Retention of duplicates resulting from doubling of the whole genome occurs for genes involved with multicomponent interactions such as transcription factors and signal transduction components. In contrast, these classes of genes are underrepresented in small segmental duplications. This complementary pattern suggests that the balance of interactors affects the fate of the duplicate pair. We discuss the different mechanisms that maintain duplicated genes, which may change over time and intersect.
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Affiliation(s)
- James A Birchler
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211, USA
| | - Hua Yang
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211, USA
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8
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Peñaloza C, Gutierrez AP, Eöry L, Wang S, Guo X, Archibald AL, Bean TP, Houston RD. A chromosome-level genome assembly for the Pacific oyster Crassostrea gigas. Gigascience 2021; 10:6187865. [PMID: 33764468 PMCID: PMC7992393 DOI: 10.1093/gigascience/giab020] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 02/10/2021] [Accepted: 03/03/2021] [Indexed: 02/06/2023] Open
Abstract
Background The Pacific oyster (Crassostrea gigas) is a bivalve mollusc with vital roles in coastal ecosystems and aquaculture globally. While extensive genomic tools are available for C. gigas, highly contiguous reference genomes are required to support both fundamental and applied research. Herein we report the creation and annotation of a chromosome-level assembly for C. gigas. Findings High-coverage long- and short-read sequence data generated on Pacific Biosciences and Illumina platforms were used to generate an initial assembly, which was then scaffolded into 10 pseudo-chromosomes using both Hi-C sequencing and a high-density linkage map. The assembly has a scaffold N50 of 58.4 Mb and a contig N50 of 1.8 Mb, representing a step advance on the previously published C. gigas assembly. Annotation based on Pacific Biosciences Iso-Seq and Illumina RNA-Seq resulted in identification of ∼30,000 putative protein-coding genes. Annotation of putative repeat elements highlighted an enrichment of Helitron rolling-circle transposable elements, suggesting their potential role in shaping the evolution of the C. gigas genome. Conclusions This new chromosome-level assembly will be an enabling resource for genetics and genomics studies to support fundamental insight into bivalve biology, as well as for selective breeding of C. gigas in aquaculture.
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Affiliation(s)
- Carolina Peñaloza
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush Campus, Midlothian EH25 9RG, UK
| | - Alejandro P Gutierrez
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush Campus, Midlothian EH25 9RG, UK
| | - Lél Eöry
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush Campus, Midlothian EH25 9RG, UK
| | - Shan Wang
- Haskin Shellfish Research Laboratory, Department of Marine and Coastal Sciences, Rutgers University, 6959 Miller Avenue, Port Norris, NJ 08349, USA
| | - Ximing Guo
- Haskin Shellfish Research Laboratory, Department of Marine and Coastal Sciences, Rutgers University, 6959 Miller Avenue, Port Norris, NJ 08349, USA
| | - Alan L Archibald
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush Campus, Midlothian EH25 9RG, UK
| | - Tim P Bean
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush Campus, Midlothian EH25 9RG, UK
| | - Ross D Houston
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush Campus, Midlothian EH25 9RG, UK
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9
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Wos G, Choudhury RR, Kolář F, Parisod C. Transcriptional activity of transposable elements along an elevational gradient in Arabidopsis arenosa. Mob DNA 2021; 12:7. [PMID: 33639991 PMCID: PMC7916287 DOI: 10.1186/s13100-021-00236-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 02/16/2021] [Indexed: 01/10/2023] Open
Abstract
Background Plant genomes can respond rapidly to environmental changes and transposable elements (TEs) arise as important drivers contributing to genome dynamics. Although some elements were reported to be induced by various abiotic or biotic factors, there is a lack of general understanding on how environment influences the activity and diversity of TEs. Here, we combined common garden experiment with short-read sequencing to investigate genomic abundance and expression of 2245 consensus TE sequences (containing retrotransposons and DNA transposons) in an alpine environment in Arabidopsis arenosa. To disentangle general trends from local differentiation, we leveraged four foothill-alpine population pairs from different mountain regions. Seeds of each of the eight populations were raised under four treatments that differed in temperature and irradiance, two factors varying with elevation. RNA-seq analysis was performed on leaves of young plants to test for the effect of elevation and subsequently of temperature and irradiance on expression of TE sequences. Results Genomic abundance of the 2245 consensus TE sequences varied greatly between the mountain regions in line with neutral divergence among the regions, representing distinct genetic lineages of A. arenosa. Accounting for intraspecific variation in abundance, we found consistent transcriptomic response for some TE sequences across the different pairs of foothill-alpine populations suggesting parallelism in TE expression. In particular expression of retrotransposon LTR Copia (e.g. Ivana and Ale clades) and LTR Gypsy (e.g. Athila and CRM clades) but also non-LTR LINE or DNA transposon TIR MuDR consistently varied with elevation of origin. TE sequences responding specifically to temperature and irradiance belonged to the same classes as well as additional TE clades containing potentially stress-responsive elements (e.g. LTR Copia Sire and Tar, LTR Gypsy Reina). Conclusions Our study demonstrated that the A. arenosa genome harbours a considerable diversity of TE sequences whose abundance and expression response varies across its native range. Some TE clades may contain transcriptionally active elements responding to a natural environmental gradient. This may further contribute to genetic variation between populations and may ultimately provide new regulatory mechanisms to face environmental challenges. Supplementary Information The online version contains supplementary material available at 10.1186/s13100-021-00236-0.
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Affiliation(s)
- Guillaume Wos
- Department of Botany, Charles University, 128 01, Prague, Czech Republic.
| | | | - Filip Kolář
- Department of Botany, Charles University, 128 01, Prague, Czech Republic
| | - Christian Parisod
- Institute of Plant Sciences, University of Bern, 3013, Bern, Switzerland
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10
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Schnable JC. Genes and gene models, an important distinction. THE NEW PHYTOLOGIST 2020; 228:50-55. [PMID: 31241760 DOI: 10.1111/nph.16011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 06/07/2019] [Indexed: 05/22/2023]
Abstract
Genome sequencing has fundamentally changed how plant biologists think about genes. All or nearly all genes can ultimately be associated with a gene model. However, many gene models appear to play little or no role in the traits of an organism. A range of structural, molecular, population and evolutionary features all show a separation between genes with known phenotypes and the overall set of annotated gene models. These different features could be combined to develop models to distinguish the genes that determine the traits of plants from the subset gene other annotated gene models which are unlikely to play a role in doing so. Efforts to identify the subset of annotated gene models likely involved in specifying the characteristics of plants would help aid a wide range of researchers.
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Affiliation(s)
- James C Schnable
- Department of Agronomy and Horticulture and Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
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11
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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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12
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Zhao D, Hamilton JP, Vaillancourt B, Zhang W, Eizenga GC, Cui Y, Jiang J, Buell CR, Jiang N. The unique epigenetic features of Pack-MULEs and their impact on chromosomal base composition and expression spectrum. Nucleic Acids Res 2019; 46:2380-2397. [PMID: 29365184 PMCID: PMC5861414 DOI: 10.1093/nar/gky025] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 01/18/2018] [Indexed: 12/11/2022] Open
Abstract
Acquisition and rearrangement of host genes by transposable elements (TEs) is an important mechanism to increase gene diversity as exemplified by the ∼3000 Pack-Mutator-like TEs in the rice genome which have acquired gene sequences (Pack-MULEs), yet remain enigmatic. To identify signatures of functioning Pack-MULEs and Pack-MULE evolution, we generated transcriptome, translatome, and epigenome datasets and compared Pack-MULEs to genes and other TE families. Approximately 40% of Pack-MULEs were transcribed with 9% having translation evidence, clearly distinguishing them from other TEs. Pack-MULEs exhibited a unique expression profile associated with specificity in reproductive tissues that may be associated with seed traits. Expressed Pack-MULEs resemble regular protein-coding genes as exhibited by a low level of DNA methylation, association with active histone marks and DNase I hypersensitive sites, and an absence of repressive histone marks, suggesting that a substantial fraction of Pack-MULEs are potentially functional in vivo. Interestingly, the expression capacity of Pack-MULEs is independent of the local genomic environment, and the insertion and expression of Pack-MULEs may have altered the local chromosomal expression pattern as well as counteracted the impact of recombination on chromosomal base composition, which has profound consequences on the evolution of chromosome structure.
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Affiliation(s)
- Dongyan Zhao
- Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA.,Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
| | - John P Hamilton
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
| | | | - Wenli Zhang
- Department of Horticulture, University of Wisconsin, Madison, WI 53705, USA.,State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agriculture University, Nanjing, Jiangsu 210095, China
| | - Georgia C Eizenga
- USDA-ARS Dale Bumpers National Rice Research Center, 2890 Highway 130 East, Stuttgart, AR 72160, USA
| | - Yuehua Cui
- Department of Statistics and Probability, Michigan State University, East Lansing, MI 48824, USA
| | - Jiming Jiang
- Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA.,Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
| | - C Robin Buell
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Ning Jiang
- Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA.,Program in Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, MI 48824, USA
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13
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Krasileva KV. The role of transposable elements and DNA damage repair mechanisms in gene duplications and gene fusions in plant genomes. CURRENT OPINION IN PLANT BIOLOGY 2019; 48:18-25. [PMID: 30849712 DOI: 10.1016/j.pbi.2019.01.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 01/16/2019] [Accepted: 01/29/2019] [Indexed: 05/02/2023]
Abstract
Plant genomes are shaped by structural variation. Gene-size insertions and among most prominent events and can have significant effects on amplification of gene families as well as facilitate new gene fusions. Transposable elements as well as plant DNA repair machinery have overlapping contributions to these events, and often work in synergy. Activity of transposable elements is often lineage specific and can preferentially affect specific gene families, such as disease resistance genes. Once duplicated, genes themselves can serve templates for additional variation that can arise from non-allelic homologous recombination. Non-homologous DNA repair mechanisms contribute to additional variation and diversify the mechanisms of gene movement, such as through ligation of extra-chromosomal DNA fragments. Genomic processes that generate structural variation can be induced by stress and, therefore, can provide adaptive potential. This review describes mechanisms that contribute to gene-size structural variation in plants, result in gene duplication and generation of new plant genes through gene fusion.
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Affiliation(s)
- Ksenia V Krasileva
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, United States.
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14
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Cerbin S, Jiang N. Duplication of host genes by transposable elements. Curr Opin Genet Dev 2018; 49:63-69. [PMID: 29571044 DOI: 10.1016/j.gde.2018.03.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 02/07/2018] [Accepted: 03/08/2018] [Indexed: 12/12/2022]
Abstract
The availability of large amounts of genomic and transcriptome sequences have allowed systematic surveys about the host gene sequences that have been duplicated by transposable elements. It is now clear that all super-families of transposons are capable of duplicating genes or gene fragments, and such incidents have been detected in a wide spectrum of organisms. Emerging evidence suggests that a considerable portion of them function as coding or non-coding sequences, driving innovations at molecular and phenotypic levels. Interestingly, the duplication events not only have to occur in the reproductive tissues to become heritable, but the duplicated copies are also preferentially expressed in those tissues. As a result, reproductive tissues may serve as the 'incubator' for genes generated by transposable elements.
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Affiliation(s)
- Stefan Cerbin
- Department of Horticulture, 1066 Bogue Street, Michigan State University, East Lansing, MI 48824, USA
| | - Ning Jiang
- Department of Horticulture, 1066 Bogue Street, Michigan State University, East Lansing, MI 48824, USA.
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15
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Wang XJ, Zhang X, Yang JT, Wang ZX. Effect on transcriptome and metabolome of stacked transgenic maize containing insecticidal cry and glyphosate tolerance epsps genes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 93:1007-1016. [PMID: 29356248 DOI: 10.1111/tpj.13825] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 12/13/2017] [Accepted: 12/21/2017] [Indexed: 05/18/2023]
Abstract
Gene stacking is a developing trend in agricultural biotechnology. Unintended effects in stacked transgenic plants are safety issues considered by the public and researchers. Omics techniques provide useful tools to assess unintended effects. In this paper, stacked transgenic maize 12-5×IE034 that contained insecticidal cry and glyphosate tolerance G10-epsps genes was obtained by crossing of transgenic maize varieties 12-5 and IE034. Transcriptome and metabolome analyses were performed for different maize varieties, including 12-5×IE034, 12-5, IE034, and conventional varieties collected from different provinces in China. The transcriptome results were as follows. The nine maize varieties had obvious differences in gene expression. There were 3561-5538 differentially expressed genes between 12-5×IE034 and its parents and transgenic receptor, which were far fewer than the number of differentially expressed genes in different traditional maize varieties. Cluster analysis indicated that there were close relationships between 12-5×IE034 and its parents. The metabolome results were as follows. For the nine detected maize varieties, the number of different metabolites ranged from 0 to 240. Compared with its parents, 12-5 and IE034, the hybrid variety 12-5×IE034 had 15 and 112 different metabolites, respectively. Hierarchical cluster analysis with Pearson's correlation analysis showed that the differences between 12-5×IE034 and its parents were fewer than those between other maize varieties. Shikimate pathway-related genes and metabolites analysis results showed that the effects of hybrid stacking are less than those from transformation and differing genotypes. Thus, the differences due to breeding stack were fewer than those due to natural variation among maize varieties. This paper provides scientific data for assessing unintended effects in stacked transgenic plants.
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Affiliation(s)
- Xu-Jing Wang
- Biotechnology Research Institute, Chinese Academy Agricultural Sciences, MOA Key Laboratory on Safety Assessment (Molecular) of Agri-GMO, Beijing, 100081, China
| | - Xin Zhang
- Biotechnology Research Institute, Chinese Academy Agricultural Sciences, MOA Key Laboratory on Safety Assessment (Molecular) of Agri-GMO, Beijing, 100081, China
| | - Jiang-Tao Yang
- Biotechnology Research Institute, Chinese Academy Agricultural Sciences, MOA Key Laboratory on Safety Assessment (Molecular) of Agri-GMO, Beijing, 100081, China
| | - Zhi-Xing Wang
- Biotechnology Research Institute, Chinese Academy Agricultural Sciences, MOA Key Laboratory on Safety Assessment (Molecular) of Agri-GMO, Beijing, 100081, China
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16
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Richards CL, Alonso C, Becker C, Bossdorf O, Bucher E, Colomé-Tatché M, Durka W, Engelhardt J, Gaspar B, Gogol-Döring A, Grosse I, van Gurp TP, Heer K, Kronholm I, Lampei C, Latzel V, Mirouze M, Opgenoorth L, Paun O, Prohaska SJ, Rensing SA, Stadler PF, Trucchi E, Ullrich K, Verhoeven KJF. Ecological plant epigenetics: Evidence from model and non-model species, and the way forward. Ecol Lett 2017; 20:1576-1590. [PMID: 29027325 DOI: 10.1111/ele.12858] [Citation(s) in RCA: 181] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 06/15/2017] [Accepted: 09/04/2017] [Indexed: 12/15/2022]
Abstract
Growing evidence shows that epigenetic mechanisms contribute to complex traits, with implications across many fields of biology. In plant ecology, recent studies have attempted to merge ecological experiments with epigenetic analyses to elucidate the contribution of epigenetics to plant phenotypes, stress responses, adaptation to habitat, and range distributions. While there has been some progress in revealing the role of epigenetics in ecological processes, studies with non-model species have so far been limited to describing broad patterns based on anonymous markers of DNA methylation. In contrast, studies with model species have benefited from powerful genomic resources, which contribute to a more mechanistic understanding but have limited ecological realism. Understanding the significance of epigenetics for plant ecology requires increased transfer of knowledge and methods from model species research to genomes of evolutionarily divergent species, and examination of responses to complex natural environments at a more mechanistic level. This requires transforming genomics tools specifically for studying non-model species, which is challenging given the large and often polyploid genomes of plants. Collaboration among molecular geneticists, ecologists and bioinformaticians promises to enhance our understanding of the mutual links between genome function and ecological processes.
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Affiliation(s)
- Christina L Richards
- Department of Integrative Biology, University of South Florida, Tampa, FL, 33620, USA
| | | | - Claude Becker
- Gregor Mendel Institute of Molecular Plant Biology, 1030, Vienna, Austrian Academy of Sciences, Vienna Biocenter (VBC), Austria
| | - Oliver Bossdorf
- Plant Evolutionary Ecology, University of Tübingen, 72076, Tübingen, Germany
| | - Etienne Bucher
- Institut de Recherche en Horticulture et Semences, 49071, Beaucouzé Cedex, France
| | - Maria Colomé-Tatché
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, 9713, Groningen, The Netherlands.,Institute of Computational Biology, Helmholtz Zentrum München, 85764, Neuherberg, Germany.,School of Life Sciences Weihenstephan, Technical University of Munich, 85354, Freising, Germany
| | - Walter Durka
- Department of Community Ecology, Helmholtz Centre for Environmental Research - UFZ, 06120, Halle, Germany.,German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103, Leipzig, Germany
| | - Jan Engelhardt
- Institut für Informatik, University of Leipzig, 04107, Leipzig, Germany
| | - Bence Gaspar
- Plant Evolutionary Ecology, University of Tübingen, 72076, Tübingen, Germany
| | - Andreas Gogol-Döring
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103, Leipzig, Germany.,Institute of Computer Science, University of Halle, 06120, Halle, Germany
| | - Ivo Grosse
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103, Leipzig, Germany.,Institute of Computer Science, University of Halle, 06120, Halle, Germany
| | - Thomas P van Gurp
- Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Katrin Heer
- Conservation Biology, Philipps-University of Marburg, 35037, Marburg, Germany
| | - Ilkka Kronholm
- Department of Biological and Environmental Sciences, Center of Excellence in Biological Interactions, University of Jyväskylä, 40014, Jyväskylän yliopisto, Finland
| | - Christian Lampei
- Institute of Plant Breeding, Seed Science and Population Genetics, 70599, Stuttgart, Germany
| | - Vít Latzel
- Institute of Botany, The Czech Academy of Sciences, 25243, Průhonice, Czech Republic
| | - Marie Mirouze
- Institut de Recherche pour le Développement, Laboratoire Génome et Développement des Plantes, 66860, Perpignan, France
| | - Lars Opgenoorth
- Department of Ecology, Philipps-University Marburg, 35037, Marburg, Germany
| | - Ovidiu Paun
- Plant Ecological Genomics, University of Vienna, 1030, Vienna, Austria
| | - Sonja J Prohaska
- Institut für Informatik, University of Leipzig, 04107, Leipzig, Germany.,The Santa Fe Institute, Santa Fe NM, 87501, USA
| | - Stefan A Rensing
- Plant Cell Biology, Philipps-University Marburg, 35037, Marburg, Germany.,BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79098, Freiburg, Germany
| | - Peter F Stadler
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103, Leipzig, Germany.,Institut für Informatik, University of Leipzig, 04107, Leipzig, Germany.,The Santa Fe Institute, Santa Fe NM, 87501, USA.,Max Planck Institute for Mathematics in the Sciences, 04103, Leipzig, Germany
| | - Emiliano Trucchi
- Plant Ecological Genomics, University of Vienna, 1030, Vienna, Austria
| | - Kristian Ullrich
- Plant Cell Biology, Philipps-University Marburg, 35037, Marburg, Germany
| | - Koen J F Verhoeven
- Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
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17
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Forestan C, Farinati S, Aiese Cigliano R, Lunardon A, Sanseverino W, Varotto S. Maize RNA PolIV affects the expression of genes with nearby TE insertions and has a genome-wide repressive impact on transcription. BMC PLANT BIOLOGY 2017; 17:161. [PMID: 29025411 PMCID: PMC5639751 DOI: 10.1186/s12870-017-1108-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 10/04/2017] [Indexed: 05/09/2023]
Abstract
BACKGROUND RNA-directed DNA methylation (RdDM) is a plant-specific epigenetic process that relies on the RNA polymerase IV (Pol IV) for the production of 24 nucleotide small interfering RNAs (siRNA) that guide the cytosine methylation and silencing of genes and transposons. Zea mays RPD1/RMR6 gene encodes the largest subunit of Pol IV and is required for normal plant development, paramutation, transcriptional repression of certain transposable elements (TEs) and transcriptional regulation of specific alleles. RESULTS In this study we applied a total RNA-Seq approach to compare the B73 and rpd1/rmr6 leaf transcriptomes. Although previous studies indicated that loss of siRNAs production in RdDM mutants provokes a strong loss of CHH DNA methylation but not massive gene or TEs transcriptional activation in both Arabidopsis and maize, our total RNA-Seq analysis of rpd1/rmr6 transcriptome reveals that loss of Pol IV activity causes a global increase in the transcribed fraction of the maize genome. Our results point to the genes with nearby TE insertions as being the most strongly affected by Pol IV-mediated gene silencing. TEs modulation of nearby gene expression is linked to alternative methylation profiles on gene flanking regions, and these profiles are strictly dependent on specific characteristics of the TE member inserted. Although Pol IV is essential for the biogenesis of siRNAs, the genes with associated siRNA loci are less affected by the pol IV mutation. CONCLUSIONS This deep and integrated analysis of gene expression, TEs distribution, smallRNA targeting and DNA methylation levels, reveals that loss of Pol IV activity globally affects genome regulation, pointing at TEs as modulator of nearby gene expression and indicating the existence of multiple level epigenetic silencing mechanisms. Our results also suggest a predominant role of the Pol IV-mediated RdDM pathway in genome dominance regulation, and subgenome stability and evolution in maize.
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Affiliation(s)
- Cristian Forestan
- Department of Agronomy, Food, Natural resources, Animals and Environment, University of Padova, Viale dell’Università 16, 35020 Legnaro, PD Italy
| | - Silvia Farinati
- Department of Agronomy, Food, Natural resources, Animals and Environment, University of Padova, Viale dell’Università 16, 35020 Legnaro, PD Italy
| | | | - Alice Lunardon
- Department of Agronomy, Food, Natural resources, Animals and Environment, University of Padova, Viale dell’Università 16, 35020 Legnaro, PD Italy
- Present Address: Department of Biology and Huck Institutes of the Life Sciences, Penn State University, University Park, Pennsylvania, PA 16802 USA
| | | | - Serena Varotto
- Department of Agronomy, Food, Natural resources, Animals and Environment, University of Padova, Viale dell’Università 16, 35020 Legnaro, PD Italy
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18
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McCullers TJ, Steiniger M. Transposable elements in Drosophila. Mob Genet Elements 2017; 7:1-18. [PMID: 28580197 PMCID: PMC5443660 DOI: 10.1080/2159256x.2017.1318201] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 04/07/2017] [Accepted: 04/07/2017] [Indexed: 11/09/2022] Open
Abstract
Transposable elements (TEs) are mobile genetic elements that can mobilize within host genomes. As TEs comprise more than 40% of the human genome and are linked to numerous diseases, understanding their mechanisms of mobilization and regulation is important. Drosophila melanogaster is an ideal model organism for the study of eukaryotic TEs as its genome contains a diverse array of active TEs. TEs universally impact host genome size via transposition and deletion events, but may also adopt unique functional roles in host organisms. There are 2 main classes of TEs: DNA transposons and retrotransposons. These classes are further divided into subgroups of TEs with unique structural and functional characteristics, demonstrating the significant variability among these elements. Despite this variability, D. melanogaster and other eukaryotic organisms utilize conserved mechanisms to regulate TEs. This review focuses on the transposition mechanisms and regulatory pathways of TEs, and their functional roles in D. melanogaster.
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Affiliation(s)
| | - Mindy Steiniger
- Department of Biology, University of Missouri, St. Louis, MO, USA
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19
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Marcon C, Paschold A, Malik WA, Lithio A, Baldauf JA, Altrogge L, Opitz N, Lanz C, Schoof H, Nettleton D, Piepho HP, Hochholdinger F. Stability of Single-Parent Gene Expression Complementation in Maize Hybrids upon Water Deficit Stress. PLANT PHYSIOLOGY 2017; 173:1247-1257. [PMID: 27999083 PMCID: PMC5291719 DOI: 10.1104/pp.16.01045] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 12/18/2016] [Indexed: 05/24/2023]
Abstract
Heterosis is the superior performance of F1 hybrids compared with their homozygous, genetically distinct parents. In this study, we monitored the transcriptomic divergence of the maize (Zea mays) inbred lines B73 and Mo17 and their reciprocal F1 hybrid progeny in primary roots under control and water deficit conditions simulated by polyethylene glycol treatment. Single-parent expression (SPE) of genes is an extreme instance of gene expression complementation, in which genes are active in only one of two parents but are expressed in both reciprocal hybrids. In this study, 1,997 genes only expressed in B73 and 2,024 genes only expressed in Mo17 displayed SPE complementation under control and water deficit conditions. As a consequence, the number of active genes in hybrids exceeded the number of active genes in the parental inbred lines significantly independent of treatment. SPE patterns were substantially more stable to expression changes by water deficit treatment than other genotype-specific expression profiles. While, on average, 75% of all SPE patterns were not altered in response to polyethylene glycol treatment, only 17% of the remaining genotype-specific expression patterns were not changed by water deficit. Nonsyntenic genes that lack syntenic orthologs in other grass species, and thus evolved late in the grass lineage, were significantly overrepresented among SPE genes. Hence, the significant overrepresentation of nonsyntenic genes among SPE patterns and their stability under water limitation might suggest a function of these genes during the early developmental manifestation of heterosis under fluctuating environmental conditions in hybrid progeny of the inbred lines B73 and Mo17.
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Affiliation(s)
- Caroline Marcon
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics (C.M., A.P., J.A.B., N.O., F.H.) and Crop Bioinformatics (L.A., H.S.), University of Bonn, 53113 Bonn, Germany
- Institute for Crop Science, Biostatistics Unit, University of Hohenheim, 70599 Stuttgart, Germany (W.A.M., H.-P.P.)
- Department of Statistics, Iowa State University, Ames, Iowa 50011-1210 (A.L., D.N.); and
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (C.L.)
| | - Anja Paschold
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics (C.M., A.P., J.A.B., N.O., F.H.) and Crop Bioinformatics (L.A., H.S.), University of Bonn, 53113 Bonn, Germany
- Institute for Crop Science, Biostatistics Unit, University of Hohenheim, 70599 Stuttgart, Germany (W.A.M., H.-P.P.)
- Department of Statistics, Iowa State University, Ames, Iowa 50011-1210 (A.L., D.N.); and
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (C.L.)
| | - Waqas Ahmed Malik
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics (C.M., A.P., J.A.B., N.O., F.H.) and Crop Bioinformatics (L.A., H.S.), University of Bonn, 53113 Bonn, Germany
- Institute for Crop Science, Biostatistics Unit, University of Hohenheim, 70599 Stuttgart, Germany (W.A.M., H.-P.P.)
- Department of Statistics, Iowa State University, Ames, Iowa 50011-1210 (A.L., D.N.); and
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (C.L.)
| | - Andrew Lithio
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics (C.M., A.P., J.A.B., N.O., F.H.) and Crop Bioinformatics (L.A., H.S.), University of Bonn, 53113 Bonn, Germany
- Institute for Crop Science, Biostatistics Unit, University of Hohenheim, 70599 Stuttgart, Germany (W.A.M., H.-P.P.)
- Department of Statistics, Iowa State University, Ames, Iowa 50011-1210 (A.L., D.N.); and
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (C.L.)
| | - Jutta A Baldauf
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics (C.M., A.P., J.A.B., N.O., F.H.) and Crop Bioinformatics (L.A., H.S.), University of Bonn, 53113 Bonn, Germany
- Institute for Crop Science, Biostatistics Unit, University of Hohenheim, 70599 Stuttgart, Germany (W.A.M., H.-P.P.)
- Department of Statistics, Iowa State University, Ames, Iowa 50011-1210 (A.L., D.N.); and
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (C.L.)
| | - Lena Altrogge
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics (C.M., A.P., J.A.B., N.O., F.H.) and Crop Bioinformatics (L.A., H.S.), University of Bonn, 53113 Bonn, Germany
- Institute for Crop Science, Biostatistics Unit, University of Hohenheim, 70599 Stuttgart, Germany (W.A.M., H.-P.P.)
- Department of Statistics, Iowa State University, Ames, Iowa 50011-1210 (A.L., D.N.); and
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (C.L.)
| | - Nina Opitz
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics (C.M., A.P., J.A.B., N.O., F.H.) and Crop Bioinformatics (L.A., H.S.), University of Bonn, 53113 Bonn, Germany
- Institute for Crop Science, Biostatistics Unit, University of Hohenheim, 70599 Stuttgart, Germany (W.A.M., H.-P.P.)
- Department of Statistics, Iowa State University, Ames, Iowa 50011-1210 (A.L., D.N.); and
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (C.L.)
| | - Christa Lanz
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics (C.M., A.P., J.A.B., N.O., F.H.) and Crop Bioinformatics (L.A., H.S.), University of Bonn, 53113 Bonn, Germany
- Institute for Crop Science, Biostatistics Unit, University of Hohenheim, 70599 Stuttgart, Germany (W.A.M., H.-P.P.)
- Department of Statistics, Iowa State University, Ames, Iowa 50011-1210 (A.L., D.N.); and
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (C.L.)
| | - Heiko Schoof
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics (C.M., A.P., J.A.B., N.O., F.H.) and Crop Bioinformatics (L.A., H.S.), University of Bonn, 53113 Bonn, Germany
- Institute for Crop Science, Biostatistics Unit, University of Hohenheim, 70599 Stuttgart, Germany (W.A.M., H.-P.P.)
- Department of Statistics, Iowa State University, Ames, Iowa 50011-1210 (A.L., D.N.); and
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (C.L.)
| | - Dan Nettleton
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics (C.M., A.P., J.A.B., N.O., F.H.) and Crop Bioinformatics (L.A., H.S.), University of Bonn, 53113 Bonn, Germany
- Institute for Crop Science, Biostatistics Unit, University of Hohenheim, 70599 Stuttgart, Germany (W.A.M., H.-P.P.)
- Department of Statistics, Iowa State University, Ames, Iowa 50011-1210 (A.L., D.N.); and
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (C.L.)
| | - Hans-Peter Piepho
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics (C.M., A.P., J.A.B., N.O., F.H.) and Crop Bioinformatics (L.A., H.S.), University of Bonn, 53113 Bonn, Germany
- Institute for Crop Science, Biostatistics Unit, University of Hohenheim, 70599 Stuttgart, Germany (W.A.M., H.-P.P.)
- Department of Statistics, Iowa State University, Ames, Iowa 50011-1210 (A.L., D.N.); and
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (C.L.)
| | - Frank Hochholdinger
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics (C.M., A.P., J.A.B., N.O., F.H.) and Crop Bioinformatics (L.A., H.S.), University of Bonn, 53113 Bonn, Germany;
- Institute for Crop Science, Biostatistics Unit, University of Hohenheim, 70599 Stuttgart, Germany (W.A.M., H.-P.P.);
- Department of Statistics, Iowa State University, Ames, Iowa 50011-1210 (A.L., D.N.); and
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (C.L.)
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20
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Chellapan BV, van Dam P, Rep M, Cornelissen BJC, Fokkens L. Non-canonical Helitrons in Fusarium oxysporum. Mob DNA 2016; 7:27. [PMID: 27990178 PMCID: PMC5148889 DOI: 10.1186/s13100-016-0083-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 12/03/2016] [Indexed: 01/18/2023] Open
Abstract
Background Helitrons are eukaryotic rolling circle transposable elements that can have a large impact on host genomes due to their copy-number and their ability to capture and copy genes and regulatory elements. They occur widely in plants and animals, and have thus far been relatively little investigated in fungi. Results Here, we comprehensively survey Helitrons in several completely sequenced genomes representing the F. oxysporum species complex (FOSC). We thoroughly characterize 5 different Helitron subgroups and determine their impact on genome evolution and assembly in this species complex. FOSC Helitrons resemble members of the Helitron2 variant that includes Helentrons and DINEs. The fact that some Helitrons appeared to be still active in FOSC provided the opportunity to determine whether Helitrons occur as a circular intermediate in FOSC. We present experimental evidence suggesting that at least one Helitron subgroup occurs with joined ends, suggesting a circular intermediate. We extend our analyses to other Pezizomycotina and find that most fungal Helitrons we identified group phylogenetically with Helitron2 and probably have similar characteristics. Conclusions FOSC genomes harbour non-canonical Helitrons that are characterized by asymmetric terminal inverted repeats, show hallmarks of recent activity and likely transpose via a circular intermediate. Bioinformatic analyses indicate that they are representative of a large reservoir of fungal Helitrons that thus far has not been characterized. Electronic supplementary material The online version of this article (doi:10.1186/s13100-016-0083-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Biju Vadakkemukadiyil Chellapan
- Department of Computational Biology and Bioinformatics, University of Kerala, Karyavattom Campus, Karyavattom PO, Trivandrum, Kerala India ; Molecular Plant Pathology, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, P.O. Box 94215, 1090 Amsterdam, GE The Netherlands
| | - Peter van Dam
- Molecular Plant Pathology, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, P.O. Box 94215, 1090 Amsterdam, GE The Netherlands
| | - Martijn Rep
- Molecular Plant Pathology, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, P.O. Box 94215, 1090 Amsterdam, GE The Netherlands
| | - Ben J C Cornelissen
- Molecular Plant Pathology, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, P.O. Box 94215, 1090 Amsterdam, GE The Netherlands
| | - Like Fokkens
- Molecular Plant Pathology, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, P.O. Box 94215, 1090 Amsterdam, GE The Netherlands
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21
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Zhang HH, Li GY, Xiong XM, Han MJ, Dai FY. Horizontal transfer of a novel Helentron in insects. Mol Genet Genomics 2016; 292:243-250. [DOI: 10.1007/s00438-016-1270-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 11/02/2016] [Indexed: 11/24/2022]
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22
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Negi P, Rai AN, Suprasanna P. Moving through the Stressed Genome: Emerging Regulatory Roles for Transposons in Plant Stress Response. FRONTIERS IN PLANT SCIENCE 2016; 7:1448. [PMID: 27777577 PMCID: PMC5056178 DOI: 10.3389/fpls.2016.01448] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 09/12/2016] [Indexed: 05/02/2023]
Abstract
The recognition of a positive correlation between organism genome size with its transposable element (TE) content, represents a key discovery of the field of genome biology. Considerable evidence accumulated since then suggests the involvement of TEs in genome structure, evolution and function. The global genome reorganization brought about by transposon activity might play an adaptive/regulatory role in the host response to environmental challenges, reminiscent of McClintock's original 'Controlling Element' hypothesis. This regulatory aspect of TEs is also garnering support in light of the recent evidences, which project TEs as "distributed genomic control modules." According to this view, TEs are capable of actively reprogramming host genes circuits and ultimately fine-tuning the host response to specific environmental stimuli. Moreover, the stress-induced changes in epigenetic status of TE activity may allow TEs to propagate their stress responsive elements to host genes; the resulting genome fluidity can permit phenotypic plasticity and adaptation to stress. Given their predominating presence in the plant genomes, nested organization in the genic regions and potential regulatory role in stress response, TEs hold unexplored potential for crop improvement programs. This review intends to present the current information about the roles played by TEs in plant genome organization, evolution, and function and highlight the regulatory mechanisms in plant stress responses. We will also briefly discuss the connection between TE activity, host epigenetic response and phenotypic plasticity as a critical link for traversing the translational bridge from a purely basic study of TEs, to the applied field of stress adaptation and crop improvement.
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Affiliation(s)
| | | | - Penna Suprasanna
- Plant Stress Physiology and Biotechnology Section, Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research CentreTrombay, India
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23
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Hoy MA, Waterhouse RM, Wu K, Estep AS, Ioannidis P, Palmer WJ, Pomerantz AF, Simão FA, Thomas J, Jiggins FM, Murphy TD, Pritham EJ, Robertson HM, Zdobnov EM, Gibbs RA, Richards S. Genome Sequencing of the Phytoseiid Predatory Mite Metaseiulus occidentalis Reveals Completely Atomized Hox Genes and Superdynamic Intron Evolution. Genome Biol Evol 2016; 8:1762-75. [PMID: 26951779 PMCID: PMC4943173 DOI: 10.1093/gbe/evw048] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2016] [Indexed: 12/16/2022] Open
Abstract
Metaseiulus occidentalis is an eyeless phytoseiid predatory mite employed for the biological control of agricultural pests including spider mites. Despite appearances, these predator and prey mites are separated by some 400 Myr of evolution and radically different lifestyles. We present a 152-Mb draft assembly of the M. occidentalis genome: Larger than that of its favored prey, Tetranychus urticae, but considerably smaller than those of many other chelicerates, enabling an extremely contiguous and complete assembly to be built-the best arachnid to date. Aided by transcriptome data, genome annotation cataloged 18,338 protein-coding genes and identified large numbers of Helitron transposable elements. Comparisons with other arthropods revealed a particularly dynamic and turbulent genomic evolutionary history. Its genes exhibit elevated molecular evolution, with strikingly high numbers of intron gains and losses, in stark contrast to the deer tick Ixodes scapularis Uniquely among examined arthropods, this predatory mite's Hox genes are completely atomized, dispersed across the genome, and it encodes five copies of the normally single-copy RNA processing Dicer-2 gene. Examining gene families linked to characteristic biological traits of this tiny predator provides initial insights into processes of sex determination, development, immune defense, and how it detects, disables, and digests its prey. As the first reference genome for the Phytoseiidae, and for any species with the rare sex determination system of parahaploidy, the genome of the western orchard predatory mite improves genomic sampling of chelicerates and provides invaluable new resources for functional genomic analyses of this family of agriculturally important mites.
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Affiliation(s)
- Marjorie A Hoy
- Department of Entomology and Nematology, University of Florida
| | - Robert M Waterhouse
- Department of Genetic Medicine and Development, University of Geneva Medical School, Switzerland Swiss Institute of Bioinformatics, Geneva, Switzerland Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology The Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Ke Wu
- Department of Entomology and Nematology, University of Florida
| | - Alden S Estep
- Department of Entomology and Nematology, University of Florida
| | - Panagiotis Ioannidis
- Department of Genetic Medicine and Development, University of Geneva Medical School, Switzerland Swiss Institute of Bioinformatics, Geneva, Switzerland
| | | | | | - Felipe A Simão
- Department of Genetic Medicine and Development, University of Geneva Medical School, Switzerland Swiss Institute of Bioinformatics, Geneva, Switzerland
| | - Jainy Thomas
- Department of Human Genetics, University of Utah
| | | | - Terence D Murphy
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland
| | | | - Hugh M Robertson
- Department of Entomology, University of Illinois at Urbana-Champaign
| | - Evgeny M Zdobnov
- Department of Genetic Medicine and Development, University of Geneva Medical School, Switzerland Swiss Institute of Bioinformatics, Geneva, Switzerland
| | - Richard A Gibbs
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine
| | - Stephen Richards
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine
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24
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Castanera R, López-Varas L, Borgognone A, LaButti K, Lapidus A, Schmutz J, Grimwood J, Pérez G, Pisabarro AG, Grigoriev IV, Stajich JE, Ramírez L. Transposable Elements versus the Fungal Genome: Impact on Whole-Genome Architecture and Transcriptional Profiles. PLoS Genet 2016; 12:e1006108. [PMID: 27294409 PMCID: PMC4905642 DOI: 10.1371/journal.pgen.1006108] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 05/13/2016] [Indexed: 11/17/2022] Open
Abstract
Transposable elements (TEs) are exceptional contributors to eukaryotic genome diversity. Their ubiquitous presence impacts the genomes of nearly all species and mediates genome evolution by causing mutations and chromosomal rearrangements and by modulating gene expression. We performed an exhaustive analysis of the TE content in 18 fungal genomes, including strains of the same species and species of the same genera. Our results depicted a scenario of exceptional variability, with species having 0.02 to 29.8% of their genome consisting of transposable elements. A detailed analysis performed on two strains of Pleurotus ostreatus uncovered a genome that is populated mainly by Class I elements, especially LTR-retrotransposons amplified in recent bursts from 0 to 2 million years (My) ago. The preferential accumulation of TEs in clusters led to the presence of genomic regions that lacked intra- and inter-specific conservation. In addition, we investigated the effect of TE insertions on the expression of their nearby upstream and downstream genes. Our results showed that an important number of genes under TE influence are significantly repressed, with stronger repression when genes are localized within transposon clusters. Our transcriptional analysis performed in four additional fungal models revealed that this TE-mediated silencing was present only in species with active cytosine methylation machinery. We hypothesize that this phenomenon is related to epigenetic defense mechanisms that are aimed to suppress TE expression and control their proliferation. Transposable elements (TEs) are enigmatic genetic units that have played important roles in the evolution of eukaryotic genomes. Since their discovery in the 1950s, they have gained increasing attention and are known today as active genome modelers in multiple species. Although these elements have been widely studied in plants, much less is known about their occurrence and impact on the fungal kingdom. Using a diverse set of basidiomycete and ascomycete fungi, we quantified and characterized a huge diversity of DNA and RNA transposable elements, and we identified species that had 0.02 to 29.8% of their genomes occupied by transposable elements. In addition, using our basidiomycete model Pleurotus ostreatus, we demonstrated how TE insertions produced detrimental effects on the expression of upstream and downstream genes, which were downregulated compared with the control groups. This silencing mechanism was present in the basidiomycetes tested but exhibited a patchy distribution in ascomycetes, and might be related to specific genome defense mechanisms that control transposon proliferation. This finding reveals the broader impact of transposable elements in fungi. In addition to their importance as long-term evolutionary forces, they play major roles in the more dynamic transcriptome regulation of certain species.
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Affiliation(s)
- Raúl Castanera
- Genetics and Microbiology Research Group, Department of Agrarian Production, Public University of Navarre, Pamplona, Navarre, Spain
| | - Leticia López-Varas
- Genetics and Microbiology Research Group, Department of Agrarian Production, Public University of Navarre, Pamplona, Navarre, Spain
| | - Alessandra Borgognone
- Genetics and Microbiology Research Group, Department of Agrarian Production, Public University of Navarre, Pamplona, Navarre, Spain
| | - Kurt LaButti
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, California, United States of America
| | - Alla Lapidus
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, California, United States of America.,Center for Algorithmic Biotechnology, St. Petersburg State University, St. Petersburg, Russia
| | - Jeremy Schmutz
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, California, United States of America.,Hudson Alpha Institute for Biotechnology, Huntsville, Alabama, United States of America
| | - Jane Grimwood
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, California, United States of America.,Hudson Alpha Institute for Biotechnology, Huntsville, Alabama, United States of America
| | - Gúmer Pérez
- Genetics and Microbiology Research Group, Department of Agrarian Production, Public University of Navarre, Pamplona, Navarre, Spain
| | - Antonio G Pisabarro
- Genetics and Microbiology Research Group, Department of Agrarian Production, Public University of Navarre, Pamplona, Navarre, Spain
| | - Igor V Grigoriev
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, California, United States of America
| | - Jason E Stajich
- Department of Plant Pathology and Microbiology, Institute for Integrative Genome Biology, University of California-Riverside, Riverside, California, United States of America
| | - Lucía Ramírez
- Genetics and Microbiology Research Group, Department of Agrarian Production, Public University of Navarre, Pamplona, Navarre, Spain
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25
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Abstract
Helitrons, the eukaryotic rolling-circle transposable elements, are widespread but most prevalent among plant and animal genomes. Recent studies have identified three additional coding and structural variants of Helitrons called Helentrons, Proto-Helentron, and Helitron2. Helitrons and Helentrons make up a substantial fraction of many genomes where nonautonomous elements frequently outnumber the putative autonomous partner. This includes the previously ambiguously classified DINE-1-like repeats, which are highly abundant in Drosophila and many other animal genomes. The purpose of this review is to summarize what we have learned about Helitrons in the decade since their discovery. First, we describe the history of autonomous Helitrons, and their variants. Second, we explain the common coding features and difference in structure of canonical Helitrons versus the endonuclease-encoding Helentrons. Third, we review how Helitrons and Helentrons are classified and discuss why the system used for other transposable element families is not applicable. We also touch upon how genome-wide identification of candidate Helitrons is carried out and how to validate candidate Helitrons. We then shift our focus to a model of transposition and the report of an excision event. We discuss the different proposed models for the mechanism of gene capture. Finally, we will talk about where Helitrons are found, including discussions of vertical versus horizontal transfer, the propensity of Helitrons and Helentrons to capture and shuffle genes and how they impact the genome. We will end the review with a summary of open questions concerning the biology of this intriguing group of transposable elements.
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26
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Bousios A, Gaut BS. Mechanistic and evolutionary questions about epigenetic conflicts between transposable elements and their plant hosts. CURRENT OPINION IN PLANT BIOLOGY 2016; 30:123-33. [PMID: 26950253 DOI: 10.1016/j.pbi.2016.02.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 02/16/2016] [Accepted: 02/17/2016] [Indexed: 05/02/2023]
Abstract
Transposable elements (TEs) constitute the majority of plant genomes, but most are epigenetically inactivated by their host. Research over the last decade has elucidated many of the molecular components that are required for TE silencing. In contrast, the evolutionary dynamics between TEs and silencing pathways are less clear. Here, we discuss current information about these dynamics from both mechanistic and evolutionary perspectives. We highlight new evidence that palindromic sequences within TEs may act as signals for host recognition and that cis-regulatory regions of TEs may be sites of ongoing arms races with host defenses. We also discuss patterns of TE aging after they are silenced; while there is not yet a consensus, it appears that TEs are removed more rapidly near genes, such that older TE insertions tend to be farther from genes. We conclude by discussing the energetic costs for maintaining silencing pathways, which appear to be substantive. The maintenance of silencing pathways across many species suggests that epigenetic emergencies are frequent.
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Affiliation(s)
| | - Brandon S Gaut
- Department of Ecology and Evolutionary Biology, UC Irvine, Irvine, CA 92697, USA.
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27
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Roffler S, Menardo F, Wicker T. The making of a genomic parasite - the Mothra family sheds light on the evolution of Helitrons in plants. Mob DNA 2015; 6:23. [PMID: 26688693 PMCID: PMC4683698 DOI: 10.1186/s13100-015-0054-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 12/04/2015] [Indexed: 11/29/2022] Open
Abstract
Background Helitrons are Class II transposons which are highly abundant in almost all eukaryotes. However, most Helitrons lack protein coding sequence. These non-autonomous elements are thought to hijack recombinase/helicase (RepHel) and possibly further enzymes from related, autonomous elements. Interestingly, many plant Helitrons contain an additional gene encoding a single-strand binding protein homologous to Replication Factor A (RPA), a highly conserved, single-copy gene found in all eukaryotes. Results Here, we describe the analysis of DHH_Mothra, a high-copy non-autonomous Helitron in the genome of rice (Oryza sativa). Mothra has a low GC-content and consists of two distinct blocs of tandem repeats. Based on homology between their termini, we identified a putative mother element which encodes an RPA-like protein but has no RepHel gene. Additionally, we found a putative autonomous sister-family with strong homology to the Mothra mother element in the RPA protein and terminal sequences, which we propose provides the RepHel domain for the Mothra family. Furthermore, we phylogenetically analyzed the evolutionary history of RPA-like proteins. Interestingly, plant Helitron RPAs (PHRPAs) are only found in monocotyledonous and dicotyledonous plants and they form a monophyletic group which branched off before the eukaryotic “core” RPAs. Conclusions Our data show how erosion of autonomous Helitrons can lead to different “levels” of autonomy within Helitron families and can create highly successful subfamilies of non-autonomous elements. Most importantly, our phylogenetic analysis showed that the PHRPA gene was most likely acquired via horizontal gene transfer from an unknown eukaryotic donor at least 145–300 million years ago in the common ancestor of monocotyledonous and dicotyledonous plants. This might have led to the evolution of a separate branch of the Helitron superfamily in plants. Electronic supplementary material The online version of this article (doi:10.1186/s13100-015-0054-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Stefan Roffler
- Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, Zürich, CH-8008 Switzerland
| | - Fabrizio Menardo
- Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, Zürich, CH-8008 Switzerland
| | - Thomas Wicker
- Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, Zürich, CH-8008 Switzerland
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28
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Tang H, Bomhoff MD, Briones E, Zhang L, Schnable JC, Lyons E. SynFind: Compiling Syntenic Regions across Any Set of Genomes on Demand. Genome Biol Evol 2015; 7:3286-98. [PMID: 26560340 PMCID: PMC4700967 DOI: 10.1093/gbe/evv219] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The identification of conserved syntenic regions enables discovery of predicted
locations for orthologous and homeologous genes, even when no such gene is present.
This capability means that synteny-based methods are far more effective than sequence
similarity-based methods in identifying true-negatives, a necessity for studying gene
loss and gene transposition. However, the identification of syntenic regions requires
complex analyses which must be repeated for pairwise comparisons between any two
species. Therefore, as the number of published genomes increases, there is a growing
demand for scalable, simple-to-use applications to perform comparative genomic
analyses that cater to both gene family studies and genome-scale studies. We
implemented SynFind, a web-based tool that addresses this need. Given one query
genome, SynFind is capable of identifying conserved syntenic regions in any set of
target genomes. SynFind is capable of reporting per-gene information, useful for
researchers studying specific gene families, as well as genome-wide data sets of
syntenic gene and predicted gene locations, critical for researchers focused on
large-scale genomic analyses. Inference of syntenic homologs provides the basis for
correlation of functional changes around genes of interests between related
organisms. Deployed on the CoGe online platform, SynFind is connected to the genomic
data from over 15,000 organisms from all domains of life as well as supporting
multiple releases of the same organism. SynFind makes use of a powerful job execution
framework that promises scalability and reproducibility. SynFind can be accessed at
http://genomevolution.org/CoGe/SynFind.pl. A video tutorial of SynFind
using Phytophthrora as an example is available at http://www.youtube.com/watch?v=2Agczny9Nyc.
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Affiliation(s)
- Haibao Tang
- Center for Genomics and Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province, China School of Plant Sciences, iPlant Collaborative, University of Arizona
| | - Matthew D Bomhoff
- School of Plant Sciences, iPlant Collaborative, University of Arizona
| | - Evan Briones
- School of Plant Sciences, iPlant Collaborative, University of Arizona
| | - Liangsheng Zhang
- Center for Genomics and Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province, China
| | - James C Schnable
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln
| | - Eric Lyons
- School of Plant Sciences, iPlant Collaborative, University of Arizona
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29
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Differential pre-mRNA Splicing Alters the Transcript Diversity of Helitrons Between the Maize Inbred Lines. G3-GENES GENOMES GENETICS 2015; 5:1703-11. [PMID: 26070844 PMCID: PMC4528327 DOI: 10.1534/g3.115.018630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The propensity to capture and mobilize gene fragments by the highly abundant Helitron family of transposable elements likely impacts the evolution of genes in Zea mays. These elements provide a substrate for natural selection by giving birth to chimeric transcripts by intertwining exons of disparate genes. They also capture flanking exons by read-through transcription. Here, we describe the expression of selected Helitrons in different maize inbred lines. We recently reported that these Helitrons produce multiple isoforms of transcripts in inbred B73 via alternative splicing. Despite sharing high degrees of sequence similarity, the splicing profile of Helitrons differed among various maize inbred lines. The comparison of Helitron sequences identified unique polymorphisms in inbred B73, which potentially give rise to the alternatively spliced sites utilized by transcript isoforms. Some alterations in splicing, however, do not have obvious explanations. These observations not only add another level to the creation of transcript diversity by Helitrons among inbred lines but also provide novel insights into the cis-acting elements governing splice-site selection during pre-mRNA processing.
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30
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Fournier GP, Andam CP, Gogarten JP. Ancient horizontal gene transfer and the last common ancestors. BMC Evol Biol 2015; 15:70. [PMID: 25897759 PMCID: PMC4427996 DOI: 10.1186/s12862-015-0350-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 04/14/2015] [Indexed: 01/22/2023] Open
Abstract
Background The genomic history of prokaryotic organismal lineages is marked by extensive horizontal gene transfer (HGT) between groups of organisms at all taxonomic levels. These HGT events have played an essential role in the origin and distribution of biological innovations. Analyses of ancient gene families show that HGT existed in the distant past, even at the time of the organismal last universal common ancestor (LUCA). Most gene transfers originated in lineages that have since gone extinct. Therefore, one cannot assume that the last common ancestors of each gene were all present in the same cell representing the cellular ancestor of all extant life. Results Organisms existing as part of a diverse ecosystem at the time of LUCA likely shared genetic material between lineages. If these other lineages persisted for some time, HGT with the descendants of LUCA could have continued into the bacterial and archaeal lineages. Phylogenetic analyses of aminoacyl-tRNA synthetase protein families support the hypothesis that the molecular common ancestors of the most ancient gene families did not all coincide in space and time. This is most apparent in the evolutionary histories of seryl-tRNA synthetase and threonyl-tRNA synthetase protein families, each containing highly divergent “rare” forms, as well as the sparse phylogenetic distributions of pyrrolysyl-tRNA synthetase, and the bacterial heterodimeric form of glycyl-tRNA synthetase. These topologies and phyletic distributions are consistent with horizontal transfers from ancient, likely extinct branches of the tree of life. Conclusions Of all the organisms that may have existed at the time of LUCA, by definition only one lineage is survived by known progeny; however, this lineage retains a genomic record of heterogeneous genetic origins. The evolutionary histories of aminoacyl-tRNA synthetases (aaRS) are especially informative in detecting this signal, as they perform primordial biological functions, have undergone several ancient HGT events, and contain many sites with low substitution rates allowing deep phylogenetic reconstruction. We conclude that some aaRS families contain groups that diverge before LUCA. We propose that these ancient gene variants be described by the term “hypnologs”, reflecting their ancient, reticulate origin from a time in life history that has been all but erased”. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0350-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gregory P Fournier
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - Cheryl P Andam
- Department of Epidemiology, School of Public Health, Harvard University, Boston, MA, 02115, USA.
| | - Johann Peter Gogarten
- Department of Molecular and Cell Biology, and the Institute for Systems Genomics, University of Connecticut, 91 North Eagleville Road, Storrs, CT, 06269-3125, USA.
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31
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Coates BS. Horizontal transfer of a non-autonomous Helitron among insect and viral genomes. BMC Genomics 2015; 16:137. [PMID: 25766741 PMCID: PMC4344730 DOI: 10.1186/s12864-015-1318-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 02/03/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The movement of mobile elements among species by horizontal transposon transfer (HTT) influences the evolution of genomes through the modification of structure and function. Helitrons are a relatively new lineage of DNA-based (class II) transposable elements (TEs) that propagate by rolling-circle replication, and are capable of acquiring host DNA. The rapid spread of Helitrons among animal lineages by HTT is facilitated by shuttling in viral particles or by unknown mechanisms mediated by close organism associations (e.g. between hosts and parasites). RESULTS A non-autonomous Helitron independently annotated as BmHel-2 from Bombyx mori and the MITE01 element from Ostrinia nubilalis was predicted in the genomes of 24 species in the insect Order Lepidoptera. Integrated Helitrons retained ≥ 65% sequence identity over a 250 bp consensus, and were predicted to retain secondary structures inclusive of a 3'-hairpin and a 5'-subterminal inverted repeat. Highly similar Hel-2 copies were predicted in the genomes of insects and associated viruses, which along with a previous documented case of real-time virus-insect cell line transposition suggests that this Helitron has likely propagated by HTT. CONCLUSIONS These findings provide evidence that insect virus may mediate the HTT of Helitron-like TEs. This movement may facilitate the shuttling of DNA elements among insect genomes. Further sampling is required to determine the putative role of HTT in insect genome evolution.
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Affiliation(s)
- Brad S Coates
- United States Department of Agriculture, Agricultural Research Service, Corn Insects & Crop Genetics Research Unit, Iowa State University, Ames, IA, 50011, USA. .,Department of Entomology, Iowa State University, Ames, IA, 50011, USA.
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32
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Abstract
Maize occupies dual roles as both (a) one of the big-three grain species (along with rice and wheat) responsible for providing more than half of the calories consumed around the world, and (b) a model system for plant genetics and cytogenetics dating back to the origin of the field of genetics in the early twentieth century. The long history of genetic investigation in this species combined with modern genomic and quantitative genetic data has provided particular insight into the characteristics of genes linked to phenotypes and how these genes differ from many other sequences in plant genomes that are not easily distinguishable based on molecular data alone. These recent results suggest that the number of genes in plants that make significant contributions to phenotype may be lower than the number of genes defined by current molecular criteria, and also indicate that syntenic conservation has been underemphasized as a marker for gene function.
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Affiliation(s)
- James C Schnable
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska 68583;
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33
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Paschold A, Larson NB, Marcon C, Schnable JC, Yeh CT, Lanz C, Nettleton D, Piepho HP, Schnable PS, Hochholdinger F. Nonsyntenic genes drive highly dynamic complementation of gene expression in maize hybrids. THE PLANT CELL 2014; 26:3939-48. [PMID: 25315323 PMCID: PMC4247586 DOI: 10.1105/tpc.114.130948] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 09/05/2014] [Accepted: 09/24/2014] [Indexed: 05/19/2023]
Abstract
Maize (Zea mays) displays an exceptional level of structural genomic diversity, which is likely unique among higher eukaryotes. In this study, we surveyed how the genetic divergence of two maize inbred lines affects the transcriptomic landscape in four different primary root tissues of their F1-hybrid progeny. An extreme instance of complementation was frequently observed: genes that were expressed in only one parent but in both reciprocal hybrids. This single-parent expression (SPE) pattern was detected for 2341 genes with up to 1287 SPE patterns per tissue. As a consequence, the number of active genes in hybrids exceeded that of their parents in each tissue by >400. SPE patterns are highly dynamic, as illustrated by their excessive degree of tissue specificity (80%). The biological significance of this type of complementation is underpinned by the observation that a disproportionally high number of SPE genes (75 to 82%) is nonsyntenic, as opposed to all expressed genes (36%). These genes likely evolved after the last whole-genome duplication and are therefore younger than the syntenic genes. In summary, SPE genes shape the remarkable gene expression plasticity between root tissues and complementation in maize hybrids, resulting in a tissue-specific increase of active genes in F1-hybrids compared with their inbred parents.
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Affiliation(s)
- Anja Paschold
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics, University of Bonn, 53113 Bonn, Germany
| | - Nick B Larson
- Department of Statistics, Iowa State University, Ames, Iowa 50011-1210
| | - Caroline Marcon
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics, University of Bonn, 53113 Bonn, Germany
| | - James C Schnable
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska 68588
| | - Cheng-Ting Yeh
- Department of Agronomy and Center for Plant Genomics, Iowa State University, Ames, Iowa 50011-3650
| | - Christa Lanz
- Department of Molecular Biology, Max-Planck-Institute for Developmental Biology, 72076 Tuebingen, Germany
| | - Dan Nettleton
- Department of Statistics, Iowa State University, Ames, Iowa 50011-1210
| | - Hans-Peter Piepho
- Institute for Crop Science, Biostatistics Unit, University of Hohenheim, 70599 Stuttgart, Germany
| | - Patrick S Schnable
- Department of Agronomy and Center for Plant Genomics, Iowa State University, Ames, Iowa 50011-3650
| | - Frank Hochholdinger
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics, University of Bonn, 53113 Bonn, Germany
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34
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Thomas J, Phillips CD, Baker RJ, Pritham EJ. Rolling-circle transposons catalyze genomic innovation in a mammalian lineage. Genome Biol Evol 2014; 6:2595-610. [PMID: 25223768 PMCID: PMC4224331 DOI: 10.1093/gbe/evu204] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Rolling-circle transposons (Helitrons) are a newly discovered group of mobile DNA widespread in plant and invertebrate genomes but limited to the bat family Vespertilionidae among mammals. Little is known about the long-term impact of Helitron activity because the genomes where Helitron activity has been extensively studied are predominated by young families. Here, we report a comprehensive catalog of vetted Helitrons from the 7× Myotis lucifugus genome assembly. To estimate the timing of transposition, we scored presence/absence across related vespertilionid genome sequences with estimated divergence times. This analysis revealed that the Helibat family has been a persistent source of genomic innovation throughout the vespertilionid diversification from approximately 30–36 Ma to as recently as approximately 1.8–6 Ma. This is the first report of persistent Helitron transposition over an extended evolutionary timeframe. These findings illustrate that the pattern of Helitron activity is akin to the vertical persistence of LINE retrotransposons in primates and other mammalian lineages. Like retrotransposition in primates, rolling-circle transposition has generated lineage-specific variation and accounts for approximately 110 Mb, approximately 6% of the genome of M. lucifugus. The Helitrons carry a heterogeneous assortment of host sequence including retroposed messenger RNAs, retrotransposons, DNA transposons, as well as introns, exons and regulatory regions (promoters, 5′-untranslated regions [UTRs], and 3′-UTRs) of which some are evolving in a pattern suggestive of purifying selection. Evidence that Helitrons have contributed putative promoters, exons, splice sites, polyadenylation sites, and microRNA-binding sites to transcripts otherwise conserved across mammals is presented, and the implication of Helitron activity to innovation in these unique mammals is discussed.
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Affiliation(s)
- Jainy Thomas
- Department of Human Genetics, University of Utah
| | - Caleb D Phillips
- Department of Biological Sciences and Museum, Texas Tech University
| | - Robert J Baker
- Department of Biological Sciences and Museum, Texas Tech University
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Helinoto, a Helitron2 transposon from the icefish Chionodraco hamatus, contains a region with three deubiquitinase-like domains that exhibit transcriptional activity. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2014; 11:49-58. [PMID: 25178533 DOI: 10.1016/j.cbd.2014.07.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 07/29/2014] [Accepted: 07/30/2014] [Indexed: 11/24/2022]
Abstract
Transposable elements have accompanied the evolution of the eukaryotic genome for millions of years. The recently discovered Helitron order (class II, subclass 2 single-strand DNA transposons) is common in eukaryotes and seems to play a highly active role in genome reshuffling. This study provides novel insights into the characteristics of Helinoto, a helitron isolated in the genome of the Antarctic fish Chionodraco hamatus. In particular, investigation of the structure of its 5' and 3' ends, which are involved in the transposition process, enabled identification of the characteristic motifs of the Helitron2 group. Moreover, identification of a deubiquitinating protease domain in the region upstream two consecutive OTU domains extended and strengthened the "deubiquitinase" character of the N-terminal portion of Helinoto. Finally, Helinoto transcriptional activity was detected in several C. hamatus tissues. Taken together, these data are particularly intriguing because they document high transcription levels for genes involved in ubiquitination, which ensures protein homeostasis in the extreme Antarctic environment.
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Oliver KR, McComb JA, Greene WK. Transposable elements: powerful contributors to angiosperm evolution and diversity. Genome Biol Evol 2014; 5:1886-901. [PMID: 24065734 PMCID: PMC3814199 DOI: 10.1093/gbe/evt141] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Transposable elements (TEs) are a dominant feature of most flowering plant genomes. Together with other accepted facilitators of evolution, accumulating data indicate that TEs can explain much about their rapid evolution and diversification. Genome size in angiosperms is highly correlated with TE content and the overwhelming bulk (>80%) of large genomes can be composed of TEs. Among retro-TEs, long terminal repeats (LTRs) are abundant, whereas DNA-TEs, which are often less abundant than retro-TEs, are more active. Much adaptive or evolutionary potential in angiosperms is due to the activity of TEs (active TE-Thrust), resulting in an extraordinary array of genetic changes, including gene modifications, duplications, altered expression patterns, and exaptation to create novel genes, with occasional gene disruption. TEs implicated in the earliest origins of the angiosperms include the exapted Mustang, Sleeper, and Fhy3/Far1 gene families. Passive TE-Thrust can create a high degree of adaptive or evolutionary potential by engendering ectopic recombination events resulting in deletions, duplications, and karyotypic changes. TE activity can also alter epigenetic patterning, including that governing endosperm development, thus promoting reproductive isolation. Continuing evolution of long-lived resprouter angiosperms, together with genetic variation in their multiple meristems, indicates that TEs can facilitate somatic evolution in addition to germ line evolution. Critical to their success, angiosperms have a high frequency of polyploidy and hybridization, with resultant increased TE activity and introgression, and beneficial gene duplication. Together with traditional explanations, the enhanced genomic plasticity facilitated by TE-Thrust, suggests a more complete and satisfactory explanation for Darwin's "abominable mystery": the spectacular success of the angiosperms.
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Affiliation(s)
- Keith R Oliver
- School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia
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Bennetzen JL, Wang H. The contributions of transposable elements to the structure, function, and evolution of plant genomes. ANNUAL REVIEW OF PLANT BIOLOGY 2014; 65:505-30. [PMID: 24579996 DOI: 10.1146/annurev-arplant-050213-035811] [Citation(s) in RCA: 310] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Transposable elements (TEs) are the key players in generating genomic novelty by a combination of the chromosome rearrangements they cause and the genes that come under their regulatory sway. Genome size, gene content, gene order, centromere function, and numerous other aspects of nuclear biology are driven by TE activity. Although the origins and attitudes of TEs have the hallmarks of selfish DNA, there are numerous cases where TE components have been co-opted by the host to create new genes or modify gene regulation. In particular, epigenetic regulation has been transformed from a process to silence invading TEs and viruses into a key strategy for regulating plant genes. Most, perhaps all, of this epigenetic regulation is derived from TE insertions near genes or TE-encoded factors that act in trans. Enormous pools of genome data and new technologies for reverse genetics will lead to a powerful new era of TE analysis in plants.
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Affiliation(s)
- Jeffrey L Bennetzen
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China
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38
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Rauch HB, Patrick TL, Klusman KM, Battistuzzi FU, Mei W, Brendel VP, Lal SK. Discovery and expression analysis of alternative splicing events conserved among plant SR proteins. Mol Biol Evol 2013; 31:605-13. [PMID: 24356560 DOI: 10.1093/molbev/mst238] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The high frequency of alternative splicing among the serine/arginine-rich (SR) family of proteins in plants has been linked to important roles in gene regulation during development and in response to environmental stress. In this article, we have searched and manually annotated all the SR proteins in the genomes of maize and sorghum. The experimental validation of gene structure by reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed, with few exceptions, that SR genes produced multiple isoforms of transcripts by alternative splicing. Despite sharing high structural similarity and conserved positions of the introns, the profile of alternative splicing diverged significantly between maize and sorghum for the vast majority of SR genes. These include many transcript isoforms discovered by RT-PCR and not represented in extant expressed sequence tag (EST) collection. However, we report the occurrence of various maize and sorghum SR mRNA isoforms that display evolutionary conservation of splicing events with their homologous SR genes in Arabidopsis and moss. Our data also indicate an important role of both 5' and 3' untranslated regions in the regulation of SR gene expression. These observations have potentially important implications for the processes of evolution and adaptation of plants to land.
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Uthup TK, Saha T, Ravindran M, Bini K. Impact of an intragenic retrotransposon on the structural integrity and evolution of a major isoprenoid biosynthesis pathway gene in Hevea brasiliensis. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2013; 73:176-88. [PMID: 24128694 DOI: 10.1016/j.plaphy.2013.09.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 09/10/2013] [Indexed: 05/01/2023]
Abstract
Isoprenoids belong to a large family of structurally and functionally different natural compounds found universally from prokaryotes to higher animals and plants. In Hevea brasiliensis, the commercially important cis-polyisoprene (rubber) is synthesised as part of its defence mechanism in addition to other common isoprenoids like phytosterols, growth hormones etc. Farnesyl diphosphate synthase (FDPS) is a key enzyme in this process which catalyses the conversion of isoprene units into polyisoprene. Although prior sequence information is available, the structural variants of the FDPS gene presently existing in Hevea population are largely unknown. Since gene structure has a major role in gene regulation, extensive sequence analysis of this gene from different genotypes was carried out to identify the prevailing structural variants. We identified several SNPs and large indels which were associated with a partial transposable element (TE). Modification of key regulatory motifs and splice sites induced by the retroelement was also identified in the first intron. Screening of popular rubber clones, wild germplasm accessions and Hevea species revealed that the retroelement is responsible for the generation of new alleles with varying degrees of sequence homology. Segregation analysis of a progeny population confirmed that the alleles are not paralogs and are inherited in a Mendelian mode. Our findings suggest that the first intron of the FDPS gene has been subjected to various chromosomal rearrangements due to the interaction of a retrotransposon, resulting in novel alleles which may substantially contribute towards the evolution of this major gene in rubber. Moreover, the results indicate the possible existence of a retrotransposon-mediated epigenetic gene regulatory mechanism in Hevea.
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Affiliation(s)
- Thomas Kadampanattu Uthup
- Genome Analysis Laboratory, Rubber Research Institute of India, Rubber Board, P O, Kottayam, Kerala Pin-686009, India.
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Schulman AH. Retrotransposon replication in plants. Curr Opin Virol 2013; 3:604-14. [PMID: 24035277 DOI: 10.1016/j.coviro.2013.08.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 08/16/2013] [Accepted: 08/19/2013] [Indexed: 12/31/2022]
Abstract
Retrotransposons comprise the bulk of large plant genomes, replicating via an RNA intermediate whereby the original, integrated element remains in place. Of the two main orders, the LTR retrotransposons considerably outnumber the LINEs. LINEs integrate into target sites simultaneously with the RNA transcript being copied into cDNA by target-primed reverse transcription. LTR retrotransposon replication is basically equivalent to the intracellular phase of retroviral life cycles. The envelope gene giving extracellular mobility to retroviruses is in fact widespread in plants and their retrotransposons. Evolutionary analyses of the retrotransposons and retroviruses suggest that both form an ancient monophyletic group. The particular adaptations of LTR retrotransposons to plant life cycles enabling their success remain to be clarified.
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Affiliation(s)
- Alan H Schulman
- Institute of Biotechnology, Viikki Biocenter, University of Helsinki, P.O. Box 65, Helsinki FIN-00014, Finland; Biotechnology and Food Research, MTT Agrifood Research Finland, Jokioinen FIN-31600, Finland.
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Bertioli DJ, Vidigal B, Nielen S, Ratnaparkhe MB, Lee TH, Leal-Bertioli SCM, Kim C, Guimarães PM, Seijo G, Schwarzacher T, Paterson AH, Heslop-Harrison P, Araujo ACG. The repetitive component of the A genome of peanut (Arachis hypogaea) and its role in remodelling intergenic sequence space since its evolutionary divergence from the B genome. ANNALS OF BOTANY 2013; 112:545-59. [PMID: 23828319 PMCID: PMC3718217 DOI: 10.1093/aob/mct128] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
BACKGROUND AND AIMS Peanut (Arachis hypogaea) is an allotetraploid (AABB-type genome) of recent origin, with a genome of about 2·8 Gb and a high repetitive content. This study reports an analysis of the repetitive component of the peanut A genome using bacterial artificial chromosome (BAC) clones from A. duranensis, the most probable A genome donor, and the probable consequences of the activity of these elements since the divergence of the peanut A and B genomes. METHODS The repetitive content of the A genome was analysed by using A. duranensis BAC clones as probes for fluorescence in situ hybridization (BAC-FISH), and by sequencing and characterization of 12 genomic regions. For the analysis of the evolutionary dynamics, two A genome regions are compared with their B genome homeologues. KEY RESULTS BAC-FISH using 27 A. duranensis BAC clones as probes gave dispersed and repetitive DNA characteristic signals, predominantly in interstitial regions of the peanut A chromosomes. The sequences of 14 BAC clones showed complete and truncated copies of ten abundant long terminal repeat (LTR) retrotransposons, characterized here. Almost all dateable transposition events occurred <3·5 million years ago, the estimated date of the divergence of A and B genomes. The most abundant retrotransposon is Feral, apparently parasitic on the retrotransposon FIDEL, followed by Pipa, also non-autonomous and probably parasitic on a retrotransposon we named Pipoka. The comparison of the A and B genome homeologous regions showed conserved segments of high sequence identity, punctuated by predominantly indel regions without significant similarity. CONCLUSIONS A substantial proportion of the highly repetitive component of the peanut A genome appears to be accounted for by relatively few LTR retrotransposons and their truncated copies or solo LTRs. The most abundant of the retrotransposons are non-autonomous. The activity of these retrotransposons has been a very significant driver of genome evolution since the evolutionary divergence of the A and B genomes.
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Affiliation(s)
- David J. Bertioli
- University of Brasilia, Department of Genetics, Campus Universitário, Brasília DF, Brazil
| | - Bruna Vidigal
- University of Brasilia, Department of Genetics, Campus Universitário, Brasília DF, Brazil
- Embrapa Genetic Resources and Biotechnology, Brasilia, DF, Brazil
| | - Stephan Nielen
- Embrapa Genetic Resources and Biotechnology, Brasilia, DF, Brazil
| | | | - Tae-Ho Lee
- Plant Genome Mapping Laboratory, The University of Georgia, Athens, GA 30605, USA
| | | | - Changsoo Kim
- Plant Genome Mapping Laboratory, The University of Georgia, Athens, GA 30605, USA
| | | | - Guillermo Seijo
- Plant Cytogenetic and Evolution Laboratory, Instituto de Botánica del Nordeste and Faculty of Exact and Natural Sciences, National University of the Northeast, Corrientes, Argentina
| | | | - Andrew H. Paterson
- Plant Genome Mapping Laboratory, The University of Georgia, Athens, GA 30605, USA
| | | | - Ana C. G. Araujo
- Embrapa Genetic Resources and Biotechnology, Brasilia, DF, Brazil
- For correspondence. E-mail
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Han MJ, Shen YH, Xu MS, Liang HY, Zhang HH, Zhang Z. Identification and evolution of the silkworm helitrons and their contribution to transcripts. DNA Res 2013; 20:471-84. [PMID: 23771679 PMCID: PMC3789558 DOI: 10.1093/dnares/dst024] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
In this study, we developed a structure-based approach to identify Helitrons in four lepidopterans and systematically analysed Helitrons in the silkworm genome. We found that the content of Helitrons varied greatly among genomes. The silkworm genome harboured 67,555 Helitron-related sequences that could be classified into 21 families and accounted for ≈ 4.23% of the genome. Thirteen of the families were new. Three families were putatively autonomous and included the replication initiator motif and helicase domain. The silkworm Helitrons were widely and randomly distributed in the genome. Most Helitron families radiated within the past 2 million years and experienced a single burst of expansion. These Helitron families captured 3724 gene fragments and contributed to at least 1.4% of the silkworm full-length cDNAs, suggesting important roles of Helitrons in the evolution of the silkworm genes. In addition, we found that some new Helitrons were generated by combinations of other Helitrons. Overall, the results presented in this study provided insights into the generation and evolution of Helitron transposons and their contribution to transcripts.
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Affiliation(s)
- Min-Jin Han
- 1State Key Laboratory of Silkworm Genome Biology, The Key Sericultural Laboratory of Agricultural Ministry, Southwest University, Chongqing 400715, China
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Li L, Petsch K, Shimizu R, Liu S, Xu WW, Ying K, Yu J, Scanlon MJ, Schnable PS, Timmermans MCP, Springer NM, Muehlbauer GJ. Mendelian and non-Mendelian regulation of gene expression in maize. PLoS Genet 2013; 9:e1003202. [PMID: 23341782 PMCID: PMC3547793 DOI: 10.1371/journal.pgen.1003202] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 11/14/2012] [Indexed: 11/25/2022] Open
Abstract
Transcriptome variation plays an important role in affecting the phenotype of an organism. However, an understanding of the underlying mechanisms regulating transcriptome variation in segregating populations is still largely unknown. We sought to assess and map variation in transcript abundance in maize shoot apices in the intermated B73×Mo17 recombinant inbred line population. RNA–based sequencing (RNA–seq) allowed for the detection and quantification of the transcript abundance derived from 28,603 genes. For a majority of these genes, the population mean, coefficient of variation, and segregation patterns could be predicted by the parental expression levels. Expression quantitative trait loci (eQTL) mapping identified 30,774 eQTL including 96 trans-eQTL “hotspots,” each of which regulates the expression of a large number of genes. Interestingly, genes regulated by a trans-eQTL hotspot tend to be enriched for a specific function or act in the same genetic pathway. Also, genomic structural variation appeared to contribute to cis-regulation of gene expression. Besides genes showing Mendelian inheritance in the RIL population, we also found genes whose expression level and variation in the progeny could not be predicted based on parental difference, indicating that non-Mendelian factors also contribute to expression variation. Specifically, we found 145 genes that show patterns of expression reminiscent of paramutation such that all the progeny had expression levels similar to one of the two parents. Furthermore, we identified another 210 genes that exhibited unexpected patterns of transcript presence/absence. Many of these genes are likely to be gene fragments resulting from transposition, and the presence/absence of their transcripts could influence expression levels of their ancestral syntenic genes. Overall, our results contribute to the identification of novel expression patterns and broaden the understanding of transcriptional variation in plants. Phenotypes are determined by the expression of genes, the environment, and the interaction of gene expression and the environment. However, a complete understanding of the inheritance of and genome-wide regulation of gene expression is lacking. One approach, called expression quantitative trait locus (eQTL) mapping provides the opportunity to examine the genome-wide inheritance and regulation of gene expression. In this paper, we conducted high-throughput sequencing of gene transcripts to examine gene expression in the shoot apex of a maize biparental mapping population. We quantified expression levels from 28,603 genes in the population and showed that the vast majority of genes exhibited the expected pattern of Mendelian inheritance. We genetically mapped the expression patterns and identified genomic regions associated with gene expression. Notably, we detected gene expression patterns that exhibited non-Mendelian inheritance. These included 145 genes that exhibited expression patterns in the progeny that were similar to only one of the parents and 210 genes with unexpected presence/absence expression patterns. The findings of non-Mendelian inheritance underscore the complexity of gene expression and provide a framework for understanding these complexities.
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Affiliation(s)
- Lin Li
- Department of Agronomy and Plant Genetics, University of Minnesota, Saint Paul, Minnesota, United States of America
| | - Katherine Petsch
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Rena Shimizu
- Department of Plant Biology, Cornell University, Ithaca, New York, United States of America
| | - Sanzhen Liu
- Department of Genetics, Development, and Cell Biology, and Department of Agronomy, Iowa State University, Ames, Iowa, United States of America
| | - Wayne Wenzhong Xu
- Supercomputing Institute for Advanced Computational Research, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Kai Ying
- Department of Genetics, Development, and Cell Biology, and Department of Agronomy, Iowa State University, Ames, Iowa, United States of America
| | - Jianming Yu
- Department of Agronomy, Kansas State University, Manhattan, Kansas, United States of America
| | - Michael J. Scanlon
- Department of Plant Biology, Cornell University, Ithaca, New York, United States of America
| | - Patrick S. Schnable
- Department of Genetics, Development, and Cell Biology, and Department of Agronomy, Iowa State University, Ames, Iowa, United States of America
| | | | - Nathan M. Springer
- Department of Plant Biology, University of Minnesota, Saint Paul, Minnesota, United States of America
| | - Gary J. Muehlbauer
- Department of Agronomy and Plant Genetics, University of Minnesota, Saint Paul, Minnesota, United States of America
- Department of Plant Biology, University of Minnesota, Saint Paul, Minnesota, United States of America
- * E-mail:
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Weber N, Halpin C, Hannah LC, Jez JM, Kough J, Parrott W. Editor's choice: Crop genome plasticity and its relevance to food and feed safety of genetically engineered breeding stacks. PLANT PHYSIOLOGY 2012; 160:1842-53. [PMID: 23060369 PMCID: PMC3510115 DOI: 10.1104/pp.112.204271] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 10/02/2012] [Indexed: 05/22/2023]
Affiliation(s)
- Natalie Weber
- Pioneer Hi-Bred International, Wilmington, Delaware 19880, USA
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