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Rurik I, Melichárková A, Gbúrová Štubová E, Kučera J, Kochjarová J, Paun O, Vďačný P, Slovák M. Homoplastic versus xenoplastic evolution: exploring the emergence of key intrinsic and extrinsic traits in the montane genus Soldanella (Primulaceae). THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 118:753-765. [PMID: 38217489 DOI: 10.1111/tpj.16630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 12/02/2023] [Accepted: 12/27/2023] [Indexed: 01/15/2024]
Abstract
Specific ecological conditions in the high mountain environment exert a selective pressure that often leads to convergent trait evolution. Reticulations induced by incomplete lineage sorting and introgression can lead to discordant trait patterns among gene and species trees (hemiplasy/xenoplasy), providing a false illusion that the traits under study are homoplastic. Using phylogenetic species networks, we explored the effect of gene exchange on trait evolution in Soldanella, a genus profoundly influenced by historical introgression. At least three features evolved independently multiple times: the single-flowered dwarf phenotype, dysploid cytotype, and ecological generalism. The present analyses also indicated that the recurring occurrence of stoloniferous growth might have been prompted by an introgression event between an ancestral lineage and a still extant species, although its emergence via convergent evolution cannot be completely ruled out. Phylogenetic regression suggested that the independent evolution of larger genomes in snowbells is most likely a result of the interplay between hybridization events of dysploid and euploid taxa and hostile environments at the range margins of the genus. The emergence of key intrinsic and extrinsic traits in snowbells has been significantly impacted not only by convergent evolution but also by historical and recent introgression events.
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Affiliation(s)
- Ivan Rurik
- Department of Zoology, Comenius University Bratislava, Ilkovičova 6, 842 15, Bratislava, Slovak Republic
| | - Andrea Melichárková
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Dúbravská cesta 9, 845 23, Bratislava, Slovak Republic
| | - Eliška Gbúrová Štubová
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Dúbravská cesta 9, 845 23, Bratislava, Slovak Republic
- Slovak National Museum, Natural History Museum, Vajanského nábrežie 2, 810 06, Bratislava, Slovak Republic
| | - Jaromír Kučera
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Dúbravská cesta 9, 845 23, Bratislava, Slovak Republic
| | - Judita Kochjarová
- Department of Phytology, Faculty of Forestry, Technical University Zvolen, Masarykova 24, 960 53, Zvolen, Slovak Republic
| | - Ovidiu Paun
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030, Vienna, Austria
| | - Peter Vďačný
- Department of Zoology, Comenius University Bratislava, Ilkovičova 6, 842 15, Bratislava, Slovak Republic
| | - Marek Slovák
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Dúbravská cesta 9, 845 23, Bratislava, Slovak Republic
- Department of Botany, Charles University, Benátská 2, 128 01, Prague, Czech Republic
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de Tomás C, Vicient CM. The Genomic Shock Hypothesis: Genetic and Epigenetic Alterations of Transposable Elements after Interspecific Hybridization in Plants. EPIGENOMES 2023; 8:2. [PMID: 38247729 PMCID: PMC10801548 DOI: 10.3390/epigenomes8010002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/21/2023] [Accepted: 12/24/2023] [Indexed: 01/23/2024] Open
Abstract
Transposable elements (TEs) are major components of plant genomes with the ability to change their position in the genome or to create new copies of themselves in other positions in the genome. These can cause gene disruption and large-scale genomic alterations, including inversions, deletions, and duplications. Host organisms have evolved a set of mechanisms to suppress TE activity and counter the threat that they pose to genome integrity. These includes the epigenetic silencing of TEs mediated by a process of RNA-directed DNA methylation (RdDM). In most cases, the silencing machinery is very efficient for the vast majority of TEs. However, there are specific circumstances in which TEs can evade such silencing mechanisms, for example, a variety of biotic and abiotic stresses or in vitro culture. Hybridization is also proposed as an inductor of TE proliferation. In fact, the discoverer of the transposons, Barbara McClintock, first hypothesized that interspecific hybridization provides a "genomic shock" that inhibits the TE control mechanisms leading to the mobilization of TEs. However, the studies carried out on this topic have yielded diverse results, showing in some cases a total absence of mobilization or being limited to only some TE families. Here, we review the current knowledge about the impact of interspecific hybridization on TEs in plants and the possible implications of changes in the epigenetic mechanisms.
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Affiliation(s)
| | - Carlos M. Vicient
- Centre for Research in Agricultural Genomics, CRAG (CSIC-IRTA-UAB-UB), Campus UAB, Cerdanyola del Vallès, 08193 Barcelona, Spain
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Wong ELY, Filatov DA. The role of recombination landscape in species hybridisation and speciation. FRONTIERS IN PLANT SCIENCE 2023; 14:1223148. [PMID: 37484464 PMCID: PMC10361763 DOI: 10.3389/fpls.2023.1223148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 06/13/2023] [Indexed: 07/25/2023]
Abstract
It is now well recognised that closely related species can hybridize and exchange genetic material, which may promote or oppose adaptation and speciation. In some cases, interspecific hybridisation is very common, making it surprising that species identity is preserved despite active gene exchange. The genomes of most eukaryotic species are highly heterogeneous with regard to gene density, abundance of repetitive DNA, chromatin compactisation etc, which can make certain genomic regions more prone or more resistant to introgression of genetic material from other species. Heterogeneity in local recombination rate underpins many of the observed patterns across the genome (e.g. actively recombining regions are typically gene rich and depleted for repetitive DNA) and it can strongly affect the permeability of genomic regions to interspecific introgression. The larger the region lacking recombination, the higher the chance for the presence of species incompatibility gene(s) in that region, making the entire non- or rarely recombining block impermeable to interspecific introgression. Large plant genomes tend to have highly heterogeneous recombination landscape, with recombination frequently occurring at the ends of the chromosomes and central regions lacking recombination. In this paper we review the relationship between recombination and introgression in plants and argue that large rarely recombining regions likely play a major role in preserving species identity in actively hybridising plant species.
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Affiliation(s)
- Edgar L. Y. Wong
- Department of Biology, University of Oxford, Oxford, United Kingdom
- Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany
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4
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Levy AA, Feldman M. Evolution and origin of bread wheat. THE PLANT CELL 2022; 34:2549-2567. [PMID: 35512194 PMCID: PMC9252504 DOI: 10.1093/plcell/koac130] [Citation(s) in RCA: 51] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 03/18/2022] [Indexed: 05/12/2023]
Abstract
Bread wheat (Triticum aestivum, genome BBAADD) is a young hexaploid species formed only 8,500-9,000 years ago through hybridization between a domesticated free-threshing tetraploid progenitor, genome BBAA, and Aegilops tauschii, the diploid donor of the D subgenome. Very soon after its formation, it spread globally from its cradle in the fertile crescent into new habitats and climates, to become a staple food of humanity. This extraordinary global expansion was probably enabled by allopolyploidy that accelerated genetic novelty through the acquisition of new traits, new intergenomic interactions, and buffering of mutations, and by the attractiveness of bread wheat's large, tasty, and nutritious grain with high baking quality. New genome sequences suggest that the elusive donor of the B subgenome is a distinct (unknown or extinct) species rather than a mosaic genome. We discuss the origin of the diploid and tetraploid progenitors of bread wheat and the conflicting genetic and archaeological evidence on where it was formed and which species was its free-threshing tetraploid progenitor. Wheat experienced many environmental changes throughout its evolution, therefore, while it might adapt to current climatic changes, efforts are needed to better use and conserve the vast gene pool of wheat biodiversity on which our food security depends.
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de Tomás C, Bardil A, Castanera R, Casacuberta JM, Vicient CM. Absence of major epigenetic and transcriptomic changes accompanying an interspecific cross between peach and almond. HORTICULTURE RESEARCH 2022; 9:uhac127. [PMID: 35928404 PMCID: PMC9343919 DOI: 10.1093/hr/uhac127] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 05/24/2022] [Indexed: 06/15/2023]
Abstract
Hybridization has been widely used in breeding of cultivated species showing low genetic variability, such as peach (Prunus persica). The merging of two different genomes in a hybrid often triggers a so-called "genomic shock" with changes in DNA methylation and in the induction of transposable element expression and mobilization. Here, we analysed the DNA methylation and transcription levels of transposable elements and genes in leaves of Prunus persica and Prunus dulcis and in an F1 hybrid using high-throughput sequencing technologies. Contrary to the "genomic shock" expectations, we found that the overall levels of DNA methylation in the transposable elements in the hybrid are not significantly altered compared with those of the parental genomes. We also observed that the levels of transcription of the transposable elements in the hybrid are in most cases intermediate as compared with that of the parental species and we have not detected cases of higher transcription in the hybrid. We also found that the proportion of genes whose expression is altered in the hybrid compared with the parental species is low. The expression of genes potentially involved in the regulation of the activity of the transposable elements is not altered. We can conclude that the merging of the two parental genomes in this Prunus persica x Prunus dulcis hybrid does not result in a "genomic shock" with significant changes in the DNA methylation or in the transcription. The absence of major changes may facilitate using interspecific peach x almond crosses for peach improvement.
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Affiliation(s)
- Carlos de Tomás
- Centre for Research in Agricultural Genomics CSIC-IRTA-UAB-UB, Campus UAB, Edifici CRAG, Bellaterra, Barcelona 08193, Spain
| | - Amélie Bardil
- Institut écologie et environnement (INEE), CNRS, Montpelier, France
| | - Raúl Castanera
- Centre for Research in Agricultural Genomics CSIC-IRTA-UAB-UB, Campus UAB, Edifici CRAG, Bellaterra, Barcelona 08193, Spain
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Specificities and Dynamics of Transposable Elements in Land Plants. BIOLOGY 2022; 11:biology11040488. [PMID: 35453688 PMCID: PMC9033089 DOI: 10.3390/biology11040488] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/10/2022] [Accepted: 03/18/2022] [Indexed: 01/27/2023]
Abstract
Simple Summary Transposable elements are dynamic components of plant genomes, and display a high diversity of lineages and distribution as the result of evolutionary driving forces and overlapping mechanisms of genetic and epigenetic regulation. They are now regarded as main contributors for genome evolution and function, and important regulators of endogenous gene expression. In this review, we survey recent progress and current challenges in the identification and classification of transposon lineages in complex plant genomes, highlighting the molecular specificities that may explain the expansion and diversification of mobile genetic elements in land plants. Abstract Transposable elements (TEs) are important components of most plant genomes. These mobile repetitive sequences are highly diverse in terms of abundance, structure, transposition mechanisms, activity and insertion specificities across plant species. This review will survey the different mechanisms that may explain the variability of TE patterns in land plants, highlighting the tight connection between TE dynamics and host genome specificities, and their co-evolution to face and adapt to a changing environment. We present the current TE classification in land plants, and describe the different levels of genetic and epigenetic controls originating from the plant, the TE itself, or external environmental factors. Such overlapping mechanisms of TE regulation might be responsible for the high diversity and dynamics of plant TEs observed in nature.
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8
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Gou X, Lv R, Wang C, Fu T, Sha Y, Gong L, Zhang H, Liu B. Balanced Genome Triplication in Wheat Causes Premature Growth Arrest and an Upheaval of Genome-Wide Gene Regulation. Front Genet 2020; 11:687. [PMID: 32733539 PMCID: PMC7360807 DOI: 10.3389/fgene.2020.00687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 06/04/2020] [Indexed: 11/13/2022] Open
Abstract
Polyploidy, or whole genome duplication (WGD), is a driving evolutionary force across the tree of life and has played a pervasive role in the evolution of the plant kingdom. It is generally believed that a major genetic attribute contributing to the success of polyploidy is increased gene and genome dosage. The evolution of polyploid wheat has lent support to this scenario. Wheat has evolved at three ploidal levels: diploidy, tetraploidy, and hexaploidy. Ample evidence testifies that the evolutionary success, be it with respect to evolvability, natural adaptability, or domestication has dramatically increased with each elevation of the ploidal levels. A long-standing question is what would be the outcome if a further elevation of ploidy is superimposed on hexaploid wheat? Here, we characterized a spontaneously occurring nonaploid wheat individual in selfed progenies of synthetic hexaploid wheat and compared it with its isogenic hexaploid siblings at the phenotypic, cytological, and genome-wide gene-expression levels. The nonaploid manifested severe defects in growth and development, albeit with a balanced triplication of the three wheat subgenomes. Transcriptomic profiling of the second leaf of nonaploid, taken at a stage when phenotypic abnormality was not yet discernible, already revealed significant dysregulation in global-scale gene expression with ca. 25.2% of the 49,436 expressed genes being differentially expressed genes (DEGs) at a twofold change cutoff relative to the hexaploid counterpart. Both up- and downregulated DEGs were identified in the nonaploid vs. hexaploid, including 457 genes showing qualitative alteration, i.e., silencing or activation. Impaired functionality at both cellular and organismal levels was inferred from gene ontology analysis of the DEGs. Homoeologous expression analysis of 9,574 sets of syntenic triads indicated that, compared with hexaploid, the proportions showing various homeologous expression patterns were highly conserved in the nonaploid although gene identity showed moderate reshuffling among some of the patterns in the nonaploid. Together, our results suggest hexaploidy is likely the upper limit of ploidy level in wheat; crossing this threshold incurs severe ploidy syndrome that is preceded by disruptive dysregulation of global gene expression.
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Affiliation(s)
- Xiaowan Gou
- School of Life Sciences, Jiangsu Normal University, Xuzhou, China
- Key Laboratory of Molecular Epigenetics, Northeast Normal University, Changchun, China
| | - Ruili Lv
- Key Laboratory of Molecular Epigenetics, Northeast Normal University, Changchun, China
| | - Changyi Wang
- Key Laboratory of Molecular Epigenetics, Northeast Normal University, Changchun, China
| | - Tiansi Fu
- Key Laboratory of Molecular Epigenetics, Northeast Normal University, Changchun, China
| | - Yan Sha
- Key Laboratory of Molecular Epigenetics, Northeast Normal University, Changchun, China
| | - Lei Gong
- Key Laboratory of Molecular Epigenetics, Northeast Normal University, Changchun, China
| | - Huakun Zhang
- Key Laboratory of Molecular Epigenetics, Northeast Normal University, Changchun, China
| | - Bao Liu
- Key Laboratory of Molecular Epigenetics, Northeast Normal University, Changchun, China
- *Correspondence: Bao Liu,
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9
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Parisod C, Badaeva ED. Chromosome restructuring among hybridizing wild wheats. THE NEW PHYTOLOGIST 2020; 226:1263-1273. [PMID: 31913521 DOI: 10.1111/nph.16415] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 12/29/2019] [Indexed: 06/10/2023]
Abstract
The wheat group offers an outstanding system to address the interplay between hybridization, chromosomal evolution and biological diversification. Most diploid wild wheats originated following hybridization between the A-genome lineage and the B-genome lineage some 4 Myr ago, resulting in an admixed D-genome lineage that presented dramatic radiation accompanied by considerable changes in genome size and chromosomal rearrangements. Comparative profiling of low-copy genes, repeated sequences and transposable elements among those divergent species characterized by different karyotypes highlights high genome dynamics and sheds new light on the processes underlying chromosomal evolution in wild wheats. One of the hybrid clades presents upsizing of metacentric chromosomes going along with the proliferation of specific repeats (i.e. 'genomic obesity'), whereas other species show stable genome size associated with increasing chromosomal asymmetry. Genetic and ecological variation in those specialized species suggest that genome restructuring was coupled with adaptive processes to support the evolution of a majority of acrocentric chromosomes. This synthesis of current knowledge on genome restructuring across the diversity of wild wheats paves the way towards surveys based on latest sequencing technologies to characterize valuable resources and address the significance of chromosomal evolution in species with complex genomes.
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Affiliation(s)
- Christian Parisod
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, Bern, 3013, Switzerland
| | - Ekaterina D Badaeva
- Vavilov Institute of General Genetics, Russian Academy of Sciences, Gubkin St. 3, Moscow, 119991, Russia
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10
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Abstract
Interspecific hybridization is the process where closely related species mate and produce offspring with admixed genomes. The genomic revolution has shown that hybridization is common, and that it may represent an important source of novel variation. Although most interspecific hybrids are sterile or less fit than their parents, some may survive and reproduce, enabling the transfer of adaptive variants across the species boundary, and even result in the formation of novel evolutionary lineages. There are two main variants of hybrid species genomes: allopolyploid, which have one full chromosome set from each parent species, and homoploid, which are a mosaic of the parent species genomes with no increase in chromosome number. The establishment of hybrid species requires the development of reproductive isolation against parental species. Allopolyploid species often have strong intrinsic reproductive barriers due to differences in chromosome number, and homoploid hybrids can become reproductively isolated from the parent species through assortment of genetic incompatibilities. However, both types of hybrids can become further reproductively isolated, gaining extrinsic isolation barriers, by exploiting novel ecological niches, relative to their parents. Hybrids represent the merging of divergent genomes and thus face problems arising from incompatible combinations of genes. Thus hybrid genomes are highly dynamic and undergo rapid evolutionary change, including genome stabilization in which selection against incompatible combinations results in fixation of compatible ancestry block combinations within the hybrid species. The potential for rapid adaptation or speciation makes hybrid genomes a particularly exciting subject of in evolutionary biology. Here we summarize how introgressed alleles or hybrid species can establish and how the resulting hybrid genomes evolve.
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Affiliation(s)
- Anna Runemark
- Department of Biology, Lund University, Lund, Sweden
- * E-mail:
| | - Mario Vallejo-Marin
- Biological and Environmental Sciences, University of Stirling, Stirling, Scotland, United Kingdom
| | - Joana I. Meier
- St John's College, Cambridge, Cambridge, United Kingdom
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
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Usai G, Mascagni F, Vangelisti A, Giordani T, Ceccarelli M, Cavallini A, Natali L. Interspecific hybridisation and LTR-retrotransposon mobilisation-related structural variation in plants: A case study. Genomics 2019; 112:1611-1621. [PMID: 31605729 DOI: 10.1016/j.ygeno.2019.09.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 07/13/2019] [Accepted: 09/12/2019] [Indexed: 11/30/2022]
Abstract
The dynamics of long-terminal-repeat retrotransposons in two poplar species (Populus deltoides and P. nigra) and in an interspecific hybrid, recently synthesized, were investigated by analyzing the genomic abundance and transcription levels of a collection of 828 full-length retroelements identified in the genome sequence of P. trichocarpa, all occurring also in the genomes of P. deltoides and P. nigra. Overall, genomic abundance and transcription levels of many retrotransposons in the hybrid resulted higher or lower than expected by calculating the mean of the parental values. A bioinformatics procedure was established to ascertain the occurrence of the same retrotransposon loci in the three genotypes. The results indicated that retrotransposon abundance variations between the hybrid and the mean value of the parents were due to i) co-segregation of retrotransposon high- or low-abundant haplotypes; ii) new retroelement insertions; iii) retrotransposon loss. Concerning retrotransposon expression, this was generally low, with only 14/828 elements over- or under-expressed in the hybrid than expected by calculating the mean of the parents. It is concluded that interspecific hybridisation between the two poplar species determine quantitative variation and differential expression of some retrotransposons, with possible consequences for the genetic differentiation of the hybrid.
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Affiliation(s)
- Gabriele Usai
- Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, I-56124 Pisa, Italy
| | - Flavia Mascagni
- Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, I-56124 Pisa, Italy
| | - Alberto Vangelisti
- Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, I-56124 Pisa, Italy
| | - Tommaso Giordani
- Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, I-56124 Pisa, Italy
| | - Marilena Ceccarelli
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Via Elce di sotto 8, 06123 Perugia, Italy
| | - Andrea Cavallini
- Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, I-56124 Pisa, Italy.
| | - Lucia Natali
- Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, I-56124 Pisa, Italy.
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Huynh S, Marcussen T, Felber F, Parisod C. Hybridization preceded radiation in diploid wheats. Mol Phylogenet Evol 2019; 139:106554. [PMID: 31288105 DOI: 10.1016/j.ympev.2019.106554] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 07/03/2019] [Accepted: 07/03/2019] [Indexed: 01/06/2023]
Abstract
Evolutionary relationships among the Aegilops-Triticum relatives of cultivated wheats have been difficult to resolve owing to incomplete lineage sorting and reticulate evolution. Recent studies have suggested that the wheat D-genome lineage (progenitor of Ae. tauschii) originated through homoploid hybridization between the A-genome lineage (progenitor of Triticum s.str.) and the B-genome lineage (progenitor of Ae. speltoides). This scenario of reticulation has been debated, calling for adequate phylogenetic analyses based on comprehensive sampling. To reconstruct the evolution of Aegilops-Triticum diploids, we here combined high-throughput sequencing of 38 nuclear low-copy loci of multiple accessions of all 13 species with inferences of the species phylogeny using the full-parameterized MCMC_SEQ method. Phylogenies recovered a monophyletic Aegilops-Triticum lineage that began diversifying ~6.6 Ma ago and gave rise to four sublineages, i.e. the A- (2 species), B- (1 species), D- (9 species) and T- (Ae. mutica) genome lineage. Full-parameterized phylogenies as well as patterns of tree dilation and tree compression supported a hybrid origin of the D-genome lineage from A and B ~3.0-4.0 Ma ago, and did not indicate additional hybridization events. Conflicting ABBA-BABA tests suggestive of further reticulation were shown here to result from ancestral population structure rather than hybridization. This comprehensive and dated phylogeny of wheat relatives indicates that the origin of the hybrid D-genome was followed by intense diversification into the majority of extant diploid as well as allopolyploid wild wheats.
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Affiliation(s)
- Stella Huynh
- Institute of Biology, University of Neuchâtel, Switzerland
| | - Thomas Marcussen
- Centre for Ecological and Evolutionary Synthesis, University of Oslo, Norway
| | - François Felber
- Institute of Biology, University of Neuchâtel, Switzerland; Musée et Jardins botaniques cantonaux de Lausanne et Pont-de-Nant, Switzerland
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13
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Choudhury RR, Parisod C. Jumping genes: Genomic ballast or powerhouse of biological diversification. Mol Ecol 2019; 26:4587-4590. [PMID: 28949090 DOI: 10.1111/mec.14247] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/04/2017] [Accepted: 07/06/2017] [Indexed: 01/08/2023]
Abstract
Studying hybridization has the potential to elucidate challenging questions in evolutionary biology such as the nature of adaptive genetic variation and reproductive isolation. A growing body of work highlights that the merging of divergent genomes goes beyond the reshuffling of standing variation from related species and promotes mutations (Abbott et al., ). However, to what extent such genome instability generates evolutionary significant variation remains largely elusive. In this issue of Molecular Ecology, Dennenmoser et al. () report considerable dynamics of transposable elements (TEs) in a recent invasive fish species of hybrid origin (Cottus; Figure ). It adds to the recent examples from plants to support TE-specific genome variation following hybridization. Insights from early, as well as established, hybrids are largely coherent with increased TE activity, and this fish system thus represents an inspiring opportunity to further address the possible association between genome dynamics and "rapid evolution of hybrid species." This work based on genome (re)sequencing contrasts with prior transcriptomics or PCR-based studies of TEs and illustrates how unprecedented amount of information promises a better understanding of the multiple patterns of variation across eukaryotic genomes; provided that we get the better of methodological advances. As discussed here, unbiased assessment of TE variation from genome surveys indeed remains a challenge precluding firm conclusions to be reached about the evolutionary significance of TEs. Despite methodological and conceptual developments that appear necessary to unambiguously uncover the unexplored iceberg below the known tip, the role of coding genes vs. TEs in promoting adaptation and speciation might be clarified in a not so remote future.
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Affiliation(s)
| | - Christian Parisod
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
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14
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Rogivue A, Choudhury RR, Zoller S, Joost S, Felber F, Kasser M, Parisod C, Gugerli F. Genome-wide variation in nucleotides and retrotransposons in alpine populations of Arabis alpina (Brassicaceae). Mol Ecol Resour 2019; 19:773-787. [PMID: 30636378 DOI: 10.1111/1755-0998.12991] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 12/14/2018] [Accepted: 12/17/2018] [Indexed: 02/01/2023]
Abstract
Advances in high-throughput sequencing have promoted the collection of reference genomes and genome-wide diversity. However, the assessment of genomic variation among populations has hitherto mainly been surveyed through single-nucleotide polymorphisms (SNPs) and largely ignored the often major fraction of genomes represented by transposable elements (TEs). Despite accumulating evidence supporting the evolutionary significance of TEs, comprehensive surveys remain scarce. Here, we sequenced the full genomes of 304 individuals of Arabis alpina sampled from four nearby natural populations to genotype SNPs as well as polymorphic long terminal repeat retrotransposons (polymorphic TEs; i.e., presence/absence of TE insertions at specific loci). We identified 291,396 SNPs and 20,548 polymorphic TEs, comparing their contributions to genomic diversity and divergence across populations. Few SNPs were shared among populations and overall showed high population-specific variation, whereas most polymorphic TEs segregated among populations. The genomic context of these two classes of variants further highlighted candidate adaptive loci having a putative impact on functional genes. In particular, 4.96% of the SNPs were identified as nonsynonymous or affecting start/stop codons. In contrast, 43% of the polymorphic TEs were present next to Arabis genes enriched in functional categories related to the regulation of reproduction and responses to biotic as well as abiotic stresses. This unprecedented data set, mapping variation gained from SNPs and complementary polymorphic TEs within and among populations, will serve as a rich resource for addressing microevolutionary processes shaping genome variation.
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Affiliation(s)
- Aude Rogivue
- WSL Swiss Federal Research Institute, Birmensdorf, Switzerland
| | - Rimjhim R Choudhury
- University of Neuchâtel, Neuchâtel, Switzerland.,Institute of Plant Sciences, University of Berne, Bern, Switzerland
| | - Stefan Zoller
- Genetic Diversity Centre, ETH Zürich, Zürich, Switzerland
| | - Stéphane Joost
- Laboratory of Geographic Information Systems (LASIG), School of Architecture, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - François Felber
- University of Neuchâtel, Neuchâtel, Switzerland.,Musée et Jardins botaniques cantonaux, Lausanne, Switzerland
| | | | | | - Felix Gugerli
- WSL Swiss Federal Research Institute, Birmensdorf, Switzerland
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15
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Liu Y, El-Kassaby YA. Novel Insights into Plant Genome Evolution and Adaptation as Revealed through Transposable Elements and Non-Coding RNAs in Conifers. Genes (Basel) 2019; 10:genes10030228. [PMID: 30889931 PMCID: PMC6470726 DOI: 10.3390/genes10030228] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 03/08/2019] [Accepted: 03/11/2019] [Indexed: 01/03/2023] Open
Abstract
Plant genomes are punctuated by repeated bouts of proliferation of transposable elements (TEs), and these mobile bursts are followed by silencing and decay of most of the newly inserted elements. As such, plant genomes reflect TE-related genome expansion and shrinkage. In general, these genome activities involve two mechanisms: small RNA-mediated epigenetic repression and long-term mutational decay and deletion, that is, genome-purging. Furthermore, the spatial relationships between TE insertions and genes are an important force in shaping gene regulatory networks, their downstream metabolic and physiological outputs, and thus their phenotypes. Such cascading regulations finally set up a fitness differential among individuals. This brief review demonstrates factual evidence that unifies most updated conceptual frameworks covering genome size, architecture, epigenetic reprogramming, and gene expression. It aims to give an overview of the impact that TEs may have on genome and adaptive evolution and to provide novel insights into addressing possible causes and consequences of intimidating genome sizes (20⁻30 Gb) in a taxonomic group, conifers.
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Affiliation(s)
- Yang Liu
- Department of Forest and Conservation Sciences, The University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada.
| | - Yousry A El-Kassaby
- Department of Forest and Conservation Sciences, The University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada.
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16
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Hu G, Wendel JF. Cis-trans controls and regulatory novelty accompanying allopolyploidization. THE NEW PHYTOLOGIST 2019; 221:1691-1700. [PMID: 30290011 DOI: 10.1111/nph.15515] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 09/30/2018] [Indexed: 05/20/2023]
Abstract
Allopolyploidy is a prevalent process in plants, having important physiological, ecological and evolutionary consequences. Transcriptomic responses to genomic merger and doubling have been demonstrated in many allopolyploid systems, encompassing a diversity of phenomena including homoeolog expression bias, genome dominance, expression-level dominance and revamping of co-expression networks. Notwithstanding the foregoing, there remains a need to develop a conceptual framework that will stimulate a deeper understanding of these diverse phenomena and their mechanistic interrelationships. Here we introduce considerations relevant to this framework with a focus on cis-trans interactions among duplicated genes and alleles in hybrids and allopolyploids. By extending classic allele-specific expression analysis to the allopolyploid level, we distinguish the distinct effects of progenitor regulatory interactions from the novel intergenomic interactions that arise from genome merger and allopolyploidization. This perspective informs experiments designed to reveal the molecular genetic basis of gene regulatory control, and will facilitate the disentangling of genetic from epigenetic and higher-order effects that impact gene expression. Finally, we suggest that the extended cis-trans model may help conceptually unify several presently disparate hallmarks of allopolyploid evolution, including genome-wide expression dominance and biased fractionation, and lead to a new level of understanding of phenotypic novelty accompanying polyploidy.
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Affiliation(s)
- Guanjing Hu
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, 50011, USA
| | - Jonathan F Wendel
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, 50011, USA
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17
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Dennenmoser S, Sedlazeck FJ, Schatz MC, Altmüller J, Zytnicki M, Nolte AW. Genome‐wide patterns of transposon proliferation in an evolutionary young hybrid fish. Mol Ecol 2019; 28:1491-1505. [DOI: 10.1111/mec.14969] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 10/15/2018] [Accepted: 10/23/2018] [Indexed: 01/19/2023]
Affiliation(s)
- Stefan Dennenmoser
- Institute for Biology and Environmental Sciences Carl von Ossietzky University Oldenburg Oldenburg Germany
| | | | - Michael C. Schatz
- Cold Spring Harbor Laboratory Cold Spring Harbor New York
- Departments of Computer Science and Biology Johns Hopkins University Baltimore Maryland
| | - Janine Altmüller
- Cologne Center for Genomics, and Institute of Human Genetics University of Cologne Cologne Germany
| | | | - Arne W. Nolte
- Institute for Biology and Environmental Sciences Carl von Ossietzky University Oldenburg Oldenburg Germany
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18
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Mhiri C, Parisod C, Daniel J, Petit M, Lim KY, Dorlhac de Borne F, Kovarik A, Leitch AR, Grandbastien MA. Parental transposable element loads influence their dynamics in young Nicotiana hybrids and allotetraploids. THE NEW PHYTOLOGIST 2019; 221:1619-1633. [PMID: 30220091 DOI: 10.1111/nph.15484] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 09/06/2018] [Indexed: 05/29/2023]
Abstract
The genomic shock hypothesis suggests that allopolyploidy is associated with genome changes driven by transposable elements, as a response to imbalances between parental insertion loads. To explore this hypothesis, we compared three allotetraploids, Nicotiana arentsii, N. rustica and N. tabacum, which arose over comparable time frames from hybridisation between increasingly divergent diploid species. We used sequence-specific amplification polymorphism (SSAP) to compare the dynamics of six transposable elements in these allopolyploids, their diploid progenitors and in corresponding synthetic hybrids. We show that element-specific dynamics in young Nicotiana allopolyploids reflect their dynamics in diploid progenitors. Transposable element mobilisation is not concomitant with immediate genome merger, but occurs within the first generations of allopolyploid formation. In natural allopolyploids, such mobilisations correlate with imbalances in the repeat profile of the parental species, which increases with their genetic divergence. Other restructuring leading to locus loss is immediate, nonrandom and targeted at specific subgenomes, independently of cross orientation. The correlation between transposable element mobilisation in allopolyploids and quantitative imbalances in parental transposable element loads supports the genome shock hypothesis proposed by McClintock.
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Affiliation(s)
- Corinne Mhiri
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France
| | - Christian Parisod
- Ecological Genomics, Institute of Plant Sciences, University of Bern, Bern, CH-3013, Switzerland
| | - Julien Daniel
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France
| | - Maud Petit
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France
| | - K Yoong Lim
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK
| | | | - Ales Kovarik
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, CZ-61265, Czech Republic
| | - Andrew R Leitch
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK
| | - Marie-Angèle Grandbastien
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France
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19
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Abstract
Transposable elements (TEs) are low-complexity elements (e.g., LINEs, SINEs, SVAs, and HERVs) that make up to two-thirds of the human genome. There is mounting evidence that TEs play an essential role in molecular functions that influence genomic plasticity and gene expression regulation. With the advent of next-generation sequencing approaches, our understanding of the relationship between TEs and psychiatric disorders will greatly improve. In this chapter, the Authors comprehensively summarize the state-of the-art of TE research in animal models and humans supporting a framework in which TEs play a functional role in mechanisms affecting a variety of behaviors, including neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. Finally, the Authors discuss recent therapeutic applications raised from the increasing experimental evidence on TE functional mechanisms.
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Affiliation(s)
- G Guffanti
- McLean Hospital - Harvard Medical School, Belmont, MA, USA.
| | - A Bartlett
- Department of Psychology, University of Massachusetts, Boston, Boston, MA, USA
| | - P DeCrescenzo
- McLean Hospital - Harvard Medical School, Belmont, MA, USA
| | - F Macciardi
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA
| | - R Hunter
- Department of Psychology, University of Massachusetts, Boston, Boston, MA, USA
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20
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Göbel U, Arce AL, He F, Rico A, Schmitz G, de Meaux J. Robustness of Transposable Element Regulation but No Genomic Shock Observed in Interspecific Arabidopsis Hybrids. Genome Biol Evol 2018; 10:1403-1415. [PMID: 29788048 PMCID: PMC6007786 DOI: 10.1093/gbe/evy095] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2018] [Indexed: 12/23/2022] Open
Abstract
The merging of two divergent genomes in a hybrid is believed to trigger a “genomic shock”, disrupting gene regulation and transposable element (TE) silencing. Here, we tested this expectation by comparing the pattern of expression of transposable elements in their native and hybrid genomic context. For this, we sequenced the transcriptome of the Arabidopsis thaliana genotype Col-0, the A. lyrata genotype MN47 and their F1 hybrid. Contrary to expectations, we observe that the level of TE expression in the hybrid is strongly correlated to levels in the parental species. We detect that at most 1.1% of expressed transposable elements belonging to two specific subfamilies change their expression level upon hybridization. Most of these changes, however, are of small magnitude. We observe that the few hybrid-specific modifications in TE expression are more likely to occur when TE insertions are close to genes. In addition, changes in epigenetic histone marks H3K9me2 and H3K27me3 following hybridization do not coincide with TEs with changed expression. Finally, we further examined TE expression in parents and hybrids exposed to severe dehydration stress. Despite the major reorganization of gene and TE expression by stress, we observe that hybridization does not lead to increased disorganization of TE expression in the hybrid. Although our study did not examine TE transposition activity in hybrids, the examination of the transcriptome shows that TE expression is globally robust to hybridization. The term “genomic shock” is perhaps not appropriate to describe transcriptional modification in a viable hybrid merging divergent genomes.
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Affiliation(s)
- Ulrike Göbel
- Botanical Institute, University of Cologne, Germany
| | - Agustin L Arce
- Laboratorio de Biología del ARN, Instituto de Agrobiotecnología del Litoral (CONICET-UNL), 3000 Santa Fe, Argentina
| | - Fei He
- Botanical Institute, University of Cologne, Germany
| | - Alain Rico
- Thermo Fisher Scientific, Villebon-sur-Yvette, France
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21
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Zhang M, Liu XK, Fan W, Yan DF, Zhong NS, Gao JY, Zhang WJ. Transcriptome analysis reveals hybridization-induced genome shock in an interspecific F 1 hybrid from Camellia. Genome 2018; 61:477-485. [PMID: 29718690 DOI: 10.1139/gen-2017-0105] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The combination of two divergent genomes during hybridization can result in "genome shock". Although genome shock has been reported in the hybrids of some herbaceous plants, the pattern and the principle it follows are far from understood, especially in woody plants. Here, the gene expression patterns were remodeled in the F1 hybrid from the crossing of Camellia azalea × Camellia amplexicaulis compared with the parents as revealed by RNA-seq. About 54.5% of all unigenes were differentially expressed between the F1 hybrid and at least one of the parents, including 6404 unigenes with the highest expression level in the F1 hybrid. A series of genes, related to flower development, essential for RNA-directed DNA methylation and histone methylation, as well as 223 transposable elements, were enriched; and most of them exhibited a higher level of expression in the F1 hybrid. These results indicated that the genome shock induced by interspecific hybridization in Camellia could indeed result in changes of gene expression patterns, potentially through regulating DNA methylation and histone methylation which may be helpful for the maintaining of genome stability and even related to the unique phenotype of the F1 hybrid.
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Affiliation(s)
- Min Zhang
- a Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Xin-Kai Liu
- b Palm Eco-Town Development Co., Ltd., Guangzhou, Guangdong 510627, China
| | - Wen Fan
- a Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Dan-Feng Yan
- b Palm Eco-Town Development Co., Ltd., Guangzhou, Guangdong 510627, China
| | - Nai-Sheng Zhong
- b Palm Eco-Town Development Co., Ltd., Guangzhou, Guangdong 510627, China
| | - Ji-Yin Gao
- b Palm Eco-Town Development Co., Ltd., Guangzhou, Guangdong 510627, China.,c Research Institute of Subtropical Forest, Chinese Academy of Forestry, Fuyang, Zhejiang 311400, China
| | - Wen-Ju Zhang
- a Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai 200438, China
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22
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Romero-Soriano V, Modolo L, Lopez-Maestre H, Mugat B, Pessia E, Chambeyron S, Vieira C, Garcia Guerreiro MP. Transposable Element Misregulation Is Linked to the Divergence between Parental piRNA Pathways in Drosophila Hybrids. Genome Biol Evol 2018; 9:1450-1470. [PMID: 28854624 PMCID: PMC5499732 DOI: 10.1093/gbe/evx091] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2017] [Indexed: 12/30/2022] Open
Abstract
Interspecific hybridization is a genomic stress condition that leads to the activation of transposable elements (TEs) in both animals and plants. In hybrids between Drosophila buzzatii and Drosophila koepferae, mobilization of at least 28 TEs has been described. However, the molecular mechanisms underlying this TE release remain poorly understood. To give insight on the causes of this TE activation, we performed a TE transcriptomic analysis in ovaries (notorious for playing a major role in TE silencing) of parental species and their F1 and backcrossed (BC) hybrids. We find that 15.2% and 10.6% of the expressed TEs are deregulated in F1 and BC1 ovaries, respectively, with a bias toward overexpression in both cases. Although differences between parental piRNA (Piwi-interacting RNA) populations explain only partially these results, we demonstrate that piRNA pathway proteins have divergent sequences and are differentially expressed between parental species. Thus, a functional divergence of the piRNA pathway between parental species, together with some differences between their piRNA pools, might be at the origin of hybrid instabilities and ultimately cause TE misregulation in ovaries. These analyses were complemented with the study of F1 testes, where TEs tend to be less expressed than in D. buzzatii. This can be explained by an increase in piRNA production, which probably acts as a defence mechanism against TE instability in the male germline. Hence, we describe a differential impact of interspecific hybridization in testes and ovaries, which reveals that TE expression and regulation are sex-biased.
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Affiliation(s)
- Valèria Romero-Soriano
- Grup de Genòmica, Bioinformàtica i Biologia Evolutiva, Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Spain
| | - Laurent Modolo
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, Université Claude Bernard Lyon 1, Villeurbanne, France
| | - Hélène Lopez-Maestre
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, Université Claude Bernard Lyon 1, Villeurbanne, France
| | - Bruno Mugat
- Institut de Génétique Humaine, UMR9002, CNRS-Université de Montpellier, France
| | - Eugénie Pessia
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, Université Claude Bernard Lyon 1, Villeurbanne, France
| | - Séverine Chambeyron
- Institut de Génétique Humaine, UMR9002, CNRS-Université de Montpellier, France
| | - Cristina Vieira
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, Université Claude Bernard Lyon 1, Villeurbanne, France
| | - Maria Pilar Garcia Guerreiro
- Grup de Genòmica, Bioinformàtica i Biologia Evolutiva, Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Spain
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23
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Dennenmoser S, Sedlazeck FJ, Iwaszkiewicz E, Li X, Altmüller J, Nolte AW. Copy number increases of transposable elements and protein-coding genes in an invasive fish of hybrid origin. Mol Ecol 2017; 26:4712-4724. [PMID: 28390096 PMCID: PMC5638112 DOI: 10.1111/mec.14134] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 03/23/2017] [Accepted: 03/27/2017] [Indexed: 12/25/2022]
Abstract
Evolutionary dynamics of structural genetic variation in lineages of hybrid origin is not well explored, although structural mutations may increase in controlled hybrid crosses. We therefore tested whether structural variants accumulate in a fish of recent hybrid origin, invasive Cottus, relative to both parental species Cottus rhenanus and Cottus perifretum. Copy-number variation in exons of 10,979 genes was assessed using comparative genome hybridization arrays. Twelve genes showed significantly higher copy numbers in invasive Cottus compared to both parents. This coincided with increased expression for three genes related to vision, detoxification and muscle development, suggesting possible gene dosage effects. Copy number increases of putative transposons were assessed by comparative mapping of genomic DNA reads against a de novo assembly of 1,005 repetitive elements. In contrast to exons, copy number increases of repetitive elements were common (20.7%) in invasive Cottus, whereas decrease was very rare (0.01%). Among the increased repetitive elements, 53.8% occurred at higher numbers in C. perifretum compared to C. rhenanus, while only 1.4% were more abundant in C. rhenanus. This implies a biased mutational process that amplifies genetic material from one ancestor. To assess the frequency of de novo mutations through hybridization, we screened 64 laboratory-bred F2 offspring between the parental species for copy-number changes at five candidate loci. We found no evidence for new structural variants, indicating that they are too rare to be detected given our sampling scheme. Instead, they must have accumulated over more generations than we observed in a controlled cross.
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Affiliation(s)
- Stefan Dennenmoser
- Department for Evolutionary GeneticsMax‐Planck Institute for Evolutionary BiologyPlönGermany
- Institute for BiologyCarl von Ossietzky University OldenburgOldenburgGermany
| | | | - Elzbieta Iwaszkiewicz
- Department for Evolutionary GeneticsMax‐Planck Institute for Evolutionary BiologyPlönGermany
| | - Xiang‐Yi Li
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland
| | - Janine Altmüller
- Cologne Center for Genomics, and Institute of Human GeneticsUniversity of CologneCologneGermany
| | - Arne W. Nolte
- Department for Evolutionary GeneticsMax‐Planck Institute for Evolutionary BiologyPlönGermany
- Institute for BiologyCarl von Ossietzky University OldenburgOldenburgGermany
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24
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Abstract
Many of the most important evolutionary variations that generated phenotypic adaptations and originated novel taxa resulted from complex cellular activities affecting genome content and expression. These activities included (i) the symbiogenetic cell merger that produced the mitochondrion-bearing ancestor of all extant eukaryotes, (ii) symbiogenetic cell mergers that produced chloroplast-bearing ancestors of photosynthetic eukaryotes, and (iii) interspecific hybridizations and genome doublings that generated new species and adaptive radiations of higher plants and animals. Adaptive variations also involved horizontal DNA transfers and natural genetic engineering by mobile DNA elements to rewire regulatory networks, such as those essential to viviparous reproduction in mammals. In the most highly evolved multicellular organisms, biological complexity scales with 'non-coding' DNA content rather than with protein-coding capacity in the genome. Coincidentally, 'non-coding' RNAs rich in repetitive mobile DNA sequences function as key regulators of complex adaptive phenotypes, such as stem cell pluripotency. The intersections of cell fusion activities, horizontal DNA transfers and natural genetic engineering of Read-Write genomes provide a rich molecular and biological foundation for understanding how ecological disruptions can stimulate productive, often abrupt, evolutionary transformations.
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Affiliation(s)
- James A Shapiro
- Department of Biochemistry and Molecular Biology, University of Chicago, GCISW123B, 979 E. 57th Street, Chicago, IL 60637, USA
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25
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Choudhury RR, Neuhaus JM, Parisod C. Resolving fine-grained dynamics of retrotransposons: comparative analysis of inferential methods and genomic resources. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 90:979-993. [PMID: 28244250 DOI: 10.1111/tpj.13524] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 02/15/2017] [Accepted: 02/22/2017] [Indexed: 06/06/2023]
Abstract
Transposable elements support genome diversification, but comparison of their proliferation and genomic distribution within and among species is necessary to characterize their role in evolution. Such inferences are challenging because of potential bias with incomplete sampling of repetitive genome regions. Here, using the assembled genome as well as genome skimming datasets in Arabis alpina, we assessed the limits of current approaches inferring the biology of transposable elements. Long terminal repeat retrotransposons (LTR-RTs) identified in the assembled genome were classified into monophyletic lineages (here called tribes), including families of similar copies in Arabis along with elements from related Brassicaceae. Inference of their dynamics using divergence of LTRs in full-length copies and mismatch distribution of genetic variation among all copies congruently highlighted recent transposition bursts, although ancient proliferation events were apparent only with mismatch distribution. Similar inferences of LTR-RT dynamics based on random sequences from genome skimming were highly correlated with assembly-based estimates, supporting accurate analyses from shallow sequencing. Proportions of LTR-RT copies next to genes from both assembled genomes and genome skimming were congruent, pointing to tribes being over- or under-represented in the vicinity of genes. Finally, genome skimming at low coverage revealed accurate inferences of LTR-RT dynamics and distribution, although only the most abundant families appeared robustly analysed at 0.1X. Examining the pitfalls and benefits of approaches relying on different genomic resources, we highlight that random sequencing reads represent adequate data suitably complementing biased samples of LTR-RT copies retrieved from assembled genomes towards comprehensive surveys of the biology of transposable elements.
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Affiliation(s)
| | - Jean-Marc Neuhaus
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Christian Parisod
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
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26
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Parisod C. Profiling Transposable Elements and Their Epigenetic Effects in Non-model Species. Methods Mol Biol 2017; 1456:243-250. [PMID: 27770371 DOI: 10.1007/978-1-4899-7708-3_19] [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] [Indexed: 06/06/2023]
Abstract
Taking transposable elements into consideration in surveys of genetic and epigenetic variation remains challenging in species lacking a high-quality reference genome. Here, molecular techniques reducing genome complexity and specifically targeting restructuring and methylation changes in TE genome fractions are described. In particular, methyl-sensitive transposon display (MSTD) uses isoschizomers and PCR amplifications to assess the methylation environment of TE insertions. MSTD offers reliable insights into genome-wide epigenetic changes associated with TEs, especially when used together with similar techniques tracking random sequences.
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Affiliation(s)
- Christian Parisod
- Laboratory of Evolutionary Botany, Biology Institute, University of Neuchâtel, Rue Emile-Argand 11, 2009, Neuchâtel, Switzerland.
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27
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Senerchia N, Felber F, North B, Sarr A, Guadagnuolo R, Parisod C. Differential introgression and reorganization of retrotransposons in hybrid zones between wild wheats. Mol Ecol 2016; 25:2518-28. [DOI: 10.1111/mec.13515] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 11/24/2015] [Accepted: 11/30/2015] [Indexed: 12/20/2022]
Affiliation(s)
- Natacha Senerchia
- Laboratory of Evolutionary Botany; Institute of Biology; University of Neuchâtel; 2000 Neuchâtel Switzerland
| | - François Felber
- Laboratory of Evolutionary Botany; Institute of Biology; University of Neuchâtel; 2000 Neuchâtel Switzerland
- Musée et Jardins Botaniques Cantonaux; 1007 Lausanne Switzerland
| | - Béatrice North
- Laboratory of Evolutionary Botany; Institute of Biology; University of Neuchâtel; 2000 Neuchâtel Switzerland
| | - Anouk Sarr
- Laboratory of Evolutionary Botany; Institute of Biology; University of Neuchâtel; 2000 Neuchâtel Switzerland
| | - Roberto Guadagnuolo
- Laboratory of Evolutionary Botany; Institute of Biology; University of Neuchâtel; 2000 Neuchâtel Switzerland
| | - Christian Parisod
- Laboratory of Evolutionary Botany; Institute of Biology; University of Neuchâtel; 2000 Neuchâtel Switzerland
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28
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Romero-Soriano V, Burlet N, Vela D, Fontdevila A, Vieira C, García Guerreiro MP. Drosophila Females Undergo Genome Expansion after Interspecific Hybridization. Genome Biol Evol 2016; 8:556-61. [PMID: 26872773 PMCID: PMC4824032 DOI: 10.1093/gbe/evw024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Genome size (or C-value) can present a wide range of values among eukaryotes. This variation has been attributed to differences in the amplification and deletion of different noncoding repetitive sequences, particularly transposable elements (TEs). TEs can be activated under different stress conditions such as interspecific hybridization events, as described for several species of animals and plants. These massive transposition episodes can lead to considerable genome expansions that could ultimately be involved in hybrid speciation processes. Here, we describe the effects of hybridization and introgression on genome size of Drosophila hybrids. We measured the genome size of two close Drosophila species, Drosophila buzzatii and Drosophila koepferae, their F1 offspring and the offspring from three generations of backcrossed hybrids; where mobilization of up to 28 different TEs was previously detected. We show that hybrid females indeed present a genome expansion, especially in the first backcross, which could likely be explained by transposition events. Hybrid males, which exhibit more variable C-values among individuals of the same generation, do not present an increased genome size. Thus, we demonstrate that the impact of hybridization on genome size can be detected through flow cytometry and is sex-dependent.
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Affiliation(s)
- Valèria Romero-Soriano
- Departament De Genètica I Microbiologia (Edifici C), Grup De Genòmica, Bioinformàtica I Biologia Evolutiva. Universitat Autònoma De Barcelona, Spain
| | - Nelly Burlet
- Laboratoire De Biométrie Et Biologie Evolutive, UMR5558, Université Lyon 1, Université Lyon, Villeurbanne, France
| | - Doris Vela
- Laboratorio De Genética Evolutiva, Pontificia Universidad Católica Del Ecuador, Quito, Ecuador
| | - Antonio Fontdevila
- Departament De Genètica I Microbiologia (Edifici C), Grup De Genòmica, Bioinformàtica I Biologia Evolutiva. Universitat Autònoma De Barcelona, Spain
| | - Cristina Vieira
- Laboratoire De Biométrie Et Biologie Evolutive, UMR5558, Université Lyon 1, Université Lyon, Villeurbanne, France
| | - María Pilar García Guerreiro
- Departament De Genètica I Microbiologia (Edifici C), Grup De Genòmica, Bioinformàtica I Biologia Evolutiva. Universitat Autònoma De Barcelona, Spain
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29
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Springer NM, Lisch D, Li Q. Creating Order from Chaos: Epigenome Dynamics in Plants with Complex Genomes. THE PLANT CELL 2016; 28:314-25. [PMID: 26869701 PMCID: PMC4790878 DOI: 10.1105/tpc.15.00911] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 02/10/2016] [Indexed: 05/02/2023]
Abstract
Flowering plants have strikingly distinct genomes, although they contain a similar suite of expressed genes. The diversity of genome structures and organization is largely due to variation in transposable elements (TEs) and whole-genome duplication (WGD) events. We review evidence that chromatin modifications and epigenetic regulation are intimately associated with TEs and likely play a role in mediating the effects of WGDs. We hypothesize that the current structure of a genome is the result of various TE bursts and WGDs and it is likely that the silencing mechanisms and the chromatin structure of a genome have been shaped by these events. This suggests that the specific mechanisms targeting chromatin modifications and epigenomic patterns may vary among different species. Many crop species have likely evolved chromatin-based mechanisms to tolerate silenced TEs near actively expressed genes. These interactions of heterochromatin and euchromatin are likely to have important roles in modulating gene expression and variability within species.
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Affiliation(s)
- Nathan M Springer
- Department of Plant Biology, Microbial and Plant Genomics Institute, University of Minnesota, Saint Paul, Minnesota 55108
| | - Damon Lisch
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
| | - Qing Li
- Department of Plant Biology, Microbial and Plant Genomics Institute, University of Minnesota, Saint Paul, Minnesota 55108
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Romero-Soriano V, Garcia Guerreiro MP. Expression of the Retrotransposon Helena Reveals a Complex Pattern of TE Deregulation in Drosophila Hybrids. PLoS One 2016; 11:e0147903. [PMID: 26812285 PMCID: PMC4728067 DOI: 10.1371/journal.pone.0147903] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 01/11/2016] [Indexed: 11/18/2022] Open
Abstract
Transposable elements (TEs), repeated mobile sequences, are ubiquitous in the eukaryotic kingdom. Their mobilizing capacity confers on them a high mutagenic potential, which must be strongly regulated to guarantee genome stability. In the Drosophila germline, a small RNA-mediated silencing system, the piRNA (Piwi-interacting RNA) pathway, is the main responsible TE regulating mechanism, but some stressful conditions can destabilize it. For instance, during interspecific hybridization, genomic stress caused by the shock of two different genomes can lead, in both animals and plants, to higher transposition rates. A recent study in D. buzatii-D. koepferae hybrids detected mobilization of 28 TEs, yet little is known about the molecular mechanisms explaining this transposition release. We have characterized one of the mobilized TEs, the retrotransposon Helena, and used quantitative expression to assess whether its high transposition rates in hybrids are preceded by increased expression. We have also localized Helena expression in the gonads to see if cellular expression patterns have changed in the hybrids. To give more insight into changes in TE regulation in hybrids, we analysed Helena-specific piRNA populations of hybrids and parental species. Helena expression is not globally altered in somatic tissues, but male and female gonads have different patterns of deregulation. In testes, Helena is repressed in F1, increasing then its expression up to parental values. This is linked with a mislocation of Helena transcripts along with an increase of their specific piRNA levels. Ovaries have additive levels of Helena expression, but the ping-pong cycle efficiency seems to be reduced in F1 hybrids. This could be at the origin of new Helena insertions in hybrids, which would be transmitted to F1 hybrid female progeny.
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Affiliation(s)
- Valèria Romero-Soriano
- Grup de Genòmica, Bioinformàtica i Biologia Evolutiva, Departament de Genètica i Microbiologia (Edifici C), Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain
| | - Maria Pilar Garcia Guerreiro
- Grup de Genòmica, Bioinformàtica i Biologia Evolutiva, Departament de Genètica i Microbiologia (Edifici C), Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain
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Lafon-Placette C, Vallejo-Marín M, Parisod C, Abbott RJ, Köhler C. Current plant speciation research: unravelling the processes and mechanisms behind the evolution of reproductive isolation barriers. THE NEW PHYTOLOGIST 2016; 209:29-33. [PMID: 26625345 DOI: 10.1111/nph.13756] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Affiliation(s)
- Clément Lafon-Placette
- Swedish University of Agricultural Sciences and Linnean Center of Plant Biology, Uppsala BioCenter, Uppsala, SE-75007, Sweden
| | - Mario Vallejo-Marín
- Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK
| | - Christian Parisod
- Laboratory of Evolutionary Botany, Institute of Biology, University of Neuchâtel, Neuchâtel, CH-2000, Switzerland
| | - Richard J Abbott
- School of Biology, University of St Andrews, St Andrews, Fife, KY16 9TH, UK
| | - Claudia Köhler
- Swedish University of Agricultural Sciences and Linnean Center of Plant Biology, Uppsala BioCenter, Uppsala, SE-75007, Sweden
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Immediate Genetic and Epigenetic Changes in F1 Hybrids Parented by Species with Divergent Genomes in the Rice Genus (Oryza). PLoS One 2015. [PMID: 26208215 PMCID: PMC4514751 DOI: 10.1371/journal.pone.0132911] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Background Inter-specific hybridization occurs frequently in higher plants, and represents a driving force of evolution and speciation. Inter-specific hybridization often induces genetic and epigenetic instabilities in the resultant homoploid hybrids or allopolyploids, a phenomenon known as genome shock. Although genetic and epigenetic consequences of hybridizations between rice subspecies (e.g., japonica and indica) and closely related species sharing the same AA genome have been extensively investigated, those of inter-specific hybridizations between more remote species with different genomes in the rice genus, Oryza, remain largely unknown. Methodology/Principal Findings We investigated the immediate chromosomal and molecular genetic/epigenetic instability of three triploid F1 hybrids produced by inter-specific crossing between species with divergent genomes of Oryza by genomic in situ hybridization (GISH) and molecular marker analysis. Transcriptional and transpositional activity of several transposable elements (TEs) and methylation stability of their flanking regions were also assessed. We made the following principle findings: (i) all three triploid hybrids are stable in both chromosome number and gross structure; (ii) stochastic changes in both DNA sequence and methylation occurred in individual plants of all three triploid hybrids, but in general methylation changes occurred at lower frequencies than genetic changes; (iii) alteration in DNA methylation occurred to a greater extent in genomic loci flanking potentially active TEs than in randomly sampled loci; (iv) transcriptional activation of several TEs commonly occurred in all three hybrids but transpositional events were detected in a genetic context-dependent manner. Conclusions/Significance Artificially constructed inter-specific hybrids of remotely related species with divergent genomes in genus Oryza are chromosomally stable but show immediate and highly stochastic genetic and epigenetic instabilities at the molecular level. These novel hybrids might provide a rich resource of genetic and epigenetic diversities for potential utilization in rice genetic improvements.
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