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Lin X, Yin J, Wang Y, Yao J, Li QQ, Latzel V, Bossdorf O, Zhang YY. Environment-induced heritable variations are common in Arabidopsis thaliana. Nat Commun 2024; 15:4615. [PMID: 38816460 PMCID: PMC11139905 DOI: 10.1038/s41467-024-49024-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 05/17/2024] [Indexed: 06/01/2024] Open
Abstract
Parental or ancestral environments can induce heritable phenotypic changes, but whether such environment-induced heritable changes are a common phenomenon remains unexplored. Here, we subject 14 genotypes of Arabidopsis thaliana to 10 different environmental treatments and observe phenotypic and genome-wide gene expression changes over four successive generations. We find that all treatments caused heritable phenotypic and gene expression changes, with a substantial proportion stably transmitted over all observed generations. Intriguingly, the susceptibility of a genotype to environmental inductions could be predicted based on the transposon abundance in the genome. Our study thus challenges the classic view that the environment only participates in the selection of heritable variation and suggests that the environment can play a significant role in generating of heritable variations.
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Affiliation(s)
- Xiaohe Lin
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, China
| | - Junjie Yin
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, China
| | - Yifan Wang
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, China
| | - Jing Yao
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, China
| | - Qingshun Q Li
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, China
- Biomedical Sciences, College of Dental Medicine, Western University of Health Sciences, Pomona, CA, USA
| | - Vit Latzel
- Institute of Botany of the CAS, Zamek 1, 252 43, Pruhonice, Czech Republic
| | - Oliver Bossdorf
- Institute of Evolution & Ecology, University of Tübingen, Auf der Morgenstelle 5, 72076, Tübingen, Germany
| | - Yuan-Ye Zhang
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, China.
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2
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Huang Y, Lee YCG. Blessing or curse: how the epigenetic resolution of host-transposable element conflicts shapes their evolutionary dynamics. Proc Biol Sci 2024; 291:20232775. [PMID: 38593848 PMCID: PMC11003778 DOI: 10.1098/rspb.2023.2775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 03/01/2024] [Indexed: 04/11/2024] Open
Abstract
Transposable elements (TEs) are selfish genetic elements whose antagonistic interactions with hosts represent a common genetic conflict in eukaryotes. To resolve this conflict, hosts have widely adopted epigenetic silencing that deposits repressive marks at TEs. However, this mechanism is imperfect and fails to fully halt TE replication. Furthermore, TE epigenetic silencing can inadvertently spread repressive marks to adjacent functional sequences, a phenomenon considered a 'curse' of this conflict resolution. Here, we used forward simulations to explore how TE epigenetic silencing and its harmful side effects shape the evolutionary dynamics of TEs and their hosts. Our findings reveal that epigenetic silencing allows TEs and their hosts to stably coexist under a wide range of conditions, because the underlying molecular mechanisms give rise to copy-number dependency of the strength of TE silencing. Interestingly, contrary to intuitive expectations that TE epigenetic silencing should evolve to be as strong as possible, we found a selective benefit for modifier alleles that weaken TE silencing under biologically feasible conditions. These results reveal that the dual nature of TE epigenetic silencing, with both positive and negative effects, complicates its evolutionary trajectory and makes it challenging to determine whether TE epigenetic silencing is a 'blessing' or a 'curse'.
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Affiliation(s)
- Yuheng Huang
- Department of Ecology and Evolutionary Biology, University of California, Irvine, USA
| | - Yuh Chwen G. Lee
- Department of Ecology and Evolutionary Biology, University of California, Irvine, USA
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3
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Jiang J, Xu YC, Zhang ZQ, Chen JF, Niu XM, Hou XH, Li XT, Wang L, Zhang YE, Ge S, Guo YL. Forces driving transposable element load variation during Arabidopsis range expansion. THE PLANT CELL 2024; 36:840-862. [PMID: 38036296 PMCID: PMC10980350 DOI: 10.1093/plcell/koad296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 10/25/2023] [Accepted: 11/06/2023] [Indexed: 12/02/2023]
Abstract
Genetic load refers to the accumulated and potentially life-threatening deleterious mutations in populations. Understanding the mechanisms underlying genetic load variation of transposable element (TE) insertion, a major large-effect mutation, during range expansion is an intriguing question in biology. Here, we used 1,115 global natural accessions of Arabidopsis (Arabidopsis thaliana) to study the driving forces of TE load variation during its range expansion. TE load increased with range expansion, especially in the recently established Yangtze River basin population. Effective population size, which explains 62.0% of the variance in TE load, high transposition rate, and selective sweeps contributed to TE accumulation in the expanded populations. We genetically mapped and identified multiple candidate causal genes and TEs, and revealed the genetic architecture of TE load variation. Overall, this study reveals the variation in TE genetic load during Arabidopsis expansion and highlights the causes of TE load variation from the perspectives of both population genetics and quantitative genetics.
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Affiliation(s)
- Juan Jiang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yong-Chao Xu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
| | - Zhi-Qin Zhang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jia-Fu Chen
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiao-Min Niu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
| | - Xing-Hui Hou
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
| | - Xin-Tong Li
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Li Wang
- Agricultural Synthetic Biology Center, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Yong E Zhang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- State Key Laboratory of Integrated Management of Pest Insects and Rodents & Key Laboratory of the Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Song Ge
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ya-Long Guo
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
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4
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ffrench-Constant RH. Transposable elements and xenobiotic resistance. FRONTIERS IN INSECT SCIENCE 2023; 3:1178212. [PMID: 38469483 PMCID: PMC10926513 DOI: 10.3389/finsc.2023.1178212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 05/24/2023] [Indexed: 03/13/2024]
Abstract
Transposable elements or TEs are well known drivers of adaptive change in plants and animals but their role in insecticide resistance remains poorly documented. This review examines the potential role of transposons in resistance and identifies key areas where our understanding remains unclear. Despite well-known model systems such as upregulation of Drosophila Cyp6g1, many putative examples lack functional validation. The potential types of transposon-associated changes that could lead to resistance are reviewed, including changes in up-regulation, message stability, loss of function and alternative splicing. Where potential mechanisms appear absent from the resistance literature examples are drawn from other areas of biology. Finally, ways are suggested in which transgenic expression could be used to validate the biological significance of TE insertion. In the absence of such functional expression studies many examples of the association of TEs and resistance genes therefore remain as correlations.
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5
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Wang Y, McNeil P, Abdulazeez R, Pascual M, Johnston SE, Keightley PD, Obbard DJ. Variation in mutation, recombination, and transposition rates in Drosophila melanogaster and Drosophila simulans. Genome Res 2023; 33:587-598. [PMID: 37037625 PMCID: PMC10234296 DOI: 10.1101/gr.277383.122] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 03/28/2023] [Indexed: 04/12/2023]
Abstract
The rates of mutation, recombination, and transposition are core parameters in models of evolution. They impact genetic diversity, responses to ongoing selection, and levels of genetic load. However, even for key evolutionary model species such as Drosophila melanogaster and Drosophila simulans, few estimates of these parameters are available, and we have little idea of how rates vary between individuals, sexes, or populations. Knowledge of this variation is fundamental for parameterizing models of genome evolution. Here, we provide direct estimates of mutation, recombination, and transposition rates and their variation in a West African and a European population of D. melanogaster and a European population of D. simulans Across 89 flies, we observe 58 single-nucleotide mutations, 286 crossovers, and 89 transposable element (TE) insertions. Compared to the European D. melanogaster, we find the West African population has a lower mutation rate (1.67 × 10-9 site-1 gen-1 vs. 4.86 × 10-9 site-1 gen-1) and a lower transposition rate (8.99 × 10-5 copy-1 gen-1 vs. 23.36 × 10-5 copy-1 gen-1), but a higher recombination rate (3.44 cM/Mb vs. 2.06 cM/Mb). The European D. simulans population has a similar mutation rate to European D. melanogaster, but a significantly higher recombination rate and a lower, but not significantly different, transposition rate. Overall, we find paternal-derived mutations are more frequent than maternal ones in both species. Our study quantifies the variation in rates of mutation, recombination, and transposition among different populations and sexes, and our direct estimates of these parameters in D. melanogaster and D. simulans will benefit future studies in population and evolutionary genetics.
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Affiliation(s)
- Yiguan Wang
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom;
| | - Paul McNeil
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
| | | | - Marta Pascual
- Departament de Genètica, Microbiologia i Estadística and IRBio, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Susan E Johnston
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
| | - Peter D Keightley
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
| | - Darren J Obbard
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
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6
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Mérot C, Stenløkk KSR, Venney C, Laporte M, Moser M, Normandeau E, Árnyasi M, Kent M, Rougeux C, Flynn JM, Lien S, Bernatchez L. Genome assembly, structural variants, and genetic differentiation between lake whitefish young species pairs (Coregonus sp.) with long and short reads. Mol Ecol 2023; 32:1458-1477. [PMID: 35416336 DOI: 10.1111/mec.16468] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 03/24/2022] [Accepted: 04/01/2022] [Indexed: 11/26/2022]
Abstract
Nascent pairs of ecologically differentiated species offer an opportunity to get a better glimpse at the genetic architecture of speciation. Of particular interest is our recent ability to consider a wider range of genomic variants, not only single-nucleotide polymorphisms (SNPs), thanks to long-read sequencing technology. We can now identify structural variants (SVs) such as insertions, deletions and other rearrangements, allowing further insights into the genetic architecture of speciation and how different types of variants are involved in species differentiation. Here, we investigated genomic patterns of differentiation between sympatric species pairs (Dwarf and Normal) belonging to the lake whitefish (Coregonus clupeaformis) species complex. We assembled the first reference genomes for both C. clupeaformis sp. Normal and C. clupeaformis sp. Dwarf, annotated the transposable elements and analysed the genomes in the light of related coregonid species. Next, we used a combination of long- and short-read sequencing to characterize SVs and genotype them at the population scale using genome-graph approaches, showing that SVs cover five times more of the genome than SNPs. We then integrated both SNPs and SVs to investigate the genetic architecture of species differentiation in two different lakes and highlighted an excess of shared outliers of differentiation. In particular, a large fraction of SVs differentiating the two species correspond to insertions or deletions of transposable elements (TEs), suggesting that TE accumulation may represent a key component of genetic divergence between the Dwarf and Normal species. Together, our results suggest that SVs may play an important role in speciation and that, by combining second- and third-generation sequencing, we now have the ability to integrate SVs into speciation genomics.
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Affiliation(s)
- Claire Mérot
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada.,UMR 6553 Ecobio, OSUR, CNRS, Université de Rennes, Rennes, France
| | - Kristina S R Stenløkk
- Department of Animal and Aquacultural Sciences (IHA), Faculty of Life Sciences (BIOVIT), Centre for Integrative Genetics (CIGENE), Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Clare Venney
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
| | - Martin Laporte
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada.,Ministère des Forêts, de la Faune et des Parcs (MFFP) du Québec, Québec, Québec, Canada
| | - Michel Moser
- Department of Animal and Aquacultural Sciences (IHA), Faculty of Life Sciences (BIOVIT), Centre for Integrative Genetics (CIGENE), Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Eric Normandeau
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
| | - Mariann Árnyasi
- Department of Animal and Aquacultural Sciences (IHA), Faculty of Life Sciences (BIOVIT), Centre for Integrative Genetics (CIGENE), Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Matthew Kent
- Department of Animal and Aquacultural Sciences (IHA), Faculty of Life Sciences (BIOVIT), Centre for Integrative Genetics (CIGENE), Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Clément Rougeux
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
| | - Jullien M Flynn
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, USA
| | - Sigbjørn Lien
- Department of Animal and Aquacultural Sciences (IHA), Faculty of Life Sciences (BIOVIT), Centre for Integrative Genetics (CIGENE), Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Louis Bernatchez
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
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7
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López-Cortegano E, Craig RJ, Chebib J, Balogun EJ, Keightley PD. Rates and spectra of de novo structural mutations in Chlamydomonas reinhardtii. Genome Res 2023; 33:45-60. [PMID: 36617667 PMCID: PMC9977147 DOI: 10.1101/gr.276957.122] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 12/06/2022] [Indexed: 12/14/2022]
Abstract
Genetic variation originates from several types of spontaneous mutation, including single-nucleotide substitutions, short insertions and deletions (indels), and larger structural changes. Structural mutations (SMs) drive genome evolution and are thought to play major roles in evolutionary adaptation, speciation, and genetic disease, including cancers. Sequencing of mutation accumulation (MA) lines has provided estimates of rates and spectra of single-nucleotide and indel mutations in many species, yet the rate of new SMs is largely unknown. Here, we use long-read sequencing to determine the full mutation spectrum in MA lines derived from two strains (CC-1952 and CC-2931) of the green alga Chlamydomonas reinhardtii The SM rate is highly variable between strains and between MA lines, and SMs represent a substantial proportion of all mutations in both strains (CC-1952 6%; CC-2931 12%). The SM spectra differ considerably between the two strains, with almost all inversions and translocations occurring in CC-2931 MA lines. This variation is associated with heterogeneity in the number and type of active transposable elements (TEs), which comprise major proportions of SMs in both strains (CC-1952 22%; CC-2931 38%). In CC-2931, a Crypton and a previously undescribed type of DNA element have caused 71% of chromosomal rearrangements, whereas in CC-1952, a Dualen LINE is associated with 87% of duplications. Other SMs, notably large duplications in CC-2931, are likely products of various double-strand break repair pathways. Our results show that diverse types of SMs occur at substantial rates, and support prominent roles for SMs and TEs in evolution.
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Affiliation(s)
- Eugenio López-Cortegano
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
| | - Rory J. Craig
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom;,California Institute for Quantitative Biosciences, UC Berkeley, Berkeley, California 94720, USA
| | - Jobran Chebib
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
| | - Eniolaye J. Balogun
- Department of Ecology and Evolutionary Biology, University of Toronto, Ontario ON M5S 3B2, Canada;,Department of Biology, University of Toronto Mississauga, Mississauga ON L5L 1C6, Canada
| | - Peter D. Keightley
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
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Scheffer H, Coate JE, Ho EKH, Schaack S. Thermal stress and mutation accumulation increase heat shock protein expression in Daphnia. Evol Ecol 2022; 36:829-844. [PMID: 36193163 PMCID: PMC9522699 DOI: 10.1007/s10682-022-10209-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 08/25/2022] [Indexed: 11/28/2022]
Abstract
Understanding the short- and long-term consequences of climate change is a major challenge in biology. For aquatic organisms, temperature changes and drought can lead to thermal stress and habitat loss, both of which can ultimately lead to higher mutation rates. Here, we examine the effect of high temperature and mutation accumulation on gene expression at two loci from the heat shock protein (HSP) gene family, HSP60 and HSP90. HSPs have been posited to serve as 'mutational capacitors' given their role as molecular chaperones involved in protein folding and degradation, thus buffering against a wide range of cellular stress and destabilization. We assayed changes in HSP expression across 5 genotypes of Daphnia magna, a sentinel species in ecology and environmental biology, with and without acute exposure to thermal stress and accumulated mutations. Across genotypes, HSP expression increased ~ 6× in response to heat and ~ 4× with mutation accumulation, individually. Both factors simultaneously (lineages with high mutation loads exposed to high heat) increased gene expression ~ 23×-much more than that predicted by an additive model. Our results corroborate suggestions that HSPs can buffer against not only the effects of heat, but also mutations-a combination of factors both likely to increase in a warming world. Supplementary Information The online version contains supplementary material available at 10.1007/s10682-022-10209-1.
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Affiliation(s)
- Henry Scheffer
- Department of Biology, Reed College, 3203 SE Woodstock Blvd, Portland, OR 97202 USA
| | - Jeremy E. Coate
- Department of Biology, Reed College, 3203 SE Woodstock Blvd, Portland, OR 97202 USA
| | - Eddie K. H. Ho
- Department of Biology, Reed College, 3203 SE Woodstock Blvd, Portland, OR 97202 USA
| | - Sarah Schaack
- Department of Biology, Reed College, 3203 SE Woodstock Blvd, Portland, OR 97202 USA
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9
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Huang Y, Shukla H, Lee YCG. Species-specific chromatin landscape determines how transposable elements shape genome evolution. eLife 2022; 11:81567. [PMID: 35997258 PMCID: PMC9398452 DOI: 10.7554/elife.81567] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 07/15/2022] [Indexed: 11/30/2022] Open
Abstract
Transposable elements (TEs) are selfish genetic parasites that increase their copy number at the expense of host fitness. The ‘success’, or genome-wide abundance, of TEs differs widely between species. Deciphering the causes for this large variety in TE abundance has remained a central question in evolutionary genomics. We previously proposed that species-specific TE abundance could be driven by the inadvertent consequences of host-direct epigenetic silencing of TEs—the spreading of repressive epigenetic marks from silenced TEs into adjacent sequences. Here, we compared this TE-mediated local enrichment of repressive marks, or ‘the epigenetic effect of TEs’, in six species in the Drosophila melanogaster subgroup to dissect step-by-step the role of such effect in determining genomic TE abundance. We found that TE-mediated local enrichment of repressive marks is prevalent and substantially varies across and even within species. While this TE-mediated effect alters the epigenetic states of adjacent genes, we surprisingly discovered that the transcription of neighboring genes could reciprocally impact this spreading. Importantly, our multi-species analysis provides the power and appropriate phylogenetic resolution to connect species-specific host chromatin regulation, TE-mediated epigenetic effects, the strength of natural selection against TEs, and genomic TE abundance unique to individual species. Our findings point toward the importance of host chromatin landscapes in shaping genome evolution through the epigenetic effects of a selfish genetic parasite. All the instructions required for life are encoded in the set of DNA present in a cell. It therefore seems natural to think that every bit of this genetic information should serve the organism. And yet most species carry parasitic ‘transposable’ sequences, or transposons, whose only purpose is to multiply and insert themselves at other positions in the genome. It is possible for cells to suppress these selfish elements. Chemical marks can be deposited onto the DNA to temporarily ‘silence’ transposons and prevent them from being able to move and replicate. However, this sometimes comes at a cost: the repressive chemical modifications can spread to nearby genes that are essential for the organism and perturb their function. Strangely, the prevalence of transposons varies widely across the tree of life. These sequences form the majority of the genome of certain species – in fact, they represent about half of the human genetic information. But their abundance is much lower in other organisms, forming a measly 6% of the genome of puffer fish for instance. Even amongst fruit fly species, the prevalence of transposable elements can range between 2% and 25%. What explains such differences? Huang et al. set out to examine this question through the lens of transposon silencing, systematically comparing how this process impacts nearby regions in six species of fruit flies. This revealed variations in the strength of the side effects associated with transposon silencing, resulting in different levels of perturbation on neighbouring genes. A stronger impact was associated with the species having fewer transposons in its genome, suggesting that an evolutionary pressure is at work to keep the abundance of transposons at a low level in these species. Further analyses showed that the genes which determine how silencing marks are distributed may also be responsible for the variations in the impact of transposon silencing. They could therefore be the ones driving differences in the abundance of transposons between species. Overall, this work sheds light on the complex mechanisms shaping the evolution of genomes, and it may help to better understand how transposons are linked to processes such as aging and cancer.
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Affiliation(s)
- Yuheng Huang
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, United States
| | - Harsh Shukla
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, United States
| | - Yuh Chwen G Lee
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, United States
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10
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Mishra B, Ulaszewski B, Meger J, Aury JM, Bodénès C, Lesur-Kupin I, Pfenninger M, Da Silva C, Gupta DK, Guichoux E, Heer K, Lalanne C, Labadie K, Opgenoorth L, Ploch S, Le Provost G, Salse J, Scotti I, Wötzel S, Plomion C, Burczyk J, Thines M. A Chromosome-Level Genome Assembly of the European Beech ( Fagus sylvatica) Reveals Anomalies for Organelle DNA Integration, Repeat Content and Distribution of SNPs. Front Genet 2022; 12:691058. [PMID: 35211148 PMCID: PMC8862710 DOI: 10.3389/fgene.2021.691058] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 12/14/2021] [Indexed: 01/14/2023] Open
Abstract
The European Beech is the dominant climax tree in most regions of Central Europe and valued for its ecological versatility and hardwood timber. Even though a draft genome has been published recently, higher resolution is required for studying aspects of genome architecture and recombination. Here, we present a chromosome-level assembly of the more than 300 year-old reference individual, Bhaga, from the Kellerwald-Edersee National Park (Germany). Its nuclear genome of 541 Mb was resolved into 12 chromosomes varying in length between 28 and 73 Mb. Multiple nuclear insertions of parts of the chloroplast genome were observed, with one region on chromosome 11 spanning more than 2 Mb which fragments up to 54,784 bp long and covering the whole chloroplast genome were inserted randomly. Unlike in Arabidopsis thaliana, ribosomal cistrons are present in Fagus sylvatica only in four major regions, in line with FISH studies. On most assembled chromosomes, telomeric repeats were found at both ends, while centromeric repeats were found to be scattered throughout the genome apart from their main occurrence per chromosome. The genome-wide distribution of SNPs was evaluated using a second individual from Jamy Nature Reserve (Poland). SNPs, repeat elements and duplicated genes were unevenly distributed in the genomes, with one major anomaly on chromosome 4. The genome presented here adds to the available highly resolved plant genomes and we hope it will serve as a valuable basis for future research on genome architecture and for understanding the past and future of European Beech populations in a changing climate.
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Affiliation(s)
- Bagdevi Mishra
- Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Frankfurt am Main, Germany.,Department for Biological Sciences, Institute of Ecology, Evolution and Diversity, Goethe University, Frankfurt am Main, Germany
| | - Bartosz Ulaszewski
- Department of Genetics, ul. Chodkiewicza 30, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Joanna Meger
- Department of Genetics, ul. Chodkiewicza 30, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Jean-Marc Aury
- Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, Evry, France
| | | | - Isabelle Lesur-Kupin
- INRAE, Univ. Bordeaux, BIOGECO, Cestas, France.,HelixVenture, Mérignac, France.,Faculty of Biology, Plant Ecology and Geobotany, Philipps University Marburg, Marburg, Germany
| | - Markus Pfenninger
- Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Frankfurt am Main, Germany
| | - Corinne Da Silva
- Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, Evry, France
| | - Deepak K Gupta
- Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Frankfurt am Main, Germany.,Department for Biological Sciences, Institute of Ecology, Evolution and Diversity, Goethe University, Frankfurt am Main, Germany.,LOEWE Centre for Translational Biodiversity Genomics (TBG), Frankfurt am Main, Germany
| | | | - Katrin Heer
- Faculty of Biology, Plant Ecology and Geobotany, Philipps University Marburg, Marburg, Germany.,Forest Genetics, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | | | - Karine Labadie
- Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, Evry, France
| | - Lars Opgenoorth
- Faculty of Biology, Plant Ecology and Geobotany, Philipps University Marburg, Marburg, Germany
| | - Sebastian Ploch
- Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Frankfurt am Main, Germany
| | | | | | | | - Stefan Wötzel
- Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Frankfurt am Main, Germany.,Department for Biological Sciences, Institute of Ecology, Evolution and Diversity, Goethe University, Frankfurt am Main, Germany
| | | | - Jaroslaw Burczyk
- Department of Genetics, ul. Chodkiewicza 30, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Marco Thines
- Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Frankfurt am Main, Germany.,Department for Biological Sciences, Institute of Ecology, Evolution and Diversity, Goethe University, Frankfurt am Main, Germany.,LOEWE Centre for Translational Biodiversity Genomics (TBG), Frankfurt am Main, Germany
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11
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Ho EKH, Schaack S. Intraspecific Variation in the Rates of Mutations Causing Structural Variation in Daphnia magna. Genome Biol Evol 2021; 13:6444992. [PMID: 34849778 PMCID: PMC8691059 DOI: 10.1093/gbe/evab241] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2021] [Indexed: 12/17/2022] Open
Abstract
Mutations that cause structural variation are important sources of genetic variation upon which other evolutionary forces can act, however, they are difficult to observe and therefore few direct estimates of their rate and spectrum are available. Understanding mutation rate evolution, however, requires adding to the limited number of species for which direct estimates are available, quantifying levels of intraspecific variation in mutation rates, and assessing whether rate estimates co-vary across types of mutation. Here, we report structural variation-causing mutation rates (svcMRs) for six categories of mutations (short insertions and deletions, long deletions and duplications, and deletions and duplications at copy number variable sites) from nine genotypes of Daphnia magna collected from three populations in Finland, Germany, and Israel using a mutation accumulation approach. Based on whole-genome sequence data and validated using simulations, we find svcMRs are high (two orders of magnitude higher than base substitution mutation rates measured in the same lineages), highly variable among populations, and uncorrelated across categories of mutation. Furthermore, to assess the impact of scvMRs on the genome, we calculated rates while adjusting for the lengths of events and ran simulations to determine if the mutations occur in genic regions more or less frequently than expected by chance. Our results pose a challenge to most prevailing theories aimed at explaining the evolution of the mutation rate, underscoring the importance of obtaining additional mutation rate estimates in more genotypes, for more types of mutation, in more species, in order to improve our future understanding of mutation rates, their variation, and their evolution.
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Affiliation(s)
- Eddie K H Ho
- Department of Biology, Reed College, Portland, Oregon, USA
| | - Sarah Schaack
- Department of Biology, Reed College, Portland, Oregon, USA
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