1
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Leduque B, Edera A, Vitte C, Quadrana L. Simultaneous profiling of chromatin accessibility and DNA methylation in complete plant genomes using long-read sequencing. Nucleic Acids Res 2024; 52:6285-6297. [PMID: 38676941 PMCID: PMC11194078 DOI: 10.1093/nar/gkae306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 03/29/2024] [Accepted: 04/10/2024] [Indexed: 04/29/2024] Open
Abstract
Epigenetic regulations, including chromatin accessibility, nucleosome positioning and DNA methylation intricately shape genome function. However, current chromatin profiling techniques relying on short-read sequencing technologies fail to characterise highly repetitive genomic regions and cannot detect multiple chromatin features simultaneously. Here, we performed Simultaneous Accessibility and DNA Methylation Sequencing (SAM-seq) of purified plant nuclei. Thanks to the use of long-read nanopore sequencing, SAM-seq enables high-resolution profiling of m6A-tagged chromatin accessibility together with endogenous cytosine methylation in plants. Analysis of naked genomic DNA revealed significant sequence preference biases of m6A-MTases, controllable through a normalisation step. By applying SAM-seq to Arabidopsis and maize nuclei we obtained fine-grained accessibility and DNA methylation landscapes genome-wide. We uncovered crosstalk between chromatin accessibility and DNA methylation within nucleosomes of genes, TEs, and centromeric repeats. SAM-seq also detects DNA footprints over cis-regulatory regions. Furthermore, using the single-molecule information provided by SAM-seq we identified extensive cellular heterogeneity at chromatin domains with antagonistic chromatin marks, suggesting that bivalency reflects cell-specific regulations. SAM-seq is a powerful approach to simultaneously study multiple epigenetic features over unique and repetitive sequences, opening new opportunities for the investigation of epigenetic mechanisms.
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Affiliation(s)
- Basile Leduque
- Institute of Plant Sciences Paris-Saclay, Centre Nationale de la Recherche Scientifique, Institute National de la Recherche Agronomique, Université Evry, Université Paris-Saclay, Orsay, France
| | - Alejandro Edera
- Institute of Plant Sciences Paris-Saclay, Centre Nationale de la Recherche Scientifique, Institute National de la Recherche Agronomique, Université Evry, Université Paris-Saclay, Orsay, France
| | - Clémentine Vitte
- Université Paris-Saclay, INRAE, CNRS, AgroParisTech, GQE – Le Moulon, Gif-sur-Yvette, France
| | - Leandro Quadrana
- Institute of Plant Sciences Paris-Saclay, Centre Nationale de la Recherche Scientifique, Institute National de la Recherche Agronomique, Université Evry, Université Paris-Saclay, Orsay, France
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2
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Hövel I, Bader R, Louwers M, Haring M, Peek K, Gent JI, Stam M. RNA-directed DNA methylation mutants reduce histone methylation at the paramutated maize booster1 enhancer. PLANT PHYSIOLOGY 2024; 195:1161-1179. [PMID: 38366582 PMCID: PMC11142347 DOI: 10.1093/plphys/kiae072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 12/19/2023] [Accepted: 12/25/2023] [Indexed: 02/18/2024]
Abstract
Paramutation is the transfer of mitotically and meiotically heritable silencing information between two alleles. With paramutation at the maize (Zea mays) booster1 (b1) locus, the low-expressed B' epiallele heritably changes the high-expressed B-I epiallele into B' with 100% frequency. This requires specific tandem repeats and multiple components of the RNA-directed DNA methylation pathway, including the RNA-dependent RNA polymerase (encoded by mediator of paramutation1, mop1), the second-largest subunit of RNA polymerase IV and V (NRP(D/E)2a, encoded by mop2), and the largest subunit of RNA Polymerase IV (NRPD1, encoded by mop3). Mutations in mop genes prevent paramutation and release silencing at the B' epiallele. In this study, we investigated the effect of mutations in mop1, mop2, and mop3 on chromatin structure and DNA methylation at the B' epiallele, and especially the regulatory hepta-repeat 100 kb upstream of the b1 gene. Mutations in mop1 and mop3 resulted in decreased repressive histone modifications H3K9me2 and H3K27me2 at the hepta-repeat. Associated with this decrease were partial activation of the hepta-repeat enhancer function, formation of a multi-loop structure, and elevated b1 expression. In mop2 mutants, which do not show elevated b1 expression, H3K9me2, H3K27me2 and a single-loop structure like in wild-type B' were retained. Surprisingly, high CG and CHG methylation levels at the B' hepta-repeat remained in all three mutants, and CHH methylation was low in both wild type and mutants. Our results raise the possibility of MOP factors mediating RNA-directed histone methylation rather than RNA-directed DNA methylation at the b1 locus.
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Affiliation(s)
- Iris Hövel
- Swammerdam Institute for Life Sciences, Universiteit van Amsterdam, P.O. Box 1210, 1090 GE Amsterdam, The Netherlands
| | - Rechien Bader
- Swammerdam Institute for Life Sciences, Universiteit van Amsterdam, P.O. Box 1210, 1090 GE Amsterdam, The Netherlands
| | - Marieke Louwers
- Swammerdam Institute for Life Sciences, Universiteit van Amsterdam, P.O. Box 1210, 1090 GE Amsterdam, The Netherlands
- argenx BV, Industriepark Zwijnaarde 7, 9052 Zwijnaarde (Ghent), Belgium
| | - Max Haring
- Swammerdam Institute for Life Sciences, Universiteit van Amsterdam, P.O. Box 1210, 1090 GE Amsterdam, The Netherlands
- University Library, Universiteit van Amsterdam, P.O. Box 19185, 1000 GD Amsterdam, The Netherlands
| | - Kevin Peek
- Swammerdam Institute for Life Sciences, Universiteit van Amsterdam, P.O. Box 1210, 1090 GE Amsterdam, The Netherlands
| | - Jonathan I Gent
- Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
| | - Maike Stam
- Swammerdam Institute for Life Sciences, Universiteit van Amsterdam, P.O. Box 1210, 1090 GE Amsterdam, The Netherlands
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3
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Bente H, Köhler C. Molecular basis and evolutionary drivers of endosperm-based hybridization barriers. PLANT PHYSIOLOGY 2024; 195:155-169. [PMID: 38298124 PMCID: PMC11060687 DOI: 10.1093/plphys/kiae050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 01/05/2024] [Accepted: 01/06/2024] [Indexed: 02/02/2024]
Abstract
The endosperm, a transient seed tissue, plays a pivotal role in supporting embryo growth and germination. This unique feature sets flowering plants apart from gymnosperms, marking an evolutionary innovation in the world of seed-bearing plants. Nevertheless, the importance of the endosperm extends beyond its role in providing nutrients to the developing embryo by acting as a versatile protector, preventing hybridization events between distinct species and between individuals with different ploidy. This phenomenon centers on growth and differentiation of the endosperm and the speed at which both processes unfold. Emerging studies underscore the important role played by type I MADS-box transcription factors, including the paternally expressed gene PHERES1. These factors, along with downstream signaling pathways involving auxin and abscisic acid, are instrumental in regulating endosperm development and, consequently, the establishment of hybridization barriers. Moreover, mutations in various epigenetic regulators mitigate these barriers, unveiling a complex interplay of pathways involved in their formation. In this review, we discuss the molecular underpinnings of endosperm-based hybridization barriers and their evolutionary drivers.
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Affiliation(s)
- Heinrich Bente
- Department of Plant Reproductive Biology and Epigenetics, Max Planck Institute of Molecular Plant Physiology, Potsdam 14476, Germany
| | - Claudia Köhler
- Department of Plant Reproductive Biology and Epigenetics, Max Planck Institute of Molecular Plant Physiology, Potsdam 14476, Germany
- Department of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala 75007, Sweden
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4
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Liu B, Yang D, Wang D, Liang C, Wang J, Lisch D, Zhao M. Heritable changes of epialleles near genes in maize can be triggered in the absence of CHH methylation. PLANT PHYSIOLOGY 2024; 194:2511-2532. [PMID: 38109503 PMCID: PMC10980416 DOI: 10.1093/plphys/kiad668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 11/15/2023] [Accepted: 11/17/2023] [Indexed: 12/20/2023]
Abstract
Trans-chromosomal interactions resulting in changes in DNA methylation during hybridization have been observed in several plant species. However, little is known about the causes or consequences of these interactions. Here, we compared DNA methylomes of F1 hybrids that are mutant for a small RNA biogenesis gene, Mop1 (Mediator of paramutation1), with that of their parents, wild-type siblings, and backcrossed progeny in maize (Zea mays). Our data show that hybridization triggers global changes in both trans-chromosomal methylation (TCM) and trans-chromosomal demethylation (TCdM), most of which involved changes in CHH methylation. In more than 60% of these TCM differentially methylated regions (DMRs) in which small RNAs are available, no significant changes in the quantity of small RNAs were observed. Methylation at the CHH TCM DMRs was largely lost in the mop1 mutant, although the effects of this mutant varied depending on the location of these DMRs. Interestingly, an increase in CHH at TCM DMRs was associated with enhanced expression of a subset of highly expressed genes and suppressed expression of a small number of lowly expressed genes. Examination of the methylation levels in backcrossed plants demonstrates that both TCM and TCdM can be maintained in the subsequent generation, but that TCdM is more stable than TCM. Surprisingly, although increased CHH methylation in most TCM DMRs in F1 plants required Mop1, initiation of a new epigenetic state of these DMRs did not require a functional copy of this gene, suggesting that initiation of these changes is independent of RNA-directed DNA methylation.
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Affiliation(s)
- Beibei Liu
- Department of Biology, Miami University, Oxford, OH 45056, USA
| | - Diya Yang
- Department of Biology, Miami University, Oxford, OH 45056, USA
| | - Dafang Wang
- Biology Department, Hofstra University, Hempstead, NY 11549, USA
| | - Chun Liang
- Department of Biology, Miami University, Oxford, OH 45056, USA
| | - Jianping Wang
- Agronomy Department, University of Florida, Gainesville, FL 32610, USA
| | - Damon Lisch
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA
| | - Meixia Zhao
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA
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5
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Roelfs KU, Känel A, Twyman RM, Prüfer D, Schulze Gronover C. Epigenetic variation in early and late flowering plants of the rubber-producing Russian dandelion Taraxacum koksaghyz provides insights into the regulation of flowering time. Sci Rep 2024; 14:4283. [PMID: 38383610 PMCID: PMC10881582 DOI: 10.1038/s41598-024-54862-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 02/17/2024] [Indexed: 02/23/2024] Open
Abstract
The Russian dandelion (Taraxacum koksaghyz) grows in temperate zones and produces large amounts of poly(cis-1,4-isoprene) in its roots, making it an attractive alternative source of natural rubber. Most T. koksaghyz plants require vernalization to trigger flower development, whereas early flowering varieties that have lost their vernalization dependence are more suitable for breeding and domestication. To provide insight into the regulation of flowering time in T. koksaghyz, we induced epigenetic variation by in vitro cultivation and applied epigenomic and transcriptomic analysis to the resulting early flowering plants and late flowering controls, allowing us to identify differences in methylation patterns and gene expression that correlated with flowering. This led to the identification of candidate genes homologous to vernalization and photoperiodism response genes in other plants, as well as epigenetic modifications that may contribute to the control of flower development. Some of the candidate genes were homologous to known floral regulators, including those that directly or indirectly regulate the major flowering control gene FT. Our atlas of genes can be used as a starting point to investigate mechanisms that control flowering time in T. koksaghyz in greater detail and to develop new breeding varieties that are more suited to domestication.
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Affiliation(s)
- Kai-Uwe Roelfs
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, 48149, Münster, Germany
| | - Andrea Känel
- Institute of Plant Biology and Biotechnology, University of Münster, 48143, Münster, Germany
| | | | - Dirk Prüfer
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, 48149, Münster, Germany
- Institute of Plant Biology and Biotechnology, University of Münster, 48143, Münster, Germany
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6
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Martin GT, Solares E, Guadardo-Mendez J, Muyle A, Bousios A, Gaut BS. miRNA-like secondary structures in maize ( Zea mays) genes and transposable elements correlate with small RNAs, methylation, and expression. Genome Res 2023; 33:1932-1946. [PMID: 37918960 PMCID: PMC10760457 DOI: 10.1101/gr.277459.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 10/16/2023] [Indexed: 11/04/2023]
Abstract
RNA molecules carry information in their primary sequence and also their secondary structure. Secondary structure can confer important functional information, but it is also a signal for an RNAi-like host epigenetic response mediated by small RNAs (smRNAs). In this study, we used two bioinformatic methods to predict local secondary structures across features of the maize genome, focusing on small regions that had similar folding properties to pre-miRNA loci. We found miRNA-like secondary structures to be common in genes and most, but not all, superfamilies of RNA and DNA transposable elements (TEs). The miRNA-like regions map to a higher diversity of smRNAs than regions without miRNA-like structure, explaining up to 27% of variation in smRNA mapping for some TE superfamilies. This mapping bias is more pronounced among putatively autonomous TEs relative to nonautonomous TEs. Genome-wide, miRNA-like regions are also associated with elevated methylation levels, particularly in the CHH context. Among genes, those with miRNA-like secondary structure are 1.5-fold more highly expressed, on average, than other genes. However, these genes are also more variably expressed across the 26 nested association mapping founder lines, and this variability positively correlates with the number of mapping smRNAs. We conclude that local miRNA-like structures are a nearly ubiquitous feature of expressed regions of the maize genome, that they correlate with higher smRNA mapping and methylation, and that they may represent a trade-off between functional requirements and the potentially negative consequences of smRNA production.
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Affiliation(s)
- Galen T Martin
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92617, USA
| | - Edwin Solares
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92617, USA
- Department of Ecology and Evolutionary Biology, University of California, Davis, California 95616, USA
| | - Jeanelle Guadardo-Mendez
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92617, USA
| | - Aline Muyle
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92617, USA
- CEFE, University of Montpellier, CNRS, EPHE, IRD, 34090 Montpellier, France
| | - Alexandros Bousios
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, United Kingdom
| | - Brandon S Gaut
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92617, USA;
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7
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Liu B, Zhao M. How transposable elements are recognized and epigenetically silenced in plants? CURRENT OPINION IN PLANT BIOLOGY 2023; 75:102428. [PMID: 37481986 DOI: 10.1016/j.pbi.2023.102428] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 06/27/2023] [Accepted: 06/28/2023] [Indexed: 07/25/2023]
Abstract
Plant genomes are littered with transposable elements (TEs). Because TEs are potentially highly mutagenic, host organisms have evolved a set of defense mechanisms to recognize and epigenetically silence them. Although the maintenance of TE silencing is well studied, our understanding of the initiation of TE silencing is limited, but it clearly involves small RNAs and DNA methylation. Once TEs are silent, the silent state can be maintained to subsequent generations. However, under some circumstances, such inheritance is unstable, leading to the escape of TEs to the silencing machinery, resulting in the transcriptional activation of TEs. Epigenetic control of TEs has been found to be closely linked to many other epigenetic phenomena, such as genomic imprinting, and is known to contribute to regulation of genes, especially those near TEs. Here we review and discuss the current models of TE silencing, its unstable inheritance after hybridization, and the effects of epigenetic regulation of TEs on genomic imprinting.
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Affiliation(s)
- Beibei Liu
- Department of Biology, Miami University, Oxford, OH 45056, USA
| | - Meixia Zhao
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA.
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8
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Liu B, Yang D, Wang D, Liang C, Wang J, Lisch D, Zhao M. Heritable changes of epialleles in maize can be triggered in the absence of DNA methylation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.15.537008. [PMID: 37131670 PMCID: PMC10153178 DOI: 10.1101/2023.04.15.537008] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Trans-chromosomal interactions resulting in changes in DNA methylation during hybridization have been observed in several plant species. However, very little is known about the causes or consequences of these interactions. Here, we compared DNA methylomes of F1 hybrids that are mutant for a small RNA biogenesis gene, Mop1 (mediator of paramutation1) with that of their parents, wild type siblings, and backcrossed progeny in maize. Our data show that hybridization triggers global changes in both trans-chromosomal methylation (TCM) and trans-chromosomal demethylation (TCdM), most of which involved changes in CHH methylation. In more than 60% of these TCM differentially methylated regions (DMRs) in which small RNAs are available, no significant changes in the quantity of small RNAs were observed. Methylation at the CHH TCM DMRs was largely lost in the mop1 mutant, although the effects of this mutant varied depending on the location of the CHH DMRs. Interestingly, an increase in CHH at TCM DMRs was associated with enhanced expression of a subset of highly expressed genes and suppressed expression of a small number of lowly expressed genes. Examination of the methylation levels in backcrossed plants demonstrates that TCM and TCdM can be maintained in the subsequent generation, but that TCdM is more stable than TCM. Surprisingly, although increased CHH methylation in F1 plants did require Mop1, initiation of the changes in the epigenetic state of TCM DMRs did not require a functional copy of this gene, suggesting that initiation of these changes is not dependent on RNA-directed DNA methylation.
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Affiliation(s)
- Beibei Liu
- Department of Biology, Miami University, Oxford, OH 45056
| | - Diya Yang
- Department of Biology, Miami University, Oxford, OH 45056
| | - Dafang Wang
- Biology Department, Hofstra University, Hempstead, NY 11549
| | - Chun Liang
- Department of Biology, Miami University, Oxford, OH 45056
| | - Jianping Wang
- Agronomy Department, University of Florida, Gainesville, FL 32610
| | - Damon Lisch
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907
| | - Meixia Zhao
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611
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9
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Marand AP, Eveland AL, Kaufmann K, Springer NM. cis-Regulatory Elements in Plant Development, Adaptation, and Evolution. ANNUAL REVIEW OF PLANT BIOLOGY 2023; 74:111-137. [PMID: 36608347 PMCID: PMC9881396 DOI: 10.1146/annurev-arplant-070122-030236] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
cis-Regulatory elements encode the genomic blueprints that ensure the proper spatiotemporal patterning of gene expression necessary for appropriate development and responses to the environment. Accumulating evidence implicates changes to gene expression as a major source of phenotypic novelty in eukaryotes, including acute phenotypes such as disease and cancer in mammals. Moreover, genetic and epigenetic variation affecting cis-regulatory sequences over longer evolutionary timescales has become a recurring theme in studies of morphological divergence and local adaptation. Here, we discuss the functions of and methods used to identify various classes of cis-regulatory elements, as well as their role in plant development and response to the environment. We highlight opportunities to exploit cis-regulatory variants underlying plant development and environmental responses for crop improvement efforts. Although a comprehensive understanding of cis-regulatory mechanisms in plants has lagged behind that in animals, we showcase several breakthrough findings that have profoundly influenced plant biology and shaped the overall understanding of transcriptional regulation in eukaryotes.
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Affiliation(s)
| | | | - Kerstin Kaufmann
- Department for Plant Cell and Molecular Biology, Institute of Biology, Humboldt-Universität zu Berlin, Berlin, Germany;
| | - Nathan M Springer
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, Minnesota, USA;
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10
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Hartwig T, Banf M, Prietsch GP, Zhu JY, Mora-Ramírez I, Schippers JHM, Snodgrass SJ, Seetharam AS, Huettel B, Kolkman JM, Yang J, Engelhorn J, Wang ZY. Hybrid allele-specific ChIP-seq analysis identifies variation in brassinosteroid-responsive transcription factor binding linked to traits in maize. Genome Biol 2023; 24:108. [PMID: 37158941 PMCID: PMC10165856 DOI: 10.1186/s13059-023-02909-w] [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: 02/06/2022] [Accepted: 03/23/2023] [Indexed: 05/10/2023] Open
Abstract
BACKGROUND Genetic variation in regulatory sequences that alter transcription factor (TF) binding is a major cause of phenotypic diversity. Brassinosteroid is a growth hormone that has major effects on plant phenotypes. Genetic variation in brassinosteroid-responsive cis-elements likely contributes to trait variation. Pinpointing such regulatory variations and quantitative genomic analysis of the variation in TF-target binding, however, remains challenging. How variation in transcriptional targets of signaling pathways such as the brassinosteroid pathway contributes to phenotypic variation is an important question to be investigated with innovative approaches. RESULTS Here, we use a hybrid allele-specific chromatin binding sequencing (HASCh-seq) approach and identify variations in target binding of the brassinosteroid-responsive TF ZmBZR1 in maize. HASCh-seq in the B73xMo17 F1s identifies thousands of target genes of ZmBZR1. Allele-specific ZmBZR1 binding (ASB) has been observed for 18.3% of target genes and is enriched in promoter and enhancer regions. About a quarter of the ASB sites correlate with sequence variation in BZR1-binding motifs and another quarter correlate with haplotype-specific DNA methylation, suggesting that both genetic and epigenetic variations contribute to the high level of variation in ZmBZR1 occupancy. Comparison with GWAS data shows linkage of hundreds of ASB loci to important yield and disease-related traits. CONCLUSION Our study provides a robust method for analyzing genome-wide variations of TF occupancy and identifies genetic and epigenetic variations of the brassinosteroid response transcription network in maize.
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Affiliation(s)
- Thomas Hartwig
- Department of Plant Biology, Carnegie Institution for Science, 260 Panama Street, Stanford, CA, 94305, USA.
- Heinrich-Heine University, Universitätsstraße 1, Düsseldorf, NRW, 40225, Germany.
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, Cologne, NRW, 50829, Germany.
| | - Michael Banf
- Department of Plant Biology, Carnegie Institution for Science, 260 Panama Street, Stanford, CA, 94305, USA
| | - Gisele Passaia Prietsch
- Department of Plant Biology, Carnegie Institution for Science, 260 Panama Street, Stanford, CA, 94305, USA
| | - Jia-Ying Zhu
- Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, Seeland, SA, 06466, Germany
| | - Isabel Mora-Ramírez
- Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, Seeland, SA, 06466, Germany
| | - Jos H M Schippers
- Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, Seeland, SA, 06466, Germany
| | - Samantha J Snodgrass
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 339A Bessey Hall, Ames, IA, 50011, USA
| | - Arun S Seetharam
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 339A Bessey Hall, Ames, IA, 50011, USA
| | - Bruno Huettel
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, Cologne, NRW, 50829, Germany
| | - Judith M Kolkman
- School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, 413 Bradfield Hall, Ithaca, NY, 14853, USA
| | - Jinliang Yang
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, 363 Keim Hall, Lincoln, NE, 68583, USA
| | - Julia Engelhorn
- Heinrich-Heine University, Universitätsstraße 1, Düsseldorf, NRW, 40225, Germany
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, Cologne, NRW, 50829, Germany
| | - Zhi-Yong Wang
- Department of Plant Biology, Carnegie Institution for Science, 260 Panama Street, Stanford, CA, 94305, USA.
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11
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Hari Sundar G V, Swetha C, Basu D, Pachamuthu K, Raju S, Chakraborty T, Mosher RA, Shivaprasad PV. Plant polymerase IV sensitizes chromatin through histone modifications to preclude spread of silencing into protein-coding domains. Genome Res 2023; 33:715-728. [PMID: 37277199 PMCID: PMC10317121 DOI: 10.1101/gr.277353.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 04/16/2023] [Indexed: 06/07/2023]
Abstract
Across eukaryotes, gene regulation is manifested via chromatin states roughly distinguished as heterochromatin and euchromatin. The establishment, maintenance, and modulation of the chromatin states is mediated using several factors including chromatin modifiers. However, factors that avoid the intrusion of silencing signals into protein-coding genes are poorly understood. Here we show that a plant specific paralog of RNA polymerase (Pol) II, named Pol IV, is involved in avoidance of facultative heterochromatic marks in protein-coding genes, in addition to its well-established functions in silencing repeats and transposons. In its absence, H3K27 trimethylation (me3) mark intruded the protein-coding genes, more profoundly in genes embedded with repeats. In a subset of genes, spurious transcriptional activity resulted in small(s) RNA production, leading to post-transcriptional gene silencing. We show that such effects are significantly pronounced in rice, a plant with a larger genome with distributed heterochromatin compared with Arabidopsis Our results indicate the division of labor among plant-specific polymerases, not just in establishing effective silencing via sRNAs and DNA methylation but also in influencing chromatin boundaries.
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Affiliation(s)
- Vivek Hari Sundar G
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore 560065, India
| | - Chenna Swetha
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore 560065, India
| | - Debjani Basu
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore 560065, India
| | - Kannan Pachamuthu
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore 560065, India
| | - Steffi Raju
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore 560065, India
| | - Tania Chakraborty
- School of Plant Sciences, The University of Arizona, Tucson, Arizona 85721, USA
| | - Rebecca A Mosher
- School of Plant Sciences, The University of Arizona, Tucson, Arizona 85721, USA
| | - P V Shivaprasad
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore 560065, India;
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12
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Gent JI, Higgins KM, Swentowsky KW, Fu FF, Zeng Y, Kim DW, Dawe RK, Springer NM, Anderson SN. The maize gene maternal derepression of r1 encodes a DNA glycosylase that demethylates DNA and reduces siRNA expression in the endosperm. THE PLANT CELL 2022; 34:3685-3701. [PMID: 35775949 PMCID: PMC9516051 DOI: 10.1093/plcell/koac199] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 06/27/2022] [Indexed: 06/01/2023]
Abstract
Demethylation of transposons can activate the expression of nearby genes and cause imprinted gene expression in the endosperm; this demethylation is hypothesized to lead to expression of transposon small interfering RNAs (siRNAs) that reinforce silencing in the next generation through transfer either into egg or embryo. Here we describe maize (Zea mays) maternal derepression of r1 (mdr1), which encodes a DNA glycosylase with homology to Arabidopsis thaliana DEMETER and which is partially responsible for demethylation of thousands of regions in endosperm. Instead of promoting siRNA expression in endosperm, MDR1 activity inhibits it. Methylation of most repetitive DNA elements in endosperm is not significantly affected by MDR1, with an exception of Helitrons. While maternally-expressed imprinted genes preferentially overlap with MDR1 demethylated regions, the majority of genes that overlap demethylated regions are not imprinted. Double mutant megagametophytes lacking both MDR1 and its close homolog DNG102 result in early seed failure, and double mutant microgametophytes fail pre-fertilization. These data establish DNA demethylation by glycosylases as essential in maize endosperm and pollen and suggest that neither transposon repression nor genomic imprinting is its main function in endosperm.
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Affiliation(s)
| | - Kaitlin M Higgins
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa 50011, USA
| | - Kyle W Swentowsky
- Department of Plant Biology, University of Georgia, Athens, Georgia 30602, USA
| | - Fang-Fang Fu
- Department of Plant Biology, University of Georgia, Athens, Georgia 30602, USA
- Co‐Innovation Center for Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing 210037, China
| | - Yibing Zeng
- Department of Genetics, University of Georgia, Athens, Georgia 30602, USA
| | - Dong won Kim
- Department of Plant Biology, University of Georgia, Athens, Georgia 30602, USA
| | - R Kelly Dawe
- Department of Plant Biology, University of Georgia, Athens, Georgia 30602, USA
- Department of Genetics, University of Georgia, Athens, Georgia 30602, USA
| | - Nathan M Springer
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, Minnesota 55108, USA
| | - Sarah N Anderson
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa 50011, USA
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13
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Velay F, Méteignier LV, Laloi C. You shall not pass! A Chromatin barrier story in plants. FRONTIERS IN PLANT SCIENCE 2022; 13:888102. [PMID: 36212303 PMCID: PMC9540200 DOI: 10.3389/fpls.2022.888102] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 08/15/2022] [Indexed: 06/16/2023]
Abstract
As in other eukaryotes, the plant genome is functionally organized in two mutually exclusive chromatin fractions, a gene-rich and transcriptionally active euchromatin, and a gene-poor, repeat-rich, and transcriptionally silent heterochromatin. In Drosophila and humans, the molecular mechanisms by which euchromatin is preserved from heterochromatin spreading have been extensively studied, leading to the identification of insulator DNA elements and associated chromatin factors (insulator proteins), which form boundaries between chromatin domains with antagonistic features. In contrast, the identity of factors assuring such a barrier function remains largely elusive in plants. Nevertheless, several genomic elements and associated protein factors have recently been shown to regulate the spreading of chromatin marks across their natural boundaries in plants. In this minireview, we focus on recent findings that describe the spreading of chromatin and propose avenues to improve the understanding of how plant chromatin architecture and transitions between different chromatin domains are defined.
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Affiliation(s)
- Florent Velay
- Aix Marseille Université, CEA, CNRS, Biosciences and Biotechnologies Institute of Aix-Marseille (BIAM), Equipe de Luminy de Génétique et Biophysique des Plantes, Marseille, F-13009, France
| | - Louis-Valentin Méteignier
- Aix Marseille Université, CEA, CNRS, Biosciences and Biotechnologies Institute of Aix-Marseille (BIAM), Equipe de Luminy de Génétique et Biophysique des Plantes, Marseille, F-13009, France
- EA2106 Biomolécules et Biotechnologies Végétales, Université de Tours, Tours, France
| | - Christophe Laloi
- Aix Marseille Université, CEA, CNRS, Biosciences and Biotechnologies Institute of Aix-Marseille (BIAM), Equipe de Luminy de Génétique et Biophysique des Plantes, Marseille, F-13009, France
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14
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Garrido-Ramos MA. The Genomics of Plant Satellite DNA. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2021; 60:103-143. [PMID: 34386874 DOI: 10.1007/978-3-030-74889-0_5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The twenty-first century began with a certain indifference to the research of satellite DNA (satDNA). Neither genome sequencing projects were able to accurately encompass the study of satDNA nor classic methodologies were able to go further in undertaking a better comprehensive study of the whole set of satDNA sequences of a genome. Nonetheless, knowledge of satDNA has progressively advanced during this century with the advent of new analytical techniques. The enormous advantages that genome-wide approaches have brought to its analysis have now stimulated a renewed interest in the study of satDNA. At this point, we can look back and try to assess more accurately many of the key questions that were left unsolved in the past about this enigmatic and important component of the genome. I review here the understanding gathered on plant satDNAs over the last few decades with an eye on the near future.
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15
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Madzima TF, Vendramin S, Lynn JS, Lemert P, Lu KC, McGinnis KM. Direct and Indirect Transcriptional Effects of Abiotic Stress in Zea mays Plants Defective in RNA-Directed DNA Methylation. FRONTIERS IN PLANT SCIENCE 2021; 12:694289. [PMID: 34489998 PMCID: PMC8418275 DOI: 10.3389/fpls.2021.694289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 07/14/2021] [Indexed: 06/13/2023]
Abstract
Plants respond to abiotic stress stimuli, such as water deprivation, through a hierarchical cascade that includes detection and signaling to mediate transcriptional and physiological changes. The phytohormone abscisic acid (ABA) is well-characterized for its regulatory role in these processes in response to specific environmental cues. ABA-mediated changes in gene expression have been demonstrated to be temporally-dependent, however, the genome-wide timing of these responses are not well-characterized in the agronomically important crop plant Zea mays (maize). ABA-mediated responses are synergistic with other regulatory mechanisms, including the plant-specific RNA-directed DNA methylation (RdDM) epigenetic pathway. Our prior work demonstrated that after relatively long-term ABA induction (8 h), maize plants homozygous for the mop1-1 mutation, defective in a component of the RdDM pathway, exhibit enhanced transcriptional sensitivity to the phytohormone. At this time-point, many hierarchically positioned transcription factors are differentially expressed resulting in primary (direct) and secondary (indirect) transcriptional outcomes. To identify more immediate and direct MOP1-dependent responses to ABA, we conducted a transcriptomic analysis using mop1-1 mutant and wild type plants treated with ABA for 1 h. One h of ABA treatment was sufficient to induce unique categories of differentially expressed genes (DEGs) in mop1-1. A comparative analysis between the two time-points revealed that distinct epigenetically-regulated changes in gene expression occur within the early stages of ABA induction, and that these changes are predicted to influence less immediate, indirect transcriptional responses. Homology with MOP1-dependent siRNAs and a gene regulatory network (GRN) were used to identify putative immediate and indirect targets, respectively. By manipulating two key regulatory networks in a temporal dependent manner, we identified genes and biological processes regulated by RdDM and ABA-mediated stress responses. Consistent with mis-regulation of gene expression, mop1-1 homozygous plants are compromised in their ability to recover from water deprivation. Collectively, these results indicate transcriptionally and physiologically relevant roles for MOP1-mediated regulation of gene expression of plant responses to environmental stress.
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Affiliation(s)
- Thelma F. Madzima
- Division of Biological Sciences, School of STEM, University of Washington Bothell, Bothell, WA, United States
| | - Stefania Vendramin
- Department of Biological Science, Florida State University, Tallahassee, FL, United States
| | - Jason S. Lynn
- Department of Biological Science, Florida State University, Tallahassee, FL, United States
| | - Phebe Lemert
- Department of Biological Science, Florida State University, Tallahassee, FL, United States
| | - Katherine C. Lu
- Division of Biological Sciences, School of STEM, University of Washington Bothell, Bothell, WA, United States
| | - Karen M. McGinnis
- Department of Biological Science, Florida State University, Tallahassee, FL, United States
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16
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Long J, Liu J, Xia A, Springer NM, He Y. Maize decrease in DNA methylation 1 targets RNA-directed DNA methylation on active chromatin. THE PLANT CELL 2021; 33:2183-2196. [PMID: 33779761 PMCID: PMC8364229 DOI: 10.1093/plcell/koab098] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 03/25/2021] [Indexed: 06/01/2023]
Abstract
DNA methylation plays vital roles in repressing transposable element activity and regulating gene expression. The chromatin-remodeling factor Decrease in DNA methylation 1 (DDM1) is crucial for maintaining DNA methylation across diverse plant species, and is required for RNA-directed DNA methylation (RdDM) to maintain mCHH islands in maize (Zea mays). However, the mechanisms by which DDM1 is involved in RdDM are not well understood. In this work, we used chromatin immunoprecipitation coupled with high-throughput sequencing to ascertain the genome-wide occupancy of ZmDDM1 in the maize genome. The results revealed that ZmDDM1 recognized an 8-bp-long GC-rich degenerate DNA sequence motif, which is enriched in transcription start sites and other euchromatic regions. Meanwhile, 24-nucleotide siRNAs and CHH methylation were delineated at the edge of ZmDDM1-occupied sites. ZmDDM1 co-purified with Argonaute 4 (ZmAGO4) proteins, providing further evidence that ZmDDM1 is a component of RdDM complexes in planta. Consistent with this, the vast majority of ZmDDM1-targeted regions co-localized with ZmAGO4-bound genomic sites. Overall, our results suggest a model that ZmDDM1 may be recruited to euchromatic regions via recognition of a GC-rich motif, thereby remodeling chromatin to provide access for RdDM activities in maize.
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Affiliation(s)
- Jincheng Long
- MOE Key Laboratory of Crop Heterosis and Utilization, National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Jinghan Liu
- MOE Key Laboratory of Crop Heterosis and Utilization, National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Aiai Xia
- MOE Key Laboratory of Crop Heterosis and Utilization, National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Nathan M. Springer
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN 55108, USA
| | - Yan He
- MOE Key Laboratory of Crop Heterosis and Utilization, National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
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17
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Martin GT, Seymour DK, Gaut BS. CHH Methylation Islands: A Nonconserved Feature of Grass Genomes That Is Positively Associated with Transposable Elements but Negatively Associated with Gene-Body Methylation. Genome Biol Evol 2021; 13:evab144. [PMID: 34146109 PMCID: PMC8374106 DOI: 10.1093/gbe/evab144] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2021] [Indexed: 12/28/2022] Open
Abstract
Methylated CHH (mCHH) islands are peaks of CHH methylation that occur primarily upstream to genes. These regions are actively targeted by the methylation machinery, occur at boundaries between heterochromatin and euchromatin, and tend to be near highly expressed genes. Here we took an evolutionary perspective by studying upstream mCHH islands across a sample of eight grass species. Using a statistical approach to define mCHH islands as regions that differ from genome-wide background CHH methylation levels, we demonstrated that mCHH islands are common and associate with 39% of genes, on average. We hypothesized that islands should be more frequent in genomes of large size, because they have more heterochromatin and hence more need for defined boundaries. We found, however, that smaller genomes tended to have a higher proportion of genes associated with 5' mCHH islands. Consistent with previous work suggesting that islands reflect the silencing of the edge of transposable elements (TEs), genes with nearby TEs were more likely to have mCHH islands. However, the presence of mCHH islands was not a function solely of TEs, both because the underlying sequences of islands were often not homologous to TEs and because genic properties also predicted the presence of 5' mCHH islands. These genic properties included length and gene-body methylation (gbM); in fact, in three of eight species, the absence of gbM was a stronger predictor of a 5' mCHH island than TE proximity. In contrast, gene expression level was a positive but weak predictor of the presence of an island. Finally, we assessed whether mCHH islands were evolutionarily conserved by focusing on a set of 2,720 orthologs across the eight species. They were generally not conserved across evolutionary time. Overall, our data establish additional genic properties that are associated with mCHH islands and suggest that they are not just a consequence of the TE silencing machinery.
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Affiliation(s)
- Galen T Martin
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California, USA
| | - Danelle K Seymour
- Department of Botany and Plant Sciences, University of California, Riverside, California, USA
| | - Brandon S Gaut
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California, USA
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18
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Han T, Wang F, Song Q, Ye W, Liu T, Wang L, Chen ZJ. An epigenetic basis of inbreeding depression in maize. SCIENCE ADVANCES 2021; 7:7/35/eabg5442. [PMID: 34452913 PMCID: PMC8397266 DOI: 10.1126/sciadv.abg5442] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 07/07/2021] [Indexed: 05/12/2023]
Abstract
Inbreeding depression is widespread across plant and animal kingdoms and may arise from the exposure of deleterious alleles and/or loss of overdominant alleles resulting from increased homozygosity, but these genetic models cannot fully explain the phenomenon. Here, we report epigenetic links to inbreeding depression in maize. Teosinte branched1/cycloidea/proliferating cell factor (TCP) transcription factors control plant development. During successive inbreeding among inbred lines, thousands of genomic regions across TCP-binding sites (TBS) are hypermethylated through the H3K9me2-mediated pathway. These hypermethylated regions are accompanied by decreased chromatin accessibility, increased levels of the repressive histone marks H3K27me2 and H3K27me3, and reduced binding affinity of maize TCP-proteins to TBS. Consequently, hundreds of TCP-target genes involved in mitochondrion, chloroplast, and ribosome functions are down-regulated, leading to reduced growth vigor. Conversely, random mating can reverse corresponding hypermethylation sites and TCP-target gene expression, restoring growth vigor. These results support a unique role of reversible epigenetic modifications in inbreeding depression.
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Affiliation(s)
- Tongwen Han
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Fang Wang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Qingxin Song
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Wenxue Ye
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Tieshan Liu
- Maize Research Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, China
| | - Liming Wang
- Maize Research Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, China
| | - Z Jeffrey Chen
- Department of Molecular Biosciences and Center for Computational Biology and Bioinformatics, The University of Texas at Austin, Austin, TX 78712, USA.
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19
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Abstract
Meiotic recombination is a fundamental process that generates genetic diversity and ensures the accurate segregation of homologous chromosomes. While a great deal is known about genetic factors that regulate recombination, relatively little is known about epigenetic factors, such as DNA methylation. In maize, we examined the effects on meiotic recombination of a mutation in a component of the RNA-directed DNA methylation pathway, Mop1 (Mediator of paramutation1), as well as a mutation in a component of the trans-acting small interference RNA biogenesis pathway, Lbl1 (Leafbladeless1). MOP1 is of particular interest with respect to recombination because it is responsible for methylation of transposable elements that are immediately adjacent to transcriptionally active genes. In the mop1 mutant, we found that meiotic recombination is uniformly decreased in pericentromeric regions but is generally increased in gene rich chromosomal arms. This observation was further confirmed by cytogenetic analysis showing that although overall crossover numbers are unchanged, they occur more frequently in chromosomal arms in mop1 mutants. Using whole genome bisulfite sequencing, our data show that crossover redistribution is driven by loss of CHH (where H = A, T, or C) methylation within regions near genes. In contrast to what we observed in mop1 mutants, no significant changes were observed in the frequency of meiotic recombination in lbl1 mutants. Our data demonstrate that CHH methylation has a significant impact on the overall recombination landscape in maize despite its low frequency relative to CG and CHG methylation.
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20
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Liu Y, Liu Q, Su H, Liu K, Xiao X, Li W, Sun Q, Birchler JA, Han F. Genome-wide mapping reveals R-loops associated with centromeric repeats in maize. Genome Res 2021; 31:1409-1418. [PMID: 34244230 PMCID: PMC8327920 DOI: 10.1101/gr.275270.121] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 06/29/2021] [Indexed: 12/31/2022]
Abstract
R-loops are stable chromatin structures comprising a DNA:RNA hybrid and a displaced single-stranded DNA. R-loops have been implicated in gene expression and chromatin structure, as well as in replication blocks and genome instability. Here, we conducted a genome-wide identification of R-loops and identified more than 700,000 R-loop peaks in the maize (Zea mays) genome. We found that sense R-loops were mainly enriched in promoters and transcription termination sites and relatively less enriched in gene bodies, which is different from the main gene-body localization of sense R-loops in Arabidopsis and Oryza sativa. At the chromosome scale, maize R-loops were enriched in pericentromeric heterochromatin regions, and a significant portion of R-loops were derived from transposable elements. In centromeres, R-loops preferentially formed within the binding regions of the centromere-specific histone CENH3, and centromeric retrotransposons were strongly associated with R-loop formation. Furthermore, centromeric retrotransposon R-loops were observed by applying the single-molecule imaging technique of atomic force microscopy. These findings elucidate the fundamental character of R-loops in the maize genome and reveal the potential role of R-loops in centromeres.
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Affiliation(s)
- Yang Liu
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qian Liu
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Handong Su
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.,College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Kunpeng Liu
- Tsinghua-Peking Joint Center for Life Sciences and Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xue Xiao
- National Laboratory for Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Wei Li
- National Laboratory for Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Qianwen Sun
- Tsinghua-Peking Joint Center for Life Sciences and Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - James A Birchler
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211-7400, USA
| | - Fangpu Han
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
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21
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Wang Y, Zhou X, Luo J, Lv S, Liu R, Du X, Jia B, Yuan F, Zhang H, Du J. Recognition of H3K9me1 by maize RNA-directed DNA methylation factor SHH2. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2021; 63:1091-1096. [PMID: 33913587 DOI: 10.1111/jipb.13103] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 04/20/2021] [Indexed: 06/12/2023]
Abstract
RNA-directed DNA methylation (RdDM) is a plant-specific de novo DNA methylation pathway, which has extensive cross-talk with histone modifications. Here, we report that the maize RdDM regulator SAWADEE HOMEODOMAIN HOMOLOG 2 (SHH2) is an H3K9me1 reader. Our structural studies reveal that H3K9me1 recognition is achieved by recognition of the methyl group via a classic aromatic cage and hydrogen-bonding and salt-bridge interactions with the free protons of the mono-methyllysine. The di- and tri-methylation states disrupt the polar interactions, decreasing the binding affinity. Our study reveals a mono-methyllysine recognition mechanism which potentially links RdDM to H3K9me1 in maize.
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Affiliation(s)
- Yuhua Wang
- National Key Laboratory of Plant Molecular Genetics and Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, The Chinese Academy of Sciences, Shanghai, 201602, China
| | - Xuelin Zhou
- National Key Laboratory of Plant Molecular Genetics and Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, The Chinese Academy of Sciences, Shanghai, 201602, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jinyan Luo
- National Key Laboratory of Plant Molecular Genetics and Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, The Chinese Academy of Sciences, Shanghai, 201602, China
| | - Suhui Lv
- School of Life Science, Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Rui Liu
- School of Life Science, Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Xuan Du
- School of Life Science, Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Bei Jia
- National Key Laboratory of Plant Molecular Genetics and Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, The Chinese Academy of Sciences, Shanghai, 201602, China
| | - Fengtong Yuan
- National Key Laboratory of Plant Molecular Genetics and Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, The Chinese Academy of Sciences, Shanghai, 201602, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Heng Zhang
- National Key Laboratory of Plant Molecular Genetics and Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, The Chinese Academy of Sciences, Shanghai, 201602, China
| | - Jiamu Du
- School of Life Science, Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China
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22
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Liu Y, Yuan J, Jia G, Ye W, Jeffrey Chen Z, Song Q. Histone H3K27 dimethylation landscapes contribute to genome stability and genetic recombination during wheat polyploidization. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 105:678-690. [PMID: 33131144 DOI: 10.1111/tpj.15063] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 10/21/2020] [Accepted: 10/27/2020] [Indexed: 05/02/2023]
Abstract
Bread wheat (Triticum aestivum) is an allohexaploid that was formed via two allopolyploidization events. Growing evidence suggests histone modifications are involved in the response to 'genomic shock' and environmental adaptation during polyploid formation and evolution. However, the role of histone modifications, especially histone H3 lysine-27 dimethylation (H3K27me2), in genome evolution remains elusive. Here we analyzed H3K27me2 and H3K27me3 profiles in hexaploid wheat and its tetraploid and diploid relatives. Although H3K27me3 levels were relatively stable among wheat species with different ploidy levels, H3K27me2 intensities increased concurrent with increased ploidy levels, and H3K27me2 peaks were colocalized with massively amplified DTC transposons (CACTA family) in euchromatin, which may silence euchromatic transposons to maintain genome stability during polyploid wheat evolution. Consistently, the distribution of H3K27me2 is mutually exclusive with another repressive histone mark, H3K9me2, that mainly silences transposons in heterochromatic regions. Remarkably, the regions with low H3K27me2 levels (named H3K27me2 valleys) were associated with the formation of DNA double-strand breaks in genomes of wheat, maize (Zea mays) and Arabidopsis. Our results provide a comprehensive view of H3K27me2 and H3K27me3 distributions during wheat evolution, which support roles for H3K27me2 in silencing euchromatic transposons to maintain genome stability and in modifying genetic recombination landscapes. These genomic insights may empower breeding improvement of crops.
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Affiliation(s)
- Yanfeng Liu
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu, 210095, China
| | - Jingya Yuan
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu, 210095, China
| | - Guanghong Jia
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu, 210095, China
| | - Wenxue Ye
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu, 210095, China
| | - Z Jeffrey Chen
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu, 210095, China
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Qingxin Song
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu, 210095, China
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23
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Wear EE, Song J, Zynda GJ, Mickelson-Young L, LeBlanc C, Lee TJ, Deppong DO, Allen GC, Martienssen RA, Vaughn MW, Hanley-Bowdoin L, Thompson WF. Comparing DNA replication programs reveals large timing shifts at centromeres of endocycling cells in maize roots. PLoS Genet 2020; 16:e1008623. [PMID: 33052904 PMCID: PMC7588055 DOI: 10.1371/journal.pgen.1008623] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 10/26/2020] [Accepted: 08/28/2020] [Indexed: 12/20/2022] Open
Abstract
Plant cells undergo two types of cell cycles–the mitotic cycle in which DNA replication is coupled to mitosis, and the endocycle in which DNA replication occurs in the absence of cell division. To investigate DNA replication programs in these two types of cell cycles, we pulse labeled intact root tips of maize (Zea mays) with 5-ethynyl-2’-deoxyuridine (EdU) and used flow sorting of nuclei to examine DNA replication timing (RT) during the transition from a mitotic cycle to an endocycle. Comparison of the sequence-based RT profiles showed that most regions of the maize genome replicate at the same time during S phase in mitotic and endocycling cells, despite the need to replicate twice as much DNA in the endocycle and the fact that endocycling is typically associated with cell differentiation. However, regions collectively corresponding to 2% of the genome displayed significant changes in timing between the two types of cell cycles. The majority of these regions are small with a median size of 135 kb, shift to a later RT in the endocycle, and are enriched for genes expressed in the root tip. We found larger regions that shifted RT in centromeres of seven of the ten maize chromosomes. These regions covered the majority of the previously defined functional centromere, which ranged between 1 and 2 Mb in size in the reference genome. They replicate mainly during mid S phase in mitotic cells but primarily in late S phase of the endocycle. In contrast, the immediately adjacent pericentromere sequences are primarily late replicating in both cell cycles. Analysis of CENH3 enrichment levels in 8C vs 2C nuclei suggested that there is only a partial replacement of CENH3 nucleosomes after endocycle replication is complete. The shift to later replication of centromeres and possible reduction in CENH3 enrichment after endocycle replication is consistent with a hypothesis that centromeres are inactivated when their function is no longer needed. In traditional cell division, or mitosis, a cell’s genetic material is duplicated and then split between two daughter cells. In contrast, in some specialized cell types, the DNA is duplicated a second time without an intervening division step, resulting in cells that carry twice as much DNA. This phenomenon, which is called the endocycle, is common during plant development. At each step, DNA replication follows an ordered program in which highly compacted DNA is unraveled and replicated in sections at different times during the synthesis (S) phase. In plants, it is unclear whether traditional and endocycle programs are the same, especially since endocycling cells are typically in the process of differentiation. Using root tips of maize, we found that in comparison to replication in the mitotic cell cycle, there is a small portion of the genome whose replication in the endocycle is shifted in time, usually to later in S phase. Some of these regions are scattered around the genome and mostly coincide with active genes. However, the most prominent shifts occur in centromeres. The shift to later replication in centromeres is noteworthy because they orchestrate the process of separating duplicated chromosomes into daughter cells, a function that is not needed in the endocycle.
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Affiliation(s)
- Emily E. Wear
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
- * E-mail:
| | - Jawon Song
- Texas Advanced Computing Center, University of Texas, Austin, Texas, United States of America
| | - Gregory J. Zynda
- Texas Advanced Computing Center, University of Texas, Austin, Texas, United States of America
| | - Leigh Mickelson-Young
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Chantal LeBlanc
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Tae-Jin Lee
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - David O. Deppong
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - George C. Allen
- Department of Horticultural Science, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Robert A. Martienssen
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Matthew W. Vaughn
- Texas Advanced Computing Center, University of Texas, Austin, Texas, United States of America
| | - Linda Hanley-Bowdoin
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - William F. Thompson
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
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24
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Abstract
Plants are subjected to extreme environmental conditions and must adapt rapidly. The phytohormone abscisic acid (ABA) accumulates during abiotic stress, signaling transcriptional changes that trigger physiological responses. Epigenetic modifications often facilitate transcription, particularly at genes exhibiting temporal, tissue-specific and environmentally-induced expression. In maize (Zea mays), MEDIATOR OF PARAMUTATION 1 (MOP1) is required for progression of an RNA-dependent epigenetic pathway that regulates transcriptional silencing of loci genomewide. MOP1 function has been previously correlated with genomic regions adjoining particular types of transposable elements and genic regions, suggesting that this regulatory pathway functions to maintain distinct transcriptional activities within genomic spaces, and that loss of MOP1 may modify the responsiveness of some loci to other regulatory pathways. As critical regulators of gene expression, MOP1 and ABA pathways each regulate specific genes. To determine whether loss of MOP1 impacts ABA-responsive gene expression in maize, mop1-1 and Mop1 homozygous seedlings were subjected to exogenous ABA and RNA-sequencing. A total of 3,242 differentially expressed genes (DEGs) were identified in four pairwise comparisons. Overall, ABA-induced changes in gene expression were enhanced in mop1-1 homozygous plants. The highest number of DEGs were identified in ABA-induced mop1-1 mutants, including many transcription factors; this suggests combinatorial regulatory scenarios including direct and indirect transcriptional responses to genetic disruption (mop1-1) and/or stimulus-induction of a hierarchical, cascading network of responsive genes. Additionally, a modest increase in CHH methylation at putative MOP1-RdDM loci in response to ABA was observed in some genotypes, suggesting that epigenetic variation might influence environmentally-induced transcriptional responses in maize.
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25
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Yu J, Xu F, Wei Z, Zhang X, Chen T, Pu L. Epigenomic landscape and epigenetic regulation in maize. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2020; 133:1467-1489. [PMID: 31965233 DOI: 10.1007/s00122-020-03549-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 01/14/2020] [Indexed: 05/12/2023]
Abstract
Epigenetic regulation has been implicated in the control of multiple agronomic traits in maize. Here, we review current advances in our understanding of epigenetic regulation, which has great potential for improving agronomic traits and the environmental adaptability of crops. Epigenetic regulation plays vital role in the control of complex agronomic traits. Epigenetic variation could contribute to phenotypic diversity and can be used to improve the quality and productivity of crops. Maize (Zea mays L.), one of the most widely cultivated crops for human food, animal feed, and ethanol biofuel, is a model plant for genetic studies. Recent advances in high-throughput sequencing technology have made possible the study of epigenetic regulation in maize on a genome-wide scale. In this review, we discuss recent epigenetic studies in maize many achieved by Chinese research groups. These studies have explored the roles of DNA methylation, posttranslational modifications of histones, chromatin remodeling, and noncoding RNAs in the regulation of gene expression in plant development and environment response. We also provide our future prospects for manipulating epigenetic regulation to improve crops.
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Affiliation(s)
- Jia Yu
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Fan Xu
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Ziwei Wei
- School of Life Sciences, Anhui Agricultural University, Hefei, China
| | - Xiangxiang Zhang
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Tao Chen
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Li Pu
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China.
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26
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Lunardon A, Johnson NR, Hagerott E, Phifer T, Polydore S, Coruh C, Axtell MJ. Integrated annotations and analyses of small RNA-producing loci from 47 diverse plants. Genome Res 2020; 30:497-513. [PMID: 32179590 PMCID: PMC7111516 DOI: 10.1101/gr.256750.119] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 01/27/2020] [Indexed: 01/25/2023]
Abstract
Plant endogenous small RNAs (sRNAs) are important regulators of gene expression. There are two broad categories of plant sRNAs: microRNAs (miRNAs) and endogenous short interfering RNAs (siRNAs). MicroRNA loci are relatively well-annotated but compose only a small minority of the total sRNA pool; siRNA locus annotations have lagged far behind. Here, we used a large data set of published and newly generated sRNA sequencing data (1333 sRNA-seq libraries containing more than 20 billion reads) and a uniform bioinformatic pipeline to produce comprehensive sRNA locus annotations of 47 diverse plants, yielding more than 2.7 million sRNA loci. The two most numerous classes of siRNA loci produced mainly 24- and 21-nucleotide (nt) siRNAs, respectively. Most often, 24-nt-dominated siRNA loci occurred in intergenic regions, especially at the 5′-flanking regions of protein-coding genes. In contrast, 21-nt-dominated siRNA loci were most often derived from double-stranded RNA precursors copied from spliced mRNAs. Genic 21-nt-dominated loci were especially common from disease resistance genes, including from a large number of monocots. Individual siRNA sequences of all types showed very little conservation across species, whereas mature miRNAs were more likely to be conserved. We developed a web server where our data and several search and analysis tools are freely accessible.
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Affiliation(s)
- Alice Lunardon
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Nathan R Johnson
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.,Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Emily Hagerott
- Department of Biology, Knox College, Galesburg, Illinois 61401, USA
| | - Tamia Phifer
- Department of Biology, Knox College, Galesburg, Illinois 61401, USA
| | - Seth Polydore
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.,Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Ceyda Coruh
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.,Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Michael J Axtell
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.,Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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27
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Han Y, Li X, Yan Y, Duan MH, Xu JH. Identification, characterization, and functional prediction of circular RNAs in maize. Mol Genet Genomics 2020; 295:491-503. [PMID: 31894398 DOI: 10.1007/s00438-019-01638-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 12/14/2019] [Indexed: 12/14/2022]
Abstract
Circular RNAs (circRNAs) are a new type of intracellular regulator that have been widely identified in animals and plants by high-throughput sequencing. However, there are still few functional studies on circRNAs in plants. To better understand maize circRNAs and their potential functions, we identified 1199 circRNAs in maize from RiboMinus RNA-Seq transcriptome data, and found distinct features of splicing site selection bias, longer flanking introns, and miniature inverted-repeat transposable element (MITE) insertions in flanking introns in maize circRNAs compared to other plant circRNAs. In total, 31 and 36 orthologous circRNAs were identified in rice and maize, respectively, but the orthologous parental genes could not produce orthologous circRNAs, mostly because of long-sequence insertions/deletions at flanking introns and approximately 24.3% of them contained MITE sequences. The majority of maize circRNAs showed high diversity of expression under different treatments and/or in different genetic backgrounds, implying that circRNAs could be involved in various regulatory networks. Twenty-six ecircRNAs were predicted to contain one or more target mimics, and 229 circRNAs had high coding potential, indicating that circRNAs could perform peptide-encoding functions in plants. These results will broaden understanding of the roles of circRNAs in plants and support further functional work on maize.
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Affiliation(s)
- Yang Han
- Zhejiang Key Laboratory of Crop Germplasm, Institute of Crop Science, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Xinxin Li
- Zhejiang Key Laboratory of Crop Germplasm, Institute of Crop Science, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Yan Yan
- Zhejiang Key Laboratory of Crop Germplasm, Institute of Crop Science, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Ming-Hua Duan
- Zhejiang Zhengjingyuan Pharmacy Chain Co., Ltd. and Hangzhou Zhengcaiyuan Pharmaceutical Co., Ltd., Hangzhou, 310021, People's Republic of China
| | - Jian-Hong Xu
- Zhejiang Key Laboratory of Crop Germplasm, Institute of Crop Science, Zhejiang University, Hangzhou, 310058, Zhejiang, China.
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28
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Crisp PA, Hammond R, Zhou P, Vaillancourt B, Lipzen A, Daum C, Barry K, de Leon N, Buell CR, Kaeppler SM, Meyers BC, Hirsch CN, Springer NM. Variation and Inheritance of Small RNAs in Maize Inbreds and F1 Hybrids. PLANT PHYSIOLOGY 2020; 182:318-331. [PMID: 31575624 PMCID: PMC6945832 DOI: 10.1104/pp.19.00817] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 09/23/2019] [Indexed: 05/20/2023]
Abstract
Small RNAs (sRNAs) regulate gene expression, play important roles in epigenetic pathways, and are hypothesized to contribute to hybrid vigor in plants. Prior investigations have provided valuable insights into associations between sRNAs and heterosis, often using a single hybrid genotype or tissue, but our understanding of the role of sRNAs and their potential value to plant breeding are limited by an incomplete picture of sRNA variation between diverse genotypes and development stages. Here, we provide a deep exploration of sRNA variation and inheritance among a panel of 108 maize (Zea mays) samples spanning five tissues from eight inbred parents and 12 hybrid genotypes, covering a spectrum of heterotic groups, genetic variation, and levels of heterosis for various traits. We document substantial developmental and genotypic influences on sRNA expression, with varying patterns for 21-nucleotide (nt), 22-nt, and 24-nt sRNAs. We provide a detailed view of the distribution of sRNAs in the maize genome, revealing a complex makeup that also shows developmental plasticity, particularly for 22-nt sRNAs. sRNAs exhibited substantially more variation between inbreds as compared with observed variation for gene expression. In hybrids, we identify locus-specific examples of nonadditive inheritance, mostly characterized as partial or complete dominance, but rarely outside the parental range. However, the global abundance of 21-nt, 22-nt, and 24-nt sRNAs varies very little between inbreds and hybrids, suggesting that hybridization affects sRNA expression principally at specific loci rather than on a global scale. This study provides a valuable resource for understanding the potential role of sRNAs in hybrid vigor.
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Affiliation(s)
- Peter A Crisp
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota 55108
| | - Reza Hammond
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, Delaware 19711
| | - Peng Zhou
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota 55108
| | - Brieanne Vaillancourt
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Anna Lipzen
- United States Department of Energy Joint Genome Institute, Walnut Creek, California 94598
| | - Chris Daum
- United States Department of Energy Joint Genome Institute, Walnut Creek, California 94598
| | - Kerrie Barry
- United States Department of Energy Joint Genome Institute, Walnut Creek, California 94598
| | - Natalia de Leon
- Department of Agronomy, University of Wisconsin, Madison, Wisconsin 53706
| | - C Robin Buell
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Shawn M Kaeppler
- Department of Agronomy, University of Wisconsin, Madison, Wisconsin 53706
| | - Blake C Meyers
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132
- Division of Plant Sciences, University of Missouri, Columbia, Missouri 65211
| | - Candice N Hirsch
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108
| | - Nathan M Springer
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota 55108
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29
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Brown K, Takawira LT, O'Neill MM, Mizrachi E, Myburg AA, Hussey SG. Identification and functional evaluation of accessible chromatin associated with wood formation in Eucalyptus grandis. THE NEW PHYTOLOGIST 2019; 223:1937-1951. [PMID: 31063599 DOI: 10.1111/nph.15897] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 04/29/2019] [Indexed: 05/03/2023]
Abstract
Accessible chromatin changes dynamically during development and harbours functional regulatory regions which are poorly understood in the context of wood development. We explored the importance of accessible chromatin in Eucalyptus grandis in immature xylem generally, and MYB transcription factor-mediated transcriptional programmes specifically. We identified biologically reproducible DNase I Hypersensitive Sites (DHSs) and assessed their functional significance in immature xylem through their associations with gene expression, epigenomic data and DNA sequence conservation. We identified in vitro DNA binding sites for six secondary cell wall-associated Eucalyptus MYB (EgrMYB) transcription factors using DAP-seq, reconstructed protein-DNA networks of predicted targets based on binding sites within or outside DHSs and assessed biological enrichment of these networks with published datasets. 25 319 identified immature xylem DHSs were associated with increased transcription and significantly enriched for various epigenetic signatures (H3K4me3, H3K27me3, RNA pol II), conserved noncoding sequences and depleted single nucleotide variants. Predicted networks built from EgrMYB binding sites located in accessible chromatin were significantly enriched for systems biology datasets relevant to wood formation, whereas those occurring in inaccessible chromatin were not. Our study demonstrates that DHSs in E. grandis immature xylem, most of which are intergenic, are of functional significance to gene regulation in this tissue.
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Affiliation(s)
- Katrien Brown
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), Genomics Research Institute (GRI), University of Pretoria, Private Bag X28, Pretoria, 0002, South Africa
| | - Lazarus T Takawira
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), Genomics Research Institute (GRI), University of Pretoria, Private Bag X28, Pretoria, 0002, South Africa
| | - Marja M O'Neill
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), Genomics Research Institute (GRI), University of Pretoria, Private Bag X28, Pretoria, 0002, South Africa
| | - Eshchar Mizrachi
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), Genomics Research Institute (GRI), University of Pretoria, Private Bag X28, Pretoria, 0002, South Africa
| | - Alexander A Myburg
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), Genomics Research Institute (GRI), University of Pretoria, Private Bag X28, Pretoria, 0002, South Africa
| | - Steven G Hussey
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), Genomics Research Institute (GRI), University of Pretoria, Private Bag X28, Pretoria, 0002, South Africa
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30
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Long-range interactions between proximal and distal regulatory regions in maize. Nat Commun 2019; 10:2633. [PMID: 31201330 PMCID: PMC6572780 DOI: 10.1038/s41467-019-10603-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 05/20/2019] [Indexed: 12/30/2022] Open
Abstract
Long-range chromatin interactions are important for transcriptional regulation of genes, many of which are related to complex agronomics traits. However, the pattern of three-dimensional chromatin interactions remains unclear in plants. Here we report the generation of chromatin interaction analysis by paired-end tag sequencing (ChIA-PET) data and the construction of extensive H3K4me3- and H3K27ac-centered chromatin interaction maps in maize. Results show that the interacting patterns between proximal and distal regulatory regions of genes are highly complex and dynamic. Genes with chromatin interactions have higher expression levels than those without interactions. Genes with proximal-proximal interactions prefer to be transcriptionally coordinated. Tissue-specific proximal–distal interactions are associated with tissue-specific expression of genes. Interactions between proximal and distal regulatory regions further interweave into organized network communities that are enriched in specific biological functions. The high-resolution chromatin interaction maps will help to understand the transcription regulation of genes associated with complex agronomic traits of maize. Chromatin interaction analysis by paired-end tag sequencing (ChIA-PET) can discover specific protein-centered chromatin interactions in high resolution. Here, the authors use ChIA-PET to reveal the complex and dynamic interactions between proximal and distal regulatory regions of genes in maize.
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31
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Long JC, Xia AA, Liu JH, Jing JL, Wang YZ, Qi CY, He Y. Decrease in DNA methylation 1 (DDM1) is required for the formation of m CHH islands in maize. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2019; 61:749-764. [PMID: 30387549 DOI: 10.1111/jipb.12733] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 10/23/2018] [Indexed: 05/26/2023]
Abstract
DNA methylation plays a crucial role in suppressing mobilization of transposable elements and regulation of gene expression. A number of studies have indicated that DNA methylation pathways and patterns exhibit distinct properties in different species, including Arabidopsis, rice, and maize. Here, we characterized the function of DDM1 in regulating genome-wide DNA methylation in maize. Two homologs of ZmDDM1 are abundantly expressed in the embryo and their simultaneous disruption caused embryo lethality with abnormalities in cell proliferation from the early stage of kernel development. We establish that ZmDDM1 is critical for DNA methylation, at CHG sites, and to a lesser extent at CG sites, in heterochromatic regions, and unexpectedly, it is required for the formation of m CHH islands. In addition, ZmDDM1 is indispensable for the presence of 24-nt siRNA, suggesting its involvement in the RdDM pathway. Our results provide novel insight into the role of ZmDDM1 in regulating the formation of m CHH islands, via the RdDM pathway maize, suggesting that, in comparison to Arabidopsis, maize may have adopted distinct mechanisms for regulating m CHH.
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Affiliation(s)
- Jin Cheng Long
- National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Ai Ai Xia
- National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Jing Han Liu
- National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Ju Li Jing
- National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Ya Zhong Wang
- National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Chuang Ye Qi
- National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Yan He
- National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
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32
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Takahashi S, Osabe K, Fukushima N, Takuno S, Miyaji N, Shimizu M, Takasaki-Yasuda T, Suzuki Y, Dennis ES, Seki M, Fujimoto R. Genome-wide characterization of DNA methylation, small RNA expression, and histone H3 lysine nine di-methylation in Brassica rapa L. DNA Res 2019; 25:511-520. [PMID: 29982343 PMCID: PMC6191303 DOI: 10.1093/dnares/dsy021] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 05/30/2018] [Indexed: 12/23/2022] Open
Abstract
Epigenetic gene regulation is crucial to plant life and can involve dynamic interactions between various histone modifications, DNA methylation, and small RNAs. Detailed analysis of epigenome information is anticipated to reveal how the DNA sequence of the genome is translated into the plant’s phenotype. The aim of this study was to map the DNA methylation state at the whole genome level and to clarify the relationship between DNA methylation and transcription, small RNA expression, and histone H3 lysine 9 di-methylation (H3K9me2) in Brassica rapa. We performed whole genome bisulfite sequencing, small RNA sequencing, and chromatin immunoprecipitation sequencing using H3K9me2 antibody in a Chinese cabbage inbred line, RJKB-T24, and examined the impact of epigenetic states on transcription. Cytosine methylation in DNA was analysed in different sequence contexts (CG, CHG, and CHH) (where H could be A, C, or T) and position (promoter, exon, intron, terminator, interspersed repeat regions), and the H3K9me2 and 24 nucleotide small interfering RNAs (24 nt-siRNA) were overlaid onto the B. rapa reference genome. The epigenome was compared with that of Arabidopsis thaliana and the relationship between the position of DNA methylation and gene expression, and the involvement of 24 nt siRNAs and H3K9me2 are discussed.
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Affiliation(s)
- Satoshi Takahashi
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan
| | - Kenji Osabe
- Plant Epigenetics Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa, Japan
| | - Naoki Fukushima
- Graduate School of Agricultural Science, Kobe University, Rokkodai, Nada-ku, Kobe, Japan
| | - Shohei Takuno
- Department of Evolutionary Studies of Biosystems, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Kanagawa, Japan
| | - Naomi Miyaji
- Graduate School of Agricultural Science, Kobe University, Rokkodai, Nada-ku, Kobe, Japan
| | - Motoki Shimizu
- Iwate Biotechnology Research Center, Narita Kitakami, Iwate, Japan
| | | | - Yutaka Suzuki
- Department of Computational Biology, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Elizabeth S Dennis
- CSIRO Agriculture and Food, Canberra, ACT, Australia.,University of Technology, Sydney, Broadway, NSW, Australia
| | - Motoaki Seki
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan.,Core Research for Evolutional Science and Technology, Japan Science and Technology, Kawaguchi, Saitama, Japan.,RIKEN Cluster for Pioneering Research, Wako, Saitama, Japan
| | - Ryo Fujimoto
- Graduate School of Agricultural Science, Kobe University, Rokkodai, Nada-ku, Kobe, Japan
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33
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Hobza R, Hudzieczek V, Kubat Z, Cegan R, Vyskot B, Kejnovsky E, Janousek B. Sex and the flower - developmental aspects of sex chromosome evolution. ANNALS OF BOTANY 2018; 122:1085-1101. [PMID: 30032185 PMCID: PMC6324748 DOI: 10.1093/aob/mcy130] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 07/13/2018] [Indexed: 05/07/2023]
Abstract
Background The evolution of dioecious plants is occasionally accompanied by the establishment of sex chromosomes: both XY and ZW systems have been found in plants. Structural studies of sex chromosomes are now being followed up by functional studies that are gradually shedding light on the specific genetic and epigenetic processes that shape the development of separate sexes in plants. Scope This review describes sex determination diversity in plants and the genetic background of dioecy, summarizes recent progress in the investigation of both classical and emerging model dioecious plants and discusses novel findings. The advantages of interspecies hybrids in studies focused on sex determination and the role of epigenetic processes in sexual development are also overviewed. Conclusions We integrate the genic, genomic and epigenetic levels of sex determination and stress the impact of sex chromosome evolution on structural and functional aspects of plant sexual development. We also discuss the impact of dioecy and sex chromosomes on genome structure and expression.
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Affiliation(s)
- Roman Hobza
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska, Brno, Czech Republic
| | - Vojtech Hudzieczek
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska, Brno, Czech Republic
| | - Zdenek Kubat
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska, Brno, Czech Republic
| | - Radim Cegan
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska, Brno, Czech Republic
| | - Boris Vyskot
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska, Brno, Czech Republic
| | - Eduard Kejnovsky
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska, Brno, Czech Republic
| | - Bohuslav Janousek
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska, Brno, Czech Republic
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Fu FF, Dawe RK, Gent JI. Loss of RNA-Directed DNA Methylation in Maize Chromomethylase and DDM1-Type Nucleosome Remodeler Mutants. THE PLANT CELL 2018; 30:1617-1627. [PMID: 29884624 PMCID: PMC6096594 DOI: 10.1105/tpc.18.00053] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 05/16/2018] [Accepted: 06/07/2018] [Indexed: 05/02/2023]
Abstract
Plants make use of distinct types of DNA methylation characterized by their DNA methyltransferases and modes of regulation. One type, RNA-directed DNA methylation (RdDM), is guided by small interfering RNAs (siRNAs) to the edges of transposons that are close to genes, areas called mCHH islands in maize (Zea mays). Another type, chromomethylation, is guided by histone H3 lysine 9 methylation to heterochromatin across the genome. We examined DNA methylation and small RNA expression in plant tissues that were mutant for both copies of the genes encoding chromomethylases as well as mutants for both copies of the genes encoding DECREASED DNA METHYLATION1 (DDM1)-type nucleosome remodelers, which facilitate chromomethylation. Both sets of double mutants were nonviable but produced embryos and endosperm. RdDM was severely compromised in the double mutant embryos, both in terms of DNA methylation and siRNAs. Loss of 24-nucleotide siRNA from mCHH islands was coupled with a gain of 21-, 22-, and 24-nucleotide siRNAs in heterochromatin. These results reveal a requirement for both chromomethylation and DDM1-type nucleosome remodeling for RdDM in mCHH islands, which we hypothesize is due to dilution of RdDM components across the genome when heterochromatin is compromised.
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Affiliation(s)
- Fang-Fang Fu
- Department of Plant Biology, University of Georgia, Athens, Georgia 30602
| | - R Kelly Dawe
- Department of Plant Biology, University of Georgia, Athens, Georgia 30602
- Department of Genetics, University of Georgia, Athens, Georgia 30602
| | - Jonathan I Gent
- Department of Plant Biology, University of Georgia, Athens, Georgia 30602
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35
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Ma Y, Min L, Wang M, Wang C, Zhao Y, Li Y, Fang Q, Wu Y, Xie S, Ding Y, Su X, Hu Q, Zhang Q, Li X, Zhang X. Disrupted Genome Methylation in Response to High Temperature Has Distinct Affects on Microspore Abortion and Anther Indehiscence. THE PLANT CELL 2018; 30:1387-1403. [PMID: 29866646 PMCID: PMC6096589 DOI: 10.1105/tpc.18.00074] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 05/21/2018] [Accepted: 05/30/2018] [Indexed: 05/17/2023]
Abstract
High-temperature (HT) stress induces male sterility, leading to yield reductions in crops. DNA methylation regulates a range of processes involved in plant development and stress responses, but its role in male sterility under HT remains unknown. Here, we investigated DNA methylation levels in cotton (Gossypium hirsutum) anthers under HT and normal temperature (NT) conditions by performing whole-genome bisulfite sequencing to investigate the regulatory roles of DNA methylation in male fertility under HT. Global disruption of DNA methylation, especially CHH methylation (where H = A, C, or T), was detected in an HT-sensitive line. Changes in the levels of 24-nucleotide small-interfering RNAs were significantly associated with DNA methylation levels. Experimental suppression of DNA methylation led to pollen sterility in the HT-sensitive line under NT conditions but did not affect the normal dehiscence of anther walls. Further transcriptome analysis showed that the expression of genes in sugar and reactive oxygen species (ROS) metabolic pathways were significantly modulated in anthers under HT, but auxin biosynthesis and signaling pathways were only slightly altered, indicating that HT disturbs sugar and ROS metabolism via disrupting DNA methylation, leading to microspore sterility. This study opens up a pathway for creating HT-tolerant cultivars using epigenetic techniques.
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Affiliation(s)
- Yizan Ma
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Ling Min
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Maojun Wang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Chaozhi Wang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Yunlong Zhao
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Yaoyao Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Qidi Fang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Yuanlong Wu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Sai Xie
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Yuanhao Ding
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Xiaojun Su
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Qin Hu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Qinghua Zhang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Xueyuan Li
- Xinjiang Academy of Agricultural Science, Urumqi 830001, Xinjiang, China
| | - Xianlong Zhang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, Hubei, China
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36
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Anderson SN, Zynda GJ, Song J, Han Z, Vaughn MW, Li Q, Springer NM. Subtle Perturbations of the Maize Methylome Reveal Genes and Transposons Silenced by Chromomethylase or RNA-Directed DNA Methylation Pathways. G3 (BETHESDA, MD.) 2018; 8:1921-1932. [PMID: 29618467 PMCID: PMC5982821 DOI: 10.1534/g3.118.200284] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 04/03/2018] [Indexed: 01/17/2023]
Abstract
DNA methylation is a chromatin modification that can provide epigenetic regulation of gene and transposon expression. Plants utilize several pathways to establish and maintain DNA methylation in specific sequence contexts. The chromomethylase (CMT) genes maintain CHG (where H = A, C or T) methylation. The RNA-directed DNA methylation (RdDM) pathway is important for CHH methylation. Transcriptome analysis was performed in a collection of Zea mays lines carrying mutant alleles for CMT or RdDM-associated genes. While the majority of the transcriptome was not affected, we identified sets of genes and transposon families sensitive to context-specific decreases in DNA methylation in mutant lines. Many of the genes that are up-regulated in CMT mutant lines have high levels of CHG methylation, while genes that are differentially expressed in RdDM mutants are enriched for having nearby mCHH islands, implicating context-specific DNA methylation in the regulation of expression for a small number of genes. Many genes regulated by CMTs exhibit natural variation for DNA methylation and transcript abundance in a panel of diverse inbred lines. Transposon families with differential expression in the mutant genotypes show few defining features, though several families up-regulated in RdDM mutants show enriched expression in endosperm tissue, highlighting the potential importance for this pathway during reproduction. Taken together, our findings suggest that while the number of genes and transposon families whose expression is reproducibly affected by mild perturbations in context-specific methylation is small, there are distinct patterns for loci impacted by RdDM and CMT mutants.
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Affiliation(s)
- Sarah N Anderson
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN 55108
| | - Gregory J Zynda
- Texas Advanced Computing Center, University of Texas, Austin, TX 78758
| | - Jawon Song
- Texas Advanced Computing Center, University of Texas, Austin, TX 78758
| | - Zhaoxue Han
- State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Matthew W Vaughn
- Texas Advanced Computing Center, University of Texas, Austin, TX 78758
| | - Qing Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Nathan M Springer
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN 55108
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37
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A Kinesin-14 Motor Activates Neocentromeres to Promote Meiotic Drive in Maize. Cell 2018; 173:839-850.e18. [DOI: 10.1016/j.cell.2018.03.009] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 11/13/2017] [Accepted: 03/02/2018] [Indexed: 01/08/2023]
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38
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Concia L, Brooks AM, Wheeler E, Zynda GJ, Wear EE, LeBlanc C, Song J, Lee TJ, Pascuzzi PE, Martienssen RA, Vaughn MW, Thompson WF, Hanley-Bowdoin L. Genome-Wide Analysis of the Arabidopsis Replication Timing Program. PLANT PHYSIOLOGY 2018; 176:2166-2185. [PMID: 29301956 PMCID: PMC5841712 DOI: 10.1104/pp.17.01537] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 01/03/2018] [Indexed: 05/21/2023]
Abstract
Eukaryotes use a temporally regulated process, known as the replication timing program, to ensure that their genomes are fully and accurately duplicated during S phase. Replication timing programs are predictive of genomic features and activity and are considered to be functional readouts of chromatin organization. Although replication timing programs have been described for yeast and animal systems, much less is known about the temporal regulation of plant DNA replication or its relationship to genome sequence and chromatin structure. We used the thymidine analog, 5-ethynyl-2'-deoxyuridine, in combination with flow sorting and Repli-Seq to describe, at high-resolution, the genome-wide replication timing program for Arabidopsis (Arabidopsis thaliana) Col-0 suspension cells. We identified genomic regions that replicate predominantly during early, mid, and late S phase, and correlated these regions with genomic features and with data for chromatin state, accessibility, and long-distance interaction. Arabidopsis chromosome arms tend to replicate early while pericentromeric regions replicate late. Early and mid-replicating regions are gene-rich and predominantly euchromatic, while late regions are rich in transposable elements and primarily heterochromatic. However, the distribution of chromatin states across the different times is complex, with each replication time corresponding to a mixture of states. Early and mid-replicating sequences interact with each other and not with late sequences, but early regions are more accessible than mid regions. The replication timing program in Arabidopsis reflects a bipartite genomic organization with early/mid-replicating regions and late regions forming separate, noninteracting compartments. The temporal order of DNA replication within the early/mid compartment may be modulated largely by chromatin accessibility.
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Affiliation(s)
- Lorenzo Concia
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
| | - Ashley M Brooks
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
| | - Emily Wheeler
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
| | - Gregory J Zynda
- Texas Advanced Computing Center, University of Texas at Austin, Austin, Texas 78758
| | - Emily E Wear
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
| | - Chantal LeBlanc
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724
| | - Jawon Song
- Texas Advanced Computing Center, University of Texas at Austin, Austin, Texas 78758
| | - Tae-Jin Lee
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
| | - Pete E Pascuzzi
- Purdue University Libraries, Purdue University, West Lafayette, Indiana 47907
| | - Robert A Martienssen
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724
| | - Matthew W Vaughn
- Texas Advanced Computing Center, University of Texas at Austin, Austin, Texas 78758
| | - William F Thompson
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
| | - Linda Hanley-Bowdoin
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
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Puterova J, Kubat Z, Kejnovsky E, Jesionek W, Cizkova J, Vyskot B, Hobza R. The slowdown of Y chromosome expansion in dioecious Silene latifolia due to DNA loss and male-specific silencing of retrotransposons. BMC Genomics 2018; 19:153. [PMID: 29458354 PMCID: PMC5819184 DOI: 10.1186/s12864-018-4547-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 02/13/2018] [Indexed: 11/10/2022] Open
Abstract
Background The rise and fall of the Y chromosome was demonstrated in animals but plants often possess the large evolutionarily young Y chromosome that is thought has expanded recently. Break-even points dividing expansion and shrinkage phase of plant Y chromosome evolution are still to be determined. To assess the size dynamics of the Y chromosome, we studied intraspecific genome size variation and genome composition of male and female individuals in a dioecious plant Silene latifolia, a well-established model for sex-chromosomes evolution. Results Our genome size data are the first to demonstrate that regardless of intraspecific genome size variation, Y chromosome has retained its size in S. latifolia. Bioinformatics study of genome composition showed that constancy of Y chromosome size was caused by Y chromosome DNA loss and the female-specific proliferation of recently active dominant retrotransposons. We show that several families of retrotransposons have contributed to genome size variation but not to Y chromosome size change. Conclusions Our results suggest that the large Y chromosome of S. latifolia has slowed down or stopped its expansion. Female-specific proliferation of retrotransposons, enlarging the genome with exception of the Y chromosome, was probably caused by silencing of highly active retrotransposons in males and represents an adaptive mechanism to suppress degenerative processes in the haploid stage. Sex specific silencing of transposons might be widespread in plants but hidden in traditional hermaphroditic model plants. Electronic supplementary material The online version of this article (10.1186/s12864-018-4547-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Janka Puterova
- Department of Plant Developmental Genetics, Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, 612 00, Brno, Czech Republic.,Department of Information Systems, Faculty of Information Technology, Brno University of Technology, 61200, Brno, Czech Republic
| | - Zdenek Kubat
- Department of Plant Developmental Genetics, Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, 612 00, Brno, Czech Republic.
| | - Eduard Kejnovsky
- Department of Plant Developmental Genetics, Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, 612 00, Brno, Czech Republic
| | - Wojciech Jesionek
- Department of Plant Developmental Genetics, Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, 612 00, Brno, Czech Republic
| | - Jana Cizkova
- Centre of Plant Structural and Functional Genomics, Institute of Experimental Botany, Czech Academy of Sciences, 783 71, Olomouc - Holice, Czech Republic
| | - Boris Vyskot
- Department of Plant Developmental Genetics, Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, 612 00, Brno, Czech Republic
| | - Roman Hobza
- Department of Plant Developmental Genetics, Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, 612 00, Brno, Czech Republic. .,Centre of Plant Structural and Functional Genomics, Institute of Experimental Botany, Czech Academy of Sciences, 783 71, Olomouc - Holice, Czech Republic.
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40
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Renny-Byfield S, Rodgers-Melnick E, Ross-Ibarra J. Gene Fractionation and Function in the Ancient Subgenomes of Maize. Mol Biol Evol 2018; 34:1825-1832. [PMID: 28430989 DOI: 10.1093/molbev/msx121] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The maize genome experienced an ancient whole genome duplication ∼10 MYA and the duplicate subgenomes have since experienced reciprocal gene loss such that many genes have returned to single-copy status. This process has not affected the subgenomes equally; reduced gene expression in one of the subgenomes mitigates the consequences of mutations and gene deletions and is thought to drive higher rates of fractionation. Here, we use published data to show that, in accordance with predictions of this model, paralogs with greater expression contribute more to phenotypic variation compared with their lowly expressed counterparts. Furthermore, paralogous genes in the least-fractionated subgenome account for a greater degree of phenotypic diversity than those resident on the more-fractionated subgenome. Intriguingly, analysis of singleton genes reveals this difference persists even after fractionation is complete. Additionally, we show that the two subgenomes of maize may differ in their epigenetic profiles.
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Affiliation(s)
- Simon Renny-Byfield
- Department of Plant Sciences, University of California, Davis, CA.,DuPont Pioneer, Johnston, IA
| | - Eli Rodgers-Melnick
- DuPont Pioneer, Johnston, IA.,Institute for Genomic Diversity, Cornell University, Ithaca, NY
| | - Jeffrey Ross-Ibarra
- Department of Plant Sciences, University of California, Davis, CA.,Center for Population Biology and Genome Center, University of California, Davis, CA
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41
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Seifert F, Thiemann A, Grant-Downton R, Edelmann S, Rybka D, Schrag TA, Frisch M, Dickinson HG, Melchinger AE, Scholten S. Parental Expression Variation of Small RNAs Is Negatively Correlated with Grain Yield Heterosis in a Maize Breeding Population. FRONTIERS IN PLANT SCIENCE 2018; 9:13. [PMID: 29441076 PMCID: PMC5797689 DOI: 10.3389/fpls.2018.00013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 01/04/2018] [Indexed: 05/26/2023]
Abstract
Heterosis refers to a quantitative phenomenon in which F1 hybrid trait values exceed the mean of the parental values in a positive direction. Generally, it is dependent on a high degree of heterozygosity, which is maintained in hybrid breeding by developing parental lines in separate, genetically distinct heterotic groups. The mobility of small RNAs (sRNAs) that mediate epigenetic regulation of gene expression renders them promising candidates for modulating the action of combined diverse genomes in trans-and evidence already indicates their contribution to transgressive phenotypes. By sequencing small RNA libraries of a panel of 21 maize parental inbred lines we found a low overlap of 35% between the sRNA populations from both distinct heterotic groups. Surprisingly, in contrast to genetic or gene expression variation, parental sRNA expression variation is negatively correlated with grain yield (GY) heterosis. Among 0.595 million expressed sRNAs, we identified 9,767, predominantly 22- and 24-nt long sRNAs, which showed an association of their differential expression between parental lines and GY heterosis of the respective hybrids. Of these sRNAs, 3,485 or 6,282 showed an association with high or low GY heterosis, respectively, thus the low heterosis associated group prevailing at 64%. The heterosis associated sRNAs map more frequently to genes that show differential expression between parental lines than reference sets. Together these findings suggest that trans-chromosomal actions of sRNAs in hybrids might add up to a negative contribution in heterosis formation, mediated by unfavorable gene expression regulation. We further revealed an exclusive accumulation of 22-nt sRNAs that are associated with low GY heterosis in pericentromeric genomic regions. That recombinational suppression led to this enrichment is indicated by its close correlation with low recombination rates. The existence of this enrichment, which we hypothesize resulted from the separated breeding of inbred lines within heterotic groups, may have implications for hybrid breeding strategies addressing the recombinational constraints characteristic of complex crop genomes.
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Affiliation(s)
- Felix Seifert
- Biocenter Klein Flottbek, University of Hamburg, Hamburg, Germany
| | | | | | - Susanne Edelmann
- Biocenter Klein Flottbek, University of Hamburg, Hamburg, Germany
| | - Dominika Rybka
- Biocenter Klein Flottbek, University of Hamburg, Hamburg, Germany
| | - Tobias A. Schrag
- Institute for Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, Stuttgart, Germany
| | - Matthias Frisch
- Institute of Agronomy and Plant Breeding II, Justus-Liebig University, Giessen, Germany
| | - Hugh G. Dickinson
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Albrecht E. Melchinger
- Institute for Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, Stuttgart, Germany
| | - Stefan Scholten
- Biocenter Klein Flottbek, University of Hamburg, Hamburg, Germany
- Institute for Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, Stuttgart, Germany
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42
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Dukowic-Schulze S, Liu C, Chen C. Not just gene expression: 3D implications of chromatin modifications during sexual plant reproduction. PLANT CELL REPORTS 2018; 37:11-16. [PMID: 29032424 DOI: 10.1007/s00299-017-2222-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 10/05/2017] [Indexed: 06/07/2023]
Abstract
DNA methylation and histone modifications are epigenetic changes on a DNA molecule that alter the three-dimensional (3D) structure locally as well as globally, impacting chromatin looping and packaging on a larger scale. Epigenetic marks thus inform higher-order chromosome organization and placement in the nucleus. Conventional epigenetic marks are joined by chromatin modifiers like cohesins, condensins and membrane-anchoring complexes to support particularly 3D chromosome organization. The most popular consequences of epigenetic modifications are gene expression changes, but chromatin modifications have implications beyond this, particularly in actively dividing cells and during sexual reproduction. In this opinion paper, we will focus on epigenetic mechanisms and chromatin modifications during meiosis as part of plant sexual reproduction where 3D management of chromosomes and re-organization of chromatin are defining features and prime tasks in reproductive cells, not limited to modulating gene expression. Meiotic chromosome organization, pairing and synapsis of homologous chromosomes as well as distribution of meiotic double-strand breaks and resulting crossovers are presumably highly influenced by epigenetic mechanisms. Special mobile small RNAs have been described in anthers, where these so-called phasiRNAs seem to direct DNA methylation in meiotic cells. Intriguingly, many of the mentioned developmental processes make use of epigenetic changes and small RNAs in a manner other than gene expression changes. Widening our approaches and opening our mind to thinking three-dimensionally regarding epigenetics in plant development holds high promise for new discoveries and could give us a boost for further knowledge.
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Affiliation(s)
- Stefanie Dukowic-Schulze
- Department of Horticultural Science, University of Minnesota, Alderman Hall, 1970 Folwell Avenue, Saint Paul, MN, 55108, USA
| | - Chang Liu
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany
| | - Changbin Chen
- Department of Horticultural Science, University of Minnesota, Alderman Hall, 1970 Folwell Avenue, Saint Paul, MN, 55108, USA.
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43
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Wang PH, Wittmeyer KT, Lee TF, Meyers BC, Chopra S. Overlapping RdDM and non-RdDM mechanisms work together to maintain somatic repression of a paramutagenic epiallele of maize pericarp color1. PLoS One 2017; 12:e0187157. [PMID: 29112965 PMCID: PMC5675401 DOI: 10.1371/journal.pone.0187157] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 10/14/2017] [Indexed: 11/18/2022] Open
Abstract
Allelic variation at the Zea mays (maize) pericarp color1 (p1) gene has been attributed to epigenetic gene regulation. A p1 distal enhancer, 5.2 kb upstream of the transcriptional start site, has demonstrated variation in DNA methylation in different p1 alleles/epialleles. In addition, DNA methylation of sequences within the 3’ end of intron 2 also plays a role in tissue-specific expression of p1 alleles. We show here a direct evidence for small RNAs’ involvement in regulating p1 that has not been demonstrated previously. The role of mediator of paramutation1 (mop1) was tested in the maintenance of somatic silencing at distinct p1 alleles: the non-paramutagenic P1-wr allele and paramutagenic P1-rr’ epiallele. The mop1-1 mutation gradually relieves the silenced phenotype after multiple generations of exposure; P1-wr;mop1-1 plants display a loss of 24-nt small RNAs and DNA methylation in the 3’ end of the intron 2, a region close to a Stowaway transposon. In addition, a MULE sequence within the proximal promoter of P1-wr shows depletion of 24nt siRNAs in mop1-1 plants. Release of silencing was not correlated with small RNAs at the distal enhancer region of the P1-wr allele. We found that the somatic silencing of the paramutagenic P1-rr’ is correlated with significantly reduced H3K9me2 in the distal enhancer of P1-rr’; mop1-1 plants, while symmetric DNA methylation is not significantly different. This study highlights that the epigenetic regulation of p1 alleles is controlled both via RdDM as well as non-RdDM mechanisms.
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Affiliation(s)
- Po-Hao Wang
- Department of Plant Science, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Kameron T. Wittmeyer
- Department of Plant Science, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Plant Biology Program, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Tzuu-fen Lee
- Department of Plant & Soil Sciences and Delaware Biotechnology Institute, University of Delaware, Newark, Delaware, United States of America
| | - Blake C. Meyers
- Department of Plant & Soil Sciences and Delaware Biotechnology Institute, University of Delaware, Newark, Delaware, United States of America
| | - Surinder Chopra
- Department of Plant Science, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Plant Biology Program, Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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44
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C L B, S Nair A. Benchmark Dataset for Whole Genome Sequence Compression. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2017; 14:1228-1236. [PMID: 27214907 DOI: 10.1109/tcbb.2016.2568186] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
UNLABELLED The research in DNA data compression lacks a standard dataset to test out compression tools specific to DNA. This paper argues that the current state of achievement in DNA compression is unable to be benchmarked in the absence of such scientifically compiled whole genome sequence dataset and proposes a benchmark dataset using multistage sampling procedure. Considering the genome sequence of organisms available in the National Centre for Biotechnology and Information (NCBI) as the universe, the proposed dataset selects 1,105 prokaryotes, 200 plasmids, 164 viruses, and 65 eukaryotes. This paper reports the results of using three established tools on the newly compiled dataset and show that their strength and weakness are evident only with a comparison based on the scientifically compiled benchmark dataset. AVAILABILITY The sample dataset and the respective links are available @ https://sourceforge.net/projects/benchmarkdnacompressiondataset/.
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45
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Abstract
Dynamic reshuffling of the chromatin landscape is a recurrent theme orchestrated in many, if not all, plant developmental transitions and adaptive responses. Spatiotemporal variations of the chromatin properties on regulatory genes and on structural genomic elements trigger the establishment of distinct transcriptional contexts, which in some instances can epigenetically be inherited. Studies on plant cell plasticity during the differentiation of stem cells, including gametogenesis, or the specialization of vegetative cells in various organs, as well as the investigation of allele-specific gene regulation have long been impaired by technical challenges in generating specific chromatin profiles in complex or hardly accessible cell populations. Recent advances in increasing the sensitivity of genome-enabled technologies and in the isolation of specific cell types have allowed for overcoming such limitations. These developments hint at multilevel regulatory events ranging from nucleosome accessibility and composition to higher order chromatin organization and genome topology. Uncovering the large extent to which chromatin dynamics and epigenetic processes influence gene expression is therefore not surprisingly revolutionizing current views on plant molecular genetics and (epi)genomics as well as their perspectives in eco-evolutionary biology. Here, we introduce current methodologies to probe genome-wide chromatin variations for which protocols are detailed in this book chapter, with an emphasis on the plant model species Arabidopsis.
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Forestan C, Farinati S, Aiese Cigliano R, Lunardon A, Sanseverino W, Varotto S. Maize RNA PolIV affects the expression of genes with nearby TE insertions and has a genome-wide repressive impact on transcription. BMC PLANT BIOLOGY 2017; 17:161. [PMID: 29025411 PMCID: PMC5639751 DOI: 10.1186/s12870-017-1108-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 10/04/2017] [Indexed: 05/09/2023]
Abstract
BACKGROUND RNA-directed DNA methylation (RdDM) is a plant-specific epigenetic process that relies on the RNA polymerase IV (Pol IV) for the production of 24 nucleotide small interfering RNAs (siRNA) that guide the cytosine methylation and silencing of genes and transposons. Zea mays RPD1/RMR6 gene encodes the largest subunit of Pol IV and is required for normal plant development, paramutation, transcriptional repression of certain transposable elements (TEs) and transcriptional regulation of specific alleles. RESULTS In this study we applied a total RNA-Seq approach to compare the B73 and rpd1/rmr6 leaf transcriptomes. Although previous studies indicated that loss of siRNAs production in RdDM mutants provokes a strong loss of CHH DNA methylation but not massive gene or TEs transcriptional activation in both Arabidopsis and maize, our total RNA-Seq analysis of rpd1/rmr6 transcriptome reveals that loss of Pol IV activity causes a global increase in the transcribed fraction of the maize genome. Our results point to the genes with nearby TE insertions as being the most strongly affected by Pol IV-mediated gene silencing. TEs modulation of nearby gene expression is linked to alternative methylation profiles on gene flanking regions, and these profiles are strictly dependent on specific characteristics of the TE member inserted. Although Pol IV is essential for the biogenesis of siRNAs, the genes with associated siRNA loci are less affected by the pol IV mutation. CONCLUSIONS This deep and integrated analysis of gene expression, TEs distribution, smallRNA targeting and DNA methylation levels, reveals that loss of Pol IV activity globally affects genome regulation, pointing at TEs as modulator of nearby gene expression and indicating the existence of multiple level epigenetic silencing mechanisms. Our results also suggest a predominant role of the Pol IV-mediated RdDM pathway in genome dominance regulation, and subgenome stability and evolution in maize.
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Affiliation(s)
- Cristian Forestan
- Department of Agronomy, Food, Natural resources, Animals and Environment, University of Padova, Viale dell’Università 16, 35020 Legnaro, PD Italy
| | - Silvia Farinati
- Department of Agronomy, Food, Natural resources, Animals and Environment, University of Padova, Viale dell’Università 16, 35020 Legnaro, PD Italy
| | | | - Alice Lunardon
- Department of Agronomy, Food, Natural resources, Animals and Environment, University of Padova, Viale dell’Università 16, 35020 Legnaro, PD Italy
- Present Address: Department of Biology and Huck Institutes of the Life Sciences, Penn State University, University Park, Pennsylvania, PA 16802 USA
| | | | - Serena Varotto
- Department of Agronomy, Food, Natural resources, Animals and Environment, University of Padova, Viale dell’Università 16, 35020 Legnaro, PD Italy
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47
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Wear EE, Song J, Zynda GJ, LeBlanc C, Lee TJ, Mickelson-Young L, Concia L, Mulvaney P, Szymanski ES, Allen GC, Martienssen RA, Vaughn MW, Hanley-Bowdoin L, Thompson WF. Genomic Analysis of the DNA Replication Timing Program during Mitotic S Phase in Maize ( Zea mays) Root Tips. THE PLANT CELL 2017; 29:2126-2149. [PMID: 28842533 PMCID: PMC5635974 DOI: 10.1105/tpc.17.00037] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 07/31/2017] [Accepted: 08/24/2017] [Indexed: 05/19/2023]
Abstract
All plants and animals must replicate their DNA, using a regulated process to ensure that their genomes are completely and accurately replicated. DNA replication timing programs have been extensively studied in yeast and animal systems, but much less is known about the replication programs of plants. We report a novel adaptation of the "Repli-seq" assay for use in intact root tips of maize (Zea mays) that includes several different cell lineages and present whole-genome replication timing profiles from cells in early, mid, and late S phase of the mitotic cell cycle. Maize root tips have a complex replication timing program, including regions of distinct early, mid, and late S replication that each constitute between 20 and 24% of the genome, as well as other loci corresponding to ∼32% of the genome that exhibit replication activity in two different time windows. Analyses of genomic, transcriptional, and chromatin features of the euchromatic portion of the maize genome provide evidence for a gradient of early replicating, open chromatin that transitions gradually to less open and less transcriptionally active chromatin replicating in mid S phase. Our genomic level analysis also demonstrated that the centromere core replicates in mid S, before heavily compacted classical heterochromatin, including pericentromeres and knobs, which replicate during late S phase.
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Affiliation(s)
- Emily E Wear
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
| | - Jawon Song
- Texas Advanced Computing Center, University of Texas, Austin, Texas 78758
| | - Gregory J Zynda
- Texas Advanced Computing Center, University of Texas, Austin, Texas 78758
| | - Chantal LeBlanc
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724
| | - Tae-Jin Lee
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
| | - Leigh Mickelson-Young
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
| | - Lorenzo Concia
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
| | - Patrick Mulvaney
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
| | - Eric S Szymanski
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
| | - George C Allen
- Department of Horticultural Science, North Carolina State University, Raleigh, North Carolina 27695
| | | | - Matthew W Vaughn
- Texas Advanced Computing Center, University of Texas, Austin, Texas 78758
| | - Linda Hanley-Bowdoin
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
| | - William F Thompson
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695
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48
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Oka R, Zicola J, Weber B, Anderson SN, Hodgman C, Gent JI, Wesselink JJ, Springer NM, Hoefsloot HCJ, Turck F, Stam M. Genome-wide mapping of transcriptional enhancer candidates using DNA and chromatin features in maize. Genome Biol 2017; 18:137. [PMID: 28732548 PMCID: PMC5522596 DOI: 10.1186/s13059-017-1273-4] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 07/05/2017] [Indexed: 11/10/2022] Open
Abstract
Background While most cells in multicellular organisms carry the same genetic information, in each cell type only a subset of genes is being transcribed. Such differentiation in gene expression depends, for a large part, on the activation and repression of regulatory sequences, including transcriptional enhancers. Transcriptional enhancers can be located tens of kilobases from their target genes, but display characteristic chromatin and DNA features, allowing their identification by genome-wide profiling. Here we show that integration of chromatin characteristics can be applied to predict distal enhancer candidates in Zea mays, thereby providing a basis for a better understanding of gene regulation in this important crop plant. Result To predict transcriptional enhancers in the crop plant maize (Zea mays L. ssp. mays), we integrated available genome-wide DNA methylation data with newly generated maps for chromatin accessibility and histone 3 lysine 9 acetylation (H3K9ac) enrichment in young seedling and husk tissue. Approximately 1500 intergenic regions, displaying low DNA methylation, high chromatin accessibility and H3K9ac enrichment, were classified as enhancer candidates. Based on their chromatin profiles, candidate sequences can be classified into four subcategories. Tissue-specificity of enhancer candidates is defined based on the tissues in which they are identified and putative target genes are assigned based on tissue-specific expression patterns of flanking genes. Conclusions Our method identifies three previously identified distal enhancers in maize, validating the new set of enhancer candidates and enlarging the toolbox for the functional characterization of gene regulation in the highly repetitive maize genome. Electronic supplementary material The online version of this article (doi:10.1186/s13059-017-1273-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rurika Oka
- Swammerdam Institute for Life Sciences, Universiteit van Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Johan Zicola
- Department Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829, Köln, Germany
| | - Blaise Weber
- Swammerdam Institute for Life Sciences, Universiteit van Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Sarah N Anderson
- Department of Plant Biology, University of Minnesota, 40 Gortner Laboratory, 1479 Gortner Avenue, St. Paul, MN, 55108, USA
| | - Charlie Hodgman
- Centre for Plant Integrative Biology, School of Biosciences, University of Nottingham, Sutton Bonington, LE12 5RD, UK
| | - Jonathan I Gent
- Department of Plant Biology, University of Georgia, Athens, GA, 30602, USA
| | | | - Nathan M Springer
- Department of Plant Biology, University of Minnesota, 40 Gortner Laboratory, 1479 Gortner Avenue, St. Paul, MN, 55108, USA
| | - Huub C J Hoefsloot
- Swammerdam Institute for Life Sciences, Universiteit van Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Franziska Turck
- Department Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829, Köln, Germany.
| | - Maike Stam
- Swammerdam Institute for Life Sciences, Universiteit van Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
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49
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Jiang H, Moreno-Romero J, Santos-González J, De Jaeger G, Gevaert K, Van De Slijke E, Köhler C. Ectopic application of the repressive histone modification H3K9me2 establishes post-zygotic reproductive isolation in Arabidopsis thaliana. Genes Dev 2017; 31:1272-1287. [PMID: 28743695 PMCID: PMC5558928 DOI: 10.1101/gad.299347.117] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 06/27/2017] [Indexed: 11/24/2022]
Abstract
Hybrid seed lethality as a consequence of interspecies or interploidy hybridizations is a major mechanism of reproductive isolation in plants. This mechanism is manifested in the endosperm, a dosage-sensitive tissue supporting embryo growth. Deregulated expression of imprinted genes such as ADMETOS (ADM) underpin the interploidy hybridization barrier in Arabidopsis thaliana; however, the mechanisms of their action remained unknown. In this study, we show that ADM interacts with the AT hook domain protein AHL10 and the SET domain-containing SU(VAR)3-9 homolog SUVH9 and ectopically recruits the heterochromatic mark H3K9me2 to AT-rich transposable elements (TEs), causing deregulated expression of neighboring genes. Several hybrid incompatibility genes identified in Drosophila encode for dosage-sensitive heterochromatin-interacting proteins, which has led to the suggestion that hybrid incompatibilities evolve as a consequence of interspecies divergence of selfish DNA elements and their regulation. Our data show that imbalance of dosage-sensitive chromatin regulators underpins the barrier to interploidy hybridization in Arabidopsis, suggesting that reproductive isolation as a consequence of epigenetic regulation of TEs is a conserved feature in animals and plants.
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Affiliation(s)
- Hua Jiang
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Linnean Center of Plant Biology, Uppsala 75007, Sweden
| | - Jordi Moreno-Romero
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Linnean Center of Plant Biology, Uppsala 75007, Sweden
| | - Juan Santos-González
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Linnean Center of Plant Biology, Uppsala 75007, Sweden
| | - Geert De Jaeger
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent 9052, Belgium
- VIB Center for Plant Systems Biology, Ghent 9052, Belgium
| | - Kris Gevaert
- Department of Biochemistry, Ghent University, Ghent 9052, Belgium
- VIB Center for Medical Biotechnology, Ghent 9052, Belgium
| | - Eveline Van De Slijke
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent 9052, Belgium
- VIB Center for Plant Systems Biology, Ghent 9052, Belgium
| | - Claudia Köhler
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Linnean Center of Plant Biology, Uppsala 75007, Sweden
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50
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Vergara Z, Gutierrez C. Emerging roles of chromatin in the maintenance of genome organization and function in plants. Genome Biol 2017; 18:96. [PMID: 28535770 PMCID: PMC5440935 DOI: 10.1186/s13059-017-1236-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Chromatin is not a uniform macromolecular entity; it contains different domains characterized by complex signatures of DNA and histone modifications. Such domains are organized both at a linear scale along the genome and spatially within the nucleus. We discuss recent discoveries regarding mechanisms that establish boundaries between chromatin states and nuclear territories. Chromatin organization is crucial for genome replication, transcriptional silencing, and DNA repair and recombination. The replication machinery is relevant for the maintenance of chromatin states, influencing DNA replication origin specification and accessibility. Current studies reinforce the idea of intimate crosstalk between chromatin features and processes involving DNA transactions.
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Affiliation(s)
- Zaida Vergara
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolas Cabrera 1, Cantoblanco, 28049, Madrid, Spain
| | - Crisanto Gutierrez
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolas Cabrera 1, Cantoblanco, 28049, Madrid, Spain.
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