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Matyášek R, Kalfusová R, Kuderová A, Řehůřková K, Sochorová J, Kovařík A. Transcriptional Silencing of 35S rDNA in Tragopogon porrifolius Correlates with Cytosine Methylation in Sequence-Specific Manner. Int J Mol Sci 2024; 25:7540. [PMID: 39062783 PMCID: PMC11276851 DOI: 10.3390/ijms25147540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Revised: 06/21/2024] [Accepted: 07/04/2024] [Indexed: 07/28/2024] Open
Abstract
Despite the widely accepted involvement of DNA methylation in the regulation of rDNA transcription, the relative participation of different cytosine methylation pathways is currently described only for a few model plants. Using PacBio, Bisulfite, and RNA sequencing; PCR; Southern hybridizations; and FISH, the epigenetic consequences of rDNA copy number variation were estimated in two T. porrifolius lineages, por1 and por2, the latter with more than twice the rDNA copy numbers distributed approximately equally between NORs on chromosomes A and D. The lower rDNA content in por1 correlated with significantly reduced (>90%) sizes of both D-NORs. Moreover, two (L and S) prominent rDNA variants, differing in the repetitive organization of intergenic spacers, were detected in por2, while only the S-rDNA variant was detected in por1. Transcriptional activity of S-rDNA in por1 was associated with secondary constriction of both A-NORs. In contrast, silencing of S-rDNA in por2 was accompanied by condensation of A-NORs, secondary constriction on D-NORs, and L-rDNA transcriptional activity, suggesting (i) bidirectional nucleolar dominance and (ii) association of S-rDNAs with A-NORs and L-rDNAs with D-NORs in T. porrifolius. Each S- and L-rDNA array was formed of several sub-variants differentiating both genetically (specific SNPs) and epigenetically (transcriptional efficiency and cytosine methylation). The most significant correlations between rDNA silencing and methylation were detected for symmetric CWG motifs followed by CG motifs. No correlations were detected for external cytosine in CCGs or asymmetric CHHs, where methylation was rather position-dependent, particularly for AT-rich variants. We conclude that variations in rDNA copy numbers in plant diploids can be accompanied by prompt epigenetic responses to maintain an appropriate number of active rDNAs. The methylation dynamics of CWGs are likely to be the most responsible for regulating silent and active rDNA states.
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Affiliation(s)
- Roman Matyášek
- Institute of Biophysics of the Czech Academy of Sciences, 612 65 Brno, Czech Republic; (R.K.); (A.K.); (K.Ř.); (J.S.); (A.K.)
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Liu J, Zhong X. Population epigenetics: DNA methylation in the plant omics era. PLANT PHYSIOLOGY 2024; 194:2039-2048. [PMID: 38366882 PMCID: PMC10980424 DOI: 10.1093/plphys/kiae089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 01/22/2024] [Accepted: 01/22/2024] [Indexed: 02/18/2024]
Abstract
DNA methylation plays an important role in many biological processes. The mechanisms underlying the establishment and maintenance of DNA methylation are well understood thanks to decades of research using DNA methylation mutants, primarily in Arabidopsis (Arabidopsis thaliana) accession Col-0. Recent genome-wide association studies (GWASs) using the methylomes of natural accessions have uncovered a complex and distinct genetic basis of variation in DNA methylation at the population level. Sequencing following bisulfite treatment has served as an excellent method for quantifying DNA methylation. Unlike studies focusing on specific accessions with reference genomes, population-scale methylome research often requires an additional round of sequencing beyond obtaining genome assemblies or genetic variations from whole-genome sequencing data, which can be cost prohibitive. Here, we provide an overview of recently developed bisulfite-free methods for quantifying methylation and cost-effective approaches for the simultaneous detection of genetic and epigenetic information. We also discuss the plasticity of DNA methylation in a specific Arabidopsis accession, the contribution of DNA methylation to plant adaptation, and the genetic determinants of variation in DNA methylation in natural populations. The recently developed technology and knowledge will greatly benefit future studies in population epigenomes.
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Affiliation(s)
- Jie Liu
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Xuehua Zhong
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
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Liu J, Zhong X. Epiallelic variation of non-coding RNA genes and their phenotypic consequences. Nat Commun 2024; 15:1375. [PMID: 38355746 PMCID: PMC10867003 DOI: 10.1038/s41467-024-45771-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 02/01/2024] [Indexed: 02/16/2024] Open
Abstract
Epigenetic variations contribute greatly to the phenotypic plasticity and diversity. Current functional studies on epialleles have predominantly focused on protein-coding genes, leaving the epialleles of non-coding RNA (ncRNA) genes largely understudied. Here, we uncover abundant DNA methylation variations of ncRNA genes and their significant correlations with plant adaptation among 1001 natural Arabidopsis accessions. Through genome-wide association study (GWAS), we identify large numbers of methylation QTL (methylQTL) that are independent of known DNA methyltransferases and enriched in specific chromatin states. Proximal methylQTL closely located to ncRNA genes have a larger effect on DNA methylation than distal methylQTL. We ectopically tether a DNA methyltransferase MQ1v to miR157a by CRISPR-dCas9 and show de novo establishment of DNA methylation accompanied with decreased miR157a abundance and early flowering. These findings provide important insights into the genetic basis of epigenetic variations and highlight the contribution of epigenetic variations of ncRNA genes to plant phenotypes and diversity.
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Affiliation(s)
- Jie Liu
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Xuehua Zhong
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA.
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Puchta H, Houben A. Plant chromosome engineering - past, present and future. THE NEW PHYTOLOGIST 2024; 241:541-552. [PMID: 37984056 DOI: 10.1111/nph.19414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 10/24/2023] [Indexed: 11/22/2023]
Abstract
Spontaneous chromosomal rearrangements (CRs) play an essential role in speciation, genome evolution and crop domestication. To be able to use the potential of CRs for breeding, plant chromosome engineering was initiated by fragmenting chromosomes by X-ray irradiation. With the rise of the CRISPR/Cas system, it became possible to induce double-strand breaks (DSBs) in a highly efficient manner at will at any chromosomal position. This has enabled a completely new level of predesigned chromosome engineering. The genetic linkage between specific genes can be broken by inducing chromosomal translocations. Natural inversions, which suppress genetic exchange, can be reverted for breeding. In addition, various approaches for constructing minichromosomes by downsizing regular standard A or supernumerary B chromosomes, which could serve as future vectors in plant biotechnology, have been developed. Recently, a functional synthetic centromere could be constructed. Also, different ways of genome haploidization have been set up, some based on centromere manipulations. In the future, we expect to see even more complex rearrangements, which can be combined with previously developed engineering technologies such as recombinases. Chromosome engineering might help to redefine genetic linkage groups, change the number of chromosomes, stack beneficial genes on mini cargo chromosomes, or set up genetic isolation to avoid outcrossing.
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Affiliation(s)
- Holger Puchta
- Joseph Gottlieb Kölreuter Institute for Plant Sciences (JKIP) - Molecular Biology, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Andreas Houben
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Seeland, Germany
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Finseth F. Female meiotic drive in plants: mechanisms and dynamics. Curr Opin Genet Dev 2023; 82:102101. [PMID: 37633231 DOI: 10.1016/j.gde.2023.102101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/10/2023] [Accepted: 07/22/2023] [Indexed: 08/28/2023]
Abstract
Female meiosis is fundamentally asymmetric, creating an arena for genetic elements to compete for inclusion in the egg to maximize their transmission. Centromeres, as mediators of chromosomal segregation, are prime candidates to evolve via 'female meiotic drive'. According to the centromere-drive model, the asymmetry of female meiosis ignites a coevolutionary arms race between selfish centromeres and kinetochore proteins, the by-product of which is accelerated sequence divergence. Here, I describe and compare plant models that have been instrumental in uncovering the mechanistic basis of female meiotic drive (maize) and the dynamics of active selfish centromeres in nature (monkeyflowers). Then, I speculate on the mechanistic basis of drive in monkeyflowers, discuss how centromere strength influences chromosomal segregation in plants, and describe new insights into the evolution of plant centromeres.
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Affiliation(s)
- Findley Finseth
- W.M. Keck Science Department, Claremont McKenna, Scripps, and Pitzer Colleges, Claremont, CA 91711, USA.
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Mo W, Shu Y, Liu B, Long Y, Li T, Cao X, Deng X, Zhai J. Single-molecule targeted accessibility and methylation sequencing of centromeres, telomeres and rDNAs in Arabidopsis. NATURE PLANTS 2023; 9:1439-1450. [PMID: 37599304 DOI: 10.1038/s41477-023-01498-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 07/24/2023] [Indexed: 08/22/2023]
Abstract
The short read-length of next-generation sequencing makes it challenging to characterize highly repetitive regions (HRRs) such as centromeres, telomeres and ribosomal DNAs. Based on recent strategies that combined long-read sequencing and exogenous enzymatic labelling of open chromatin, we developed single-molecule targeted accessibility and methylation sequencing (STAM-seq) in plants by further integrating nanopore adaptive sampling to investigate the HRRs in wild-type Arabidopsis and DNA methylation mutants that are defective in CG- or non-CG methylation. We found that CEN180 repeats show higher chromatin accessibility and lower DNA methylation on their forward strand, individual rDNA units show a negative correlation between their DNA methylation and accessibility, and both accessibility and CHH methylation levels are lower at telomere compared to adjacent subtelomeric region. Moreover, DNA methylation-deficient mutants showed increased chromatin accessibility at HRRs, consistent with the role of DNA methylation in maintaining heterochromatic status in plants. STAM-seq can be applied to study accessibility and methylation of repetitive sequences across diverse plant species.
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Affiliation(s)
- Weipeng Mo
- Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Yi Shu
- Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Bo Liu
- Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Yanping Long
- Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Tong Li
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Xiaofeng Cao
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xian Deng
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
| | - Jixian Zhai
- Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China.
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