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Závodník M, Pavlištová V, Machelová A, Lyčka M, Mozgová I, Caklová K, Dvořáčková M, Fajkus J. KU70 and CAF-1 in Arabidopsis: Divergent roles in rDNA stability and telomere homeostasis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 118:1922-1936. [PMID: 38493352 DOI: 10.1111/tpj.16718] [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: 09/26/2023] [Revised: 02/07/2024] [Accepted: 02/29/2024] [Indexed: 03/18/2024]
Abstract
Deficiency in chromatin assembly factor-1 (CAF-1) in plants through dysfunction of its components, FASCIATA1 and 2 (FAS1, FAS2), leads to the specific and progressive loss of rDNA and telomere repeats in plants. This loss is attributed to defective repair mechanisms for the increased DNA breaks encountered during replication, a consequence of impaired replication-dependent chromatin assembly. In this study, we explore the role of KU70 in these processes. Our findings reveal that, although the rDNA copy number is reduced in ku70 mutants when compared with wild-type plants, it is not markedly affected by diverse KU70 status in fas1 mutants. This is consistent with our previous characterisation of rDNA loss in fas mutants as a consequence part of the single-strand annealing pathway of homology-dependent repair. In stark contrast to rDNA, KU70 dysfunction fully suppresses the loss of telomeres in fas1 plants and converts telomeres to their elongated and heterogeneous state typical for ku70 plants. We conclude that the alternative telomere lengthening pathway, known to be activated in the absence of KU70, overrides progressive telomere loss due to CAF-1 dysfunction.
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Affiliation(s)
- Michal Závodník
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Brno, CZ-62500, Czech Republic
- Department of Cell Biology and Radiobiology, Institute of Biophysics of the Czech Academy of Sciences, v.v.i., Brno, CZ-61265, Czech Republic
| | - Veronika Pavlištová
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Brno, CZ-62500, Czech Republic
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
| | - Adéla Machelová
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Brno, CZ-62500, Czech Republic
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
| | - Martin Lyčka
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Brno, CZ-62500, Czech Republic
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
| | - Iva Mozgová
- Biology Centre, Czech Academy of Sciences, Institute of Plant Molecular Biology, České Budějovice, Czech Republic
- University of South Bohemia, Faculty of Science, České Budějovice, Czech Republic
| | - Karolína Caklová
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
| | - Martina Dvořáčková
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Brno, CZ-62500, Czech Republic
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
| | - Jiří Fajkus
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Brno, CZ-62500, Czech Republic
- Department of Cell Biology and Radiobiology, Institute of Biophysics of the Czech Academy of Sciences, v.v.i., Brno, CZ-61265, Czech Republic
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
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Vaquero-Sedas MI, Vega-Palas MA. Epigenetic nature of Arabidopsis thaliana telomeres. PLANT PHYSIOLOGY 2023; 191:47-55. [PMID: 36218957 PMCID: PMC9806604 DOI: 10.1093/plphys/kiac471] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 09/22/2022] [Indexed: 05/15/2023]
Abstract
The epigenetic features of defined chromosomal domains condition their biochemical and functional properties. Therefore, there is considerable interest in studying the epigenetic marks present at relevant chromosomal loci. Telomeric regions, which include telomeres and subtelomeres, have been traditionally considered heterochromatic. However, whereas the heterochromatic nature of subtelomeres has been widely accepted, the epigenetic status of telomeres remains controversial. Here, we studied the epigenetic features of Arabidopsis (Arabidopsis thaliana) telomeres by analyzing multiple genome-wide ChIP-seq experiments. Our analyses revealed that Arabidopsis telomeres are not significantly enriched either in euchromatic marks like H3K4me2, H3K9ac, and H3K27me3 or in heterochromatic marks such as H3K27me1 and H3K9me2. Thus, telomeric regions in Arabidopsis have a bimodal chromatin organization with telomeres lacking significant levels of canonical euchromatic and heterochromatic marks followed by heterochromatic subtelomeres. Since heterochromatin is known to influence telomere function, the heterochromatic modifications present at Arabidopsis subtelomeres could play a relevant role in telomere biology.
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Affiliation(s)
- María I Vaquero-Sedas
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, IBVF (CSIC-US), Seville E41092, Spain
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Konečná K, Sováková PP, Anteková K, Fajkus J, Fojtová M. Distinct Responses of Arabidopsis Telomeres and Transposable Elements to Zebularine Exposure. Int J Mol Sci 2021; 22:ijms22010468. [PMID: 33466545 PMCID: PMC7796508 DOI: 10.3390/ijms22010468] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 12/21/2020] [Accepted: 12/28/2020] [Indexed: 12/17/2022] Open
Abstract
Involvement of epigenetic mechanisms in the regulation of telomeres and transposable elements (TEs), genomic regions with the protective and potentially detrimental function, respectively, has been frequently studied. Here, we analyzed telomere lengths in Arabidopsis thaliana plants of Columbia, Landsberg erecta and Wassilevskija ecotypes exposed repeatedly to the hypomethylation drug zebularine during germination. Shorter telomeres were detected in plants growing from seedlings germinated in the presence of zebularine with a progression in telomeric phenotype across generations, relatively high inter-individual variability, and diverse responses among ecotypes. Interestingly, the extent of telomere shortening in zebularine Columbia and Wassilevskija plants corresponded to the transcriptional activation of TEs, suggesting a correlated response of these genomic elements to the zebularine treatment. Changes in lengths of telomeres and levels of TE transcripts in leaves were not always correlated with a hypomethylation of cytosines located in these regions, indicating a cytosine methylation-independent level of their regulation. These observations, including differences among ecotypes together with distinct dynamics of the reversal of the disruption of telomere homeostasis and TEs transcriptional activation, reflect a complex involvement of epigenetic processes in the regulation of crucial genomic regions. Our results further demonstrate the ability of plant cells to cope with these changes without a critical loss of the genome stability.
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Affiliation(s)
- Klára Konečná
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute for Technology (CEITEC), Masaryk University, Kamenice 5, CZ-62500 Brno, Czech Republic; (K.K.); (P.P.S.); (K.A.); (J.F.)
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic
| | - Pavla Polanská Sováková
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute for Technology (CEITEC), Masaryk University, Kamenice 5, CZ-62500 Brno, Czech Republic; (K.K.); (P.P.S.); (K.A.); (J.F.)
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic
| | - Karin Anteková
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute for Technology (CEITEC), Masaryk University, Kamenice 5, CZ-62500 Brno, Czech Republic; (K.K.); (P.P.S.); (K.A.); (J.F.)
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic
| | - Jiří Fajkus
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute for Technology (CEITEC), Masaryk University, Kamenice 5, CZ-62500 Brno, Czech Republic; (K.K.); (P.P.S.); (K.A.); (J.F.)
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, CZ-61265 Brno, Czech Republic
| | - Miloslava Fojtová
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute for Technology (CEITEC), Masaryk University, Kamenice 5, CZ-62500 Brno, Czech Republic; (K.K.); (P.P.S.); (K.A.); (J.F.)
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, CZ-61265 Brno, Czech Republic
- Correspondence: ; Tel.: +420-54949-8063
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Aguilar M, Prieto P. Telomeres and Subtelomeres Dynamics in the Context of Early Chromosome Interactions During Meiosis and Their Implications in Plant Breeding. FRONTIERS IN PLANT SCIENCE 2021; 12:672489. [PMID: 34149773 PMCID: PMC8212018 DOI: 10.3389/fpls.2021.672489] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 05/06/2021] [Indexed: 05/08/2023]
Abstract
Genomic architecture facilitates chromosome recognition, pairing, and recombination. Telomeres and subtelomeres play an important role at the beginning of meiosis in specific chromosome recognition and pairing, which are critical processes that allow chromosome recombination between homologs (equivalent chromosomes in the same genome) in later stages. In plant polyploids, these terminal regions are even more important in terms of homologous chromosome recognition, due to the presence of homoeologs (equivalent chromosomes from related genomes). Although telomeres interaction seems to assist homologous pairing and consequently, the progression of meiosis, other chromosome regions, such as subtelomeres, need to be considered, because the DNA sequence of telomeres is not chromosome-specific. In addition, recombination operates at subtelomeres and, as it happens in rye and wheat, homologous recognition and pairing is more often correlated with recombining regions than with crossover-poor regions. In a plant breeding context, the knowledge of how homologous chromosomes initiate pairing at the beginning of meiosis can contribute to chromosome manipulation in hybrids or interspecific genetic crosses. Thus, recombination in interspecific chromosome associations could be promoted with the aim of transferring desirable agronomic traits from related genetic donor species into crops. In this review, we summarize the importance of telomeres and subtelomeres on chromatin dynamics during early meiosis stages and their implications in recombination in a plant breeding framework.
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Affiliation(s)
- Miguel Aguilar
- Área de Fisiología Vegetal, Universidad de Córdoba, Córdoba, Spain
| | - Pilar Prieto
- Plant Breeding Department, Institute for Sustainable Agriculture, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Córdoba, Spain
- *Correspondence: Pilar Prieto, ; orcid.org/0000-0002-8160-808X
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Adamusová K, Khosravi S, Fujimoto S, Houben A, Matsunaga S, Fajkus J, Fojtová M. Two combinatorial patterns of telomere histone marks in plants with canonical and non-canonical telomere repeats. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 102:678-687. [PMID: 31834959 DOI: 10.1111/tpj.14653] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 11/21/2019] [Accepted: 11/28/2019] [Indexed: 05/24/2023]
Abstract
Telomeres, nucleoprotein structures at the ends of linear eukaryotic chromosomes, are crucial for the maintenance of genome integrity. In most plants, telomeres consist of conserved tandem repeat units comprising the TTTAGGG motif. Recently, non-canonical telomeres were described in several plants and plant taxons, including the carnivorous plant Genlisea hispidula (TTCAGG/TTTCAGG), the genus Cestrum (Solanaceae; TTTTTTAGGG), and plants from the Asparagales order with either a vertebrate-type telomere repeat TTAGGG or Allium genus-specific CTCGGTTATGGG repeat. We analyzed epigenetic modifications of telomeric histones in plants with canonical and non-canonical telomeres, and further in telomeric chromatin captured from leaves of Nicotiana benthamiana transiently transformed by telomere CRISPR-dCas9-eGFP, and of Arabidopsis thaliana stably transformed with TALE_telo C-3×GFP. Two combinatorial patterns of telomeric histone modifications were identified: (i) an Arabidopsis-like pattern (A. thaliana, G. hispidula, Genlisea nigrocaulis, Allium cepa, Narcissus pseudonarcissus, Petunia hybrida, Solanum tuberosum, Solanum lycopersicum) with telomeric histones decorated predominantly by H3K9me2; (ii) a tobacco-like pattern (Nicotiana tabacum, N. benthamiana, C. elegans) with a strong H3K27me3 signal. Our data suggest that epigenetic modifications of plant telomere-associated histones are related neither to the sequence of the telomere motif nor to the lengths of the telomeres. Nor the phylogenetic position of the species plays the role; representatives of the Solanaceae family are included in both groups. As both patterns of histone marks are compatible with fully functional telomeres in respective plants, we conclude that the described specific differences in histone marks are not critical for telomere functions.
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Affiliation(s)
- Kateřina Adamusová
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, 625 00, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, 611 37, Brno, Czech Republic
| | - Solmaz Khosravi
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, 06466, Seeland, Germany
| | - Satoru Fujimoto
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Andreas Houben
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, 06466, Seeland, Germany
| | - Sachihiro Matsunaga
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Jiří Fajkus
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, 625 00, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, 611 37, Brno, Czech Republic
| | - Miloslava Fojtová
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, 625 00, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, 611 37, Brno, Czech Republic
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Udroiu I, Sgura A. Alternative Lengthening of Telomeres and Chromatin Status. Genes (Basel) 2019; 11:genes11010045. [PMID: 31905921 PMCID: PMC7016797 DOI: 10.3390/genes11010045] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 12/22/2019] [Accepted: 12/23/2019] [Indexed: 12/16/2022] Open
Abstract
Telomere length is maintained by either telomerase, a reverse transcriptase, or alternative lengthening of telomeres (ALT), a mechanism that utilizes homologous recombination (HR) proteins. Since access to DNA for HR enzymes is regulated by the chromatin status, it is expected that telomere elongation is linked to epigenetic modifications. The aim of this review is to elucidate the epigenetic features of ALT-positive cells. In order to do this, it is first necessary to understand the telomeric chromatin peculiarities. So far, the epigenetic nature of telomeres is still controversial: some authors describe them as heterochromatic, while for others, they are euchromatic. Similarly, ALT activity should be characterized by the loss (according to most researchers) or formation (as claimed by a minority) of heterochromatin in telomeres. Besides reviewing the main works in this field and the most recent findings, some hypotheses involving the role of telomere non-canonical sequences and the possible spatial heterogeneity of telomeres are given.
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Telomeres in Plants and Humans: Not So Different, Not So Similar. Cells 2019; 8:cells8010058. [PMID: 30654521 PMCID: PMC6356271 DOI: 10.3390/cells8010058] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 01/07/2019] [Accepted: 01/07/2019] [Indexed: 01/01/2023] Open
Abstract
Parallel research on multiple model organisms shows that while some principles of telomere biology are conserved among all eukaryotic kingdoms, we also find some deviations that reflect different evolutionary paths and life strategies, which may have diversified after the establishment of telomerase as a primary mechanism for telomere maintenance. Much more than animals, plants have to cope with environmental stressors, including genotoxic factors, due to their sessile lifestyle. This is, in principle, made possible by an increased capacity and efficiency of the molecular systems ensuring maintenance of genome stability, as well as a higher tolerance to genome instability. Furthermore, plant ontogenesis differs from that of animals in which tissue differentiation and telomerase silencing occur during early embryonic development, and the “telomere clock” in somatic cells may act as a preventive measure against carcinogenesis. This does not happen in plants, where growth and ontogenesis occur through the serial division of apical meristems consisting of a small group of stem cells that generate a linear series of cells, which differentiate into an array of cell types that make a shoot and root. Flowers, as generative plant organs, initiate from the shoot apical meristem in mature plants which is incompatible with the human-like developmental telomere shortening. In this review, we discuss differences between human and plant telomere biology and the implications for aging, genome stability, and cell and organism survival. In particular, we provide a comprehensive comparative overview of telomere proteins acting in humans and in Arabidopsis thaliana model plant, and discuss distinct epigenetic features of telomeric chromatin in these species.
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