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Valero-Rubira I, Castillo AM, Burrell MÁ, Vallés MP. Microspore embryogenesis induction by mannitol and TSA results in a complex regulation of epigenetic dynamics and gene expression in bread wheat. Front Plant Sci 2023; 13:1058421. [PMID: 36699843 PMCID: PMC9868772 DOI: 10.3389/fpls.2022.1058421] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 12/07/2022] [Indexed: 06/17/2023]
Abstract
Reprogramming of microspores development towards embryogenesis mediated by stress treatment constitutes the basis of doubled haploid production. Recently, compounds that alter histone post-translational modifications (PTMs) have been reported to enhance microspore embryogenesis (ME), by altering histones acetylation or methylation. However, epigenetic mechanisms underlying ME induction efficiency are poorly understood. In this study, the epigenetic dynamics and the expression of genes associated with histone PTMs and ME induction were studied in two bread wheat cultivars with different ME response. Microspores isolated at 0, 3 and 5 days, treated with 0.7M mannitol (MAN) and 0.7M mannitol plus 0.4µM trichostatin A (TSA), which induced ME more efficiently, were analyzed. An additional control of gametophytic development was included. Microspores epigenetic state at the onset of ME induction was distinctive between cultivars by the ratio of H3 variants and their acetylated forms, the localization and percentage of labeled microspores with H3K9ac, H4K5ac, H4K16ac, H3K9me2 and H3K27me3, and the expression of genes related to pollen development. These results indicated that microspores of the high responding cultivar could be at a less advanced stage in pollen development. MAN and TSA resulted in a hyperacetylation of H3.2, with a greater effect of TSA. Histone PTMs were differentially affected by both treatments, with acetylation being most concerned. The effect of TSA was observed in the H4K5ac localization pattern at 3dT in the mid-low responding cultivar. Three gene networks linked to ME response were identified. TaHDT1, TaHAG2, TaYAO, TaNFD6-A, TabZIPF1 and TaAGO802-B, associated with pollen development, were down-regulated. TaHDA15, TaHAG3, TaHAM, TaYUC11D, Ta-2B-LBD16 TaMS1 and TaDRM3 constituted a network implicated in morphological changes by auxin signaling and cell wall modification up-regulated at 3dT. The last network included TaHDA18, TaHAC1, TaHAC4, TaABI5, TaATG18fD, TaSDG1a-7A and was related to ABA and ethylene hormone signaling pathways, DNA methylation and autophagy processes, reaching the highest expression at 5dT. The results indicated that TSA mainly modified the regulation of genes related to pollen and auxin signaling. This study represents a breakthrough in identifying the epigenetic dynamics and the molecular mechanisms governing ME induction efficiency, with relevance to recalcitrant wheat genotypes and other crops.
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Affiliation(s)
- Isabel Valero-Rubira
- Departamento de Genética y Producción Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (EEAD-CSIC), Zaragoza, Spain
| | - Ana María Castillo
- Departamento de Genética y Producción Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (EEAD-CSIC), Zaragoza, Spain
| | - María Ángela Burrell
- Departamento de Patología, Anatomía y Fisiología, Facultad de Ciencias, Universidad de Navarra, Pamplona, Spain
| | - Maria Pilar Vallés
- Departamento de Genética y Producción Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (EEAD-CSIC), Zaragoza, Spain
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Finnegan EJ, Robertson M, Helliwell CA. Resetting FLOWERING LOCUS C Expression After Vernalization Is Just Activation in the Early Embryo by a Different Name. Front Plant Sci 2021; 11:620155. [PMID: 33519879 PMCID: PMC7838089 DOI: 10.3389/fpls.2020.620155] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 12/08/2020] [Indexed: 05/29/2023]
Abstract
The reproductive success of many plants depends on their capacity to respond appropriately to their environment. One environmental cue that triggers flowering is the extended cold of winter, which promotes the transition from vegetative to reproductive growth in a response known as vernalization. In annual plants of the Brassicaceae, the floral repressor, FLOWERING LOCUS C (FLC), is downregulated by exposure to low temperatures. Repression is initiated during winter cold and then maintained as the temperature rises, allowing plants to complete their life cycle during spring and summer. The two stages of FLC repression, initiation and maintenance, are distinguished by different chromatin states at the FLC locus. Initiation involves the removal of active chromatin marks and the deposition of the repressive mark H3K27me3 over a few nucleosomes in the initiation zone, also known as the nucleation region. H3K27me3 then spreads to cover the entire locus, in a replication dependent manner, to maintain FLC repression. FLC is released from repression in the next generation, allowing progeny of a vernalized plant to respond to winter. Activation of FLC in this generation has been termed resetting to denote the restoration of the pre-vernalized state in the progeny of a vernalized plant. It has been assumed that resetting must differ from the activation of FLC expression in progeny of plants that have not experienced winter cold. Considering that there is now strong evidence indicating that chromatin undergoes major modifications during both male and female gametogenesis, it is time to challenge this assumption.
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Pecinka A, Chevalier C, Colas I, Kalantidis K, Varotto S, Krugman T, Michailidis C, Vallés MP, Muñoz A, Pradillo M. Chromatin dynamics during interphase and cell division: similarities and differences between model and crop plants. J Exp Bot 2020; 71:5205-5222. [PMID: 31626285 DOI: 10.1093/jxb/erz457] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 09/30/2019] [Indexed: 06/10/2023]
Abstract
Genetic information in the cell nucleus controls organismal development and responses to the environment, and finally ensures its own transmission to the next generations. To achieve so many different tasks, the genetic information is associated with structural and regulatory proteins, which orchestrate nuclear functions in time and space. Furthermore, plant life strategies require chromatin plasticity to allow a rapid adaptation to abiotic and biotic stresses. Here, we summarize current knowledge on the organization of plant chromatin and dynamics of chromosomes during interphase and mitotic and meiotic cell divisions for model and crop plants differing as to genome size, ploidy, and amount of genomic resources available. The existing data indicate that chromatin changes accompany most (if not all) cellular processes and that there are both shared and unique themes in the chromatin structure and global chromosome dynamics among species. Ongoing efforts to understand the molecular mechanisms involved in chromatin organization and remodeling have, together with the latest genome editing tools, potential to unlock crop genomes for innovative breeding strategies and improvements of various traits.
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Affiliation(s)
- Ales Pecinka
- Institute of Experimental Botany, Czech Acad Sci, Centre of the Region Haná for Agricultural and Biotechnological Research, Olomouc, Czech Republic
| | | | - Isabelle Colas
- James Hutton Institute, Cell and Molecular Science, Pr Waugh's Lab, Invergowrie, Dundee, UK
| | - Kriton Kalantidis
- Department of Biology, University of Crete, and Institute of Molecular Biology Biotechnology, FoRTH, Heraklion, Greece
| | - Serena Varotto
- Department of Agronomy Animal Food Natural Resources and Environment (DAFNAE) University of Padova, Agripolis viale dell'Università, Legnaro (PD), Italy
| | - Tamar Krugman
- Institute of Evolution, University of Haifa, Haifa, Israel
| | - Christos Michailidis
- Institute of Experimental Botany, Czech Acad Sci, Praha 6 - Lysolaje, Czech Republic
| | - María-Pilar Vallés
- Department of Genetics and Plant Breeding, Estación Experimental Aula Dei (EEAD), Spanish National Research Council (CSIC), Zaragoza, Spain
| | - Aitor Muñoz
- Department of Plant Molecular Genetics, National Center of Biotechnology/Superior Council of Scientific Research, Autónoma University of Madrid, Madrid, Spain
| | - Mónica Pradillo
- Department of Genetics, Physiology and Microbiology, Faculty of Biology, Complutense University of Madrid, Madrid, Spain
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Abstract
In this chapter we describe protocols for immunolabeling and FISH of pollen grains undergoing postmeiotic mitosis using Aegilops speltoides, Secale cereale, and Hordeum vulgare as models. Tissue sectioning of pollen overcomes the problem of the pollen grain wall impermeability that interferes with immunolocalization and in situ hybridization. The crucial element of the protocol is the generation and immobilization of tissue sections. Our method facilitates the investigation of the microspore cell divisions and pollen grain maturation.
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Affiliation(s)
- Dan D Wu
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Stadt Seeland, Germany
- Triticeae Research Institute, Sichuan Agricultural University, Wenjiang, China
| | - Alevtina Ruban
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Stadt Seeland, Germany
| | - Twan Rutten
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Stadt Seeland, Germany
| | - Yong H Zhou
- Triticeae Research Institute, Sichuan Agricultural University, Wenjiang, China
| | - Andreas Houben
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Stadt Seeland, Germany.
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5
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Abstract
The reproductive adaptations of land plants have played a key role in their terrestrial colonization and radiation. This encompasses mechanisms used for the production, dispersal and union of gametes to support sexual reproduction. The production of small motile male gametes and larger immotile female gametes (oogamy) in specialized multicellular gametangia evolved in the charophyte algae, the closest extant relatives of land plants. Reliance on water and motile male gametes for sexual reproduction was retained by bryophytes and basal vascular plants, but was overcome in seed plants by the dispersal of pollen and the guided delivery of non-motile sperm to the female gametes. Here we discuss the evolutionary history of male gametogenesis in streptophytes (green plants) and the underlying developmental biology, including recent advances in bryophyte and angiosperm models. We conclude with a perspective on research trends that promise to deliver a deeper understanding of the evolutionary and developmental mechanisms of male gametogenesis in plants.
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Affiliation(s)
- Dieter Hackenberg
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom.
| | - David Twell
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom.
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Pandey P, Daghma DS, Houben A, Kumlehn J, Melzer M, Rutten T. Dynamics of post-translationally modified histones during barley pollen embryogenesis in the presence or absence of the epi-drug trichostatin A. Plant Reprod 2017; 30:95-105. [PMID: 28526911 DOI: 10.1007/s00497-017-0302-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 05/11/2017] [Indexed: 05/11/2023]
Abstract
Improving pollen embryogenesis. Despite the agro-economic importance of pollen embryogenesis, the mechanisms underlying this process are still poorly understood. We describe the dynamics of chromatin modifications (histones H3K4me2, H3K9ac, H3K9me2, and H3K27me3) and chromatin marks (RNA polymerase II CDC phospho-Ser5, and CENH3) during barley pollen embryogenesis. Immunolabeling results show that, in reaction to stress, immature pollen rapidly starts reorganizing several important chromatin modifications indicative of a change in cell fate. This new chromatin modification pattern was accomplished within 24 h from whereon it remained unaltered during subsequent mitotic activity. This indicates that cell fate transition, the central element of pollen embryogenesis, is completed early on during the induction process. Application of the histone deacetylase inhibitor trichostatin A stimulated pollen embryogenesis when used on pollen with a gametophytic style chromatin pattern. However, when this drug was administered to embryogenic pollen, the chromatin markers reversed toward a gametophytic profile, embryogenesis was halted and all pollen invariably died.
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Affiliation(s)
- Pooja Pandey
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
- Imperial College London, London, UK
| | - Diaa S Daghma
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
- Institute for Experimental Trauma Surgery, Justus-Liebig University of Giessen, Giessen, Germany
| | - Andreas Houben
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
| | - Jochen Kumlehn
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
| | - Michael Melzer
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
| | - Twan Rutten
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany.
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Sharma SK, Yamamoto M, Mukai Y. Distinct chromatin environment associated with phosphorylated H3S10 histone during pollen mitosis I in orchids. Protoplasma 2017; 254:161-165. [PMID: 26769710 DOI: 10.1007/s00709-015-0925-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 12/07/2015] [Indexed: 06/05/2023]
Abstract
Pollen developmental pathway in plants involving synchronized transferal of cellular divisions from meiosis (microsporogenesis) to mitosis (pollen mitosis I/II) eventually offers a unique "meiosis-mitosis shift" at pollen mitosis I. Since the cell type (haploid microspore) and fate of pollen mitosis I differ from typical mitosis (in meristem cells), it is immensely important to analyze the chromosomal distribution of phosphorylated H3S10 histone during atypical pollen mitosis I to comprehend the role of histone phosphorylation in pollen development. We investigated the chromosomal phosphorylation of H3S10 histone during pollen mitosis I in orchids using immunostaining technique. The chromosomal distribution of H3S10ph during pollen mitosis I revealed differential pattern than that of typical mitosis in plants, however, eventually following the similar trends of mitosis in animals where H3S10 phosphorylation begins in the pericentromeric regions first, later extending to the whole chromosomes, and finally declining at anaphase/early cytokinesis (differentiation of vegetative and generative cells). The study suggests that the chromosomal distribution of H3S10ph during cell division is not universal and can be altered between different cell types encoded for diverse cellular processes. During pollen development, phosphorylation of histone might play a critical role in chromosome condensation events throughout pollen mitosis I in plants.
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Affiliation(s)
- Santosh Kumar Sharma
- Laboratory of Plant Molecular Genetics, Division of Natural Sciences, Osaka Kyoiku University, Kashiwara, Osaka, 582-8582, Japan.
| | - Maki Yamamoto
- Department of Rehabilitation Sciences, Kansai University of Welfare Sciences, Kashiwara, Osaka, Japan
| | - Yasuhiko Mukai
- Laboratory of Plant Molecular Genetics, Division of Natural Sciences, Osaka Kyoiku University, Kashiwara, Osaka, 582-8582, Japan
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8
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Yang H, Yang N, Wang T. Proteomic analysis reveals the differential histone programs between male germline cells and vegetative cells in Lilium davidii. Plant J 2016; 85:660-674. [PMID: 26846354 DOI: 10.1111/tpj.13133] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 01/12/2016] [Accepted: 01/25/2016] [Indexed: 06/05/2023]
Abstract
In flowering plants, male germline fate is determined after asymmetric division of the haploid microspore. Daughter cells have distinct fates: the generative cell (GC) undergoes further mitosis to generate sperm cells (SCs), and the vegetative cell (VC) terminally differentiates. However, our understanding of the mechanisms underlying germline development remains limited. Histone variants and modifications define chromatin states, and contribute to establishing and maintaining cell identities by affecting gene expression. Here, we constructed a lily protein database, then extracted and detailed histone entries into a comprehensive lily histone database. We isolated large amounts of nuclei from VCs, GCs and SCs from lily, and profiled histone variants of all five histone families in all three cell types using proteomics approaches. We revealed 92 identities representing 32 histone variants: six for H1, 11 for H2A, eight for H2B, five for H3 and two for H4. Nine variants, including five H1, two H2B, one H3 and one H4 variant, specifically accumulated in GCs and SCs. We also detected H3 modification patterns in the three cell types. GCs and SCs had almost identical histone profiles and similar H3 modification patterns, which were significantly different from those of VCs. Our study also revealed the presence of multiple isoforms, and differential expression patterns between isoforms of a variant. The results suggest that differential histone programs between the germline and companion VCs may be established following the asymmetric division, and are important for identity establishment and differentiation of the male germline as well as the VC.
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Affiliation(s)
- Hao Yang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ning Yang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Tai Wang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
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9
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Borg M, Berger F. Chromatin remodelling during male gametophyte development. Plant J 2015; 83:177-188. [PMID: 25892182 DOI: 10.1111/tpj.12856] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 04/10/2015] [Accepted: 04/14/2015] [Indexed: 05/28/2023]
Abstract
The plant life cycle alternates between a diploid sporophytic phase and haploid gametophytic phase, with the latter giving rise to the gametes. Male gametophyte development encompasses two mitotic divisions that results in a simple three-celled structure knows as the pollen grain, in which two sperm cells are encased within a larger vegetative cell. Both cell types exhibit a very different type of chromatin organization - highly condensed in sperm cell nuclei and highly diffuse in the vegetative cell. Distinct classes of histone variants have dynamic and differential expression in the two cell lineages of the male gametophyte. Here we review how the dynamics of histone variants are linked to reprogramming of chromatin activities in the male gametophyte, compaction of the sperm cell genome and zygotic transitions post-fertilization.
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Affiliation(s)
- Michael Borg
- Gregor Mendel Institute, Vienna Biocenter, Dr. Bohr-Gasse 3, 1030, Vienna, Austria
| | - Frédéric Berger
- Gregor Mendel Institute, Vienna Biocenter, Dr. Bohr-Gasse 3, 1030, Vienna, Austria
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10
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Sharma SK, Yamamoto M, Mukai Y. Immuno-cytogenetic manifestation of epigenetic chromatin modification marks in plants. Planta 2015; 241:291-301. [PMID: 25539867 DOI: 10.1007/s00425-014-2233-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 12/16/2014] [Indexed: 05/26/2023]
Abstract
Histone proteins and the nucleosomes along with DNA are the essential components of eukaryotic chromatin. Post-translational histone-DNA interactions and modifications eventually offer significant alteration in the chromatin environment and potentially influence diverse fundamental biological processes, some of which are known to be epigenetically inherited and constitute the "epigenetic code". Such chromatin modifications evidently uncover remarkable diversity and biological specificity associated with distinct patterns of covalent histone marks. The past few years have witnessed major breakthroughs in plant biology research by utilizing chromatin modification-specific antibodies through molecular cytogenetic tools to ascertain hallmark signatures of chromatin domains on the chromosomes. Here, we survey current information on chromosomal distribution patterns of chromatin modifications with special emphasis on histone methylation, acetylation, phosphorylation, and centromere-specific histone 3 (CENH3) marks in plants using immuno-FISH as a basic tool. Major available information has been classified under typical and comparative cytogenetic detection of chromatin modifications in plants. Further, spatial distribution of chromatin environment that exists between different cell types such as angiosperm/gymnosperm, monocot/dicot, diploid/polyploids, vegetative/generative cells, as well as different stages, i.e., mitosis versus meiosis has also been discussed in detail. Several challenges and future perspectives of molecular cytogenetics in the grooming field of plant chromatin dynamics have also been addressed.
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Affiliation(s)
- Santosh Kumar Sharma
- Division of Natural Sciences, Laboratory of Plant Molecular Genetics, Osaka Kyoiku University, 4-698-1 Asahigaoka, Kashiwara, Osaka 582-8582, Japan,
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González-Sánchez M, Heredia V, Diez M, Puertas MJ. Rye B chromosomes influence the dynamics of histone H3 methylation during microgametogenesis. Cytogenet Genome Res 2014; 143:189-99. [PMID: 25096176 DOI: 10.1159/000365422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We have studied the trimethylation dynamics of lysines 4 and 27 of histone H3 in rye with and without B chromosomes (Bs) in root tip mitosis, meiosis, and pollen grain mitosis by immunostaining. In root meristems, H3K4me3 immunolabeling was homogeneous along the chromosome arms of the normal complement (As), with the exception of the pericentromeric and subtelomeric regions which were unlabeled. On the contrary, a signal was observed on the long arm of the B chromosome, in the region where most of the B-specific repeats are located. H3K27me3 immunosignals were observed on the subtelomeric heterochromatic region of the As and the Bs and some interstitial bands of the As. Thus, the terminal region of the Bs showed both signals, whereas the subtelomeric region of the As showed H3K27me3 immunosignals only. During meiosis and first pollen grain mitosis, the immunosignals were observed distributed as in the root tip mitosis in plants with or without Bs. However, we observed remarkable changes in the immunolabeling patterns during the second pollen grain mitosis between 0B and +B plants. In 0B plants, H3K4me3 immunosignals were similarly distributed in the vegetative and generative nuclei. In B-carrying plants, the vegetative nucleus showed a lighter signal than the generative one. In 0B plants, all nuclei of the microgametophyte showed H3K27me3 immunosignals. In B-carrying plants, the generative nucleus and, correspondingly, the second metaphase, anaphase, and sperm nuclei did not show any signal. When the Bs were lost as micronuclei, they did not show any H3K4me3 or H3K27me3 signal. Most remarkably, Bs are able to change the pattern of H3 methylation on K4 and K27 during the second pollen mitosis, resulting in differently labeled sperm nuclei in 0 and +B plants.
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El-Tantawy AA, Solís MT, Risueño MC, Testillano PS. Changes in DNA methylation levels and nuclear distribution patterns after microspore reprogramming to embryogenesis in barley. Cytogenet Genome Res 2014; 143:200-8. [PMID: 25074410 DOI: 10.1159/000365232] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Under specific stress treatments, the microspore can be induced in vitro to deviate from its gametophytic development and to reprogram towards embryogenesis, becoming a totipotent cell and forming haploid embryos. These can further regenerate homozygous plants for production of new isogenic lines, an important biotechnological tool for crop breeding. DNA methylation constitutes a prominent epigenetic modification of the chromatin fiber which regulates gene expression. Changes in DNA methylation accompany the reorganization of the nuclear architecture during plant cell differentiation and proliferation; however, the relationship between global DNA methylation and genome-wide expression patterns is still poorly understood. In this work, the dynamics of global DNA methylation levels and distribution patterns were analyzed during microspore reprogramming to embryogenesis and during pollen development in Hordeum vulgare. Quantification of global DNA methylation levels and 5-methyl-deoxycytidine (5mdC) immunofluorescence were conducted at specific stages of pollen development and after reprogramming to embryogenesis to analyze the epigenetic changes that accompany the change of developmental program and cell fate. The results showed low DNA methylation levels in microspores and a high increase along pollen development and maturation; an intense 5mdC signal was concentrated in the generative and sperm nuclei whereas the vegetative nucleus exhibited a weaker DNA methylation signal. After inductive stress treatment, low methylation levels and faint 5mdC signals were observed in nuclei of reprogrammed microspores and 2-4-cell proembryos. This data revealed a global DNA hypomethylation during the change of the developmental program and first embryogenic divisions. This is in contrast with the hypermethylation of generative and sperm cells of the male germline during pollen maturation, suggesting an epigenetic regulation after induction of microspore embryogenesis. At later embryogenesis stages, global DNA methylation progressively increased, accompanying embryo development and differentiation events like in zygotic embryos, corroborating that DNA methylation is critical for the regulation of gene expression in microspore embryogenesis.
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Affiliation(s)
- Ahmed-Abdalla El-Tantawy
- Pollen Biotechnology of Crop Plants Group, Centro de Investigaciones Biológicas, (CIB) CSIC, Madrid, Spain
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Abstract
Senescence processes are part of the plant developmental programme. They involve reprogramming of gene expression and are under the control of a complex regulatory network closely linked to other developmental and stress-responsive pathways. Recent evidence indicates that leaf senescence is regulated via epigenetic mechanisms. In the present review, the epigenetic control of plant senescence is discussed in the broader context of environment-sensitive plant development. The review outlines the concept of epigenetic control of interconnected regulatory pathways steering stress responses and plant development. Besides giving an overview of techniques used in the field, it summarizes recent findings on global alterations in chromatin structure, histone and DNA modifications, and ATP-dependent chromatin remodelling during plant senescence and linked processes.
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Affiliation(s)
- Nicole Ay
- Department of Plant Physiology, Institute of Biology, Martin-Luther University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle, Germany
| | - Bianka Janack
- Department of Plant Physiology, Institute of Biology, Martin-Luther University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle, Germany
| | - Klaus Humbeck
- Department of Plant Physiology, Institute of Biology, Martin-Luther University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle, Germany
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She W, Grimanelli D, Baroux C. An efficient method for quantitative, single-cell analysis of chromatin modification and nuclear architecture in whole-mount ovules in Arabidopsis. J Vis Exp 2014:e51530. [PMID: 24998753 PMCID: PMC4195603 DOI: 10.3791/51530] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
In flowering plants, the somatic-to-reproductive cell fate transition is marked by the specification of spore mother cells (SMCs) in floral organs of the adult plant. The female SMC (megaspore mother cell, MMC) differentiates in the ovule primordium and undergoes meiosis. The selected haploid megaspore then undergoes mitosis to form the multicellular female gametophyte, which will give rise to the gametes, the egg cell and central cell, together with accessory cells. The limited accessibility of the MMC, meiocyte and female gametophyte inside the ovule is technically challenging for cytological and cytogenetic analyses at single cell level. Particularly, direct or indirect immunodetection of cellular or nuclear epitopes is impaired by poor penetration of the reagents inside the plant cell and single-cell imaging is demised by the lack of optical clarity in whole-mount tissues. Thus, we developed an efficient method to analyze the nuclear organization and chromatin modification at high resolution of single cell in whole-mount embedded Arabidopsis ovules. It is based on dissection and embedding of fixed ovules in a thin layer of acrylamide gel on a microscopic slide. The embedded ovules are subjected to chemical and enzymatic treatments aiming at improving tissue clarity and permeability to the immunostaining reagents. Those treatments preserve cellular and chromatin organization, DNA and protein epitopes. The samples can be used for different downstream cytological analyses, including chromatin immunostaining, fluorescence in situ hybridization (FISH), and DNA staining for heterochromatin analysis. Confocal laser scanning microscopy (CLSM) imaging, with high resolution, followed by 3D reconstruction allows for quantitative measurements at single-cell resolution.
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Affiliation(s)
- Wenjing She
- Institute of Plant Biology and Zürich-Basel Plant Science Center, University of Zürich
| | - Daniel Grimanelli
- Institut de Recherche pour le Développement (UMR 232), Centre National de la Recherche Scientifique (ERL 5300), Université de Montpellier II
| | - Célia Baroux
- Institute of Plant Biology and Zürich-Basel Plant Science Center, University of Zürich;
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