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Abstract
The plant haploid generation is specified late in higher plant development, and post-meiotic haploid plant cells divide mitotically to produce a haploid gametophyte, in which a subset of cells differentiates into the gametes. The immediate mother of the angiosperm seed is the female gametophyte, also called the embryo sac. In most flowering plants the embryo sac is comprised of two kinds of gametes (egg and central cell) and two kinds of subsidiary cells (antipodals and synergids) all of which descend from a single haploid spore produced by meiosis. The embryo sac develops within a specialized organ of the flower called the ovule, which supports and controls many steps in the development of both the embryo sac and the seed. Double fertilization of the central cell and egg cell by the two sperm cells of a pollen grain produce the endosperm and embryo of the seed, respectively. The endosperm and embryo develop under the influence of their precursor gametes and the surrounding tissues of the ovule and the gametophyte. The final size and pattern of the angiosperm seed then is the result of complex interactions across multiple tissues of three different generations (maternal sporophyte, maternal gametophyte, and the fertilization products) and three different ploidies (haploid gametophyte, diploid parental sporophyte and embryo, and triploid endosperm).
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52
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Evolution, Initiation, and Diversity in Early Plant Embryogenesis. Dev Cell 2019; 50:533-543. [DOI: 10.1016/j.devcel.2019.07.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 06/07/2019] [Accepted: 07/07/2019] [Indexed: 11/22/2022]
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53
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Zhou S, Jiang W, Zhao Y, Zhou DX. Single-cell three-dimensional genome structures of rice gametes and unicellular zygotes. NATURE PLANTS 2019; 5:795-800. [PMID: 31332313 DOI: 10.1038/s41477-019-0471-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 06/11/2019] [Indexed: 06/10/2023]
Abstract
Chromatin conformation capture (3C)1 and high-throughput 3C (Hi-C)2 assays allow the study of three-dimensional (3D) genome structures in cell populations or tissues, based on average proximities of folded DNA. However, differences between cells can be observed only by single-cell measurements that avoid ensemble averaging3-5. To study 3D chromatin organization and dynamics before and after fertilization in flowering plants, we analysed the 3D genomes of rice eggs, sperm cells, unicellular zygotes and shoot mesophyll cells. We show that chromatin architectures of rice eggs and sperm cells are comparable to those of mesophyll cells and are reorganized after fertilization. The rice single-cell 3D genomes display specific features of chromosome compartments and telomere/centromere configuration compared to those in mammalian single cells. Active and silent chromatin domains combine to form multiple foci in the nuclear space. Notably, the 3D genomes of the eggs and unicellular zygotes contain a compact silent centre (CSC) that is absent in sperm cells. CSC appears to be reorganized after fertilization, and may be involved in the regulation of zygotic genome activation (ZGA). Our results reveal specific 3D genome features of plant gametes and the unicellular zygote, and provide a spatial chromatin basis for ZGA and epigenetic regulation in plants.
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Affiliation(s)
- Shaoli Zhou
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Wei Jiang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Yu Zhao
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Dao-Xiu Zhou
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
- Institute of Plant Science of Paris-Saclay, CNRS, INRA, Université Paris-Sud, Université Paris-Saclay, Orsay, France.
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54
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Ohnishi Y, Kokubu I, Kinoshita T, Okamoto T. Sperm Entry into the Egg Cell Induces the Progression of Karyogamy in Rice Zygotes. PLANT & CELL PHYSIOLOGY 2019; 60:1656-1665. [PMID: 31076767 DOI: 10.1093/pcp/pcz077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 04/16/2019] [Indexed: 05/11/2023]
Abstract
Karyogamy is a prerequisite event for plant embryogenesis, in which dynamic changes in nuclear architecture and the establishment of appropriate gene expression patterns must occur. However, the precise role of the male and female gametes in the progression of karyogamy still remains elusive. Here, we show that the sperm cell possesses the unique property to drive steady and swift nuclear fusion. When we fertilized egg cells with sperm cells in vitro, the immediate fusion of the male and female nuclei in the zygote progressed. This rapid nuclear fusion did not occur when two egg cells were artificially fused. However, the nuclear fusion of two egg nuclei could be accelerated by additional sperm entry or the exogenous application of calcium, suggesting that possible increase of cytosolic Ca2+ level via sperm entry into the egg cell efficiently can facilitate karyogamy. In contrast to zygotes, the egg-egg fusion cells failed to proliferate beyond an early developmental stage. Our transcriptional analyses also revealed the rapid activation of zygotic genes in zygotes, whereas there was no expression in fused cells without the male contribution. Thus, the male sperm cell has the ability to cause immediate karyogamy and to establish appropriate gene expression patterns in the zygote.
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Affiliation(s)
- Yukinosuke Ohnishi
- Department of Biological Sciences, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji, Tokyo, Japan
- Kihara Institute for Biological Research, Yokohama City University, Maioka 641-12, Totsuka, Yokohama, Kanagawa, Japan
| | - Iwao Kokubu
- Department of Biological Sciences, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji, Tokyo, Japan
| | - Tetsu Kinoshita
- Kihara Institute for Biological Research, Yokohama City University, Maioka 641-12, Totsuka, Yokohama, Kanagawa, Japan
| | - Takashi Okamoto
- Department of Biological Sciences, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji, Tokyo, Japan
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55
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Zhao P, Zhou X, Shen K, Liu Z, Cheng T, Liu D, Cheng Y, Peng X, Sun MX. Two-Step Maternal-to-Zygotic Transition with Two-Phase Parental Genome Contributions. Dev Cell 2019; 49:882-893.e5. [DOI: 10.1016/j.devcel.2019.04.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/13/2019] [Accepted: 04/11/2019] [Indexed: 10/26/2022]
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56
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Rahman MH, Toda E, Kobayashi M, Kudo T, Koshimizu S, Takahara M, Iwami M, Watanabe Y, Sekimoto H, Yano K, Okamoto T. Expression of Genes from Paternal Alleles in Rice Zygotes and Involvement of OsASGR-BBML1 in Initiation of Zygotic Development. PLANT & CELL PHYSIOLOGY 2019; 60:725-737. [PMID: 30801122 DOI: 10.1093/pcp/pcz030] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 02/07/2019] [Indexed: 05/11/2023]
Abstract
Upon fertilization in angiosperms, one sperm cell fuses with the egg cell to produce a zygote, and, via karyogamy, the parental genetic information is combined to form the diploid zygotic genome. Recently, analyses with parentally imbalanced rice zygotes indicated that parental genomes are utilized synergistically in zygotes with different functions, and that genes transcribed from the paternal or maternal allele might play important roles in zygotic development. Herein, we first conducted single nucleotide polymorphism-based mRNA-sequencing using intersubspecific rice zygotes. Twenty-three genes, with paternal allele-specific expression in zygotes, were identified, and, surprisingly, their allele dependencies in the globular-like embryo tended to be biallelic. This suggests that the paternal-dependent expression of these genes is temporary, occurring during the early stages of zygote development. Of the 23 genes, we focused on Oryza sativa Apospory-specific Genome Region (ASGR)-BABY-BOOM LIKE (BBML) 1 (OsASGR-BBML1), presumed to encode an AP2-transcription factor, due to its reported role in zygotic development. Interestingly, ectopic expression of OsASGR-BBML1 in egg cells induced nuclear and cell divisions, indicating that exogenously expressed OsASGR-BBML1 converts the proliferation status of the egg cell from quiescent to active. In addition, the suppression of the function of OsASGR-BBML1 and its homologs in zygotes resulted in the developmental arrest, suggesting that OsASGR-BBML1 possesses an important role in initiating zygotic development. Monoallelic or preferential gene expression from the paternal genome in the zygote might be a safety mechanism allowing egg cells to suppress the gene expression cascade toward early embryogenesis that is normally triggered by fusion with a sperm cell.
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Affiliation(s)
- Md Hassanur Rahman
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Erika Toda
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | | | - Toru Kudo
- Department of Life Sciences, Meiji University, Kanagawa, Japan
| | | | - Mirei Takahara
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Momoka Iwami
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Yoriko Watanabe
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Hiroyuki Sekimoto
- Department of Chemical and Biological Sciences, Japan Women's University, Tokyo, Japan
| | - Kentaro Yano
- Department of Life Sciences, Meiji University, Kanagawa, Japan
| | - Takashi Okamoto
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
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57
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Kalinowska K, Chamas S, Unkel K, Demidov D, Lermontova I, Dresselhaus T, Kumlehn J, Dunemann F, Houben A. State-of-the-art and novel developments of in vivo haploid technologies. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2019; 132:593-605. [PMID: 30569366 PMCID: PMC6439148 DOI: 10.1007/s00122-018-3261-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 12/05/2018] [Indexed: 05/02/2023]
Abstract
The ability to generate (doubled) haploid plants significantly accelerates the crop breeding process. Haploids have been induced mainly through the generation of plants from cultivated gametophic (haploid) cells and tissues, i.e., in vitro haploid technologies, or through the selective loss of a parental chromosome set upon inter- or intraspecific hybridization. Here, we focus our review on the mechanisms responsible for the in vivo formation of haploids in the context of inter- and intraspecific hybridization. The application of a modified CENH3 for uniparental genome elimination, the IG1 system used for paternal as well as the BBM-like and the patatin-like phospholipase essential for maternal haploidy induction are discussed in detail.
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Affiliation(s)
- Kamila Kalinowska
- Biochemie-Zentrum Regensburg, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Sindy Chamas
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, 06466, Stadt Seeland, Germany
| | - Katharina Unkel
- Institute for Breeding Research on Horticultural Crops, Federal Research Centre for Cultivated Plants, Julius Kühn-Institute (JKI), Erwin-Baur-Str. 27, 06484, Quedlinburg, Germany
| | - Dmitri Demidov
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, 06466, Stadt Seeland, Germany
| | - Inna Lermontova
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, 06466, Stadt Seeland, Germany
| | - Thomas Dresselhaus
- Biochemie-Zentrum Regensburg, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Jochen Kumlehn
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, 06466, Stadt Seeland, Germany
| | - Frank Dunemann
- Institute for Breeding Research on Horticultural Crops, Federal Research Centre for Cultivated Plants, Julius Kühn-Institute (JKI), Erwin-Baur-Str. 27, 06484, Quedlinburg, Germany
| | - Andreas Houben
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, 06466, Stadt Seeland, Germany.
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58
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Li C, Xu H, Russell SD, Sundaresan V. Step-by-step protocols for rice gamete isolation. PLANT REPRODUCTION 2019; 32:5-13. [PMID: 30756188 DOI: 10.1007/s00497-019-00363-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/28/2019] [Indexed: 06/09/2023]
Abstract
A detailed, step-by-step protocol for isolation of rice gametes for transcriptional profiling, with a general workflow that includes controls for RNA contamination from surrounding cells and tissues is presented. Characterization of the transcriptome and other -omics studies of flowering plant gametes are challenging as a consequence of the small sizes and relative inaccessibility of these cells. Collecting such poorly represented cells is also complicated by potential contamination from surrounding sporophytic, adjacent gametophytic tissues and difficulties in extracting high-quality intact cells. Here we present detailed, step-by-step procedures for collecting intact, unfixed rice (Oryza sativa) egg cells and sperm cells without enzymatic treatments. In addition, we also present a general workflow for assessing sample purity by RT-PCR, using primers specific for marker genes preferentially expressed in surrounding cells and tissues. These protocols should facilitate future studies of genome-scale characterization of gametes in this important model crop.
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Affiliation(s)
- Chenxin Li
- Department of Plant Biology, University of California, Davis, CA, 95616, USA
| | - Hengping Xu
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Scott D Russell
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA.
| | - Venkatesan Sundaresan
- Department of Plant Biology, University of California, Davis, CA, 95616, USA.
- Department of Plant Sciences, University of California, Davis, CA, 95616, USA.
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59
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Affiliation(s)
- Matthew R. Willmann
- Plant Transformation Facility, Cornell University, School of Integrative Plant Science, Ithaca, New York
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60
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Ueda M, Berger F. New cues for body axis formation in plant embryos. CURRENT OPINION IN PLANT BIOLOGY 2019; 47:16-21. [PMID: 30223185 DOI: 10.1016/j.pbi.2018.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/28/2018] [Accepted: 08/28/2018] [Indexed: 06/08/2023]
Abstract
Plant embryogenesis initiates with the fusion of sperm and egg cell, and completes the generation of the basic outline of the future plant. Here, we summarize the recent findings about the signaling cascade triggering the zygotic transcription, and the intracellular events and regulatory factors involved in the formation of the two major body axes. We highlight the lack of systematic de novo transcriptional activation in the zygote, and emphasize the importance of cytoskeletal reorganization to polarize the zygote and control the first asymmetric division that establishes the apical-basal axis. Finally, the limited knowledge of mechanisms that control the cell divisions separating the inner and outer cell layers is summarized and we propose approaches to enhance our understanding of basic principles of plant embryogenesis.
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Affiliation(s)
- Minako Ueda
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan; Institute of Transformative Bio-Molecules (ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan.
| | - Frédéric Berger
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
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61
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Wang Y. Engineering stable heterosis. J Genet Genomics 2019; 46:1-3. [DOI: 10.1016/j.jgg.2019.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 01/09/2019] [Indexed: 12/27/2022]
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62
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Armenta-Medina A, Gillmor CS. Genetic, molecular and parent-of-origin regulation of early embryogenesis in flowering plants. Curr Top Dev Biol 2019; 131:497-543. [DOI: 10.1016/bs.ctdb.2018.11.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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63
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Vijverberg K, Ozias-Akins P, Schranz ME. Identifying and Engineering Genes for Parthenogenesis in Plants. FRONTIERS IN PLANT SCIENCE 2019; 10:128. [PMID: 30838007 PMCID: PMC6389702 DOI: 10.3389/fpls.2019.00128] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 01/24/2019] [Indexed: 05/16/2023]
Abstract
Parthenogenesis is the spontaneous development of an embryo from an unfertilized egg cell. It naturally occurs in a variety of plant and animal species. In plants, parthenogenesis usually is found in combination with apomeiosis (the omission of meiosis) and pseudogamous or autonomous (with or without central cell fertilization) endosperm formation, together known as apomixis (clonal seed production). The initiation of embryogenesis in vivo and in vitro has high potential in plant breeding methods, particularly for the instant production of homozygous lines from haploid gametes [doubled haploids (DHs)], the maintenance of vigorous F1-hybrids through clonal seed production after combining it with apomeiosis, reverse breeding approaches, and for linking diploid and polyploid gene pools. Because of this large interest, efforts to identify gene(s) for parthenogenesis from natural apomicts have been undertaken by using map-based cloning strategies and comparative gene expression studies. In addition, engineering parthenogenesis in sexual model species has been investigated via mutagenesis and gain-of-function strategies. These efforts have started to pay off, particularly by the isolation of the PsASGR-BabyBoom-Like from apomictic Pennisetum, a gene proven to be transferable to and functional in sexual pearl millet, rice, and maize. This review aims to summarize the current knowledge on parthenogenesis, the possible gene candidates also outside the grasses, and the use of these genes in plant breeding protocols. It shows that parthenogenesis is able to inherit and function independently from apomeiosis and endosperm formation, is expressed and active in the egg cell, and can induce embryogenesis in polyploid, diploid as well as haploid egg cells in plants. It also shows the importance of genes involved in the suppression of transcription and modifications thereof at one hand, and in embryogenesis for which transcription is allowed or artificially overexpressed on the other, in parthenogenetic reproduction. Finally, it emphasizes the importance of functional endosperm to allow for successful embryo growth and viable seed production.
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Affiliation(s)
- Kitty Vijverberg
- Biosystematics Group, Experimental Plant Sciences, Wageningen University and Research, Wageningen, Netherlands
- *Correspondence: Kitty Vijverberg,
| | - Peggy Ozias-Akins
- Department of Horticulture, Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Tifton Campus, Tifton, GA, United States
| | - M. Eric Schranz
- Biosystematics Group, Experimental Plant Sciences, Wageningen University and Research, Wageningen, Netherlands
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64
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van Nocker S. Hybrids without hybridization-can it revolutionize horticulture? HORTICULTURE RESEARCH 2018; 5:76. [PMID: 30588321 PMCID: PMC6303291 DOI: 10.1038/s41438-018-0113-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 12/17/2018] [Indexed: 06/09/2023]
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65
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Khanday I, Skinner D, Yang B, Mercier R, Sundaresan V. A male-expressed rice embryogenic trigger redirected for asexual propagation through seeds. Nature 2018; 565:91-95. [PMID: 30542157 DOI: 10.1038/s41586-018-0785-8] [Citation(s) in RCA: 208] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/29/2018] [Indexed: 11/09/2022]
Abstract
The molecular pathways that trigger the initiation of embryogenesis after fertilization in flowering plants, and prevent its occurrence without fertilization, are not well understood1. Here we show in rice (Oryza sativa) that BABY BOOM1 (BBM1), a member of the AP2 family2 of transcription factors that is expressed in sperm cells, has a key role in this process. Ectopic expression of BBM1 in the egg cell is sufficient for parthenogenesis, which indicates that a single wild-type gene can bypass the fertilization checkpoint in the female gamete. Zygotic expression of BBM1 is initially specific to the male allele but is subsequently biparental, and this is consistent with its observed auto-activation. Triple knockout of the genes BBM1, BBM2 and BBM3 causes embryo arrest and abortion, which are fully rescued by male-transmitted BBM1. These findings suggest that the requirement for fertilization in embryogenesis is mediated by male-genome transmission of pluripotency factors. When genome editing to substitute mitosis for meiosis (MiMe)3,4 is combined with the expression of BBM1 in the egg cell, clonal progeny can be obtained that retain genome-wide parental heterozygosity. The synthetic asexual-propagation trait is heritable through multiple generations of clones. Hybrid crops provide increased yields that cannot be maintained by their progeny owing to genetic segregation. This work establishes the feasibility of asexual reproduction in crops, and could enable the maintenance of hybrids clonally through seed propagation5,6.
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Affiliation(s)
- Imtiyaz Khanday
- Department of Plant Biology, University of California, Davis, CA, USA.,Innovative Genomics Institute, Berkeley, CA, USA
| | - Debra Skinner
- Department of Plant Biology, University of California, Davis, CA, USA
| | - Bing Yang
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, USA
| | - Raphael Mercier
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
| | - Venkatesan Sundaresan
- Department of Plant Biology, University of California, Davis, CA, USA. .,Innovative Genomics Institute, Berkeley, CA, USA. .,Department of Plant Sciences, University of California, Davis, CA, USA.
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66
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Begcy K, Dresselhaus T. Epigenetic responses to abiotic stresses during reproductive development in cereals. PLANT REPRODUCTION 2018; 31:343-355. [PMID: 29943158 PMCID: PMC6244825 DOI: 10.1007/s00497-018-0343-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 06/22/2018] [Indexed: 05/03/2023]
Abstract
KEY MESSAGE Overview of current understanding of epigenetic alterations after abiotic stresses during reproductive development in cereals. Abiotic stresses, including heat, drought, cold, flooding, and salinity, negatively impact crop productivity. Various stages during reproductive development are especially sensitive to environmental stresses, which may lead to complete sterility and severe yield losses. Plants exhibit diverse responses to ameliorate stress damage. Changes in DNA methylation, histone modification as well as regulation of small RNA and long noncoding RNA pathways have been shown to represent key modulators in plant stress responses. During reproductive development in cereals, various protein complexes controlling histone and DNA methylation have been identified, revealing conserved and novel mechanisms regulating abiotic stress responses in cereals and other plant species. New findings highlight the role of transposable elements during stress periods. Here, we review our current understanding of epigenetic stress responses during male and female gametophyte formation (germline development), fertilization, early seed devolvement, and seed maturation in cereals. An integrative model of epigenetic responses during reproductive development in cereals is proposed, emphasizing the role of DNA methylation and histone modifications during abiotic stresses.
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Affiliation(s)
- Kevin Begcy
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, 93053, Regensburg, Germany.
| | - Thomas Dresselhaus
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, 93053, Regensburg, Germany.
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67
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Hwang YS, Seo M, Kim SK, Bang S, Kim H, Han JY. Zygotic gene activation in the chicken occurs in two waves, the first involving only maternally derived genes. eLife 2018; 7:39381. [PMID: 30375976 PMCID: PMC6242549 DOI: 10.7554/elife.39381] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 10/29/2018] [Indexed: 12/11/2022] Open
Abstract
The first wave of transcriptional activation occurs after fertilisation in a species-specific pattern. Despite its importance to initial embryonic development, the characteristics of transcription following fertilisation are poorly understood in Aves. Here, we report detailed insights into the onset of genome activation in chickens. We established that two waves of transcriptional activation occurred, one shortly after fertilisation and another at Eyal-Giladi and Kochav Stage V. We found 1544 single nucleotide polymorphisms across 424 transcripts derived from parents that were expressed in offspring during the early embryonic stages. Surprisingly, only the maternal genome was activated in the zygote, and the paternal genome remained silent until the second-wave, regardless of the presence of a paternal pronucleus or supernumerary sperm in the egg. The identified maternal genes involved in cleavage that were replaced by bi-allelic expression. The results demonstrate that only maternal alleles are activated in the chicken zygote upon fertilisation, which could be essential for early embryogenesis and evolutionary outcomes in birds. The early stages of animal development involve a handover of genetic control. Initially, the egg cell is maintained by genetic information inherited from the mother, but soon after fertilization it starts to depend on its own genes instead. Activating genes inside the fertilized egg cell (zygote) so that they can take control of development is known as zygotic genome activation. Despite the fact that birds are often used to study how embryos develop, zygotic genome activation in birds is not well understood. Fertilization in birds, including chickens, is different to mammals in that it requires multiple sperm to fertilize an egg cell. As such, zygotic genome activation in birds is likely to differ from that in mammals. By examining gene expression in embryos from mixed-breed chickens, Hwang, Seo et al. showed that there are two stages of zygotic genome activation in chickens. The genes derived from the mother become active in the first stage, while genes from the father become active in the second stage. Genome activation in birds is therefore very different to the same process in mammals, which involves genome activation of both parents from the first stage. This extra level of control may help to prevent genetic complications resulting from the presence of multiple sperm, each of which carries a different set of genes from the father.
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Affiliation(s)
- Young Sun Hwang
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea.,Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Minseok Seo
- C&K Genomics, Seoul, Republic of Korea.,Channing Division of Network Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, United States
| | - Sang Kyung Kim
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea.,Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | | | - Heebal Kim
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea.,Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea.,C&K Genomics, Seoul, Republic of Korea
| | - Jae Yong Han
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea.,Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
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68
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Abstract
This review by Figueiredo and Köhler describes the molecular mechanisms driving seed development. They review the role of the hormone auxin for the initial development of the three seed structures and as a trigger of fertilization-independent seed development. The evolution of seeds defines a remarkable landmark in the history of land plants. A developing seed contains three genetically distinct structures: the embryo, the nourishing tissue, and the seed coat. While fertilization is necessary to initiate seed development in most plant species, apomicts have evolved mechanisms allowing seed formation independently of fertilization. Despite their socio–economical relevance, the molecular mechanisms driving seed development have only recently begun to be understood. Here we review the current knowledge on the role of the hormone auxin for the initial development of the three seed structures and as a trigger of fertilization-independent seed development.
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Affiliation(s)
- Duarte D Figueiredo
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala SE-750 07, Sweden
| | - Claudia Köhler
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala SE-750 07, Sweden
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Anderson SN, Springer NM. Potential roles for transposable elements in creating imprinted expression. Curr Opin Genet Dev 2018; 49:8-14. [DOI: 10.1016/j.gde.2018.01.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 01/25/2018] [Accepted: 01/29/2018] [Indexed: 10/18/2022]
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