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Flores-Tornero M, Proost S, Mutwil M, Scutt CP, Dresselhaus T, Sprunck S. Transcriptomics of manually isolated Amborella trichopoda egg apparatus cells. PLANT REPRODUCTION 2019; 32:15-27. [PMID: 30707279 DOI: 10.1007/s00497-019-00361-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 01/09/2019] [Indexed: 05/27/2023]
Abstract
A protocol for the isolation of egg apparatus cells from the basal angiosperm Amborella trichopoda to generate RNA-seq data for evolutionary studies of fertilization-associated genes. Sexual reproduction is particularly complex in flowering plants (angiosperms). Studies in eudicot and monocot model species have significantly contributed to our knowledge on cell fate specification of gametophytic cells and on the numerous cellular communication events necessary to deliver the two sperm cells into the embryo sac and to accomplish double fertilization. However, for a deeper understanding of the evolution of these processes, morphological, genomic and gene expression studies in extant basal angiosperms are inevitable. The basal angiosperm Amborella trichopoda is of special importance for evolutionary studies, as it is likely sister to all other living angiosperms. Here, we report about a method to isolate Amborella egg apparatus cells and on genome-wide gene expression profiles in these cells. Our transcriptomics data revealed Amborella-specific genes and genes conserved in eudicots and monocots. Gene products include secreted proteins, such as small cysteine-rich proteins previously reported to act as extracellular signaling molecules with important roles during double fertilization. The detection of transcripts encoding EGG CELL 1 (EC1) and related prolamin-like family proteins in Amborella egg cells demonstrates the potential of the generated data set to study conserved molecular mechanisms and the evolution of fertilization-related genes and their encoded proteins.
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Affiliation(s)
- María Flores-Tornero
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Sebastian Proost
- Max-Planck Institute for Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam, Germany
- Laboratory of Molecular Bacteriology (Rega Institute), KU Leuven, Louvain, Belgium
| | - Marek Mutwil
- Max-Planck Institute for Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam, Germany
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
| | - Charles P Scutt
- Laboratoire Reproduction et Développement des Plantes, École Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, INRA, Université de Lyon, Lyon, France
| | - Thomas Dresselhaus
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Stefanie Sprunck
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany.
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Schmid MW, Schmidt A, Grossniklaus U. The female gametophyte: an emerging model for cell type-specific systems biology in plant development. FRONTIERS IN PLANT SCIENCE 2015; 6:907. [PMID: 26579157 PMCID: PMC4630298 DOI: 10.3389/fpls.2015.00907] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 10/10/2015] [Indexed: 05/03/2023]
Abstract
Systems biology, a holistic approach describing a system emerging from the interactions of its molecular components, critically depends on accurate qualitative determination and quantitative measurements of these components. Development and improvement of large-scale profiling methods ("omics") now facilitates comprehensive measurements of many relevant molecules. For multicellular organisms, such as animals, fungi, algae, and plants, the complexity of the system is augmented by the presence of specialized cell types and organs, and a complex interplay within and between them. Cell type-specific analyses are therefore crucial for the understanding of developmental processes and environmental responses. This review first gives an overview of current methods used for large-scale profiling of specific cell types exemplified by recent advances in plant biology. The focus then lies on suitable model systems to study plant development and cell type specification. We introduce the female gametophyte of flowering plants as an ideal model to study fundamental developmental processes. Moreover, the female reproductive lineage is of importance for the emergence of evolutionary novelties such as an unequal parental contribution to the tissue nurturing the embryo or the clonal production of seeds by asexual reproduction (apomixis). Understanding these processes is not only interesting from a developmental or evolutionary perspective, but bears great potential for further crop improvement and the simplification of breeding efforts. We finally highlight novel methods, which are already available or which will likely soon facilitate large-scale profiling of the specific cell types of the female gametophyte in both model and non-model species. We conclude that it may take only few years until an evolutionary systems biology approach toward female gametogenesis may decipher some of its biologically most interesting and economically most valuable processes.
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Affiliation(s)
| | | | - Ueli Grossniklaus
- Department of Plant & Microbial Biology and Zurich-Basel Plant Science Center, University of ZurichZurich, Switzerland
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Abiko M, Maeda H, Tamura K, Hara-Nishimura I, Okamoto T. Gene expression profiles in rice gametes and zygotes: identification of gamete-enriched genes and up- or down-regulated genes in zygotes after fertilization. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:1927-40. [PMID: 23570690 PMCID: PMC3638821 DOI: 10.1093/jxb/ert054] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
In angiosperms, fertilization and subsequent zygotic development occur in embryo sacs deeply embedded in the ovaries; therefore, these processes are poorly elucidated. In this study, microarray-based transcriptome analyses were conducted on rice sperm cells, egg cells, and zygotes isolated from flowers to identify candidate genes involved in gametic and/or early zygotic development. Cell type-specific transcriptomes were obtained, and up- or down-regulated genes in zygotes after fertilization were identified, in addition to genes enriched in male and female gametes. A total of 325 putatively up-regulated and 94 putatively down-regulated genes in zygotes were obtained. Interestingly, several genes encoding homeobox proteins or transcription factors were identified as highly up-regulated genes after fertilization, and the gene ontology for up-regulated genes was highly enriched in functions related to chromatin/DNA organization and assembly. Because a gene encoding methyltransferase 1 was identified as a highly up-regulated gene in zygotes after fertilization, the effect of an inhibitor of this enzyme on zygote development was monitored. The inhibitor appeared partially to affect polarity or division asymmetry in rice zygotes, but it did not block normal embryo generation.
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Affiliation(s)
- Mafumi Abiko
- Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo 192–0397, Japan
| | - Hiroki Maeda
- Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo 192–0397, Japan
| | - Kentaro Tamura
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606–8502, Japan
| | - Ikuko Hara-Nishimura
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606–8502, Japan
| | - Takashi Okamoto
- Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo 192–0397, Japan
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4
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Techniques of cell type-specific transcriptome analysis and applications in researches of sexual plant reproduction. ACTA ACUST UNITED AC 2011. [DOI: 10.1007/s11515-011-1090-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Kawano N, Susaki D, Sasaki N, Higashiyama T, Kanaoka MM. Isolation of Gametophytic Cells and Identification of Their Cell-Specific Markers in Torenia fournieri, T. concolor and Lindernia micrantha. CYTOLOGIA 2011. [DOI: 10.1508/cytologia.76.177] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Nao Kawano
- Division of Biological Science, Graduate School of Science, Nagoya University
| | - Daichi Susaki
- Division of Biological Science, Graduate School of Science, Nagoya University
| | - Narie Sasaki
- Division of Biological Science, Graduate School of Science, Nagoya University
| | - Tetsuya Higashiyama
- Division of Biological Science, Graduate School of Science, Nagoya University
- ERATO Live-Holonics Project, Japan Science and Technology Agency (JST)
| | - Masahiro M. Kanaoka
- Division of Biological Science, Graduate School of Science, Nagoya University
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Okamoto T. In vitro fertilization with rice gametes: production of zygotes and zygote and embryo culture. Methods Mol Biol 2011; 710:17-27. [PMID: 21207258 DOI: 10.1007/978-1-61737-988-8_2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
In vitro fertilization (IVF) systems using isolated male and female gametes have been utilized to dissect fertilization-induced events in angiosperms, such as egg activation, zygote development, and early embryogenesis, since the female gametophytes of plants are deeply embedded within ovaries. A rice IVF system was established to take advantage of the abundant resources stemming from rice research for investigations into the mechanisms of fertilization and early embryogenesis. Fusion of gametes can be performed using electrofusion and the fusion product, a zygote, forms a cell wall and an additional nucleolus. The zygote divides into an asymmetric two-celled embryo and develops into an early globular embryo, as in planta. The embryo further develops into irregularly shaped cell masses and fertile plants can be regenerated from the cell masses. This rice IVF system is a powerful tool for studying the molecular mechanisms involved in the early embryogenesis of angiosperms and for making new cultivars.
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Affiliation(s)
- Takashi Okamoto
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan.
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Abstract
Methods have been developed to isolate gametes of higher plants and to fertilize them in vitro. Zygotes, embryos, fertile plants and endosperm can now be obtained from in vitro fusion of pairs of sperm and egg cells and of pairs of sperm and central cells, respectively. This allows examination of the earliest developmental processes precisely timed after fertilization. The isolated egg and central cell, fertilized and cultured in vitro, are able to self-organize apart from each other and without mother tissue in the typically manner. Thus, this system is a powerful and unique model for studies of early zygotic embryogenesis and endosperm development. The underlying processes are now comparatively studied in detail by investigations of expression of genes and their corresponding proteins. The use of these techniques opens new avenues in fundamental and applied research in the areas of developmental and reproductive plant biology.
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Affiliation(s)
- Erhard Kranz
- Biozentrum Klein Flottbek und Botanischer Garten, Entwicklungsbiologie und Biotechnologie, Ohnhorststr. 18, Universität Hamburg, 22609 Hamburg, Germany
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In vitro fertilization: analysis of early post-fertilization development using cytological and molecular techniques. ACTA ACUST UNITED AC 2007. [DOI: 10.1007/s00497-007-0060-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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9
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Uchiumi T, Uemura I, Okamoto T. Establishment of an in vitro fertilization system in rice (Oryza sativa L.). PLANTA 2007; 226:581-9. [PMID: 17361458 DOI: 10.1007/s00425-007-0506-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2006] [Accepted: 02/26/2007] [Indexed: 05/11/2023]
Abstract
In vitro fertilization (IVF) systems using isolated male and female gametes have been utilized to dissect fertilization-induced events in angiosperms, such as egg activation, zygote development and early embryogenesis, as the female gametophytes of plants are deeply embedded within ovaries. In this study, a rice IVF system was established to take advantage of the abundant resources stemming from rice research for investigations into the mechanisms of fertilization and early embryogenesis. Fusion of gametes was performed using a modified electrofusion method, and the fusion product, a zygote, formed cell wall and an additional nucleolus. The zygote divided into a two-celled embryo 15-24 h after fusion, and developed into a globular-like embryo consisting of an average of 15-16 cells by 48 h after fusion. Comparison of the developmental processes of zygotes produced by IVF with those of zygotes generated in planta suggested that zygotes produced by IVF develop and grow into early globular stage embryos in a highly similar manner to those in planta. Although the IVF-produced globular embryos did not develop into late globular-stage or differentiated embryos, but into irregularly shaped cell masses, fertile plants were regenerated from the cell masses and the seeds harvested from these plants germinated normally. The rice IVF system reported here will be a powerful tool for studying the molecular mechanisms involved in the early embryogenesis of angiosperms and for making new cultivars.
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Affiliation(s)
- Takao Uchiumi
- Department of Biological Sciences, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji, Tokyo 192-0397, Japan
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Hoshino Y, Murata N, Shinoda K. Isolation of individual egg cells and zygotes in Alstroemeria followed by manual selection with a microcapillary-connected micropump. ANNALS OF BOTANY 2006; 97:1139-44. [PMID: 16621859 PMCID: PMC2803394 DOI: 10.1093/aob/mcl072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2005] [Revised: 12/08/2005] [Accepted: 02/11/2006] [Indexed: 05/08/2023]
Abstract
AIMS To develop a procedure for isolating living egg cells and zygotes from Alstroemeria ovules. SCOPE An attempt was made to isolate egg cells and zygotes from the ovules of Alstroemeria aurea. The ovules were histologically observed using a clearing procedure which revealed the localization and sizes of the embryo sacs and egg apparatus within the ovules. For the isolation of egg cells, ovules were cut into sections with a surgical blade and treated with an enzyme solution. Subsequently, these ovule sections were dissected using a glass needle under an inverted microscope. Egg cells successfully isolated by this procedure were collected using microcapillaries connected to a micropump. For zygote isolation, ovules were excised from ovaries 24 h after self-pollination. By treating excised ovules with an enzyme solution and subsequently dissecting them using a glass needle, zygotes were successfully isolated from the ovules and collected with a microcapillary. The isolated zygotes were associated with pollen tubes and one of the synergids. Egg cells and zygotes were viable for up to 2 h following isolation, as determined by fluorescein diacetate staining. CONCLUSIONS The procedures for isolating egg cells and zygotes in Alstroemeria were established, and each egg cell and zygote was captured with a microcapillary.
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Affiliation(s)
- Yoichiro Hoshino
- Field Science Center for Northern Biosphere, Hokkaido University, Kita 11, Nishi 10, Sapporo 060-0811, Japan.
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Faure JE. Double fertilization in flowering plants: discovery, study methods and mechanisms. COMPTES RENDUS DE L'ACADEMIE DES SCIENCES. SERIE III, SCIENCES DE LA VIE 2001; 324:551-8. [PMID: 11455878 DOI: 10.1016/s0764-4469(01)01325-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The double fertilization of flowering plants was discovered a century ago. The cytology of the gametes is now well known. However the description of the fertilization steps is still poor and most of the cellular and molecular mechanisms involved are unknown. Recent research using in vitro fertilization demonstrated that the early steps of fertilization share some homology with those in animal species. In particular, gamete fusion is followed by a cytosolic calcium increase in the fertilized egg as well as a calcium influx. Further understanding of fertilization also comes from the analysis of mutants isolated in Arabidopsis thaliana. Important new ideas have already emerged from these studies such as the importance of the female gametophyte in embryo development, and an early silencing of the male genome during the first days following gamete fusion.
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Affiliation(s)
- J E Faure
- Ecole normale supérieure, Laboratory of Plant Reproduction and Development, UMR 5667 CNRS-Inra-ENS-Lyon-UCB-Lyon-I, 69364 Lyon, France.
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Holm PB, Olsen O, Schnorf M, Brinch-Pedersen H, Knudsen S. Transformation of barley by microinjection into isolated zygote protoplasts. Transgenic Res 2000; 9:21-32. [PMID: 10853266 DOI: 10.1023/a:1008974729597] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Barley zygote protoplasts were mechanically isolated, embedded in agarose droplets, and microinjected with a rice actin promoter Act1-gusA-nos gene construct. On average 62% of the cells survived the injection and of these 55% continued development into embryo-like structures and eventually to plants. PCR screening for the presence of a 307-bp fragment in the middle of the gusA gene showed that on average 21% of the derived structures contained this fragment. However, among the hundreds of injected zygotes, derived structures and regenerants we only found significant GUS expression in two cases (embryo-like structures nine days after injection). Two lines of green plants, derived from zygotes microinjected with linearized plasmid (line A147-1) or an isolated Act1-gusA-nos gene cassette (line A166-h) proved to be transgenic. Line A147-1 appeared to contain a single and intact copy of the expression cassette but a PCR based progeny analysis indicated the presence of additional shorter fragments of the cassette. Line A166-h appeared to contain a single fragment of the gusA gene that was transferred to the progeny as a single Mendelian trait. One additional fragment of the gusA gene was identified in this line. The present data show that transformation of barley by microinjection of DNA into isolated zygotes is feasible but also that gene expression rarely is achieved, possibly due to degradation of the introduced DNA.
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Affiliation(s)
- P B Holm
- Danish Institute of Agricultural Sciences, Department of Plant Biology, Research Centre Flakkebjerg, Slagelse, Denmark.
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