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Dresselhaus T, Jürgens G. Comparative Embryogenesis in Angiosperms: Activation and Patterning of Embryonic Cell Lineages. ANNUAL REVIEW OF PLANT BIOLOGY 2021; 72:641-676. [PMID: 33606951 DOI: 10.1146/annurev-arplant-082520-094112] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Following fertilization in flowering plants (angiosperms), egg and sperm cells unite to form the zygote, which generates an entire new organism through a process called embryogenesis. In this review, we provide a comparative perspective on early zygotic embryogenesis in flowering plants by using the Poaceae maize and rice as monocot grass and crop models as well as Arabidopsis as a eudicot model of the Brassicaceae family. Beginning with the activation of the egg cell, we summarize and discuss the process of maternal-to-zygotic transition in plants, also taking recent work on parthenogenesis and haploid induction into consideration. Aspects like imprinting, which is mainly associated with endosperm development and somatic embryogenesis, are not considered. Controversial findings about the timing of zygotic genome activation as well as maternal versus paternal contribution to zygote and early embryo development are highlighted. The establishment of zygotic polarity, asymmetric division, and apical and basal cell lineages represents another chapter in which we also examine and compare the role of major signaling pathways, cell fate genes, and hormones in early embryogenesis. Except for the model Arabidopsis, little is known about embryopatterning and the establishment of the basic body plan in angiosperms. Using available in situ hybridization, RNA-sequencing, and marker data, we try to compare how and when stem cell niches are established. Finally, evolutionary aspects of plant embryo development are discussed.
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Affiliation(s)
- Thomas Dresselhaus
- Department of Cell Biology and Plant Biochemistry, University of Regensburg, D-93053 Regensburg, Germany;
| | - Gerd Jürgens
- Department of Cell Biology, Max Planck Institute for Developmental Biology, D-72076 Tübingen, Germany
- Center for Plant Molecular Biology, University of Tübingen, D-72076 Tübingen, Germany;
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Zhang M, Xu X, Zheng Y, Zhang Y, Deng X, Luo S, Wu Q, Xu J, Zhang S. Expression of a plastid-localized sugar transporter in the suspensor is critical to embryogenesis. PLANT PHYSIOLOGY 2021; 185:1021-1038. [PMID: 33793862 PMCID: PMC8133565 DOI: 10.1093/plphys/kiaa084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 11/29/2020] [Indexed: 05/05/2023]
Abstract
Plant growth and development rely on sugar transport between source and sink cells and between different organelles. The plastid-localized sugar transporter GLUCOSE-6-PHOSPHATE TRANSLOCATER1 (GPT1) is an essential gene in Arabidopsis (Arabidopsis thaliana). Using a partially rescued gpt1 mutant and cell-specific RNAi suppression of GPT1, we demonstrated that GPT1 is essential to the function of the embryo suspensor and the development of the embryo. GPT1 showed a dynamic expression/accumulation pattern during embryogenesis. Inhibition of GPT1 accumulation via RNAi using a suspensor-specific promoter resulted in embryos and seedlings with defects similar to auxin mutants. Loss of function of GPT1 in the suspensor also led to abnormal/ectopic cell division in the lower part of the suspensor, which gave rise to an ectopic embryo, resulting in twin embryos in some seeds. Furthermore, loss of function of GPT1 resulted in vacuolar localization of PIN-FORMED1 (PIN1) and altered DR5 auxin activity. Proper localization of PIN1 on the plasma membrane is essential to polar auxin transport and distribution, a key determinant of pattern formation during embryogenesis. Our findings suggest that the function of GPT1 in the embryo suspensor is linked to sugar and/or hormone distribution between the embryo proper and the maternal tissues, and is important for maintenance of suspensor identity and function during embryogenesis.
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Affiliation(s)
- Mengmeng Zhang
- College of Plant Protection, The Key Laboratory of Plant Immunity, Nanjing Agriculture University, Nanjing 210095, China
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xuwen Xu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yueping Zheng
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yan Zhang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xiangxiong Deng
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Suan Luo
- College of Plant Protection, The Key Laboratory of Plant Immunity, Nanjing Agriculture University, Nanjing 210095, China
| | - Qiuping Wu
- College of Plant Protection, The Key Laboratory of Plant Immunity, Nanjing Agriculture University, Nanjing 210095, China
| | - Juan Xu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Shuqun Zhang
- Division of Biochemistry, University of Missouri, Columbia, MO 65211, USA
- Author for communication:
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Jacob D, Brian J. The short and intricate life of the suspensor. PHYSIOLOGIA PLANTARUM 2020; 169:110-121. [PMID: 31808953 DOI: 10.1111/ppl.13057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 11/04/2019] [Accepted: 12/04/2019] [Indexed: 06/10/2023]
Abstract
The suspensor is a short-lived tissue critical for proper embryonic development in many higher plants. While the tissue was initially thought to simply suspend the embryo in the endosperm, it has been found through decades of research that it serves multiple important purposes. The suspensor has been found to be vital for proper embryo patterning and numerous studies have been undertaken into the complex transcriptional cross-talk between the suspensor and the embryo proper. Indeed, many suspensor mutants also display abnormalities in the embryo. The suspensor's role as a nutrient conduit has been shown using ultrastructural and histochemical techniques. Biochemical approaches have found that the suspensor is a centre of early embryonic hormone production in several species. The suspensor has also been frequently used as a model for programmed cell death as it shows signs of termination almost immediately upon developing. This review covers the essential functions of the suspensor throughout its short existence from multiple disciplines including structural, genetic and biochemical perspectives.
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Affiliation(s)
- Downs Jacob
- Faculty of Science, University of Sydney, Sydney, NSW, 2006, Australia
| | - Jones Brian
- Faculty of Science, University of Sydney, Sydney, NSW, 2006, Australia
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Cell lineage-specific transcriptome analysis for interpreting cell fate specification of proembryos. Nat Commun 2020; 11:1366. [PMID: 32170064 PMCID: PMC7070050 DOI: 10.1038/s41467-020-15189-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 02/24/2020] [Indexed: 12/17/2022] Open
Abstract
In Arabidopsis, a zygote undergoes asymmetrical cell division that establishes the first two distinct cell types of early proembryos, apical and basal cells. However, the genome-wide transcriptional activities that guide divergence of apical and basal cell development remain unknown. Here, we present a comprehensive transcriptome analysis of apical and basal cell lineages, uncovering distinct molecular pathways during cell lineage specification. Selective deletion of inherited transcripts and specific de novo transcription contribute to the establishment of cell lineage-specific pathways for cell fate specification. Embryo-related pathways have been specifically activated in apical cell lineage since 1-cell embryo stage, but quick transcriptome remodeling toward suspensor-specific pathways are found in basal cell lineage. Furthermore, long noncoding RNAs and alternative splicing isoforms may be involved in cell lineage specification. This work also provides a valuable lineage-specific transcriptome resource to elucidate the molecular pathways for divergence of apical and basal cell lineages at genome-wide scale. Asymmetric division of the Arabidopsis zygote produces apical and basal cells that mainly develop into embryo and suspensor, respectively. Here, Zhou et al. show that de novo transcription and selective RNA turnover establish distinct apical and basal transcriptomes as early as the 1-cell stage of embryo development.
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Winnicki K. The Winner Takes It All: Auxin-The Main Player during Plant Embryogenesis. Cells 2020; 9:E606. [PMID: 32138372 PMCID: PMC7140527 DOI: 10.3390/cells9030606] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 02/21/2020] [Accepted: 02/27/2020] [Indexed: 12/11/2022] Open
Abstract
In plants, the first asymmetrical division of a zygote leads to the formation of two cells with different developmental fates. The establishment of various patterns relies on spatial and temporal gene expression, however the precise mechanism responsible for embryonic patterning still needs elucidation. Auxin seems to be the main player which regulates embryo development and controls expression of various genes in a dose-dependent manner. Thus, local auxin maxima and minima which are provided by polar auxin transport underlie cell fate specification. Diverse auxin concentrations in various regions of an embryo would easily explain distinct cell identities, however the question about the mechanism of cellular patterning in cells exposed to similar auxin concentrations still remains open. Thus, specification of cell fate might result not only from the cell position within an embryo but also from events occurring before and during mitosis. This review presents the impact of auxin on the orientation of the cell division plane and discusses the mechanism of auxin-dependent cytoskeleton alignment. Furthermore, close attention is paid to auxin-induced calcium fluxes, which regulate the activity of MAPKs during postembryonic development and which possibly might also underlie cellular patterning during embryogenesis.
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Affiliation(s)
- Konrad Winnicki
- Department of Cytophysiology, Faculty of Biology and Environmental Protection, University of Lodz, 90-236 Lódź, Poland
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Zhou X, Shi C, Zhao P, Sun M. Isolation of living apical and basal cell lineages of early proembryos for transcriptome analysis. PLANT REPRODUCTION 2019; 32:105-111. [PMID: 30547251 DOI: 10.1007/s00497-018-00353-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 11/24/2018] [Indexed: 06/09/2023]
Abstract
Plant zygotes usually undergo asymmetrical cell division, giving rise to the formation of two daughter cells with distinct developmental cell fate. The small apical cell will develop into the major part of embryo proper, whereas the larger basal cell will divide to form a transient suspensor. Thus, the apical and basal cell lineages are an excellent model to study cell fate determination in relation to zygote polarity. However, the molecular mechanism underlying the differentiation of two distinct cell lineages is not yet understood, possibly due to the technique limitations. Previously, we have established a protocol for isolating apical cell and basal cell for cDNA library construction in tobacco. However, the method for isolating tiny Arabidopsis embryos has long been considered much more difficult. Here, we present a detailed protocol for isolating early Arabidopsis proembryos and separating apical and basal cell lineages of proembryos, which allow us to establish cell lineage-specific transcriptomes of early proembryos.
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Affiliation(s)
- Xuemei Zhou
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Ce Shi
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Peng Zhao
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China.
| | - Mengxiang Sun
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China.
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Xie F, Yan H, Sun Y, Wang Y, Chen H, Mao W, Zhang L, Sun M, Peng X. RPL18aB helps maintain suspensor identity during early embryogenesis. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2018; 60:266-269. [PMID: 29193792 DOI: 10.1111/jipb.12616] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/28/2017] [Indexed: 06/07/2023]
Abstract
During embryogenesis, plants are thought to use a mechanism that allows the suspensor to maintain its identity. Here, we reported that RPL18aB is involved in this mechanism in Arabidopsis thaliana. The suspensor cells proliferated in rpl18aB and formed a multicellular structure rather than undergo programmed cell death, as in wild type. Suspensors of rpl18aB expressed the embryo proper marker, DRN::GFP, but not the suspensor marker, WOX8::GFP. In addition, auxin accumulated throughout the suspensors of rpl18aB proembryos. Suspensor-specific expression of RPL18aB could rescue the cell proliferation defects in rpl18aB suspensors. These findings supported a role for RPL18aB in maintaining suspensor identity.
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Affiliation(s)
- Fei Xie
- State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Hailong Yan
- State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yang Sun
- State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yameng Wang
- State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Hong Chen
- State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Wanying Mao
- State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Liyao Zhang
- State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Mengxiang Sun
- State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Xiongbo Peng
- State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
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Peng X, Sun MX. The suspensor as a model system to study the mechanism of cell fate specification during early embryogenesis. PLANT REPRODUCTION 2018; 31:59-65. [PMID: 29473100 PMCID: PMC5845063 DOI: 10.1007/s00497-018-0326-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Accepted: 02/14/2018] [Indexed: 05/24/2023]
Abstract
The advances in the suspensor. During early embryogenesis, the proembryo consists of two domains, the embryo proper and the suspensor. Unlike the embryo proper, which has been investigated extensively, research on the suspensor has been limited in past decades. Recent studies have revealed that the suspensor plays an important role in early embryogenesis and the process of suspensor formation and degeneration may provide a unique model for studies on cell division pattern, cell fate determination, and cell death. In this review, we briefly summarize the advances in research on the suspensor, which provide new insight in our understanding of the mechanism of early embryogenesis and show great potential for a unique model for future investigations.
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Affiliation(s)
- Xiongbo Peng
- State Key Laboratory of Hybrid Rice, College of Life Science, Wuhan University, Wuhan, 430072, China
| | - Meng-Xiang Sun
- State Key Laboratory of Hybrid Rice, College of Life Science, Wuhan University, Wuhan, 430072, China.
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