Development and function of the flowering plant female gametophyte

Serbes, Isil Erbasol; Palovaara, Joakim; Groß‐Hardt, Rita

doi:10.1016/bs.ctdb.2018.11.016

Cited by 37 publications

(13 citation statements)

References 176 publications

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“…It would be of interest to determine whether such a variation in polar nuclear fusion between species is related to variations in the expression or activity of Gex1. Molecular genetics have enabled the identification of factors required for female gametophyte development in Arabidopsis and other species ( Erbasol Serbes et al, 2019 ). We now await the results of comparative analyses of female gametogenesis at the molecular level.…”

Section: Discussionmentioning

confidence: 99%

Arabidopsis GEX1 Is a Nuclear Membrane Protein of Gametes Required for Nuclear Fusion During Reproduction

et al. 2020

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During the life cycle of flowering plants, nuclear fusion, or karyogamy, occurs three times: once during female gametogenesis, when the two polar nuclei fuse in the central cell, and twice during double fertilization. In Arabidopsis thaliana , nuclear fusion events during sexual reproduction proceed without the breakdown of the nuclear envelope, indicating that nuclear membrane fusion is essential for the completion of this process. Arabidopsis gamete expressed 1 (GEX1) is a membrane protein that is conserved among plant species. GEX1 shares homology with the yeast karyogamy protein Kar5, which is primarily expressed in the nuclear membrane. The GEX1 family represents a putative karyogamy factor. Herein, we show that GEX1 is required for the nuclear fusion events in Arabidopsis reproduction. GEX1-deficient mature female gametophytes were found to contain two unfused polar nuclei in close proximity within the central cell. Electron microscopy showed that the outer membrane of the polar nuclei was connected via the endoplasmic reticulum, whereas the inner membrane remained unfused. These results indicate that GEX1 is involved in polar nuclear membrane fusion following the fusion of the outer nuclear membrane. Furthermore, sperm nuclear fusion events were defective in the fertilized egg and central cell following plasmogamy in the fertilization of gex1-1 female gametophytes by gex1-1 pollen. An analysis of GEX1 localization in the female gametophyte using a transgenic line expressing GFP-tagged GEX1 driven by the GEX1 promoter showed that GEX1 is a nuclear membrane protein in the egg and central cell. Time-lapse live-cell imaging showed that in developing female gametophytes, the nuclear GFP-GEX1 signal was first detectable in the central cell shortly before the polar nuclei came in close contact, and then in the egg cell. Thus, we suggest that the GEX1-family proteins are nuclear membrane proteins involved in karyogamy in the reproduction of eukaryotes including flowering plants.

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Section: Discussionmentioning

confidence: 99%

Arabidopsis GEX1 Is a Nuclear Membrane Protein of Gametes Required for Nuclear Fusion During Reproduction

et al. 2020

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“…In addition, aspects of evolution and potential involvement of environmental conditions and stress regulations in apomixis control are presented. Detailed descriptions on gene regulatory programs underlying sexual reproduction can be found in other recent reviews [11][12][13].…”

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confidence: 99%

Controlling Apomixis: Shared Features and Distinct Characteristics of Gene Regulation

Schmidt

2020

Genes

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In higher plants, sexual and asexual reproduction through seeds (apomixis) have evolved as alternative strategies. As apomixis leads to the formation of clonal offspring, its great potential for agricultural applications has long been recognized. However, the genetic basis and the molecular control underlying apomixis and its evolutionary origin are to date not fully understood. Both in sexual and apomictic plants, reproduction is tightly controlled by versatile mechanisms regulating gene expression, translation, and protein abundance and activity. Increasing evidence suggests that interrelated pathways including epigenetic regulation, cell-cycle control, hormonal pathways, and signal transduction processes are relevant for apomixis. Additional molecular mechanisms are being identified that involve the activity of DNA- and RNA-binding proteins, such as RNA helicases which are increasingly recognized as important regulators of reproduction. Together with other factors including non-coding RNAs, their association with ribosomes is likely to be relevant for the formation and specification of the apomictic reproductive lineage. Subsequent seed formation appears to involve an interplay of transcriptional activation and repression of developmental programs by epigenetic regulatory mechanisms. In this review, insights into the genetic basis and molecular control of apomixis are presented, also taking into account potential relations to environmental stress, and considering aspects of evolution.

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“…During the female gametophyte development, positional cues, hormones, and coordinated cell-to-cell communication have been proposed to orchestrate the establishment of embryo sac polarity and development (Kägi and Groß-Hardt, 2007;Pagnussat et al, 2007Pagnussat et al, , 2009Moll et al, 2008;Sundaresan and Alandete-Saez, 2010;Kirioukhova et al, 2011;Lituiev et al, 2013;Martin et al, 2013;Kong et al, 2015;Panoli et al, 2015;Tekleyohans et al, 2017). A plethora of genetic factors have been identified to be involved in the development of embryo sac and its cellular differentiation (Yang et al, 2010;Chevalier et al, 2011;Erbasol Serbes et al, 2019). In the following paragraphs, specific genetic regulations of the central cell are summarized ( Table 1).…”

Section: Types Of Embryo Sacmentioning

confidence: 99%

Central Cell in Flowering Plants: Specification, Signaling, and Evolution

Yang

2020

Front. Plant Sci.

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During the reproduction of animals and lower plants, one sperm cell usually outcompetes the rivals to fertilize a single egg cell. But in flowering plants, two sperm cells fertilize the two adjacent dimorphic female gametes, the egg and central cell, respectively, to initiate the embryo and endosperm within a seed. The endosperm nourishes the embryo development and is also the major source of nutrition in cereals for humankind. Central cell as one of the key innovations of flowering plants is the biggest cell in the multicellular haploid female gametophyte (embryo sac). The embryo sac differentiates from the meiotic products through successive events of nuclear divisions, cellularization, and cell specification. Nowadays, accumulating lines of evidence are raveling multiple roles of the central cell rather than only the endosperm precursor. In this review, we summarize the current understanding on its cell fate specification, intercellular communication, and evolution. We also highlight some key unsolved questions for the further studies in this field.

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Development and function of the flowering plant female gametophyte

Cited by 37 publications

References 176 publications

Arabidopsis GEX1 Is a Nuclear Membrane Protein of Gametes Required for Nuclear Fusion During Reproduction

Arabidopsis GEX1 Is a Nuclear Membrane Protein of Gametes Required for Nuclear Fusion During Reproduction

Controlling Apomixis: Shared Features and Distinct Characteristics of Gene Regulation

Central Cell in Flowering Plants: Specification, Signaling, and Evolution

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