Patterning the Female Gametophyte of Flowering Plants

Tekleyohans, Dawit G.; Nakel, Thomas; Groß‐Hardt, Rita

doi:10.1104/pp.16.01472

Cited by 35 publications

(32 citation statements)

References 73 publications

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“…Previous studies have supported the lateral inhibition model for the differentiation of the female gametophyte cells. Although all cells in the female gametophyte have the gametic cell competence, the accessory cells like the synergid and antipodal cells, are repressed in the gametic cell fate (Groß-Hardt et al, 2007; Tekleyohans et al, 2017). In the present study, the RNA-seq of the female gametophyte cells identified many of the DEGs and the highly expressed genes in each type of cell (Table S3).…”

Section: Discussionmentioning

confidence: 99%

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Dynamics of the cell fate specifications during female gametophyte development inArabidopsis

Susaki

Suzuki

Maruyama

et al. 2020

Preprint

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The female gametophytes of angiosperms contain cells with distinct functions, such as those that enable reproduction via pollen tube attraction and fertilization. Although the female gametophyte undergoes unique developmental processes, such as several rounds of nuclear division without cell plate formation, and the final cellularization, it remains unknown when and how the cell fate is determined during their development. Here, we visualized the living dynamics of female gametophyte development and performed transcriptome analysis of its individual cell types, to assess the cell fate specifications in Arabidopsis thaliana. We recorded time lapses of the nuclear dynamics and cell plate formation from the one-nucleate stage to the seven-cell stage after cellularization, using the in vitro ovule culture system. The movies showed that the nuclear division occurred along the micropylar-chalazal axis. During cellularization, the polar nuclei migrated while associating with forming edge of the cell plate. Then, each polar nucleus migrated to fuse linearly towards each other. We also tracked the gene expression dynamics and identified that the expression of the MYB98pro::GFP, a synergid-specific marker, was initiated before cellularization, and then restricted to the synergid cells after cellularization. This indicated that cell fates are determined immediately after cellularization. Transcriptome analysis of the female gametophyte cells of the wild type and myb98 mutant, revealed that the myb98 synergid cells had the egg cell-like gene expression profile. Although in the myb98, the egg cell-specific gene expressions were properly initiated only in the egg cells after cellularization, but subsequently expressed ectopically in one of the two synergid cells. These results, together with the various initiation timings of the egg cell-specific genes suggest the complex regulation of the individual gametophyte cells, such as cellularization-triggered fate initiation, MYB98-dependent fate maintenance, cell morphogenesis, and organelle positioning. Our system of live-cell imaging and cell-type-specific gene expression analysis provides insights into the dynamics and mechanisms of cell fate specifications in the development of female gametophytes in plants.

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Section: Discussionmentioning

confidence: 99%

“…Genes expressed specifically in each female gametophyte cell and used as markers of the cell fate have been identified in several plants, particularly Arabidopsis (Tekleyohans et al, 2017). However, it is not clear when and how these cells specify their cell fates and exhibit specific gene expressions.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of the cell fate specifications during female gametophyte development inArabidopsis

Susaki

Suzuki

Maruyama

et al. 2020

Preprint

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“…The second mitotic division can occur before pollen germination, like in Arabidopsis thaliana, or during pollen germination (Berger and Twell, 2011). Unlike in the male lineage where all microspores will develop into pollen, in most flowering plants only one megaspore survives and mitotically divides to give rise to the seven-celled female gametophyte containing the two female gametes, the egg cell and the central cell (Tekleyohans et al, 2017). In contrast to animals where germ cells separate early from the somatic linage, plant germ cells originate from differentiated cells that acquire the competence to undergo meiotic divisions (Schmidt et al, 2015) The formation of male and female plant gametes is connected with a partial resetting of epigenetic marks that likely serves to achieve meiotic competence (Borges and Martienssen, 2013; Baroux and Autran, 2015; Borg and Berger, 2015).…”

Section: Introductionmentioning

confidence: 99%

Functional role of Polymerase IV during pollen development inCapsella

Wang

Butel

Santos‐González

et al. 2019

Preprint

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In Arabidopsis thaliana, the DNA-dependent RNA polymerase IV (Pol IV) is required for the formation of transposable element (TE)-derived small RNA (sRNA) transcripts. These transcripts are processed by DICER-LIKE 3 into 24-nt small interfering RNAs (siRNAs) that guide RNA-dependent DNA methylation. In the pollen grain, Pol IV is also required for the accumulation of 21/22-nt epigenetically-activated siRNAs (easiRNAs) that likely silence TEs by post-transcriptional mechanisms. Despite this proposed functional role, loss of Pol IV function in Arabidopsis does not cause a discernable pollen defect. Here, we show that loss of NRPD1, encoding the largest subunit of Pol IV in the Brassicaceae Capsella rubella, causes post-meiotic arrest of pollen development at the microspore stage. As in Arabidopsis, all TE-derived siRNAs were depleted in Capsella nrpd1 microspores. In wild-type background, we found that the same TEs produced 21/22-nt and 24-nt siRNAs, leading us to propose that Pol IV is generating the direct precursors for 21-24-nt siRNAs, which are targeted by different DICERs. Arrest of Capsella nrpd1 microspores was accompanied by deregulation of genes targeted by Pol IV-dependent siRNAs. The distance of TEs to genes was much closer in Capsella rubella compared to Arabidopsis thaliana, providing a possible explanation for the essential role of Pol IV for pollen development in Capsella. Our study in Capsella uncovers a functional requirement of Pol IV in microspores, emphasizing the relevance of investigating different plant models.One-sentence summaryLoss of Polymerase IV function in Capsella rubella causes microspore arrest, revealing an important functional role of Polymerase IV during pollen development.The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantcell.org) is: Claudia Kohler (Claudia.Kohler@slu.se)

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“…Thus, specific attention is dedicated to the precursor cell of the embryo. As outlined in Tekleyohans et al (2017), differentiation of the egg cell was recently shown to be promoted by a family of plant-specific transcriptional regulators in Marchantia, which provides the advantage of having only a single copy of these genes. Now Resentini et al (2017) report that expression of the eggcell-specific EC1 gene family is regulated by the transcriptional regulator SUPPRESSOR OF FRIGIDA4 and chromatin modification in Arabidopsis.…”

mentioning

confidence: 99%

“…Tekleyohans et al (2017) provide an Update on female gametophyte patterning along its micropylarchalazal axis. A lateral inhibition model is proposed suggesting that the two female gametes control the development and cell fate of accessory cells.…”

mentioning

confidence: 99%