ellendan

• Glöckle, Barbara; Urban, W.; Nagahara, Shiori; Andersen, Ellen Dehnes; Higashiyama, Tetsuya & Grini, Paul Eivind [Show all 7 contributors for this article] (2018). Pollen differentiation as well as pollen tube guidance and discharge are independent of the presence of gametes. Development. ISSN 0950-1991. 145(1), p. 1–8. doi: 10.1242/dev.152645. Full text in Research Archive Show summary

  After meiosis, an unequal cell division generates the male gamete lineage in flowering plants. The generative cell will undergo a second division, giving rise to the two gametes, i.e. the sperm cells. The other cell will develop into the vegetative cell that plays a crucial role in pollen tube formation and sperm delivery. Recently, the vegetative cell has been suggested to be important for programming of the chromatin state in sperm cells and/or the resulting fertilization products. Blocking the initial unequal division genetically, we first highlight that the default differentiation state after male meiosis is a vegetative fate, which is consistent with earlier work. We find that uni-nucleated mutant microspores differentiated as wild-type vegetative cells, including chromatin remodeling and the transcriptional activation of transposable elements. Moreover, live-cell imaging revealed that this vegetative cell is sufficient for the correct guidance of the pollen tube to the female gametes. Hence, we conclude that vegetative cell differentiation and function does not depend on the formation or presence of the actual gametes but rather on external signals or a cell-autonomous pace keeper.

• Shirzadi, Reza; Andersen, Ellen Dehnes; Bjerkan, Katrine; Gloeckle, Barbara M; Heese, Maren & Ungru, Alexander [Show all 11 contributors for this article] (2011). Genome-Wide Transcript Profiling of Endosperm without Paternal Contribution Identifies Parent-of-Origin-Dependent Regulation of AGAMOUS-LIKE36. PLoS Genetics. ISSN 1553-7390. 7(2). doi: 10.1371/journal.pgen.1001303. Full text in Research Archive Show summary

  Seed development in angiosperms is dependent on the interplay among different transcriptional programs operating in the embryo, the endosperm, and the maternally-derived seed coat. In angiosperms, the embryo and the endosperm are products of double fertilization during which the two pollen sperm cells fuse with the egg cell and the central cell of the female gametophyte. In Arabidopsis, analyses of mutants in the cell-cycle regulator CYCLIN DEPENDENT KINASE A;1 (CKDA;1) have revealed the importance of a paternal genome for the effective development of the endosperm and ultimately the seed. Here we have exploited cdka;1 fertilization as a novel tool for the identification of seed regulators and factors involved in parent-of-origin–specific regulation during seed development. We have generated genome-wide transcription profiles of cdka;1 fertilized seeds and identified approximately 600 genes that are downregulated in the absence of a paternal genome. Among those, AGAMOUS-LIKE (AGL) genes encoding Type-I MADS-box transcription factors were significantly overrepresented. Here, AGL36 was chosen for an in-depth study and shown to be imprinted. We demonstrate that AGL36 parent-of-origin–dependent expression is controlled by the activity of METHYLTRANSFERASE1 (MET1) maintenance DNA methyltransferase and DEMETER (DME) DNA glycosylase. Interestingly, our data also show that the active maternal allele of AGL36 is regulated throughout endosperm development by components of the FIS Polycomb Repressive Complex 2 (PRC2), revealing a new type of dual epigenetic regulation in seeds.

• Bouyer, D; Roudier, F; Heese, M; Andersen, Ellen Dehnes; Gey, D & Nowack, MK [Show all 11 contributors for this article] (2011). Polycomb Repressive Complex 2 Controls the Embryo-to-Seedling Phase Transition. PLoS Genetics. ISSN 1553-7390. 7(3). doi: 10.1371/journal.pgen.1002014. Full text in Research Archive

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