Transcriptional integration of paternal and maternal factors in the Arabidopsis zygote

  1. Thomas Laux1
  1. 1BIOSS Centre for Biological Signaling Studies, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany;
  2. 2Institute of Transformative Bio-Molecules (ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan;
  3. 3Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan;
  4. 4Laboratory of Plant Growth Regulation, Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST), Ikoma, Nara 630-0192, Japan;
  5. 5Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium;
  6. 6Center for Plant Systems Biology, Vlaams Instituut voor Biotechnologie (VIB), 9052 Ghent, Belgium;
  7. 7Medical Biotechnology Center, VIB, B-9000 Ghent, Belgium;
  8. 8Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium;
  9. 9Exploratory Research for Advanced Technology (ERATO), Japan Science and Tech Agency (JST), Higashiyama Live-Holonics Project, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan;
  10. 10CREST, JST, Ikoma, Nara 630-0192 Japan
  1. Corresponding authors: m-ueda{at}itbm.nagoya-u.ac.jp, laux{at}biologie.uni-freiburg.de

Abstract

In many plants, the asymmetric division of the zygote sets up the apical–basal axis of the embryo. Unlike animals, plant zygotes are transcriptionally active, implying that plants have evolved specific mechanisms to control transcriptional activation of patterning genes in the zygote. In Arabidopsis, two pathways have been found to regulate zygote asymmetry: YODA (YDA) mitogen-activated protein kinase (MAPK) signaling, which is potentiated by sperm-delivered mRNA of the SHORT SUSPENSOR (SSP) membrane protein, and up-regulation of the patterning gene WOX8 by the WRKY2 transcription factor. How SSP/YDA signaling is transduced into the nucleus and how these pathways are integrated have remained elusive. Here we show that paternal SSP/YDA signaling directly phosphorylates WRKY2, which in turn leads to the up-regulation of WOX8 transcription in the zygote. We further discovered the transcription factors HOMEODOMAIN GLABROUS11/12 (HDG11/12) as maternal regulators of zygote asymmetry that also directly regulate WOX8 transcription. Our results reveal a framework of how maternal and paternal factors are integrated in the zygote to regulate embryo patterning.

Keywords

Footnotes

  • Received October 20, 2016.
  • Accepted March 13, 2017.

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