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Open Access

Meristem‐specific expression of epigenetic regulators safeguards transposon silencing in Arabidopsis

Tuncay Baubec, Andreas Finke, Ortrun Mittelsten Scheid, Ales Pecinka

Author Affiliations

  1. Tuncay Baubec1,2,
  2. Andreas Finke3,
  3. Ortrun Mittelsten Scheid1 and
  4. Ales Pecinka*,1,3
  1. 1Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna, Austria
  2. 2Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
  3. 3Max Planck Institute for Plant Breeding Research, Cologne, Germany
  1. *Corresponding author. Tel: +49 221 5062 465; Fax: +49 221 5062 413; E‐mail: pecinka{at}mpipz.mpg.de

Abstract

In plants, transposable elements (TEs) are kept inactive by transcriptional gene silencing (TGS). TGS is established and perpetuated by RNA‐directed DNA methylation (RdDM) and maintenance methylation pathways, respectively. Here, we describe a novel RdDM function specific for shoot apical meristems that reinforces silencing of TEs during early vegetative growth. In meristems, RdDM counteracts drug‐induced interference with TGS maintenance and consequently prevents TE activation. Simultaneous disturbance of both TGS pathways leads to transcriptionally active states of repetitive sequences that are inherited by somatic tissues and partially by the progeny. This apical meristem‐specific mechanism is mediated by increased levels of TGS factors and provides a checkpoint for correct epigenetic inheritance during the transition from vegetative to reproductive phase and to the next generation.

Synopsis

Embedded Image

Repetitive DNA sequences are prone to be activated in plant embryonic tissues. Reinforced silencing in the shoot apical meristem is shown here to prevent their expression in post‐embryonic tissues.

  • The DNA methylation inhibitor zebularine induces transcriptional activation of repetitive sequences in embryonic, but not post‐embryonic, plant tissues.

  • RNA‐dependent DNA methylation (RdDM) is required for re‐silencing of these sequences in the shoot apical meristem (SAM).

  • Abundance of de novo and maintenance methylation factors in the SAM secure correct transmission of epigenetic states during vegetative growth.

  • Received August 23, 2013.
  • Revision received January 22, 2014.
  • Accepted January 23, 2014.

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