DNA methylation maintenance consolidates RNA-directed DNA methylation and transcriptional gene silencing over generations in Arabidopsis thaliana

Markus Kuhlmann, Andreas Finke, Martin Mascher, Michael Mette*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

In plants, 24 nucleotide short interfering RNAs serve as a signal to direct cytosine methylation at homologous DNA regions in the nucleus. If the targeted DNA has promoter function, this RNA-directed DNA methylation may result in transcriptional gene silencing. In a genetic screen for factors involved in RNA-directed transcriptional silencing of a ProNOS-NPTII reporter transgene in Arabidopsis thaliana, we captured alleles of DOMAINS REARRANGED METHYLTRANSFERASE 2, the gene encoding the DNA methyltransferase that is mainly responsible for de novo DNA methylation in the context of RNA-directed DNA methylation. Interestingly, methylation of the reporter gene ProNOS was not completely erased in these mutants, but persisted in the symmetric CG context, indicating that RNA-directed DNA methylation had been consolidated by DNA methylation maintenance. Taking advantage of the segregation of the transgenes giving rise to Pro- NOS short interfering RNAs and carrying the ProNOS-NPTII reporter in our experimental system, we found that ProNOS DNA methylation maintenance was first evident after two generations of ongoing RNA-directed DNA methylation, and then increased in extent with further generations. As ProNOS DNA methylation had already reached its final level in the first generation of RNA-directed DNA methylation, our findings suggest that establishment of DNA methylation at a particular region may be divided into distinct stages. An initial phase of efficient, but still fully reversible, de novo DNA methylation and transcriptional gene silencing is followed by transition to efficient maintenance of cytosine methylation in a symmetric sequence context accompanied by persistence of gene silencing.

Original languageEnglish (US)
Pages (from-to)269-281
Number of pages13
JournalPlant Journal
Volume80
Issue number2
DOIs
StatePublished - Jan 1 2014

Keywords

  • Arabidopsis thaliana
  • At5g14620
  • DNA methylation maintenance
  • DRM2
  • RNA-directed DNA methylation
  • Transcriptional gene silencing
  • Transgenerational effect

ASJC Scopus subject areas

  • Genetics
  • Plant Science
  • Cell Biology

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