An atypical epigenetic mechanism affects uniparental expression of Pol IV-dependent sirnas

Rebecca A. Mosher, Ek Han Tan, Juhyun Shin, Robert L. Fischer, Craig S. Pikaard, David C. Baulcombe

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

Background: Small RNAs generated by RNA polymerase IV (Pol IV) are the most abundant class of small RNAs in flowering plants. In Arabidopsis thaliana Pol IV-dependent short interfering (p4-si)RNAs are imprinted and accumulate specifically from maternal chromosomes in the developing seeds. Imprinted expression of protein-coding genes is controlled by differential DNA or histone methylation placed in gametes. To identify epigenetic factors required for maternal-specific expression of p4-siRNAs we analyzed the effect of a series of candidate mutations, including those required for genomic imprinting of protein-coding genes, on uniparental expression of a representative p4-siRNA locus. Results: Paternal alleles of imprinted genes are marked by DNA or histone methylation placed by DNA METHYLTRANSFERASE 1 or the Polycomb Repressive Complex 2. Here we demonstrate that repression of paternal p4-siRNA expression at locus 08002 is not controlled by either of these mechanisms. Similarly, loss of several chromatin modification enzymes, including a histone acetyltransferase, a histone methyltransferase, and two nucleosome remodeling proteins, does not affect maternal expression of locus 08002. Maternal alleles of imprinted genes are hypomethylated by DEMETER DNA glycosylase, yet expression of p4-siRNAs occurs irrespective of demethylation by DEMETER or related glycosylases. Conclusions: Differential DNA methylation and other chromatin modifications associated with epigenetic silencing are not required for maternal-specific expression of p4-siRNAs at locus 08002. These data indicate that there is an as yet unknown epigenetic mechanism causing maternal-specific p4-siRNA expression that is distinct from the well-characterized mechanisms associated with DNA methylation or the Polycomb Repressive Complex 2.

Original languageEnglish (US)
Article numbere25756
JournalPloS one
Volume6
Issue number10
DOIs
StatePublished - Oct 7 2011

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General

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    Mosher, R. A., Tan, E. H., Shin, J., Fischer, R. L., Pikaard, C. S., & Baulcombe, D. C. (2011). An atypical epigenetic mechanism affects uniparental expression of Pol IV-dependent sirnas. PloS one, 6(10), [e25756]. https://doi.org/10.1371/journal.pone.0025756