Expression analysis of Arabidopsis XH/XS-domain proteins indicates overlapping and distinct functions for members of this gene family

Haroon Butt, Sonja Graner, Christian Luschnig*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


RNA-directed DNA methylation (RdDM) is essential for de novo DNA methylation in higher plants, and recent reports established novel elements of this silencing pathway in the model organism Arabidopsis thaliana. INVOLVED IN DE NOVO DNA METHYLATION 2 (IDN2) and the closely related FACTOR OF DNA METHYLATION (FDM) are members of a plant-specific family of dsRNA-binding proteins characterized by conserved XH/XS domains and implicated in the regulation of RdDM at chromatin targets. Genetic analyses have suggested redundant as well as non-overlapping activities for different members of the gene family. However, detailed insights into the function of XH/XS-domain proteins are still elusive. By the generation and analysis of higher-order mutant combinations affected in IDN2 and further members of the gene family, we have provided additional evidence for their redundant activity. Distinct roles for members of the XH/XS-domain gene family were indicated by differences in their expression and subcellular localization. Fluorescent protein-tagged FDM genes were expressed either in nuclei or in the cytoplasm, suggestive of activities of XH/XS-domain proteins in association with chromatin as well as outside the nuclear compartment. In addition, we observed altered location of a functional FDM1-VENUS reporter from the nucleus into the cytoplasm under conditions when availability of further FDM proteins was limited. This is suggestive of a mechanism by which redistribution of XH/XS-domain proteins could compensate for the loss of closely related proteins.

Original languageEnglish (US)
Pages (from-to)1217-1227
Number of pages11
JournalJournal of experimental botany
Issue number4
StatePublished - Mar 2014
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by grants from the Austrian Science Fund FWF to C.L. (P19585, P25931) and by a PhD scholarship from the Pakistani Commission for Higher Education (HEC) to H.B.


  • Arabidopsis
  • RdDM.
  • gene family
  • protein localization

ASJC Scopus subject areas

  • Physiology
  • Plant Science


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