Email updates

Keep up to date with the latest news and content from Genome Biology and BioMed Central.

Open Access Research

Natural variation of H3K27me3 distribution between two Arabidopsis accessions and its association with flanking transposable elements

Xue Dong13, Julia Reimer1, Ulrike Göbel1, Julia Engelhorn1, Fei He2, Heiko Schoof3* and Franziska Turck1*

Author Affiliations

1 Max Planck Institute for Plant Breeding Research, Carl von Linne Weg 10, 50829 Köln, Germany

2 Current address: Institute for Evolution and Biodiversity, University of Münster, Hüfferstr. 1, 48149 Münster, Germany

3 Current address: University of Bonn, Institute of Crop Science and Resource Conservation, Crop Bioinformatics, Katzenburgweg 2, 53115 Bonn, Germany

For all author emails, please log on.

Genome Biology 2012, 13:R117  doi:10.1186/gb-2012-13-12-r117

Published: 19 December 2012

Abstract

Background

Histone H3 lysine 27 tri-methylation and lysine 9 di-methylation are independent repressive chromatin modifications in Arabidopsis thaliana. H3K27me3 is established and maintained by Polycomb repressive complexes whereas H3K9me2 is catalyzed by SUVH histone methyltransferases. Both modifications can spread to flanking regions after initialization and were shown to be mutually exclusive in Arabidopsis.

Results

We analyzed the extent of natural variation of H3K27me3 in the two accessions Landsberg erecta (Ler) and Columbia (Col) and their F1 hybrids. The majority of H3K27me3 target genes in Col were unchanged in Ler and F1 hybrids. A small number of Ler-specific targets were detected and confirmed. Consistent with a cis-regulatory mechanism for establishing H3K27me3, differential targets showed allele-specific H3K27me3 in hybrids. Five Ler-specific targets showed the active mark H3K4me3 in Col and for this group, differential H3K27me3 enrichment accorded to expression variation. On the other hand, the majority of Ler-specific targets were not expressed in Col, Ler or 17 other accessions. Instead of H3K27me3, the antagonistic mark H3K9me2 and other heterochromatic features were observed at these loci in Col. These loci were frequently flanked by transposable elements, which were often missing in the Ler genome assembly.

Conclusion

There is little variation in H3K27me3 occupancy within the species, although H3K27me3 targets were previously shown as overrepresented among differentially expressed genes. The existing variation in H3K27me3 seems mostly explained by flanking polymorphic transposable elements. These could nucleate heterochromatin, which then spreads into neighboring H3K27me3 genes, thus converting them to H3K9me2 targets.