GSE100011
Ectopic application of the repressive histone modification H3K9me2 establishes postzygotic reproductive isolation in Arabidopsis thaliana
Hybrid seed lethality as a consequence of interspecies or interploidy hybridizations is a major mechanism of reproductive isolation in plants. This mechanism is manifested in the endosperm, a dosage sensitive tissue supporting embryo growth. Deregulated expression of imprinted genes like ADMETOS (ADM) underpin the interploidy hybridization barrier in Arabidopsis thaliana, however, the mechanisms of their action remained unknown. In this study we show that ADM interacts with the AT-hook domain protein AHL10 and the SET domain-containing SU(VAR)3-9 homolog SUVH9 and ectopically recruits the heterochromatic mark H3K9me2 to AT-rich transposable elements (TEs), causing deregulated expression of neighboring genes. Several hybrid incompatibility genes identified in Drosophila encode for heterochromatin-interacting proteins, which has led to the suggestion that hybrid incompatibilities evolve as consequence of interspecies divergence of selfish DNA elements and their regulation. Our data showing that imbalance of dosage-sensitive chromatin regulators underpins hybrid incompatibility in Arabidopsis strongly support this view, demonstrating that reproductive isolation as a consequence of epigenetic regulation of TEs is a conserved feature in animals and plants. Overall design: 54 genome-wide ChIP sequencing libraries and 6 genome-wide cytosine methylation libraries. All libraries derive from INTACT purified endosperm from seeds at 4 days after pollination from the cross of maternal 2x Col-0 with paternal 2x Col-0 and the mutant backgrounds osd1-1, osd1-1 adm-2, adm-2, 2x suvh2-2 suvh9-1, 4x suvh2-2 suvh9-, 2x ahl10-1, 4x ahl10-1, and osd1-2.