An Arabidopsis natural epiallele maintained by a feed-forward silencing loop between histone and DNA

Astrid Agorio (1, 2, 3) , Stéphanie Durand (1, 2, 3) , Elisa Fiume (1, 2, 3) , Cécile Brousse (1, 2, 3) , Isabelle Gy (1, 2, 3) , Matthieu Simon (1, 2, 3) , Sarit Anava (4, 5) , Oded Rechavi (4, 5) , Olivier Loudet (1, 2, 3) , Christine Camilleri (1, 2, 3) , Nicolas Bouche (1, 2, 3)

1 IJPB - Institut Jean-Pierre Bourgin
2 Université Paris-Saclay
3 CNRS - Centre National de la Recherche Scientifique
4 Department of Neurobiology, Wise Faculty of Life Sciences
5 Sagol School of Neuroscience

The extent of epigenetic variation is currently well documented, but the number of natural epialleles described so far remains very limited. Determining the relevance of epigenetic changes for natural variation is an important question of research that we investigate by isolating natural epialleles segregating in Arabidopsis recombinant populations. We previously described a genetic incompatibility among Arabidopsis strains based on the silencing of a gene involved in fitness. Here, we isolated a new epiallele resulting from the silencing of a transfer-RNA editing gene in an Arabidopsis accession from the Netherlands ( Nok-1). Crosses with the reference accession Col-0 show a complete incompatibility between this epiallele and another locus localized on a different chromosome. We demonstrate that conversion of an unmethylated version of this allele occurs in hybrids, associated with modifications of small RNA populations. These epialleles can also spontaneously revert within the population. Furthermore, we bring evidence that neither METHYLTRANSFERASE 1, maintaining methylation at CGs, nor components of RNA-directed DNA methylation, are key factors for the transmission of the epiallele over generations. This depends only on the self-reinforcing loop between CHROMOMETHYLASE 3 and KRYPTONITE, involving DNA methylated in the CHG context and histone H3 lysine 9 methylation. Our findings reveal a predominant role of this loop in maintaining a natural epiallele.

Mots clés: epigenetic variation; transfer-rnas; jmjc domain; methylation; thaliana; gene; inheritance; mutation; mutants; hybrids

Domaines: Sciences du Vivant [q-bio]

Astrid Agorio, Stéphanie Durand, Elisa Fiume, Cécile Brousse, Isabelle Gy, et al.. An Arabidopsis natural epiallele maintained by a feed-forward silencing loop between histone and DNA. PLoS Genetics, 2017, 13 (1), pp.1-23. ⟨10.1371/journal.pgen.1006551⟩. ⟨hal-01602603⟩