Histone arginine methylation is required for vernalization-induced epigenetic silencing of FLC in winter-annual Arabidopsis thaliana

doi:10.1073/pnas.0710423104

Histone arginine methylation is required for vernalization-induced epigenetic silencing of FLC in winter-annual Arabidopsis thaliana

*Laboratory of Genetics and
^†Department of Biochemistry, University of Wisconsin, Madison, WI 53706

Contributed by Richard M. Amasino, November 2, 2007 (received for review September 6, 2007)

Abstract

Certain plant varieties typically require prolonged exposure to the cold of winter to become competent to flower rapidly in the spring. This process is known as vernalization. In Arabidopsis thaliana, vernalization renders plants competent to flower by epigenetically silencing the strong floral repressor FLOWERING LOCUS C (FLC). As a result of vernalization, levels of lysine-9 and lysine-27 trimethylation on histone 3, modifications that are characteristic of facultative heterochromatin in plants, increase at FLC chromatin. We have identified a mutant, protein arginine methyltransferase 5 (atprmt5), that fails to flower rapidly after vernalization treatment. AtPRMT5 encodes a type II protein arginine methyltransferase (PRMT) that, in winter-annual strains, is required for epigenetic silencing of FLC and for the vernalization-mediated histone modifications characteristic of the vernalized state. Furthermore, the levels of arginine methylation of FLC chromatin increase after vernalization. Therefore, arginine methylation of FLC chromatin is part of the histone code that is required for mitotic stability of the vernalized state.

Footnotes

^§To whom correspondence should be addressed at:
Biochemistry Addition, University of Wisconsin, 433 Babcock Drive, Madison, WI 53706.
E-mail: amasino{at}biochem.wisc.edu
This contribution is part of the special series of Inaugural Articles by members of the National Academy of Sciences elected on April 25, 2006.
Author contributions: R.J.S. and S.S. contributed equally to this work; R.J.S., S.S., and R.M.A. designed research; R.J.S. and S.S. performed research; R.J.S., S.S., and R.M.A. analyzed data; and R.J.S. and R.M.A. wrote the paper.
↵ ^‡Present address: Section of Molecular Cell and Developmental Biology, University of Texas, Austin, TX 78712.
The authors declare no conflict of interest.
This article contains supporting information online at www.pnas.org/cgi/content/full/0710423104/DC1.