Minisymposium 11: Reproductive Development

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Abs # M1104: Epigenetic Maintenance of the Vernalized State in Arabidopsis Requires Like Heterochromatin Protein 1

Presenter:	Sung, Sibum       Contact Presenter
Authors	Sung, Sibum  (A)   He, Yuehui  (A) (E)  Eshoo, Tifani W (A)   Tamada, Yosuke  (A)   Johnson, Lianna  (B)   Nakahigashi, Kenji  (C) (D)  Goto, Koji  (C) (D)  Jacobsen, Steve E (B)   Amasino, Richard M (A)
Affiliations:	(A): Department of Biochemistry, University of Wisconsin at Madison, Madison WI, USA (B): Howard Hughes Medical Institute, Department of Molecular, Cell, and Developmental Biology, and Molecular Biology Institute, University of Ca (C): Research Institute for Biological Sciences, Okayama, 716-1241 Japan (D): CREST, Japan Science and Technology Corporation, Japan (E): Present address: Department of Biological Sciences, Faculty of Science, National University of Singapore, Science Drive 4, Singapore 117543

Vernalization is the process by which sensing a prolonged exposure to winter cold leads to competence to flower in the spring. In winter-annual Arabidopsis accessions, flowering is suppressed in the fall by expression of the potent floral repressor, FLOWERING LOCUS C (FLC). Vernalization promotes flowering via epigenetic repression of FLC. Repression is accompanied by a series of histone modifications of FLC chromatin that include dimethylation of Histone H3 at Lys9 (H3K9) and Lys27 (H3K27). Here, we report that Arabidopsis LIKE HETEROCHROMATIN PROTEIN 1 (LHP1) is necessary to maintain the epigenetically repressed state of FLC upon return to warm conditions typical of spring. LHP1 is enriched at FLC chromatin after prolonged exposure to cold. Furthermore, LHP1 activity is needed to maintain the increased levels of H3K9 dimethylation at FLC chromatin that are characteristic of the vernalized state. We also show that dimethylation on H3K9 at FLC chromatin and the maintenance of epigenetic silencing require a cis-element in the first intron of FLC.