Portal de Periódicos da CAPES

Vernalization-Induced Trimethylation of Histone H3 Lysine 27 at FLC Is Not Maintained in Mitotically Quiescent Cells

2007; Elsevier BV; Volume: 17; Issue: 22 Linguagem: Inglês

10.1016/j.cub.2007.10.026

1879-0445

E. Jean Finnegan, Elizabeth S. Dennis,

Plant Gene Expression Analysis

Vernalization promotes flowering in Arabidopsis through epigenetic repression of the floral repressor, FLOWERING LOCUS C (FLC) [1Sheldon C.C. Rouse D.T. Finnegan E.J. Peacock W.J. Dennis E.S. The molecular basis of vernalization: The central role of FLOWERING LOCUS C (FLC).Proc. Natl. Acad. Sci. USA. 2000; 97: 418-422Crossref PubMed Scopus (475) Google Scholar, 2Bastow R. Mylne J.S. Lister C. Lippman Z. Martienssen R.A. Dean C. Vernalization requires epigenetic silencing of FLC by histone methylation.Nature. 2004; 427: 164-167Crossref PubMed Scopus (652) Google Scholar, 3Sung S. Amasino R.M. Vernalization in Arabidopsis thaliana is mediated by the PHD finger protein VIN3.Nature. 2004; 427: 159-164Crossref PubMed Scopus (603) Google Scholar]. Vernalization, like other polycomb-mediated repression events [4Ringrose L. Paro R. Polycomb/Trithorax response elements and epigenetic memory of cell identity.Development. 2007; 134: 223-232Crossref PubMed Scopus (361) Google Scholar], occurs in two stages; FLC repression is established at low temperatures, then maintained during subsequent growth at 22°C [5Sheldon C.C. Conn A.B. Dennis E.S. Peacock W.J. Different regulatory regions are required for the vernalization-induced repression of FLOWERING LOCUS C and for the epigenetic maintenance of repression.Plant Cell. 2002; 14: 2527-2537Crossref PubMed Scopus (186) Google Scholar, 6Sung S. He Y. Eshoo T.W. Tamada Y. Johnson L. Nakahigashi K. Goto K. Jacobsen S.E. Amasino R.M. Epigenetic maintenance of the vernalized state in Arabidopsis thaliana requires LIKE HETEROCHROMATIN PROTEIN 1.Nat. Genet. 2006; 38: 706-710Crossref PubMed Scopus (232) Google Scholar]. Low temperatures induce VIN3 activity, which is required for changes in histone modifications and the associated FLC repression [3Sung S. Amasino R.M. Vernalization in Arabidopsis thaliana is mediated by the PHD finger protein VIN3.Nature. 2004; 427: 159-164Crossref PubMed Scopus (603) Google Scholar]. Plant polycomb proteins FIE, VRN2, CLF, and SWN, together with VIN3, form a complex that adds histone H3 lysine 27 methylation at FLC in vernalized plants [2Bastow R. Mylne J.S. Lister C. Lippman Z. Martienssen R.A. Dean C. Vernalization requires epigenetic silencing of FLC by histone methylation.Nature. 2004; 427: 164-167Crossref PubMed Scopus (652) Google Scholar, 3Sung S. Amasino R.M. Vernalization in Arabidopsis thaliana is mediated by the PHD finger protein VIN3.Nature. 2004; 427: 159-164Crossref PubMed Scopus (603) Google Scholar, 7Wood C.C. Robertson M. Tanner G. Peacock W.J. Dennis E.S. Helliwell C.A. The Arabidopsis thaliana vernalization response requires a polycomb-like protein complex that also includes VERNALIZATION INSENSITIVE 3.Proc. Natl. Acad. Sci. USA. 2006; 103: 14631-14636Crossref PubMed Scopus (238) Google Scholar]. VRN1 and LHP1 are required for maintenance of FLC repression [2Bastow R. Mylne J.S. Lister C. Lippman Z. Martienssen R.A. Dean C. Vernalization requires epigenetic silencing of FLC by histone methylation.Nature. 2004; 427: 164-167Crossref PubMed Scopus (652) Google Scholar, 3Sung S. Amasino R.M. Vernalization in Arabidopsis thaliana is mediated by the PHD finger protein VIN3.Nature. 2004; 427: 159-164Crossref PubMed Scopus (603) Google Scholar, 6Sung S. He Y. Eshoo T.W. Tamada Y. Johnson L. Nakahigashi K. Goto K. Jacobsen S.E. Amasino R.M. Epigenetic maintenance of the vernalized state in Arabidopsis thaliana requires LIKE HETEROCHROMATIN PROTEIN 1.Nat. Genet. 2006; 38: 706-710Crossref PubMed Scopus (232) Google Scholar, 8Mylne J.S. Barrett L. Tessadori F. Mesnage S. Johnson L. Bernatavichute Y.V. Jacobsen S.E. Fransz P. Dean C. LHP1, the Arabidopsis homologue of HETERCHROMATIN PROTEIN 1, is required for epigenetic silencing of FLC.Proc. Natl. Acad. Sci. USA. 2006; 103: 5012-5017Crossref PubMed Scopus (199) Google Scholar]. Tissue must be undergoing cell division during low-temperature treatments for acceleration of flowering to occur [9Wellensiek S.J. Dividing cells as the prerequisite for vernalization.Plant Physiol. 1964; 39: 832-835Crossref PubMed Google Scholar, 10Schwabe W.W. Studies in vernalisation of cereals.Ann. Bot. (Lond.). 1936; 27: 671-683Google Scholar]. We show that low-temperature treatments repress FLC in cells that are not mitotically active, but this repression is not fully maintained. Trimethyl-lysine 27 (K27me3), is enriched at the start of the FLC gene during the cold, before spreading across the locus after vernalization. In the absence of DNA replication, K27me3 is added to chromatin at the start of FLC but is removed on return to 22°C. This suggests that DNA replication is essential for maintenance of vernalization-induced repression of FLC.