Polycomb repression: It's all in the balance.
In our recent paper1 we suggested a molecular explanation for the long standing observation that plants need to be mitotically active to respond to a prolonged period of low temperatures by flowering early (vernalization).2 In Arabidopsis, vernalization is associated with the epigenetic repression of the floral repressor, FLC.3-5FLC repression is established during the low temperature treatment and is marked by the loss of chromatin marks associated with active genes and the gain of histone H3 trimethyl-lysine 27 (K27me3) at the start of transcription/translation.1 After the end of the cold treatment, this repressive modification spreads across FLC chromatin to mark the entire locus.1 In cells not undergoing mitosis, we found that FLC is repressed by low temperatures, but that this repression is only partially maintained. We concluded that DNA replication is not required for the initial response to low temperatures, but rather for the maintenance of this response. Here we discuss the implications of our observations in terms of the plasticity of chromatin modifications in plants.
Finnegan
Ej
E
CSIRO; Plant Industry; Canberra, Australia.
Dennis
Es
E
PLoS Biol. 2007 May;5(5):e129
17439305
Curr Biol. 2007 Nov 20;17(22):1978-83
17980595
Cell. 2004 Dec 29;119(7):941-53
15620353
Science. 2007 Oct 19;318(5849):447-50
17761849
Nucleic Acids Res. 2004 Dec 14;32(22):6511-8
15598823
Cell. 2007 Mar 9;128(5):877-87
17320162
Genes Dev. 2001 Dec 15;15(24):3286-95
11751634
Proc Natl Acad Sci U S A. 2007 Nov 20;104(47):18439-44
18003914
Nature. 2004 Jan 8;427(6970):164-7
14712277
Cell. 1980 May;20(1):55-64
6993010
Proc Natl Acad Sci U S A. 2004 Feb 10;101(6):1525-30
14732680
Nat Struct Mol Biol. 2007 Mar;14(3):240-2
17310255
Plant Cell. 2004 Oct;16(10):2601-13
15377760
Plant Cell. 2007 Oct;19(10):2975-87
17921315
Cell. 2007 Oct 5;131(1):29-32
17923085
J Biol Chem. 1990 Oct 5;265(28):17157-61
2211618
Plant Physiol. 1964 Sep;39(5):832-5
16656010
Nat Struct Mol Biol. 2007 Mar;14(3):243-5
17310254
Trends Genet. 2004 Jul;20(7):320-6
15219397
Nature. 2007 Oct 11;449(7163):731-4
17713478
Proc Natl Acad Sci U S A. 2000 Mar 28;97(7):3753-8
10716723
Nature. 2007 Oct 11;449(7163):689-94
17851529
Plant J. 2005 Nov;44(3):420-32
16236152
Cell. 2007 Sep 21;130(6):1083-94
17825402
Cell. 2006 Apr 21;125(2):315-26
16630819
Cell. 2007 Mar 9;128(5):889-900
17320163
Nucleic Acids Res. 2007;35(18):6290-6
17881378
Nature. 2004 Jan 8;427(6970):159-64
14712276
Mol Cell. 2007 Jan 12;25(1):1-14
17218267