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  • The EMBO Journal (2005) 24, 1418 - 1429
  • doi:10.1038/sj.emboj.7600604

Published online: 17 March 2005

Pivotal role of AtSUVH2 in heterochromatic histone methylation and gene silencing in Arabidopsis

Kathrin Naumann1,a, Andreas Fischer1,a, Ingo Hofmann1, Veiko Krauss2, Sameer Phalke1, Kristina Irmler1, Gerd Hause3, Anne-Cathleen Aurich1, Rainer Dorn1, Thomas Jenuwein4 and Gunter Reuter1

  1. Institute of Genetics, Biologicum, Martin Luther University Halle, Halle, Germany
  2. Department of Genetics, University of Leipzig, Leipzig, Germany
  3. Biocenter, Martin Luther University Halle, Halle, Germany
  4. Research Institute of Molecular Pathology, The Vienna Biocenter, Vienna, Austria

Correspondence to:

Gunter Reuter, Institute of Genetics, Biologicum, Martin Luther University, Weinbergweg 10, 06120 Halle, Germany. Tel.: +49 345 552 6300/303; Fax: +49 345 552 7294; E-mail: reuter@genetik.uni-halle.de

aThese authors contributed equally to this work

Received 20 July 2004; Accepted 8 February 2005

SU(VAR)3–9 like histone methyltransferases control heterochromatic domains in eukaryotes. In Arabidopsis, 10 SUVH genes encode SU(VAR)3–9 homologues where SUVH1, SUVH2 and SUVH4 (KRYPTONITE) represent distinct subgroups of SUVH genes. Loss of SUVH1 and SUVH4 causes weak reduction of heterochromatic histone H3K9 dimethylation, whereas in SUVH2 null plants mono- and dimethyl H3K9, mono- and dimethyl H3K27, and monomethyl H4K20, the histone methylation marks of Arabidopsis heterochromatin are significantly reduced. Like animal SU(VAR)3–9 proteins SUVH2 displays strong dosage-dependent effects. Loss of function suppresses, whereas overexpression enhances, gene silencing, causes ectopic heterochromatization and significant growth defects. Furthermore, modification of transgene silencing by SUVH2 is partially transmitted to the offspring plants. This epigenetic stability correlates with heritable changes in DNA methylation. Mutational dissection of SUVH2 indicates an implication of its N-terminus and YDG domain in directing DNA methylation to target sequences, a prerequisite for consecutive histone methylation. Gene silencing by SUVH2 depends on MET1 and DDM1, but not CMT3. In Arabidopsis, SUVH2 with its histone H3K9 and H4K20 methylation activity has a central role in heterochromatic gene silencing.

  • Keywords:

    • DNA methylation,
    • gene silencing,
    • heterochromatin,
    • histone methylation