DNA methylation and chromatin structure affect transcriptional and post-transcriptional transgene silencing in Arabidopsis.
In plants, transgenes can be silenced at both the transcriptional [1] and post-transcriptional levels [2]. Methylation of the transgene promoter correlates with transcriptional gene silencing (TGS) [3] whereas methylation of the coding sequence is associated with post-transcriptional gene silencing (PTGS) [4]. In animals, TGS requires methylation and changes in chromatin conformation [5]. The involvement of methylation during PTGS in plants is unclear and organisms with non-methylated genomes such as Caenorhabditis elegans or Drosophila can display RNA interference (RNAi), a silencing process mechanistically related to PTGS [6]. Here, we crossed Arabidopsis mutants impaired in a SWI2/SNF2 chromatin component (ddm1 [7]) or in the major DNA methyltransferase (met1 [8] and E. Richards, personal communication) with transgenic lines in which a reporter consisting of the cauliflower mosaic virus 35S promoter fused to the beta-glucuronidase (GUS) gene (35S-GUS) was silenced by TGS or PTGS. We observed an efficient release of 35S-GUS TGS by both the ddm1 and met1 mutations and stochastic release of 35S-GUS PTGS by these two mutations during development. These results show that DNA methylation and chromatin structure are common regulators of TGS and PTGS.
Morel
J B
JB
Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique, 78026 Versailles Cedex, France.
Mourrain
P
P
Béclin
C
C
Vaucheret
H
H
D000818:Animals; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins; D002843:Chromatin / Q000378:metabolism*; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000378:metabolism; D020868:Gene Silencing; D017343:Genes, Plant; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D019076:Transgenes
D029681:Arabidopsis Proteins; D002843:Chromatin; C118957:DDM1 protein, Arabidopsis; D004268:DNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors