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RNA-directed DNA methylation (RdDM) is a small interfering RNA (siRNA)-mediated epigenetic modification that contributes to transposon silencing in plants. RdDM requires a complex transcriptional machinery comprising two RNA polymerase II-related RNA polymerases, called Pol IV and Pol V, as well as chromatin remodelers, transcription factors, and other(More)
We used a transgene system to study spreading of RNA-directed DNA methylation (RdDM) during transcriptional gene silencing in Arabidopsis thaliana. Forward and reverse genetics approaches using this system delineated a stepwise pathway for the biogenesis of secondary siRNAs and unidirectional spreading of methylation from an upstream enhancer element into(More)
RNA-directed DNA methylation (RdDM) is a small RNA-mediated epigenetic modification in plants. We report here the identification of DOMAINS REARRANGED METHYLTRANSFERASE 2 (DRM2) in a forward screen for mutants defective in RdDM in Arabidopsis thaliana. The finding of a mutation in the presumptive active site argues in favor of direct catalytic activity for(More)
Interphase chromosome organization and dynamics can be studied in living cells using fluorescent tagging techniques that exploit bacterial operator/repressor systems and auto-fluorescent proteins. A nuclear-localized Repressor Protein-Fluorescent Protein (RP-FP) fusion protein binds to operator repeats integrated as transgene arrays at defined locations in(More)
RNA-directed DNA methylation (RdDM) is a small interfering RNA (siRNA)-mediated epigenetic modification that contributes to transposon silencing in plants. RdDM requires a complex transcriptional machinery that includes specialized RNA polymerases, named Pol IV and Pol V, as well as chromatin remodelling proteins, transcription factors, RNA binding(More)
The dms4 (defective in meristem silencing 4) mutant of Arabidopsis thaliana is unique in having defects in both RNA-directed DNA methylation (RdDM) and plant development. DMS4 is an evolutionarily conserved, putative transcription factor of the Iwr1 (interacts with RNA polymerase II) type. DMS4 interacts with Pol II and also with RNA polymerases IV and V,(More)
Short interfering RNAs (siRNAs) homologous to transcriptional regulatory regions can induce RNA-directed DNA methylation (RdDM) and transcriptional gene silencing (TGS) of target genes. In our system, siRNAs are produced by transcribing an inverted DNA repeat (IR) of enhancer sequences, yielding a hairpin RNA that is processed by several Dicer activities(More)
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