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Intergenic Transcription By Rna Polymerase Ii Coordinates Pol Iv And Pol V In Sirna-Directed Transcriptional Gene Silencing In Arabidopsis, Binglian Zheng, Zhengming Wang, Shengben Li, Bin Yu, Jin -Yuan Liu, Xuemei Chen

Center for Plant Science Innovation: Faculty and Staff Publications

Intergenic transcription by RNA Polymerase II (Pol II) is widespread in plant and animal genomes, but the functions of intergenic transcription or the resulting noncoding transcripts are poorly understood. Here, we show that Arabidopsis Pol II is indispensable for endogenous siRNA-mediated transcriptional gene silencing (TGS) at intergenic low-copy-number loci, despite the presence of two other polymerases—Pol IV and Pol V—that specialize in TGS through siRNAs. We show that Pol II produces noncoding scaffold transcripts that originate outside of heterochromatic, siRNA-generating loci. Through these transcripts and physical interactions with the siRNA effector protein ARGONAUTE4 (AGO4), Pol II recruits AGO4/siRNAs to homologous …