TY - JOUR TI - A DCL3 dicing code within Pol IV-RDR2 transcripts diversifies the siRNA pool guiding RNA-directed DNA methylation AU - Loffer, Andrew AU - Singh, Jasleen AU - Fukudome, Akihito AU - Mishra, Vibhor AU - Wang, Feng AU - Pikaard, Craig S A2 - Zilberman, Daniel A2 - Manley, James L A2 - Fukuhara, Toshiyuki VL - 11 PY - 2022 DA - 2022/01/31 SP - e73260 C1 - eLife 2022;11:e73260 DO - 10.7554/eLife.73260 UR - https://doi.org/10.7554/eLife.73260 AB - In plants, selfish genetic elements, including retrotransposons and DNA viruses, are transcriptionally silenced by RNA-directed DNA methylation. Guiding the process are short interfering RNAs (siRNAs) cut by DICER-LIKE 3 (DCL3) from double-stranded precursors of ~30 bp that are synthesized by NUCLEAR RNA POLYMERASE IV (Pol IV) and RNA-DEPENDENT RNA POLYMERASE 2 (RDR2). We show that Pol IV’s choice of initiating nucleotide, RDR2’s initiation 1–2 nt internal to Pol IV transcript ends and RDR2’s terminal transferase activity collectively yield a code that influences which precursor end is diced and whether 24 or 23 nt siRNAs are produced. By diversifying the size, sequence, and strand specificity of siRNAs derived from a given precursor, alternative patterns of DCL3 dicing allow for maximal siRNA coverage at methylated target loci. KW - dicer endonuclease KW - dicer-like 3 KW - siRNA biogenesis KW - RNA-directed DNA methylation KW - RNA silencing KW - RNA polymerase JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -