title: Sequencing of RDR6-dependent double-stranded RNAs reveals novel features of plant siRNA biogenesis.
abstract: Biogenesis of trans-acting siRNAs (tasiRNAs) is initiated by miRNA-directed cleavage of TAS gene transcripts and requires RNA-dependent RNA polymerase 6 (RDR6) and Dicer-like 4 (DCL4). Here, we show that following miR173 cleavage the entire polyadenylated parts of Arabidopsis TAS1a/b/c and TAS2 transcripts are converted by RDR6 to double-stranded (ds)RNAs. Additionally, shorter dsRNAs are produced following a second cleavage directed by a TAS1c-derived siRNA. This tasiRNA and miR173 guide Argonaute 1 complexes to excise the segments from TAS2 and three TAS1 transcripts including TAS1c itself to be converted to dsRNAs, which restricts siRNA production to a region between the two cleavage sites. TAS1c is also feedback regulated by a cis-acting siRNA. We conclude that TAS1c generates a master siRNA that controls a complex network of TAS1/TAS2 siRNA biogenesis and gene regulation. TAS1/TAS2 short dsRNAs produced in this network are processed by DCL4 from both ends in distinct registers, which increases repertoires of tasiRNAs.
authors.affiliation: Institute of Botany, University of Basel, Schönbeinstrasse 6, 4056 Basel, Switzerland.
authors.forename: Rajendran
authors.initials: R
authors.lastname: Rajeswaran
authors.forename: Michael
authors.initials: M
authors.lastname: Aregger
authors.forename: Anna S
authors.initials: AS
authors.lastname: Zvereva
authors.forename: Basanta K
authors.initials: BK
authors.lastname: Borah
authors.forename: Ekaterina G
authors.initials: EG
authors.lastname: Gubaeva
authors.forename: Mikhail M
authors.initials: MM
authors.lastname: Pooggin
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism*; D001483:Base Sequence; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D017343:Genes, Plant; D035683:MicroRNAs / Q000378:metabolism; D008969:Molecular Sequence Data; D026723:Polyadenylation; D059367:RNA Cleavage; D012322:RNA Precursors / Q000737:chemistry / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012330:RNA, Double-Stranded / Q000737:chemistry / Q000378:metabolism*; D018749:RNA, Plant / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C534587:MIRN173 microRNA, Arabidopsis; D035683:MicroRNAs; D012322:RNA Precursors; D012330:RNA, Double-Stranded; D018749:RNA, Plant; D034741:RNA, Small Interfering; C514575:RDR6 protein, Arabidopsis; D012324:RNA-Dependent RNA Polymerase