title: Intra- and intercellular RNA interference in Arabidopsis thaliana requires components of the microRNA and heterochromatic silencing pathways.
abstract: In RNA interference (RNAi), double-stranded RNA (dsRNA) is processed into short interfering RNA (siRNA) to mediate sequence-specific gene knockdown. The genetics of plant RNAi is not understood, nor are the bases for its spreading between cells. Here, we unravel the requirements for biogenesis and action of siRNAs directing RNAi in Arabidopsis thaliana and show how alternative routes redundantly mediate this process under extreme dsRNA dosages. We found that SMD1 and SMD2, required for intercellular but not intracellular RNAi, are allelic to RDR2 and NRPD1a, respectively, previously implicated in siRNA-directed heterochromatin formation through the action of DCL3 and AGO4. However, neither DCL3 nor AGO4 is required for non-cell autonomous RNAi, uncovering a new pathway for RNAi spreading or detection in recipient cells. Finally, we show that the genetics of RNAi is distinct from that of antiviral silencing and propose that this experimental silencing pathway has a direct endogenous plant counterpart.
authors.affiliation: Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique (CNRS) UPR2357, 12 rue du Général Zimmer, 67084 Strasbourg Cedex, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: Dunoyer
authors.forename: Christophe
authors.initials: C
authors.lastname: Himber
authors.forename: Virginia
authors.initials: V
authors.lastname: Ruiz-Ferrer
authors.forename: Abdelmalek
authors.initials: A
authors.lastname: Alioua
authors.forename: Olivier
authors.initials: O
authors.lastname: Voinnet
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000502:physiology; D045604:Extracellular Fluid / Q000502:physiology; D006570:Heterochromatin / Q000502:physiology*; D007424:Intracellular Fluid / Q000502:physiology; D035683:MicroRNAs / Q000502:physiology*; D034622:RNA Interference / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics*
chemical_list: D006570:Heterochromatin; D035683:MicroRNAs