title: Transitivity-dependent and -independent cell-to-cell movement of RNA silencing.
abstract: One manifestation of RNA silencing, known as post-transcriptional gene silencing (PTGS) in plants and RNA interference (RNAi) in animals, is a nucleotide sequence-specific RNA turnover mechanism with the outstanding property of propagating throughout the organism, most likely via movement of nucleic acids. Here, the cell-to-cell movement of RNA silencing in plants is investigated. We show that a short-distance movement process, once initiated from a small group of cells, can spread over a limited and nearly constant number of cells, independent of the presence of homologous transcripts. There is also a long-range cell-to-cell movement process that occurs as a relay amplification, which requires the combined activity of SDE1, a putative RNA-dependent RNA polymerase, and SDE3, a putative RNA helicase. Extensive and limited cell-to-cell movements of silencing are triggered by the same molecules, occur within the same tissues and likely recruit the same plasmodesmata channels. We propose that they are in fact manifestations of the same process, and that extensive cell-to-cell movement of RNA silencing results from re-iterated short-distance signalling events. The likely nature of the nucleic acids involved is presented.
authors.affiliation: Institut de Biologie Moléculaire des Plantes du CNRS, 12 rue du Général Zimmer, 67084 Strasbourg, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Himber
authors.forename: Patrice
authors.initials: P
authors.lastname: Dunoyer
authors.forename: Guillaume
authors.initials: G
authors.lastname: Moissiard
authors.forename: Christophe
authors.initials: C
authors.lastname: Ritzenthaler
authors.forename: Olivier
authors.initials: O
authors.lastname: Voinnet
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D002450:Cell Communication / Q000235:genetics; D017343:Genes, Plant; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008957:Models, Genetic; D059828:Plant Cells; D010944:Plants / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012231:Rhizobium / Q000235:genetics; D013489:Suppression, Genetic; D014026:Nicotiana / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D008164:Luminescent Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins