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PMID: 18801846 Published · ppublish English Journal Article Research Support, Non-U.S. Gov't

The CaMV transactivator/viroplasmin interferes with RDR6-dependent trans-acting and secondary siRNA pathways in Arabidopsis.

Nucleic acids research ·Vol. 36 ·No. 18 ·2008-10-00 ·Pages 5896-909

Shivaprasad PV, Rajeswaran R, Blevins T, Schoelz J, Meins F, Hohn T, Pooggin MM

Abstract

Several RNA silencing pathways in plants restrict viral infections and are suppressed by distinct viral proteins. Here we show that the endogenous trans-acting (ta)siRNA pathway, which depends on Dicer-like (DCL) 4 and RNA-dependent RNA polymerase (RDR) 6, is suppressed by infection of Arabidopsis with Cauliflower mosaic virus (CaMV). This effect was associated with overaccumulation of unprocessed, RDR6-dependent precursors of tasiRNAs and is due solely to expression of the CaMV transactivator/viroplasmin (TAV) protein. TAV expression also impaired secondary, but not primary, siRNA production from a silenced transgene and increased accumulation of mRNAs normally silenced by the four known tasiRNA families and RDR6-dependent secondary siRNAs. Moreover, TAV expression upregulated DCL4, DRB4 and AGO7 that mediate tasiRNA biogenesis. Our findings suggest that TAV is a general inhibitor of silencing amplification that impairs DCL4-mediated processing of RDR6-dependent double-stranded RNA to siRNAs. The resulting deficiency in tasiRNAs and other RDR6-/DCL4-dependent siRNAs appears to trigger a feedback mechanism that compensates for the inhibitory effects.

MeSH Terms
Arabidopsis/genetics,metabolism,virology Arabidopsis Proteins/antagonists & inhibitors Caulimovirus/metabolism RNA Interference RNA Precursors/biosynthesis RNA, Double-Stranded/biosynthesis RNA, Small Interfering/biosynthesis,chemistry RNA-Dependent RNA Polymerase/antagonists & inhibitors Ribonuclease III Ribonucleases/metabolism Trans-Activators/metabolism Transgenes Viral Proteins/metabolism
Chemicals
Arabidopsis Proteins RNA Precursors RNA, Double-Stranded RNA, Small Interfering Trans-Activators Viral Proteins gene VI protein, Cauliflower mosaic virus viroplasmin protein, Cauliflower mosaic virus RDR6 protein, Arabidopsis RNA-Dependent RNA Polymerase DCL4 protein, Arabidopsis Ribonucleases Ribonuclease III
Authors & Affiliations
7 authors, click to expand affiliations / ORCID
Shivaprasad Padubidri V
Institute of Botany, University of Basel, Schönbeinstrasse 6, 4056 Basel, Switzerland.
Rajeswaran Rajendran
Blevins Todd
Schoelz James
Meins Frederick
Hohn Thomas
Pooggin Mikhail M
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Article Info
Journal
Nucleic acids research
Abbr.
Nucleic Acids Res
ISSN
1362-4962
DOI
10.1093/nar/gkn590
Published
2008-10-00
Epub
2008-00-18
Pages
5896-909
Language
English
Region
England
NLM ID
0411011
PMCID
PMC2566869
Subset
IM
External Links
PubMed source DOI: 10.1093/nar/gkn590 PMC Full Text View journal details
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