Abstract

In diverse eukaryotic organisms, Dicer-processed, virus-derived small interfering RNAs direct antiviral immunity by RNA silencing or RNA interference. Here we show that in addition to core dicing and slicing components of RNAi, the RNAi-mediated viral immunity in Arabidopsis thaliana requires host RNA-directed RNA polymerase (RDR) 1 or RDR6 to produce viral secondary siRNAs following viral RNA replication-triggered biogenesis of primary siRNAs. We found that the two antiviral RDRs exhibited specificity in targeting the tripartite positive-strand RNA genome of cucumber mosaic virus (CMV). RDR1 preferentially amplified the 52-terminal siRNAs of each of the three viral genomic RNAs, whereas an increased production of siRNAs targeting the 32 half of RNA3 detected in rdr1 mutant plants appeared to be RDR6-dependent. However, siRNAs derived from a single-stranded 336-nucleotide satellite RNA of CMV were not amplified by either antiviral RDR, suggesting avoidance of the potent RDR-dependent silencing as a strategy for the molecular parasite of CMV to achieve preferential replication. Our work thus identifies a distinct mechanism for the amplification of immunity effectors, which together with the requirement for the biogenesis of endogenous siRNAs, may play a role in the emergence and expansion of eukaryotic RDRs.

Autore Pugliese

• Cillo Fabrizio

Tutti gli autori

• X.-B. Wang; Q. Wu; T. Ito; F. Cillo; W.-X. Li; X. Chen; J.-L. Yu; S.-W. Ding

Titolo volume/Rivista

Proceedings of the National Academy of Sciences of the United States of America

Anno di pubblicazione

2010

ISSN

1091-6490

ISBN

Non Disponibile

Numero di citazioni Wos

Nessuna citazione

Ultimo Aggiornamento Citazioni

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Numero di citazioni Scopus

Non Disponibile

Ultimo Aggiornamento Citazioni

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Settori ERC

Non Disponibile

Codici ASJC

Non Disponibile