אסיף מאגר המחקר החקלאי

Virus infection triggers widespread silencing of host genes by a distinct class of endogenous siRNAs in Arabidopsis

Year:

2014

Source of publication :

Authors :

Volume :

111

Co-Authors:

Cao, M., Center for Plant Cell Biology, Department of Plant Pathology and Microbiology, University of California, Riverside, CA, United States
Du, P., Center for Plant Cell Biology, Department of Plant Pathology and Microbiology, University of California, Riverside, CA, United States, State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing, China
Wang, X., Center for Plant Cell Biology, Department of Plant Pathology and Microbiology, University of California, Riverside, CA, United States
Yu, Y.-Q., Center for Plant Cell Biology, Department of Plant Pathology and Microbiology, University of California, Riverside, CA, United States
Qiu, Y.-H., Center for Plant Cell Biology, Department of Plant Pathology and Microbiology, University of California, Riverside, CA, United States
Li, W., Center for Plant Cell Biology, Department of Plant Pathology and Microbiology, University of California, Riverside, CA, United States
Gal-On, A., Department of Plant Pathology and Weed Science, Volcani Center, Bet Dagan, Israel
Zhou, C., National Citrus Engineering Research Center, Citrus Research Institute, Southwest University, Chongqing, China
Li, Y., State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing, China
Ding, S.-W., Center for Plant Cell Biology, Department of Plant Pathology and Microbiology, University of California, Riverside, CA, United States

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Abstract:

Antiviral immunity controlled by RNA interference (RNAi) in plants and animals is thought to specifically target only viral RNAs by the virus-derived small interfering RNAs (siRNAs). Here we show that activation of antiviral RNAi in Arabidopsis plants is accompanied by the production of an abundant class of endogenous siRNAs mapped to the exon regions of more than 1,000 host genes and rRNA. These virus-Activated siRNAs (vasiRNAs) are predominantly 21 nucleotides long with an approximately equal ratio of sense and antisense strands. Genetically, vasiRNAs are distinct from the known plant endogenous siRNAs characterized to date and instead resemble viral siRNAs by requiring Dicer-like 4 and RNA-dependent RNA polymerase 1 (RDR1) for biogenesis. However, loss of EXORIBONUCLEASE4/ THYLENE-INSENSITIVE5 enhances vasiRNA biogenesis and virus resistance without altering the biogenesis of viral siRNAs. We show that vasiRNAs are active in directing widespread silencing of the target host genes and that Argonaute-2 binds to and is essential for the silencing activity of vasiRNAs. Production of vasiRNAs is readily detectable in Arabidopsis after infection by viruses from two distinct supergroups of plant RNA virus families and is targeted for inhibition by the silencing suppressor protein 2b of Cucumbermosaic virus. These findings reveal RDR1 production of Arabidopsis endogenous siRNAs and identify production of vasiRNAs to direct widespread silencing of host genes as a conserved response of plants to infection by diverse viruses. A possible function for vasiRNAs to confer broad-spectrum antiviral activity distinct to the virus-specific antiviral RNAi by viral siRNAs is discussed.

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