RNA-Dependent RNA Polymerase 1 from Nicotiana tabacum Suppresses RNA Silencing and Enhances Viral Infection in Nicotiana benthamiana
Endogenous eukaryotic RNA-dependent RNA polymerases (RDRs) produce double-stranded RNA intermediates in diverse processes of small RNA synthesis in RNA silencing pathways. RDR6 is required in plants for posttranscriptional gene silencing induced by sense transgenes (S-PTGS) and has an important role...
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Published in | The Plant cell Vol. 22; no. 4; pp. 1358 - 1372 |
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Main Authors | , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
England
American Society of Plant Biologists
01.04.2010
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Subjects | |
Online Access | Get full text |
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Summary: | Endogenous eukaryotic RNA-dependent RNA polymerases (RDRs) produce double-stranded RNA intermediates in diverse processes of small RNA synthesis in RNA silencing pathways. RDR6 is required in plants for posttranscriptional gene silencing induced by sense transgenes (S-PTGS) and has an important role in amplification of antiviral silencing. Whereas RDR1 is also involved in antiviral defense in plants, this does not necessarily proceed through triggering silencing. In this study, we show that Nicotiana benthamiana transformed with RDR1 from Nicotiana tabacum (Nt-RDR1 plants) exhibits hypersusceptibility to Plum pox potyvirus and other viruses, resembling RDR6-silenced (RDR6i) N. benthamiana. Analysis of transient induction of RNA silencing in N. benthamiana Nt-RDR1 and RDR6i plants revealed that Nt-RDR1 possesses silencing suppression activity. We found that Nt-RDR1 does not interfere with RDR6-dependent siRNA accumulation but turns out to suppress RDR6-dependent S-PTGS. Our results, together with previously published data, suggest that RDR1 might have a dual role, contributing, on one hand, to salicylic acid-mediated antiviral defense, and suppressing, on the other hand, the RDR6-mediated antiviral RNA silencing. We propose a scenario in which the natural loss-of-function variant of RDR1 in N. benthamiana may be the outcome of selective pressure to maintain a high RDR6-dependent antiviral defense, which would be required to face the hypersensitivity of this plant to a large number of viruses. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Online version contains Web-only data. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantcell.org) is: Hui-Shan Guo(guohs@im.ac.cn). www.plantcell.org/cgi/doi/10.1105/tpc.109.072058 |
ISSN: | 1040-4651 1532-298X |
DOI: | 10.1105/tpc.109.072058 |