Abstract
The mechanisms underlying induction and suppression of RNA silencing in the ongoing plant-virus arms race are poorly understood. We show here that virus-derived small RNAs produced by Arabidopsis Dicer-like 4 (DCL4) program an effector complex conferring antiviral immunity. Inhibition of DCL4 by a viral-encoded suppressor revealed the subordinate antiviral activity of DCL2. Accordingly, inactivating both DCL2 and DCL4 was necessary and sufficient to restore systemic infection of a suppressor-deficient virus. The effects of DCL2 were overcome by increasing viral dosage in inoculated leaves, but this could not surmount additional, non-cell autonomous effects of DCL4 specifically preventing viral unloading from the vasculature. These findings define a molecular framework for studying antiviral silencing and defense in plants.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Arabidopsis / enzymology
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Arabidopsis / genetics
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Arabidopsis / metabolism
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Arabidopsis / virology*
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Arabidopsis Proteins / antagonists & inhibitors
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / metabolism*
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Carmovirus / physiology
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Cell Cycle Proteins / antagonists & inhibitors
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Green Fluorescent Proteins / metabolism
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Mutation
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Plant Diseases / virology
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Plant Leaves / virology
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Plant Viruses / physiology*
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Plants, Genetically Modified
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RNA Interference*
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RNA Viruses / physiology
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RNA, Double-Stranded / metabolism
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RNA, Small Interfering / metabolism*
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RNA, Viral / metabolism*
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RNA-Induced Silencing Complex / metabolism
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Recombinant Fusion Proteins / metabolism
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Ribonuclease III / antagonists & inhibitors
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Ribonuclease III / genetics
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Ribonuclease III / metabolism*
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Ribonucleases / antagonists & inhibitors
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Ribonucleases / genetics
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Ribonucleases / metabolism*
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Signal Transduction
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Viral Proteins / metabolism*
Substances
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Arabidopsis Proteins
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Cell Cycle Proteins
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RNA, Double-Stranded
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RNA, Small Interfering
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RNA, Viral
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RNA-Induced Silencing Complex
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Recombinant Fusion Proteins
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Viral Proteins
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Green Fluorescent Proteins
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DCL4 protein, Arabidopsis
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Ribonucleases
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DCL2 protein, Arabidopsis
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Ribonuclease III