Hierarchical action and inhibition of plant Dicer-like proteins in antiviral defense.
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.
Deleris
Angélique
A
Institut de Biologie Moléculaire des Plantes, CNRS Unité Propre de Recherche (UPR) 2357, 12, rue du Général Zimmer, 67084 Strasbourg Cedex, France.
Gallego-Bartolome
Javier
J
Bao
Jinsong
J
Kasschau
Kristin D
KD
Carrington
James C
JC
Voinnet
Olivier
O
D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism / Q000821:virology*; D029681:Arabidopsis Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D019184:Carmovirus / Q000502:physiology; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D009154:Mutation; D010935:Plant Diseases / Q000821:virology; D018515:Plant Leaves / Q000821:virology; D010942:Plant Viruses / Q000502:physiology*; D030821:Plants, Genetically Modified; D034622:RNA Interference; D012328:RNA Viruses / Q000502:physiology; D012330:RNA, Double-Stranded / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism*; D012367:RNA, Viral / Q000378:metabolism*; D034743:RNA-Induced Silencing Complex / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D043244:Ribonuclease III / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012260:Ribonucleases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014764:Viral Proteins / Q000378:metabolism*
D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D012330:RNA, Double-Stranded; D034741:RNA, Small Interfering; D012367:RNA, Viral; D034743:RNA-Induced Silencing Complex; D011993:Recombinant Fusion Proteins; D014764:Viral Proteins; D049452:Green Fluorescent Proteins; C504982:DCL4 protein, Arabidopsis; D012260:Ribonucleases; C511919:DCL2 protein, Arabidopsis; D043244:Ribonuclease III