A counterdefensive strategy of plant viruses: suppression of posttranscriptional gene silencing.
Posttranscriptional gene silencing (PTGS) in plants inactivates some aberrant or highly expressed RNAs in a sequence-specific manner in the cytoplasm. A silencing mechanism similar to PTGS appears to function as an adaptive antiviral response. We demonstrate that the P1/HC-Pro polyprotein encoded by tobacco etch virus functions as a suppressor of PTGS. A locus comprised of a highly expressed beta-glucuronidase (GUS) transgene was shown to exhibit PTGS. Genetic crosses and segregation analyses revealed that a P1/ HC-Pro transgene suppressed PTGS of the GUS sequence. Nuclear transcription assays indicated that the silencing suppression activity of P1/HC-Pro was at the posttranscriptional level. These data reveal that plant viruses can condition enhanced susceptibility within a host through interdiction of a potent defense response.
Kasschau
K D
KD
Institute of Biological Chemistry, Washington State University, Pullman 99164-6340, USA.
Carrington
J C
JC
D003546:Cysteine Endopeptidases / Q000502:physiology; D004274:DNA, Recombinant / Q000235:genetics / Q000378:metabolism; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D015967:Gene Expression Regulation, Viral / Q000502:physiology; D017343:Genes, Plant; D016153:Genes, Suppressor; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D010935:Plant Diseases / Q000235:genetics / Q000821:virology; D010942:Plant Viruses / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D012323:RNA Processing, Post-Transcriptional / Q000502:physiology; D014026:Nicotiana / Q000378:metabolism / Q000821:virology*; D014764:Viral Proteins / Q000502:physiology
D004274:DNA, Recombinant; D004279:DNA, Viral; D008164:Luminescent Proteins; D014764:Viral Proteins; D049452:Green Fluorescent Proteins; D005966:Glucuronidase; D003546:Cysteine Endopeptidases; C072775:HC-Pro protein, potyvirus