title: Viral virulence protein suppresses RNA silencing-mediated defense but upregulates the role of microrna in host gene expression.
abstract: Small interfering RNAs (siRNAs) and microRNAs (miRNAs) are processed by the ribonuclease Dicer from distinct precursors, double-stranded RNA (dsRNA) and hairpin RNAs, respectively, although either may guide RNA silencing via a similar complex. The siRNA pathway is antiviral, whereas an emerging role for miRNAs is in the control of development. Here, we describe a virulence factor encoded by turnip yellow mosaic virus, p69, which suppresses the siRNA pathway but promotes the miRNA pathway in Arabidopsis thaliana. p69 suppression of the siRNA pathway is upstream of dsRNA and is as effective as genetic mutations in A. thaliana genes involved in dsRNA production. Possibly as a consequence of p69 suppression, p69-expressing plants contained elevated levels of a Dicer mRNA and of miRNAs as well as a correspondingly enhanced miRNA-guided cleavage of two host mRNAs. Because p69-expressing plants exhibited disease-like symptoms in the absence of viral infection, our findings suggest a novel mechanism for viral virulence by promoting the miRNA-guided inhibition of host gene expression.
authors.affiliation: Institute of Molecular and Cell Biology, National University of Singapore, Singapore 117609.
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.forename: Wan Xiang
authors.initials: WX
authors.lastname: Li
authors.forename: Daoxin
authors.initials: D
authors.lastname: Xie
authors.forename: Jin Rong
authors.initials: JR
authors.lastname: Peng
authors.forename: Shou Wei
authors.initials: SW
authors.lastname: Ding
mesh_terms: D017360:Arabidopsis / Q000145:classification / Q000235:genetics; D001483:Base Sequence; D018744:DNA, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D020868:Gene Silencing; D005966:Glucuronidase / Q000235:genetics; D035683:MicroRNAs / Q000235:genetics*; D010942:Plant Viruses / Q000472:pathogenicity*; D030821:Plants, Genetically Modified; D034622:RNA Interference; D018749:RNA, Plant / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014764:Viral Proteins / Q000235:genetics*; D014774:Virulence / Q000235:genetics
chemical_list: D018744:DNA, Plant; D035683:MicroRNAs; D018749:RNA, Plant; D014764:Viral Proteins; D005966:Glucuronidase