title: A viral protein suppresses siRNA-directed interference in tobacco mosaic virus infection.
abstract: Plant viruses encode suppressors of post-transcriptional gene silencing (PTGS), an adaptive defense response that limits virus replication and its spread in plants. The helper component proteinase (HC-Pro) of the potato virus A (PVA, genus Potyvirus) suppresses PTGS of silenced transgenes. Here, the effect of HC-Pro on siRNA-directed interference in the tobacco mosaic virus (TMV) was examined by using a transient Agrobacterium tumefaciens-based delivery system in intact tissues. It was shown that the interference effect was completely blocked by co-infiltration with HC-Pro plus siRNA constructs in both systemic and hypersensitive hosts. In the system host, all plants agro-infiltrated with HC-Pro plus siRNA constructs displayed the same symptoms as the negative control. Meanwhile, TMV RNA accumulation was found to be abundant in the upper leaves using reverse transcriptase-PCR (RT-PCR) and Northern blot assays. On the contrary, plants agro-infiltrated with the siRNA construct alone were free of symptoms. Therefore, our study suggests that the transient expression of HC-Pro inhibited the siRNA-directed host defenses against TMV infection.
authors.affiliation: College of Plant Protection, North West Science and Technology University of Agriculture and Forestry, Shaanxi 712100, China.
authors.forename: Ming-Min
authors.initials: MM
authors.lastname: Zhao
authors.forename: De-Rong
authors.initials: DR
authors.lastname: An
authors.forename: Guang-Hua
authors.initials: GH
authors.lastname: Huang
authors.forename: Zu-Hua
authors.initials: ZH
authors.lastname: He
authors.forename: Jiang-Ye
authors.initials: JY
authors.lastname: Chen
mesh_terms: D003546:Cysteine Endopeptidases / Q000235:genetics* / Q000378:metabolism*; D020868:Gene Silencing; D024861:Genetic Enhancement / Q000379:methods*; D010935:Plant Diseases / Q000821:virology*; D018515:Plant Leaves / Q000378:metabolism / Q000821:virology; D030821:Plants, Genetically Modified / Q000378:metabolism / Q000821:virology; D034741:RNA, Small Interfering / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism* / Q000821:virology*; D014027:Tobacco Mosaic Virus / Q000502:physiology*; D014162:Transfection / Q000379:methods; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism*
chemical_list: D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D014764:Viral Proteins; D003546:Cysteine Endopeptidases; C072775:HC-Pro protein, potyvirus