title: Identification of a major pathogenicity determinant and suppressors of RNA silencing encoded by a South Pacific isolate of Banana bunchy top virus originating from Pakistan.
abstract: Five genes encoded by Banana bunchy top virus (BBTV) originating from Pakistan were expressed in Nicotiana benthamiana using a Potato virus X (PVX) vector. Expression of the master replication-associated protein (mRep) and movement protein (MP) resulted in necrotic cell death of inoculated tissues, as well as leaf curling and necrosis along the veins in newly emerging leaves. The systemic necrosis induced by the expression of MP was discolored (dark) in comparison to that induced by mRep. Expression of the cell-cycle link protein (Clink), the coat protein (CP), and the nuclear shuttle protein from the PVX vector induced somewhat milder symptoms, consisting of mild leaf curling and mosaic, although expression of the CP caused a necrotic response in inoculated leaf. The accumulation of viral RNA was enhanced by MP, Clink, and CP. Of the five BBTV-encoded gene products two, the MP and Clink, stabilized GFP-specific mRNA and reduced GFP-specific small interfering RNA in N. benthamiana line 16c when expressed under the control of the 35S promoter and co-inoculated with a construct for the expression of GFP hairpin RNA construct. These results identified MP and Clink as suppressors of RNA silencing. Taken together the ability of MP to induce severe symptoms in plants and suppress RNA silencing implicates this product as a major pathogenicity determinant of BBTV.
authors.affiliation: Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, P.O. Box 577, Jhang Road, Faisalabad, Pakistan.
authors.forename: Imran
authors.initials: I
authors.lastname: Amin
authors.forename: Muhammad
authors.initials: M
authors.lastname: Ilyas
authors.forename: Javaria
authors.initials: J
authors.lastname: Qazi
authors.forename: Rohina
authors.initials: R
authors.lastname: Bashir
authors.forename: Jitender S
authors.initials: JS
authors.lastname: Yadav
authors.forename: Shahid
authors.initials: S
authors.lastname: Mansoor
authors.forename: Claude M
authors.initials: CM
authors.lastname: Fauquet
authors.forename: Rob W
authors.initials: RW
authors.lastname: Briddon
mesh_terms: D052658:Babuvirus / Q000235:genetics* / Q000472:pathogenicity; D015967:Gene Expression Regulation, Viral; D010154:Pakistan; D010935:Plant Diseases / Q000821:virology*; D018515:Plant Leaves / Q000821:virology*; D053830:Plant Viral Movement Proteins / Q000235:genetics; D030821:Plants, Genetically Modified / Q000821:virology; D034622:RNA Interference; D014026:Nicotiana / Q000821:virology; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D053830:Plant Viral Movement Proteins; D037521:Virulence Factors