title: Three gene products of a begomovirus-betasatellite complex restore expression of a transcriptionally silenced green fluorescent protein transgene in Nicotiana benthamiana.
abstract: Single-stranded DNA geminiviruses replicate via double-stranded DNA intermediates forming mini-chromosomes that are targets for transcriptional gene silencing (TGS) in plants. The ability of the cotton leaf curl Kokhran virus (CLCuKoV)-cotton leaf curl Multan betasatellite (CLCuMuB) proteins, replication-associated protein (Rep), transcriptional activator protein (TrAP), C4, V2 and βC1, to suppress TGS was investigated by using the Nicotiana benthamiana line 16-TGS (16-TGS) harbouring a transcriptionally silenced green fluorescent protein (GFP) transgene. Inoculation of 16-TGS plants with a recombinant potato virus X vector carrying Rep, TrAP or βC1 resulted in re-expression of GFP. Northern blot analysis confirmed that the observed GFP fluorescence was associated with GFP mRNA accumulation. These results indicated that Rep, TrAP and βC1 proteins of CLCuKoV-CLCuMuB can re-activate the expression of a transcriptionally silenced GFP transgene in N. benthamiana. Although Rep, TrAP, or βC1 proteins have, for other begomoviruses or begomoviruses-betasatellites, been previously shown to have TGS suppressor activity, this is the first report demonstrating that a single begomovirus-betasatellite complex encodes three suppressors of TGS.
authors.affiliation: RLP AgroScience GmbH, AlPlanta-Institute for Plant Research, Breitenweg 71, 67435, Neustadt, Germany, saeed_hafeez@yahoo.com.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Saeed
authors.forename: Gabi
authors.initials: G
authors.lastname: Krczal
authors.forename: Michael
authors.initials: M
authors.lastname: Wassenegger
mesh_terms: D053839:Begomovirus / Q000235:genetics / Q000378:metabolism*; D020868:Gene Silencing; D049452:Green Fluorescent Proteins / Q000235:genetics* / Q000378:metabolism; D010935:Plant Diseases / Q000235:genetics / Q000821:virology; D030821:Plants, Genetically Modified / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D017863:Potexvirus / Q000235:genetics / Q000378:metabolism; D012526:Satellite Viruses / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D015534:Trans-Activators; D014764:Viral Proteins; D049452:Green Fluorescent Proteins