title: Functional Analysis of Cotton Leaf Curl Kokhran Virus/Cotton Leaf Curl Multan Betasatellite RNA Silencing Suppressors.
abstract: In South Asia, Cotton leaf curl disease (CLCuD) is caused by a complex of phylogenetically-related begomovirus species and a specific betasatellite, Cotton leaf curl Multan betasatellite (CLCuMuB). The post-transcriptional gene silencing (PTGS) suppression activities of the transcriptional activator protein (TrAP), C4, V2 and βC1 proteins encoded by Cotton leaf curl Kokhran virus (CLCuKoV)/CLCuMuB were assessed in Nicotiana benthamiana. A variable degree of local silencing suppression was observed for each viral protein tested, with V2 protein exhibiting the strongest suppression activity and only the C4 protein preventing the spread of systemic silencing. The CLCuKoV-encoded TrAP, C4, V2 and CLCuMuB-encoded βC1 proteins were expressed in Escherichia coli and purified. TrAP was shown to bind various small and long nucleic acids including single-stranded (ss) and double-stranded (ds) RNA and DNA molecules. C4, V2, and βC1 bound ssDNA and dsDNA with varying affinities. Transgenic expression of C4 under the constitutive 35S Cauliflower mosaic virus promoter and βC1 under a dexamethasone inducible promoter induced severe developmental abnormalities in N. benthamiana. The results indicate that homologous proteins from even quite closely related begomoviruses may differ in their suppressor activity and mechanism of action. The significance of these findings is discussed.
authors.affiliation: RLP AgroScience GmbH, AlPlanta-Institute for Plant Research, Breitenweg 71, Neustadt D-67435, Germany. saeed_hafeez@yahoo.com.|National Institute for Biotechnology and Genetic Engineering, Jhang Road, PO Box 577, Faisalabad 38000, Pakistan. saeed_hafeez@yahoo.com.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Saeed
authors.affiliation: National Institute for Biotechnology and Genetic Engineering, Jhang Road, PO Box 577, Faisalabad 38000, Pakistan. rob.briddon@gmail.com.
authors.forename: Rob W
authors.initials: RW
authors.lastname: Briddon
authors.affiliation: RLP AgroScience GmbH, AlPlanta-Institute for Plant Research, Breitenweg 71, Neustadt D-67435, Germany. athanasios.dalakouras@agroscience.rlp.de.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Dalakouras
authors.affiliation: RLP AgroScience GmbH, AlPlanta-Institute for Plant Research, Breitenweg 71, Neustadt D-67435, Germany. gabi.krczal@agroscience.rlp.de.
authors.forename: Gabi
authors.initials: G
authors.lastname: Krczal
authors.affiliation: RLP AgroScience GmbH, AlPlanta-Institute for Plant Research, Breitenweg 71, Neustadt D-67435, Germany. michael.wassenegger@agroscience.rlp.de.|Centre for Organismal Studies (COS) Heidelberg, University of Heidelberg, Im Neuenheimer Feld 360, Heidelberg D-69120, Germany. michael.wassenegger@agroscience.rlp.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Wassenegger
keywords: RNA silencing suppressor; begomovirus; betasatellite; post-transcriptional gene silencing; siRNA