title: Tomato yellow leaf curl Sardinia virus can overcome transgene-mediated RNA silencing of two essential viral genes.
abstract: To evaluate RNA silencing for the control of geminivirus infection, two classes of post-transcriptionally silenced (PTS) plants were tested using Tomato yellow leaf curl Sardinia virus (TYLCSV) Rep-210-transgenic plants, a sensexantisense hybrid and two multicopy sense lines. In both classes, PTS plants accumulated low or undetectable amounts of Rep-210 protein and mRNA but high amounts of Rep-210 small interfering RNAs. PTS plants were susceptible to TYLCSV when challenged by agroinoculation or using high viruliferous whitefly (Bemisia tabaci) pressure, although some plants were resistant at low whitefly pressure. Delayed infections were also observed, indicating that TYLCSV could overcome transgene silencing of rep and of the nested C4 gene. TYLCSV infection boosted transgene silencing but this did not lead to recovery. The data suggest that if the virus reaches a threshold level of expression/replication in the initially infected cells then virus spreading can no longer be prevented.
authors.affiliation: Istituto di Virologia Vegetale, CNR, Strada delle Cacce 73, 10135 Torino, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Noris
authors.affiliation: ENEA CR Casaccia, Settore Biotec, Via Anguillarese 301, 00060 Rome, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Lucioli
authors.affiliation: ENEA CR Casaccia, Settore Biotec, Via Anguillarese 301, 00060 Rome, Italy.
authors.forename: Raffaela
authors.initials: R
authors.lastname: Tavazza
authors.affiliation: Istituto di Virologia Vegetale, CNR, Strada delle Cacce 73, 10135 Torino, Italy.
authors.forename: Piero
authors.initials: P
authors.lastname: Caciagli
authors.affiliation: Istituto di Virologia Vegetale, CNR, Strada delle Cacce 73, 10135 Torino, Italy.
authors.forename: Gian Paolo
authors.initials: GP
authors.lastname: Accotto
authors.affiliation: ENEA CR Casaccia, Settore Biotec, Via Anguillarese 301, 00060 Rome, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Tavazza
mesh_terms: D017791:Geminiviridae / Q000235:genetics*; D005814:Genes, Viral / Q000235:genetics*; D018551:Solanum lycopersicum / Q000821:virology*; D034622:RNA Interference; D019076:Transgenes / Q000502:physiology*; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D014764:Viral Proteins; C080288:replication protein AL1, Begomovirus