Tomato yellow leaf curl Sardinia virus can overcome transgene-mediated RNA silencing of two essential viral genes.
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.
Noris
Emanuela
E
Istituto di Virologia Vegetale, CNR, Strada delle Cacce 73, 10135 Torino, Italy.
Lucioli
Alessandra
A
ENEA CR Casaccia, Settore Biotec, Via Anguillarese 301, 00060 Rome, Italy.
Tavazza
Raffaela
R
ENEA CR Casaccia, Settore Biotec, Via Anguillarese 301, 00060 Rome, Italy.
Caciagli
Piero
P
Istituto di Virologia Vegetale, CNR, Strada delle Cacce 73, 10135 Torino, Italy.
Accotto
Gian Paolo
GP
Istituto di Virologia Vegetale, CNR, Strada delle Cacce 73, 10135 Torino, Italy.
Tavazza
Mario
M
ENEA CR Casaccia, Settore Biotec, Via Anguillarese 301, 00060 Rome, Italy.
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*
D014764:Viral Proteins; C080288:replication protein AL1, Begomovirus