Accumulation of transgene-derived siRNAs is not sufficient for RNAi-mediated protection against Citrus tristeza virus in transgenic Mexican lime
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AuthorLopez, Carmelo; Cervera, Magdalena; Fagoaga, Carmen; Moreno, Pedro; Navarro, Luis; Flores, Ricardo; Pena, Leandro
Cita bibliográficaLopez, Carmelo, Cervera, M., Fagoaga, C., Moreno, P., Navarro, L., Flores, R., Pena, L. (2010). Accumulation of transgene-derived siRNAs is not sufficient for RNAi-mediated protection against Citrus tristeza virus in transgenic Mexican lime. Molecular Plant Pathology, 11(1), 33-41.
P>Mexican lime plants transformed with the 3'-terminal 549 nucleotides of the Citrus tristeza virus (CTV) genome in sense, antisense and intron-hairpin formats were analysed for transgene-derived transcript and short interfering RNA (siRNA) accumulation, and for CTV resistance. Propagations from all sense, antisense and empty-vector transgenic lines were susceptible to CTV, except for a single sense-line plant with a complex transgene integration pattern that showed transgene-derived siRNAs in association with low levels of the transgene-derived transcript. In contrast, nine of 30 intron-hairpin lines showed CTV resistance, with 9%-56% of bud-propagated plants, depending on the line, remaining uninfected on graft inoculation, and the others being susceptible. Although resistance was always associated with the presence of transgene-derived siRNAs, their level in different sense and intron-hairpin transformants was variable irrespective of the response to CTV infection. In intron-hairpin lines with single transgene integration, CTV resistance was correlated with low accumulation of the transgene-derived transcript rather than with high accumulation of transgene-derived siRNAs.