Plant Molecular Biology (2006) 60, 153-165

Carmen Fagoaga, Carmelo López, Alfonso Hermoso de Mendoza, Pedro Moreno, Luis Navarro, Ricardo Flores and Leandro Peña (2006)
Post-transcriptional gene silencing of the p23 silencing suppressor of Citrus tristeza virus confers resistance to the virus in transgenic Mexican lime
Plant Molecular Biology 60 (2), 153-165
Abstract: Previously, we have shown that most Mexican limes (Citrus aurantifolia (Christ.) Swing.) expressing the p23 gene of Citrus tristeza virus (CTV) exhibit aberrations resembling viral leaf symptoms. Here we report that five independent transgenic lines having normal phenotype displayed characteristics typical of post-transcriptional gene silencing (PTGS): multiple copies of the transgene, low levels of the corresponding mRNA, methylation of the silenced transgene, and accumulation of p23-specific small interfering RNAs (siRNAs). When graft- or aphid-inoculated with CTV, some propagations of these silenced lines were immune: they neither expressed symptoms nor accumulated virions and viral RNA as estimated by DAS-ELISA and Northern blot hybridization, respectively. Other propagations were moderately resistant because they became infected later and showed attenuated symptoms compared to controls. The susceptible propagations, in addition to symptom expression and elevated virus titer, accumulated p23-specific siRNAs at levels significantly higher than immune or non-inoculated propagations, and showed transgene demethylation. This variable response among clonal transformants indicates that factors other than the genetic background of the transgenic plants play a key role in PTGS-mediated resistance.
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Database assignments for author(s): Carmelo Lopez, Leandro Peña

Research topic(s) for pests/diseases/weeds:
molecular biology - genes
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Citrus tristeza virus	Citrus (genus)