Efficiency assessment of genetic designs with coat protein in transgene-mediated resistance against chrysanthemum virus b
One of the efficient methods for control of virus diseases is to create resistant cultivars. Plant genetic engineering provides new methods for developing virus resistant plants based on the integration of viral genes and sequences into the plant genome. In this report we compared two different strategies for developing resistance in transgenic chrysanthemum to Chrysanthemum virus B (CVB). Transgenic chrysanthemum plants were generated with constitutive expression of the full CVB coat protein gene in sense, double-sense and antisense orientation. We also tested another promising strategy to create virus resistant plants - gene silencing via RNA interference (RNAi) technology. In this approach we inserted a short (276 bp) fragment of CVB coat protein sequence. More than 10 transgenic lines for each of the four constructions were obtained. The resistance to CVB in these transgenic lines were evaluated under greenhouse conditions where plants were artificially inoculated by grafting with CVB-infected cuttings. Virus levels in infected transgenic and non-transgenic plants were estimated by ELISA, Western- and Northern blot analysis. Different level of resistance were observed. Some of the lines transformed with the double-sense construction were completely virus resistant. Three RNAi lines showed dramatic decrease in the levels of virus infection relative to the levels found in non-transgenic infected plants. Significant differences in the level of infection were observed in a few lines expressing the coat protein sequences in sense and antisense orientation.