In the framework 
of obtaining resistance against BNYVV, Kallerhoff et al. (1990) showed that protoplasts of CP-transformed sugar beet suspension cells, though amenable to infection, presented lower virus multiplication rates in comparison to protoplasts of non-transformed cells. Further, Ehlers et al. (1991) described a protocol for the generation of CP-expressing hairy roots obtained through A. rhizogenes-mediated transformation. CP-based resistance at the plant level however, obtained via Agrobacterium tumefaciens-mediated transformation, was first reported by Mannerlöf et al. (1996) using two constructs carrying the coding region of the CP. Progenies obtained after two cycles of selfing, were challenged with BNYVV and evaluated for resistance. Although accumulation of the viral protein could not be detected, expression of the CP gene was found correlated with reduced virus titers both in greenhouse and field trial experiments. Presently, such a discrepancy between translatable levels and reduced virus accumulation has been explained on the basis of additional mechanisms such as RNA-mediated interferences (RNAi) (for a review see Prins et al.,
2008).