Nicotiana benthamiana plants transgenic for PPV-SwC coat protein are resistant to PPV infection

Two constructs containing the coat protein gene (CP) of PPV-SwC - in (+) and (-) sense - were obtained and used to transform Nicotiana benthamiana plants via Agrobacterium tumefaciens. Transformed lines were analysed for the integration of the CP gene by PCR and Southern blot. Sixty transgenic lines were selected. Expression of CP gene was investigated by immuno-western blot using a monoclonal antibody specific for PPV-SwC. Various levels of CP expression were detected in transgenic plants. R1 lines were challenged with the homologous virus and with isolates belonging to D, M and EA PPV groups. A variable degree of resistance was obtained, going from complete susceptibility to immunity. Susceptible plants showed a slight delay in symptoms expression when compared to non transformed control. No correlation was established by CP expression level and observed resistance.