SUSCEPTIBILITY OF TRANSGENIC TOBACCO PLANTS EXPRESSING TOBACCO RATTLEVIRUS COAT PROTEIN TO NEMATODE-TRANSMITTED AND MECHANICALLY INOCULATED TOBACCO RATTLE VIRUS

Transgenic Samsun NN tobacco plants expressing the coat protein of tob acco rattle virus were exposed to mechanical leaf inoculation with tob acco rattle virus and to viruliferous trichodorid vector nematodes. Wh ereas plants were resistant to mechanical inoculation the vector nemat odes successfully transmitted tobacco rattle virus to the roots as wel l as to the leaves of these plants. It is suggested that transgenic re sistance is overcome either because vector nematodes inject relatively large numbers of virus particles into a cell or because they inject d estabilized particles. The results indicate that coat protein-mediated resistance is unlikely to be of value for controlling tobacco rattle virus in field crops.