Susceptibility of transgenic tobacco plants expressing tobacco rattle virus coat protein to nematode-transmitted and mechanically inoculated tobacco rattle virus

1 Zoology and 2 Virology Departments, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, U.K. and 3 Institute of Molecular Plant Sciences, Leiden University, Gorlaeus Laboratories, Einsteinweg 55, 2333 CC Leiden, The Netherlands Transgenic Samsun NN tobacco plants expressing the coat protein of tobacco rattle virus were exposed to mechanical leaf inoculation with tobacco rattle virus and to viruliferous trichodorid vector nematodes. Whereas plants were resistant to mechanical inoculation the vector nematodes successfully transmitted tobacco rattle virus to the roots as well as to the leaves of these plants. It is suggested that transgenic resistance is overcome either because vector nematodes inject relatively large numbers of virus particles into a cell or because they inject destabilized particles. The results indicate that coat protein-mediated resistance is unlikely to be of value for controlling tobacco rattle virus in field crops. Present address: Department of Soil Ecology, Research Institute for Plant Protection (IPO-DLO), Binnenhaven 12, P.O. Box 9060, 6700 GW Wageningen, The Netherlands. Present address: Institut für Parasitologie, Universität Zürich, Winterthurstrasse 266 a , CH-8057 Zürich, Switzerland. Received 14 June 1993; accepted 6 August 1993.