CONCURRENT SUPPRESSION OF VIRUS-REPLICATION AND RESCUE OF MOVEMENT-DEFECTIVE VIRUS IN TRANSGENIC PLANTS EXPRESSING THE COAT PROTEIN OF POTATO-VIRUS-X

A line of transgenic tobacco expressing the coat protein (CP) of potat o virus X (PVX) was resistant against a broad spectrum of PVX strains, Inoculation of leaves and protoplasts with PVX expressing the jellyfi sh green fluorescent protein reporter gene revealed that this resistan ce mechanism suppressed PVX replication in the initially infected cell and systemic spread of the virus. Cell-to-cell movement was also slow er in the resistant plants. The resistance at the level of replication was effective against wild-type PVX and also against movement-defecti ve isolates with a frameshift mutation or deletion in the CP ORF. Howe ver, the cell-to-cell movement defect of the mutant viruses was rescue d on the resistant plants. Based on these results it is proposed that the primary resistance mechanism is at the level of replication. (C) 1 997 Academic Press.