REPLICASE-MEDIATED RESISTANCE

Transformation of a plant with a DNA sequence derived from a gene encoding a viral replicase can endow it with a high level of resistance to the virus. To date, plants have been made resistant to tobacco mosaic virus, pea early browning virus, cucumber mosaic virus and potato virus X. It is considered that expression of replicase-derived sequences at the protein level interferes with normal functioning and/or assembly of viral replicase enzyme complexes leading to a general, marked inhibition of viral replication in the cells of these transgenic plants. Analogous studies of animal viruses in tissues culture cells indicate that mutants of viral-encoded replication-associated proteins can act as inhibitors of virus replication. This paper discusses the present status and future prospects for the control of virus disease using sequences derived from viral genes encoding replicase and replication-associated proteins. © 1993 Academic Press. All rights reserved.