Enhancement of Resistance to Potato Leafroll Virus Multiplication in Potato by Combining the Effects of Host Genes and Transgenes. H. Barker. Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, United Kingdom. K. D. Webster, C. A. Jolly, B. Reavy, A. Kumar, and M. A. Mayo. Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, United Kingdom. MPMI 7:528-530. Accepted 21 March 1994. Copyright 1994 The American Phytopathological Society.

Four potato clones with host gene-mediated resistance to potato leafroll virus (PLRV) multiplication were transformed with the PLRV coat protein (CP) gene. Plants of lines expressing high levels of transcript were highly resistant to PLRV multiplication; virus concentration was only 20-40 ng/g of leaf, which is approximately 1% of the concentration reached in susceptible cultivars. The effects of the transgenic and host-derived resistance genes appear to be additive.