REDUCED FIELD SPREAD OF POTATO LEAFROLL VIRUS IN POTATOES TRANSFORMEDWITH THE POTATO LEAFROLL VIRUS COAT PROTEIN GENE

Russet Burbank potato was transformed with plant expression vectors co ntaining the potato leafroll luteovirus (PLRV) coat protein (CP) gene. Transgenic potato lines contained a gene expression cassette with two copies of a PLRV CP gene in which the nucleotide sequence was modifie d to improve expression of the gene. In addition, the two copies of th e PLRV CP gene were each driven by a different promoter. Field test sc reening for PLRV resistance identified 15 lines which showed moderate resistance to PLRV infection and virus titer build-up and a longer inc ubation period for systemic infection. By conducting field resistance assays during a period when the vector of PLRV was not present, it was possible to test whether the observed resistance was sufficient to re strict aphid transmission of PLRV in a field test. Two years of field testing demonstrated that PLRV-spread from an infected plant to adjace nt healthy plants of the same line was severely restricted in nearly a ll the transgenic lines in the field. These lines have useful resistan ce to PLRV and could aid in managing PLRV disease in Russet Burbank po tato.