EXPERIENCES WITH NEPOVIRAL SEQUENCES AND THEIR USE IN TRANSGENIC PLANT PROTECTION.

To address efficacy and risks of new strategies for virus control, the nucleotide sequences at the 3' end of RNA-2 of arabis mosaic (ArMV), strawberry latent ringspot (SLRV) and cherry leaf roll (CLRV) nepoviruses have been determined. Each was distinct although similar in general organisation. The 3' nontranslated regions were 210, 350 and 1500 bases in ArMV, SLRV and CLRV respectively. In a birch isolate of CLRV, this long untranslated region was duplicated in RNA-1 and RNA-2. Knowledge of the N-terminal amino acid sequences in the capsid proteins allowed appropriate coding regions to be identified and transferred via Agrobacterium tumefaciens into plants. When the coding regions of ArMV capsid protein was transferred to tobacco plants they were rendered tolerant of disease and resistant to invasion by the isolate used to provide the capsid protein. Though similar in size and coding capacity, the extragenomic satellite RNAs from ArMV or SLRV had very few base sequences in common.