DETECTION OF TOBACCO RATTLE VIRUS IN POTATO-TUBERS AND ROOTS BY POLYMERASE CHAIN-REACTION (PCR)

Tobacco rattle virus (TRV) was detected by PCR in potato tubers and in root samples. Oligonucleotide primers were synthesized to nucleotides of the 16 k protein gene of RNA-1 of the TRV strain 'SYM'. After phenol extraction of the total nucleic acids of the samples and reverse transcription, the PCR reaction mixture was subjected to 25 cycles and the amplification product was detected by electrophoresis. TRV RNA was found in roots and in freshly harvested tubers in September, as well as in tubers which were stored until March. This indicates that there was no elimination of TRV during the storage period. The field samples of potato cv. Desiree tested in September were symptomlessly infected, whereas the stored tubers of various cultivars showed internal symptoms. Nucleic acids extracts of latently-infected and spraing-affected tubers inoculated on tobacco plants led to local necrotic rings. Nucleic acids from infected tobacco cv. Samsun plants led to systemic symptoms as well. TRV was identified by ISEM and ELISA only in the systemically-infected tobacco plants, but not in the locally infected tobacco plants. This suggests the presence of the 'NM'-type of TRV in tubers, which produces only RNA-I but no complete virus particles.