The main viral species associated with grapevine (Vitis spp.) leafroll etiology are Grapevine leafroll-associated virus 1 and 3 (GLRaV-1 and -3). To partially evaluate the variability of these viruses, two DNA fragments (396 bp of GLRaV-1 and 602 bp of GLRaV-3) were amplified by RT-PCR using two sets of primers after total RNA extraction from veins and petioles of infected grapevines. The amplified DNA fragments were cloned and the reamplified viral DNAs, obtained from the recombinant clones, were studied with regard to denatured single-strand DNA conformational differences. Two different electrophoretic profiles were observed for each virus species. At least one viral clone representing each mobility profile was sequenced. The two nucleotide sequences obtained for GLRaV-1 showed the highest homologies (79,8% and 87,4%) with an Australian isolate, whereas the two nucleotide sequences of GLRaV-3 exhibited the highest homologies (75,1% and 81,8%) with a North American isolate. These results demonstrated the occurrence of GLRaV-1 and -3 sequence variants infecting the analysed grapevines.
grapevine; Vitis; GLRaV-1; GLRaV-3; SSCP
