A mild strain of Grapevine leafroll-associated virus 3 is present in desirable clones of Crimson seedless table grapes in Western Australia

Also cited as: Le Progrès Agricole et Viticole, Hors Serie - Special Congrès ICVG; XVI Extended abstract published Conference proceedings / Elisabeth Boudon-Padieu (ed.): pp.237-238We have obtained superior clones of Crimson Seedless (CS) table grapes in Western Australia (WA) by introducing combinations of the following viruses into the plants: a mild strain of Grapevine leafroll-associated virus 3 (GLRaV-3), GLRaV-9 and -5 and Grapevine virus A. We detected two strains of GLRaV- 3 in different clones of Crimson Seedless. One strain (GLRaV-3-s) produces a severe phenotype, it spreads naturally and is associated with poor quality grape berries. The other strain (GLRaV-3-m) gives a mild phenotype and is associated with larger, crisper and heavier berries as compared to the virus-free CS clone 8210. The nucleotide sequences of the coat protein genes of the mild and severe strains were compared and revealed a high degree of homology. Further sequencing analysis is in progress. A molecular assay is now available to differentiate between these two strains of GLRaV-3 and this will enable us to discard inferior plants infected with the severe strain.Nuredin Habili, Ian Cameron and John Randle