Grapevine cultivar Shine Muscat in China: occurrence of viruses and attempts to produce certified propagation material.

Virus diseases in grapevine 'Shine Muscat', an economically significant table grape cultivar in China, have become a major concern for grapevine growers. To investigate which viruses are frequent in 'Shine Muscat' and screen for healthy propagation material for this cultivar, a total of 140 samples (dormant canes) of 'Shine Muscat' plants were collected from 45 vineyards in different viticultural areas in China. RT-PCR was conducted to detect the presence of grapevine leafroll-associated virus 1 (GLRaV-1), GLRaV-2, GLRaV-3, grapevine fanleaf virus (GFLV), grapevine fleck virus (GFkV), grapevine virus A (GVA), grapevine rupestris stem pitting-associated virus (GRSPaV), grapevine Pinot gris virus (GPGV) and grapevine berry inner necrosis virus (GINV). No virus-free cane was found and all samples were infected with a mixture of at least two viruses; double, triple and quadruple infections accounted for about 31%, 30%, and 22% of the infections, respectively. The most frequent viruses in 'Shine Muscat' plants were GPGV (67.86%), GVA (59.29%) and GRSPaV (55.0%), and GFLV and GLRaV-1 were not detected in any of the samples. In vitro-grown 'Shine Muscat' plantlets carrying GFkV/GINV/GVA/GRSPaV were subjected to thermotherapy or chemotherapy followed by shoot-tip culture. GINV, GFkV and GVA were easily eliminated from the cultivar by both sanitation methods, whereas the frequency of GRSPaV elimination was relatively low. The results presented here contribute to our understanding of virus diseases in grapevine cv. Shine Muscat and to improving the sanitary status of the cultivar's planting material. [ABSTRACT FROM AUTHOR]