North American Grape 'Norton' is Resistant to Grapevine Vein Clearing Virus

Grapevines (Vitis spp.) host viruses belonging to 17 families. Virus-associated diseases are a constant challenge to grape production. Genetic resources for breeding virus-resistant grape cultivars are scarce. 'Norton' is a hybrid grape of North American Vitis aestivalis and is resistant to powdery mildew and downy mildew. In this study, we assessed resistance of 'Norton' to grapevine vein clearing virus (GVCV), which is prevalent in native, wild Vitaceae and in vineyards in the Midwest region of the U.S. We did not detect GVCV in 'Norton' as either the scion or the rootstock up to 3 years after it was grafted with a GVCV-infected 'Chardonel' grapevine. Upon sequencing of small RNAs, we were able to assemble the GVCV genome from virus small RNAs in GVCV-infected 'Chardonel' scion or rootstock, but not from grafted 'Norton' scion and rootstock. This study unveils a new trait of 'Norton' that can be used in breeding GVCV-resistant grape cultivars, and to investigate genetic mechanisms of 'Norton' resistance to GVCV.