Distinct responses of Vitis aestivalis ‘Norton’ and Vitis vinifera ‘Kishmish Vatkana’ to seven viruses revealed by small RNA sequencing
Grapevines are frequently infected by multiple viruses. Our previous study showed that ‘Norton’ grapevine (Vitis aestivalis) is resistant to grapevine vein clearing virus, a DNA virus in the family Caulimoviridae. To study the reaction of ‘Norton’ to RNA viruses, we transferred seven RNA viruses to ‘Norton’ from ‘Kishmish Vatkana’ (‘KV’) (Vitis vinifera) via graft-transmission. We profiled viral small RNAs (vsRNAs) of the seven viruses and compared viral titers in ‘Norton’ and ‘KV’. Total vsRNAs of grapevine leafroll-associated virus 1 (GLRaV-1), GLRaV-2, GLRaV-3, grapevine virus A (GVA) and grapevine Pinot gris virus (GPGV) were significantly less abundant in ‘Norton’ than in ‘KV’, but total vsRNAs of grapevine fleck virus (GFkV) were more abundant in ‘Norton’ than in ‘KV’. Total vsRNAs of grapevine rupestris stem pitting-associated virus (GRSPaV) were not different between ‘Norton’ and ‘KV’. Grafting direction of ‘Norton’ to ‘KV’ or ‘KV’ to ‘Norton’ did not affect the quantity of vsRNAs. The genome coverage of GLRaV-1, GLRaV-2, GLRaV-3 and GVA vsRNAs was lower in ‘Norton’ than ‘KV’. The 21-nt and 22-nt classes of vsRNAs were predominant for all seven viruses. Virus quantification by qPCR indicated that GLRaV-1 was undetectable in ‘Norton’, GLRaV-2, GLRaV-3, and GVA were less abundant in ‘Norton’, but GFkV was more abundant in ‘Norton’ than in ‘KV’. These results demonstrated that ‘Norton’ grapevine suppresses GLRaV-1, GLRaV-2, GLRaV-3, and GVA, but supports GFkV in comparison with ‘KV’. This study revealed new facets of complex molecular interactions between grapevines and multiple viruses.