Comparison of RNA extracts from in vitro shoot tip cultures of leafroll-affected and leafroll-free grapevine cultivars

The RNA content of in vitro shoot tip cultures from grapevine leafroll (GLR) disease-affected grapevines was analyzed and compared to that of similar cultures from GLR-free grapevines. A previously unreported low-molecular-weight single-stranded RNA (LMWssRNA) was detected in in vitro shoot tip cultures of 65 % (11 out of 17) of GLR-affected cultivars. This LMWssRNA was absent from disease-free cultivars and may be associated with a virus or a strain of a virus responsible for GLR. Numerous high-molecular-weight (HMW) dsRNA bands were also detected in GLR-affected grapevine cultivars. The intensities and mobilities (apparent molecular weights) of these dsRNA bands varied considerably from one GLR-affected cultivar to the next, but were reproducible for each cultivar. The detection of multiple distinctive RNA banding patterns is consistent with the possibility that more than one agent can cause grapevine leafroll disease