- Volume 69, Issue 1, 1988

The F13 isolate of grapevine fanleaf virus (GFLV) differs from other isolates in that it induces severe symptoms on Chenopodium quinoa. We show here that its particles contain three RNA species with sizes, estimated by electrophoresis in agarose gels containing formaldehyde, of 6800 nucleotides (RNA1), 3900 nucleotides (RNA2) and 1150 nucleotides (RNA3). The three RNA species are polyadenylated and probably have a genome-linked protein at their 5′ end. RNA1 and RNA2 are known to be genomic RNAs. Evidence for the satellite nature of RNA3 came from Northern blot analysis with DNA probes. A probe originating from the 3′ end region of RNA3 and corresponding to one-third of the molecule did not hybridize with either RNA1 or RNA2. Conversely 3′-terminal cDNA probes of RNA1 and RNA2 did not hybridize significantly to RNA3. Further proof of the satellite nature of RNA3 is that it depends on RNA1 and RNA2 for its multiplication in C. quinoa. RNA3 acts as mRNA in wheatgerm extract and directs the synthesis of a M r 39000 protein.

The particles of a Japanese isolate of apple stem grooving virus (ASGV) contained a single coat protein species with a mol. wt. of 27000 and a single RNA species with a mol. wt. of 2.30 × 106. The corresponding values for particles of a Japanese isolate of apple chlorotic leaf spot virus (ACLSV) were 22000 and 2.48 × 106, respectively. RNAs of both ASGV and ACLSV were plus-sense and polyadenylated. Four virus-specific dsRNA species [mol. wt. (× 10-6) 4.8, 4.3, 3.9 and 3.5] were detected in extracts of ASGV-infected plants, whereas three major [mol. wt. (× 10-6) 4.9, 4.3 and 3.9] and two minor (4.5 and 3.1) virus-specific dsRNAs were found in ACLSV-infected plants. The biochemical properties of ASGV closely resemble those of potato virus T (PVT) which supports the proposal that ASGV and PVT should be placed in a new virus group.