Variation in the hypervariable region of cucumber mosaic virus satellite RNAs is affected by the helper virus and the initial sequence context.
The D satellite RNA (sat RNA) of cucumber mosaic virus (CMV) was previously shown to contain a region of hypervariability around nucleotide 230, in wild-type populations and in cDNA clones and progeny of one such clone (pDsat4) after passage with the subgroup I strain Fny-CMV. This hypervariable region (HVR) consists of a series of consecutive A and/or U residues. We found that variability is also generated in the HVR of transcript derived from pDsat4 after passage with the subgroup II strain LS-CMV and with tomato aspermy virus (TAV). However, the progeny differ with respect to the sequence of the HVR after passage with both LS-CMV and TAV. Another D-sat RNA cDNA clone that contains a C residue in the HVR, pDsat1, was previously shown not to develop variability in the HVR upon passage with Fny-CMV. However, when the C (position 231) was changed to an A residue, variability developed by the third passage with Fny-CMV. An additional cDNA clone derived from the B1-sat RNA, pBsat5, also contains a C residue in the region analogous to the D-sat RNA HVR and did not develop variability upon passage with either Fny- or LS-CMV. Changing this C to a U residue did not result in the development of hypervariability in the progeny of transcript from this mutant. Models to explain the generation of hypervariability are discussed.
Palukaitis
P
P
Department of Plant Pathology, Cornell University, Ithaca, New York 14853.
Roossinck
M J
MJ
D001483:Base Sequence; D017799:Cucumovirus / Q000235:genetics*; D018076:DNA, Complementary; D006378:Helper Viruses / Q000235:genetics*; D008969:Molecular Sequence Data; D012313:RNA / Q000235:genetics*; D019244:RNA, Satellite; D012367:RNA, Viral / Q000235:genetics*
D018076:DNA, Complementary; D019244:RNA, Satellite; D012367:RNA, Viral; D012313:RNA