Cucumber mosaic virus (CMV) supports the replication and encapsidation of its satellite RNA, both in solanaceous and cucurbit host plants; however, different strains of CMV support the replication of satellite RNAs with different efficiency. In addition, replication of satellite RNA is very efficient in solanaceous host plants and generally poor in cucurbit host plants. The WL1-satellite (WL1-sat) RNA is an exception, and replicates to high levels in both solanaceous and curcubit host plants with most CMV strains as the helper virus. Two strains of CMV were used in this study: Fny-CMV, which replicates the WL1-sat RNA efficiently in all hosts tested; and Sny-CMV, which does not replicate the WL1-sat RNA to detectable levels in zucchini squash (Cucurbita pepo), but does replicate WL1-sat RNA efficiently in other hosts. Using pseudorecombinants constructed between Fny-CMV and Sny-CMV we have mapped to RNA 1 the ability to support the efficient replication of WL1-sat RNA in zucchini squash.
"There are some reports on the CMV strains that cannot support satRNAs (Gal-On et al., 1995; McGarvey et al., 1995; Roossinck & Palukaitis, 1991). For example, Sny-CMV can support replication of WL1-satRNA in tobacco, but not in zucchini (Gal-On et al., 1995; Roossinck & Palukaitis, 1991). Roossinck et al. (1997) found that the amino acid residue at position 978 of the 1a protein in Sny-CMV was important for WL1-satRNA replication in zucchini. "
[Show abstract][Hide abstract] ABSTRACT: Five isolates of Cucumber mosaic virus (CMV) from Lilium sp. (lily), which were isolated from specimens in Japan, Korea and Taiwan, were unable to support satellite RNA (satRNA) accumulation. In order to map the CMV sequences that are involved in satRNA support, HL-CMV (Japanese lily isolate), Y-CMV (ordinary strain) and Y-satellite RNA (Y-sat) were used as the source material. The pseudorecombinants between Y-CMV and HL-CMV revealed that RNA1 was essential for satRNA replication in lily. The results of chimeric constructs and various mutations showed that two amino acid residues (at positions 876 and 891) in the 1a protein were the determinants for the inability of HL-CMV to support a satRNA. Specifically, Thr at position 876 had a more pronounced effect than Met at position 891. Specific changes in RNA sequence were also detected in the 3' terminus of Y-sat and these particular alterations allowed it to be supported by HL-CMV. It is believed that, through evolution, the adaptation of CMV to lily resulted in the introduction of amino acid changes in the 1a protein, changes that coincidentally affected the ability of lily CMV to support satRNAs.
Journal of General Virology 09/2005; 86(Pt 8):2359-69. DOI:10.1099/vir.0.81059-0 · 3.18 Impact Factor
"PSV-W differs from the two CMV strains (CMV-Sny and CMV-Ix) in that it does not replicate satRNA in any of the host species thus far tested, regardless of the satRNA variant involved (Naidu et al., 1995). CMV-Sny, on the other hand, supports the replication of certain satRNAs in solanaceous plant species but not in cucurbits (Roossinck & Palukaitis, 1991), whereas CMV-Ix supports the replication of certain satRNAs (T-and GP-satRNAs) but not others (D-satRNA), in the same host species (Tousignant et al., 1996). It is thus possible that more than one mechanism may be responsible for the failure of certain cucumoviruses to replicate satRNA. "
[Show abstract][Hide abstract] ABSTRACT: Full-length cDNA clones from which infectious transcripts could be generated were constructed from the genomic RNAs of two distinct strains of peanut stunt cucumovirus (PSV), PSV-ER and PSV-W. PSV-ER, a subgroup I strain, is known to support efficient replication of satellite RNA (satRNA) in infected plants, whereas PSV-W, a subgroup II strain, does not support satRNA replication. Although artificial reassortants (pseudorecombinants) of all possible combinations of infectious transcripts representing RNA1, RNA2 and RNA3 were infectious, only those having RNA1 from PSV-ER supported the replication of satRNA. These results demonstrate conclusively that support of PSV satRNA replication maps to RNA1. Comparisons of secondary structure predictions of the C-terminal helicase-like domain of the 1a proteins of four PSV strains belonging to two subgroups did not reveal any obvious differences between strains that differ in satRNA support. The complete nucleotide sequence of RNA1 from strains PSV-ER and PSV-W were determined and found to be 79% identical. Sequence comparison analysis of RNA1 sequences of cucumoviruses confirmed the placement of the PSV strains into two distinct subgroups.
Journal of General Virology 09/1998; 79 ( Pt 8)(8):2013-21. DOI:10.1099/0022-1317-79-8-2013 · 3.18 Impact Factor
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