Mutants of tobacco vein mottling virus (TVMV) were constructed in which the tyrosine residue (Tyr1860) that links the VPg to the viral RNA was changed to phenylalanine or serine or was inverted in position with the adjacent glycine residue. In another mutant, the tyrosine residue nearest to Tyr1860 (Tyr1867) was changed to a phenylalanine residue. The resulting mutants were tested for their ability to infect Nicotiana tabacum plants or protoplasts. The Tyr1860 mutants did not accumulate to detectable levels in infected plants when tested by ELISA and Northern blot analysis. Moreover, the Tyr1860-associated mutants were not infectious in protoplasts, indicating that mutations involving the linking amino acid of the TVMV VPg abolished viral replication. In contrast to the Tyr1860 mutants, transcripts from the mutation of Tyr1867 to a phenylalanine residue infected both protoplasts and plants. Analysis of progeny RNA from plants inoculated with the Tyr1867 mutant indicated that a reversion to wild type had occurred in systemically infected leaves.
|Number of pages||4|
|State||Published - Jun 15 1996|
Bibliographical noteFunding Information:
We are grateful to Amy Crume for technical assistance and Dr. C. D. Atreya and Dr. J. Wolfe for advice on the mutagenesis. This work was supported by USDA Grant 90-37262-5519.
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