Replication, Recombination, and Symptom-Modulation Properties of the Satellite RNAs of Turnip Crinkle Virus
Turnip crinkle virus (TCV) is a member of the carmovirus group and the only group member that is associated with confirmed sat-RNAs. The host range of TCV is quite widespread, including numerous cruciferous and some noncruciferous hosts (Broadbent and Hea
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Introduction
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2
Symptom Modulation by TCV Sat-RNAs
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3.1 3.1.1 3.1.2 3.2
Replication of TCV Sat-RNAs Ci.l'-Seqllences Involved in Sat-RNA C Replication Ci.l'-Scqllcnce Involved in the Synthesis of Sat-RNA C Minus Strands Ci.l'-Sequence Involved in the Synthesis 01' Sat-RNA C Plus Strands RoJe of the CP in Replication of TCV Sat-RNAs .
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4 4.1 4.2
Recombination Among TCV Sat-RNAs Recombination Betwcen Sat-RNA D and Sat-RNA C . Recombination Between TCV and Sat-RNA D
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25 27
2H 30
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Rcpair of Sat-RNA 3' End Truncations
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Origin of TCV Sat-RNAs
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Prospects .
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Refcrences. . .
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1 Introduction Turnip crinkle virus (TCV) is a member of the carmovirus group and the only group member that is associated with confirmed sat-RNAs. The host range ofTCV is quite widespread, including numerous cruciferous and so me noncruciferous hosts (BROADBENT and HEATHCOTE 1958). TCV has a single RNA genome of 4054 bases (CARRINUTON et al. 1989; OH et al. 1995) and two subgenomic RNAs of 1721 bases and 1447 bases (CARRINGTON et al. 1987; WANG and SIMON 1997) (Fig. I). The genomic RNA is the mRNA for two overlapping polypeptides required for viral replication, p28 and p88. The translation of p88, which contains the conscrved polymerase active site motif GDD, requires an in-frame ribosomal readthrough of an amber codon at the end of the p28 open reading frame (ORF). Two small ORFs (p8 and p9), have been implicated in viral movement (HACKER et al. 1992) and are Department of Biochemistry and MoleCl"ar Biology, University of Massachusetts, Amherst, MA 0 I 003, USA
P. K. Vogt et al. (eds.), Satellites and Defective Viral RNAs © Springer-Verlag Berlin Heidelberg 1999
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A.E . Simon
A
.-
4054 b
p38 IM#!__----...
'r----~~----~ p28/p88
oc:o
,
rr-
172 1 b
1447 b
B 4054 b
TCV 194 b
sat-R AD
I ~
sat-R AC Fig. tA,B. The TCV system. A The genoillic and subgenomic RNAs of TCV. B SC
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