RNA Species of Tobacco Rattle Virus Strains and Their Nucleotide Sequence Relationships

Abstract

SUMMARYThe nucleotide sequences of the genome RNA species (RNA-1 and RNA-2) of three strains of tobacco rattle virus OR, SYM and CAM, were compared by hybridization with complementary DNA copies. Strain OR was found to contain two RNA-2 species, which differ by about 5 × 104 in mol. wt. (150 nucleotides), but about 90~ of whose nucleotide sequences are homologous. The larger of the two contained the genetic information for yellow symptoms in infected Nicotiana spp., whereas the smaller, which probably arose from it by mutation, did not. The RNA-2 species of strains OR, SYM and CAM had no detectable nucleotide sequences in common. RNA-1 of strain OR and of strain SYM were almost identical in sequence, but had no detectable sequence in common with RNA-1 of strain CAM. Only in strain CAM was any nucleotide sequence homology between RNA-1 and RNA-2 detected, amounting to about 450 residues.

The Complete Nucleotide Sequence of Tobacco Rattle Virus RNA-1

“…RNA from TRV strains SYM (Kurppa et al, 1981), PRN (Cadman & Harrison, 1959), ORY (Lister & Bracker, 1969) and N5 (Harrison et al, 1983) were propagated in Nicotiana clevelandii as described by Robinson & Harrison (1985) and RNA was extracted from purified virions as described by Robinson (1983). Strain ORY was held under licence from the Department of Agriculture and Fisheries for Scotland.…”

A model for the generation of tobacco rattle virus (TRV) anomalous isolates: pea early browning virus RNA-2 acquires TRV sequences from both RNA-1 and RNA-2

“…The tobravirus group consists of isolates of three distinct bipartite viruses, pea early browning virus (PEBV), tobacco rattle virus (TRV) and pepper ringspot virus (PRV) (Robinson, 1983;Robinson & Harrison, 1985 a, b). Considerable homology between the RNA-1 molecules of isolates of the same virus has been demonstrated by hybridization (Robinson & Harrison, 1985a, b).…”

Origin and Messenger Activity of Two Small RNA Species Found in Particles of Tobacco Rattle Virus Strain SYM

“…wt. 0-54 x 106) of strain CAM (Robinson, 1983). The value of R0t~ for hybridization of cDNA to excess unlabelled RNA is proportional to the sequence complexity of the RNA (Hell et al, 1976).…”

“…s/l. All preparations of RNA-1 and RNA-2 are contaminated with one another to some extent (Robinson, 1983), so that cDNA copies of any virus-specific RNA sequence will hybridize completely to either preparation at sufficiently large Rot. However, sequences from different parts of the genome will be present in these RNA preparations at different concentrations and will give rise to pseudo-first order reactions proceeding at different rates that may overlap in the overall kinetic curve.…”

“…Thus, RNA-4 of strain SYM and of strain PRN seem to correspond closely to one another in structure and function. It is perhaps not surprising that the subgenomic messengers derived from the RNA-1 species of these two strains should be so similar in view of the extensive nucleotide sequence homology between the RNA-1 species themselves (Robinson, 1983).…”