Tombusvirus

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Classification

Higher order taxa

Viruses; ssRNA positive-strand viruses, no DNA stage; Tombusviridae, Tombusvirus.

Species

NCBI: Taxonomy

Tomato bushy stunt virus (TBSV), Cauliflower mosaic virus, Cymbidium ringspot virus, Carnation Italian ringspot virus, Cucumber necrosis virus, Artichoke mottled crinkle virus

Description and significance

Infects a wide variety of dicotyledenous plants: tomato, eggplant, tobacco, etc. Symptoms are generally not severe but can range from stunted growth, chlorotic to necrotic lesions on leaves, and deformation of leaf tissue. The virus is spread mainly via manual transmission through either propagation of infected tissue or use of contaminated tools. No vector is presently known to transmit the viral particles. It has been suggested that the virus may persist or spread via contaminated irrigation water.

Genome structure

Tomato bushy stunt virus is composed of a monopartite genome 4.7 kilobases in length. The genome is enclosed by a spherical capsid comprising 180 subunits. The genome encompasses five open reading frames coding for five protein products: p33, p92, p41, p22, and p19, respectively. p92 is the RNA-dependent RNA polymerase and results from the readthrough of a leaky amber stop codon located at the 3' terminus of p33, the auxiliary protein necessary for replication. Together, p33 and p92 form the viral replicase complex. p41 and p22 are the capsid and movement proteins, respectively. p19 serves as a strong suppressor of viral RNA silencing. Translation of p41, p22, and p19 results from replication of subgenomic RNA during the viral replication stage. Due to the localization of p33 and p92 to peroxisomal membranes, it is thought that the peroxisomes serve as the primary sites of viral replication for TBSV.

References

McCartney, A. W., Greenwood, J. S., Fabian, M. R., White, K. A., Mullen, R. T. 2005. Localization of the Tomato Bushy Stunt Virus Replication Protein p33 Reveals a Peroxisome-to-Endoplasmic Reticulum Sorting Pathway. Plant Cell 17: 3513-3531.

Rajendran, K. S. and Nagy, P. D. 2003. Characterization of the RNA-binding domains in the replicase proteins of tomato bushy stunt virus. Journal of Virology; 77 (17). 9244-9258.

Scholtof H. B. 1999. Rapid delivery of foreign genes into plants by direct rub-inoculation with intact plasmid DNA of a Tomato bushy stunt virus gene vector. Journal of Virology; 73(9), p. 7823-7829.