Plant Viruses Online   

Descriptions and Lists from the VIDE Database

Beet western yellows ST9-associated RNA virus

Index

• Nomenclature
• Host range, transmission and symptoms
• Physical and biochemical properties
• Taxonomy and relationships
• Comments and References

Data collated by M.J. Gibbs (1995).

Nomenclature

ICTV decimal code

64.0.5.2.T.10

Host range and symptoms

Transmission

Transmitted by a vector; an insect; Myzus persicae; Aphididae. Transmitted in a persistent manner (probably). Virus requires, for vector transmission, a helper virus (beet western yellows luteovirus). The virus genome is probably transcapsidated in the virions of the helper virus (Falk and Duffus, 1984). Virus transmitted by mechanical inoculation (when transcripts from a DNA encoding the genome of the virus were inoculated to young plants of shepherd's purse (Capsella bursa-pastoris).

Geographical distribution

Found, but with no evidence of spread, in California, U.S.A.

Experimental host range

Few (<3) families susceptible. Experimentally infected plants mostly show stunting, yellowing and twisting.

Diagnostically susceptible host species and symptoms

• Capsella bursa-pastoris - lethal yellowing and necrosis, but causes milder yellowing, twisting and stunting when with beet western yellows luteovirus.

Diagnostically insusceptible host species

Cichorium endiva, C. intybus, Lactuca sativa, Nicotiana clevelandii and Solanum nigrum.

Maintenance and propagation hosts

Capsella bursa-pastoris.

Assay hosts (Local lesions or Whole plants)

Capsella bursa-pastoris (W).

Susceptible host species

• Brassica oleracea var. botrytis
• Capsella bursa-pastoris
• Raphanus sativus

Insusceptible host species

• Cichorium endiva
• Cichorium intybus
• Lactuca sativa
• Nicotiana clevelandii
• Solanum nigrum

Families containing susceptible hosts

• Cruciferae (3/3)

Families containing insusceptible hosts

• Compositae (3/3)
• Solanaceae (2/2)

Physical and biochemical properties

Biochemical properties

Genome consists of RNA; single-stranded; linear. Total genome size 2.843 kb (Chin et al., 1993). Genome unipartite; largest (or only) genome part 2.843 kb. Infectivity retained when deproteinised with phenol or detergent (Passmore et al., 1993). Poly A region absent. Additional factor not required for infectivity. Nucleotide sequence references: Chin et al., 1993.

NCBI sequence data (Entrez search)

Sequence database accession code(s)

L04281.

Features of the genome

Features of the genome: Four ORFs. Only ORF3 encodes a protein with recognizable function, the polymerase. ORF2 may be translated after tRNA suppression of the amber stop codon of ORF1, but sequence analysis suggests that the reported sequence may be in error and that ORFs 2 and 3 may be a single ORF (Gibbs, 1995). ORF4 is probably translated from a subgenomic RNA.

Sub-genomic mRNA found in infected cells; c. 400 bp long and co-terminal with the 3´ end. 2 virus specified dsRNA species found in infected cells (one from the helper virus and of c. 2.9 kb pairs).

Replication

Replication does not depend on a helper virus; ST9 a-virus does not produce its own virion proteins or virions, however plants co-infected with it and its helper produce 10 times more virions than the helper does alone (Sanger et al., 1994).

Taxonomy and relationships

(ungrouped)

Additional comments on relationships

This virus is not sufficiently similar to viruses in any of the currently recognized groups to be comfortably placed with them. Its polymerase protein shows affinities with those of the carmoviruses, dianthoviruses, type 1 and 2 luteoviruses, machlomoviruses, necroviruses, tombusviruses, umbraviruses and pea enation mosaic virus RNA-2.

Comments and References

General comments

This organism has features of a satellite RNA, but can replicate independently, and therefore is included as a virus.

References

• Chin, L.-S., Forster, J.L., Falk, B.W. and Bruening, G. (1993). Proc. Natl. Acad. Sci. USA 90: 10168.
• Falk, B.W. and Duffus, J.E. (1984). Phytopathology 74: 1224.
• Gibbs, M.J. (1995). D. Phil. thesis, Oxford University.
• Sanger, M. Passmore, B., Falk, B.W., Bruening, G., Ding, B. and Lucas, W.J. (1994). Virology 200: 48.

Cite this publication as: Brunt, A.A., Crabtree, K., Dallwitz, M.J., Gibbs, A.J., Watson, L. and Zurcher, E.J. (eds.) (1996 onwards). `Plant Viruses Online: Descriptions and Lists from the VIDE Database. Version: 20^th August 1996.' URL http://biology.anu.edu.au/Groups/MES/vide/

Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993) should also be cited.