Plant Viruses Online   

Descriptions and Lists from the VIDE Database

Daphne X potexvirus

Index

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

Data collated by R.L.S. Forster, 1986.

Nomenclature

Synonyms

daphne latent X potexvirus.

Acronym

DVX

ICTV decimal code

56.0.1.T.007

Host range and symptoms

Natural host range and symptoms

Symptoms none.
• Daphne cneorum, D. odora - symptomless.

Transmission

Transmitted by means not involving a vector; Not transmitted between peas by the aphid Myzus persicae. Virus transmitted by mechanical inoculation; not transmitted by seed.

Ecology and control

Studies reported by Forster and Milne (1976; 1978). In New Zealand, no Daphne cneorum plants have been found free of daphne X virus out of more than 100 tested. D. cneorum plants imported from West Germany free of daphne X virus have been propagated and used to replace infected stock plants in nurseries.

Geographical distribution

Spreads in Australia and New Zealand.

Experimental host range

Several (3-9) families susceptible.

Diagnostically susceptible host species and symptoms

• Cucumis sativus - sunken chlorotic local lesions; then systemic faint chlorotic spotting, but later leaves are symptomless.
• Gomphrena globosa - necrotic local lesions, often with red haloes; not systemic.
• Nicotiana clevelandii - chlorotic and necrotic local lesions; systemic chlorotic rings or mottle.
• Pisum sativum - necrotic local lesions; then systemic chlorotic mottle and sometimes stem blackening.
• Vigna unguiculata ssp. cylindrica - small necrotic local lesions; not systemic.

Diagnostically insusceptible host species

Vicia faba, Spinacia oleracea.

Maintenance and propagation hosts

Nicotiana clevelandii - inoculated leaves are also good source for purification.

Assay hosts (Local lesions or Whole plants)

Cucumis sativus (L), Gomphrena globosa (L), Vigna unguiculata ssp. cylindrica (L).

Susceptible host species

• Chenopodium quinoa
• Cucumis melo
• Cucumis sativus
• Cucurbita maxima
• Daphne cneorum
• Daphne odora
• Datura stramonium
• Gomphrena globosa
• Nicotiana clevelandii
• Pisum sativum
• Vigna unguiculata ssp. cylindrica

Insusceptible host species

• Spinacia oleracea
• Vicia faba

Families containing susceptible hosts

• Amaranthaceae (1/1)
• Chenopodiaceae (1/2)
• Cucurbitaceae (3/3)
• Leguminosae-Papilionoideae (2/3)
• Solanaceae (2/2)
• Thymelaeaceae (2/2)

Families containing insusceptible hosts

• Chenopodiaceae (1/2)
• Leguminosae-Papilionoideae (1/3)

Physical and biochemical properties

Properties of particles in sap

TIP: 80 °C. LIV: 35 days. DEP: log₁₀ minus 5. Leaf sap contains many virions.

Purification method

Forster and Milne (1978c).

Particle morphology

Virions filamentous; not enveloped; usually flexuous; with a clear modal length; of 500 nm; 12 nm wide. Axial canal obscure. Basic helix obvious.

Physical properties

One sedimenting component in purified preparations; sedimentation coefficient 110 S. Density 1.28 g cm^-3 in CsCl.

Biochemical properties

Virions contain 6 % nucleic acid; 94 % protein; 0 % lipid.

Genome consists of RNA; single-stranded; linear. Total genome size 6.5 kb. Genome unipartite; largest (or only) genome part 6.5 kb. Genomic nucleic acid isolated by Guilford and Forster (1986). Infectivity retained when deproteinised with phenol or detergent. Poly A region present; at the 3´-terminal and 200 bases long. Additional factor not required for infectivity.

Features of the genome

Non-genomic nucleic acid found in the virions; is subgenomic mRNA. Sub-genomic mRNA found in infected cells; Five subgenomic RNAs were detected in infected tissues (4.9; 4.0; 2.1; 1.4 and 0.8 Kb). The 0.8 Kb subgenomic RNA is the mRNA for the coat protein (Guilford and Forster, 1986).

Features of proteins

Virion protein(s) one; M_r 23000.

Replication

Replication does not depend on a helper virus.

Cytopathology

Virions found in leaves; in cytoplasm. Inclusions present in infected cells; are crystals in the cytoplasm; they contain virions.

Taxonomy and relationships

Potexvirus

Virus(es) with serologically unrelated virions

Clover yellow mosaic, narcissus mosaic, potato X and white clover mosaic viruses, although preliminary tests (Milne and Forster, 1976) had suggested a distant relationship to white clover mosaic virus.

Best tests for diagnosis

Only two other viruses infecting daphne have flexuous filamentous virions; daphne S virus has virions c. 720 nm long (Forster and Milne, 1978a), and daphne Y virus has virions c. 730 nm long (Forster and Milne, 1976). Unlike daphne X virus, these viruses do not infect Cucumis sativus or Gomphrena globosa.

Comments and References

References

• Forster, R.L.S. and Milne, K.S. (1976). N.Z. Jl agric. Res. 19: 359.
• Forster, R.L.S. and Milne, K.S. (1978a). N.Z. Jl agric. Res. 21: 131.
• Forster, R.L.S. and Milne, K.S. (1978b). N.Z. Jl agric. Res. 21: 137.
• Forster, R.L.S. and Milne, K.S. (1978c). CMI/AAB Descr. Pl. Viruses No. 195, 3 pp.
• Guilford, P.J. and Forster, R.L.S. (1986). J. gen. Virol. 67: 83.
• Milne, K.S. and Forster, R.L.S. (1976). Acta Hort. 59: 95.

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.