Asparagus virus 1

Morphology

Virions consist of a capsid. Virus capsid is not enveloped. Capsid/nucleocapsid is elongated with helical symmetry. The capsid is filamentous, flexuous with a clear modal length with a length of 740 nm and a width of 13 nm. Axial canal is indistinct. Basic helix is obscure. Electron microscopic preparation and references: Virus preparation contains few virions. Reference for electron microscopic methods: Fujisawa et al. (1983, Howell and Mink (1985).

Physicochemical and Physical Properties

There are 1 sedimenting component(s) found in purified preparations. The sedimentation coefficient is 146 S20w. A260/A280 ratio is 1.24. The thermal inactivation point (TIP) is at 50-55°C. The longevity in vitro (LIV) is 2–11 days. Although the titer is dependent on the host, the decimal exponent (DEX) of the dilution end point is usually around 3-4.

Nucleic Acid

The Mr of the genome constitutes 6% of the virion by weight. The genome is monopartite, only one particle size is recovered of linear, positive-sense, single-stranded RNA.

Proteins

Proteins constitute about 94% of the particle weight. The viral genome encodes structural proteins and non-structural proteins.

Lipids

Lipids are not reported.

Antigenicity

The virus is serologically related to bean yellow mosaic, lettuce mosaic and turnip mosaic viruses. The virus does not show serological relationships to beet mosaic, iris mild mosaic and potato Y viruses.

Transmission and Vector Relationships

Virus is transmitted by a vector. Virus is transmitted by mechanical inoculation; not transmitted by contact between hosts; not transmitted by seeds; not transmitted by pollen.

Vector Transmission

Virus is transmitted by arthropods, by insects of the order Hemiptera, family Aphididae; Aphis craccivora, Myzus persicae. The principal natural vector(s) are Myzus persicae. Virus is not transmitted by Aphis gossypii, Macrosiphum euphorbiae. Virus is transmitted in a non-persistent manner.

Experimental Hosts and Symptoms

Under experimental conditions susceptibility to infection by virus is found in several families. Susceptible host species are found in the Family Alliaceae, Amaranthaceae, Asparagaceae, Chenopodiaceae, Tetragoniaceae. The following species were susceptible to experimental virus infection: Allium tuberosum, Asparagus officinalis, Chenopodium album, Chenopodium amaranticolor, Chenopodium capitatum, Chenopodium quinoa, Gomphrena globosa, Tetragonia tetragonioides. Host: Experimentally infected hosts mainly show symptoms of necrotic local lesions.

Experimentally infected insusceptible Hosts

Families containing insusceptible hosts: Alliaceae, Amaranthaceae, Caryophyllaceae, Chenopodiaceae, Compositae, Cruciferae, Cucurbitaceae, Gramineae, Labiatae, Leguminosae-Papilionoideae, Liliaceae, Pedaliaceae, or Solanaceae, Umbelliferae. Species inoculated with virus that do not show signs of susceptibility: Allium cepa, Allium fistulosum, Amaranthus retroflexus, Apium graveolens, Beta vulgaris, Brassica campestris ssp. rapa, Capsicum frutescens, Celosia cristata, Chenopodium murale, Cucumis sativus, Cucurbita pepo, Datura stramonium, Daucus carota, Dianthus caryophyllus, Glycine max, Gomphrena globosa, Lactuca sativa, Lilium elegans, Lycopersicon esculentum, Nicotiana benthamiana, Nicotiana clevelandii, Nicotiana glutinosa, Nicotiana sylvestris, Nicotiana tabacum, Ocimum basilicum, Petunia x hybrida, Phaseolus vulgaris, Pisum sativum, Sesamum indicum, Solanum tuberosum, Vicia faba, Vigna unguiculata, Vigna unguiculata ssp. sesquipedalis, Zea mays, Zinnia elegans.

Diagnostic Hosts

Diagnostic host species and symptoms:

Chenopodium album, C. amaranticolor, C. quinoa, Tetragonia tetragonioides — chlorotic or necrotic local lesions.

Diagnostic host: insusceptible host species

Beta vulgaris, Cucumis sativus, Glycine max, Nicotiana tabacum, Phaseolus vulgaris, Vigna unguiculata.

Maintenance and Propagation Hosts

Most commonly used maintenance and propagation host species are Asparagus officinalis, Chenopodium amaranticolor, C. quinoa, Tetragonia tetragonioides.

Assay Hosts

Host: Assay hosts (for Local lesions or Whole plants): Chenopodium amaranticolor (L), Chenopodium quinoa (L), Tetragonia tetragonioides (L). References to host data: Hein (1960, Mink and Uyeda (1977, Fujisawa et al. (1983).

Histopathology

Virus can be best detected in leaves, stems, roots and mesophyll. Virions are found in the cytoplasm.

Cytopathology

Inclusions are present in infected cells. Inclusion bodies in the host cell are found in the cytoplasm. Cytoplasmic inclusions are pinwheels. Inclusions do not contain mature virions.

Geographical Distribution

The virus is probably distributed worldwide (wherever asparagus is grown commercially). The virus spreads in East Asia, Eurasia, and North America. The virus occurs in Germany, Italy, Japan, the United Kingdom, and the United States of America.

Ecology, Epidemiology and Control

Studies reported by Yang and Clore (1976, Howell and Mink (1985, Bertaccini et al. (1990).

Comments

Asparagus infected with Asparagus 1 and 2 viruses are significantly more susceptible to damage caused by Fusarium oxysporum f. sp. asparagi.