Details of DPV and References
DPV NO: 42 June 1971
Species: Tulare apple mosaic virus | Acronym: TAMV
Tulare apple mosaic virus
R. W. Fulton Department of Plant Pathology, University of Wisconsin, Madison, Wisconsin, USA
- Main Diseases
- Geographical Distribution
- Host Range and Symptomatology
- Transmission by Vectors
- Transmission through Seed
- Transmission by Grafting
- Transmission by Dodder
- Nucleic Acid Hybridization
- Stability in Sap
- Properties of Particles
- Particle Structure
- Particle Composition
- Properties of Infective Nucleic Acid
- Molecular Structure
- Genome Properties
- Relations with Cells and Tissues
- Ecology and Control
Described by Yarwood (1955).
- Apple mosaic virus (Rev. appl. Mycol. 35: 902)
An RNA-containing virus with isometric particles c. 33 nm in diameter. The virus is readily transmitted by inoculation of sap, but loses infectivity rapidly in sap unless a stabilizing agent is present. The virus has been found only once in nature, in an apple tree in Tulare County, California.
Associated with a severe mosaic disease of apple (Fig. 1).
Found only once in nature, in an apple tree in Tulare County, California. This tree no longer exists; as far as is known the virus exists only in experimental material.
Host Range and Symptomatology
In limited tests, 16 species in 9 dicotyledonous families were susceptible.
- Nicotiana tabacum(tobacco). Necrotic lines and rings appear on inoculated leaves; necrotic lines and oak-leaf patterns appear on systemically infected leaves (Fig. 2). Infected tobacco recovers and produces leaves free of symptoms, but containing virus.
- Phaseolus vulgaris (French bean). On Bountiful and certain other varieties, small brown lesions appear 3-5 days after inoculation (Fig. 3).
- Vinca roseais suitable for maintaining cultures and Nicotiana tabacum is a good source of virus for purification.
- Phaseolus vulgariscv. Bountiful or Pencil Pod.
Transmission by Vectors
No vectors known.
Transmission through Seed
Transmission by Dodder
Transmitted by Cuscuta subinclusa and C. campestris (Yarwood, 1955).
The virus is a moderately good immunogen in rabbits. A course of 8-10 intramuscular injections, at 3-4 day intervals, each of 1 mg virus emulsified in Freunds incomplete adjuvant, induces antiserum titres of 1/640 to 1/1280 (Fulton, 1967). Precipitates are granular; the virus reacts well in agar gel-diffusion tests, giving a single band of precipitate.
None have been described. The virus does not cross protect against tobacco streak virus (Fulton, 1956) and there are no serological cross reactions, although the viruses are similar in properties and cause similar symptoms in some hosts.
Stability in Sap
The virus in undiluted sap has a half-life of about 5 min (Yarwood, 1955). Infectivity is stabilized in diluted sap by reducing agents (0.02 M) such as 2-mercaptoethanol and cysteine hydrochloride. Inactivation is caused by o-quinones formed in the sap by oxidation (Mink, 1965). When infectivity is stabilized, the thermal inactivation point (10 min) is between 60 and 62°C.
Two methods have been used:
Mink, Bancroft & Nadakavukaren (1963).
Freeze infected leaves at -22°C,
powder and pack to half fill a 600 ml beaker. Add a stabilizing solution of 0.02
M sodium diethyldithiocarbamate and 0.02 M cysteine-HCl (350-400 ml), and infiltrate
into the tissue under reduced pressure. Homogenize the mixture mechanically for 1-2
min and express liquid through cheesecloth. Add n-butanol to the liquid to
8.5% (v/v), with stirring. Remove the precipitate by centrifuging cold for 10 min
at 8000 g. Sediment the virus from the supernatant liquid by centrifuging 1.75 hr
at 78,000 g. Resuspend the pellets in 2.5 ml of 0.15 M pH 5.0 acetate
buffer, keep at 4°C for a few hours, then centrifuge at 3000 g
for 10 min. Dialyse the supernatant liquid against 0.15 M pH 5.0 acetate buffer until
a precipitate appears (1-2 days). Remove the precipitate by centrifugation; the
purified virus remains in the supernatant liquid. Its stability is greatest at
pH 5.0 in 0.01 M acetate buffer.
Another effective method is that used for tobacco streak virus (Fulton, 1967). Homogenize tissue cold in 1.5 ml of buffer/g tissue, plus Al2O3 equal to 15% of the tissue weight. The buffer is 0.02 M phosphate, pH 8.0, and contains 0.02 M 2-mercaptoethanol. After centrifuging 15-20 min at 1500 g, stir the supernatant liquid with hydrated calcium phosphate, 0.8 ml/g tissue, then centrifuge at 1500 g for 15-20 min. Virus is then sedimented from the supernatant liquid by centrifuging 3 hr at 78,000 g. Resuspend the pellets in 0.01 M disodium ethylene diamine tetraacetate, pH 6.0, adjust the pH to 4.8-5.0 with citric acid and remove the precipitate by centrifugation. Readjust the pH of the supernatant liquid to pH 6.0 and concentrate the virus by high speed centrifugation. When resuspended in distilled water and kept at 2°C for several months, purified virus loses little infectivity.
Properties of Particles
The virus has two kinds of nucleoprotein particles, with sedimentation
coefficients (s20,w) of about 85 and 91 S; only the
latter are infective
(Mink et al., 1963).
A260/A280 of the mixture of particle types: c. 1.36.
Particles are isometric, c. 33 nm in diameter (Fig. 4). They disintegrate readily in phosphotungstate unless first fixed in glutaraldehyde.
RNA: About 12% of particle weight for the mixture of particle types.
Molar percentages of the nucleotides: G24; A24; C21; U31
(Barnett & Fulton, 1969).
Protein: Subunits have a M. Wt of about 19,000 and contain about 181 amino acid residues (Barnett & Fulton, 1969).
Relations with Cells and Tissues
Symptoms in apple are similar to those of common apple mosaic. The geographical designation was proposed by Gilmer (1958) to differentiate the disease from common apple mosaic. Apple is very difficult to infect by mechanical inoculation, but can be infected through dodder.
References list for DPV: Tulare apple mosaic virus (42)
- Barnett & Fulton, Virology 39: 556, 1969.
- Fulton, Phytopathology 46: 694, 1956.
- Fulton, Virology 32: 153, 1967.
- Gilmer, Phytopathology 48: 432, 1958.
- Mink, Virology 26: 700, 1965.
- Mink, Bancroft & Nadakavukaren, Phytopathology 53: 973, 1963.
- Yarwood, Hilgardia 23: 613, 1955.