Species: Tulare apple mosaic virus
R. W. Fulton
Department of Plant Pathology, University of Wisconsin, Madison, Wisconsin, USA
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
Properties of Infective Nucleic Acid
Relations with Cells and Tissues
Ecology and Control
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.
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.
A260/A280 of the mixture of particle types: c. 1.36.
Protein: Subunits have a M. Wt of about 19,000 and contain about 181 amino acid residues (Barnett & Fulton, 1969).
Mosaic symptoms in apple (courtesy C. E. Yarwood).
Local necrotic and systemic symptoms in tobacco.
Primary lesions in bean.
Purified preparation of the virus, fixed in glutaraldehyde and stained with phosphotungstate. Bar represents 100 nm. (Micrograph by G. Gaard.)