Tobacco ringspot virus
Canada Agriculture Research Station, Vancouver 8, B.C., Canada
- Described by
Fromme, Wingard & Priode (1927).
- Selected synonyms
- Tobacco ringspot virus No. 1 (Rev. appl. Mycol. 15: 831)
- Annulus tabaci (Rev. appl. Mycol. 28: 514)
- Nicotiana virus 12 (Rev. appl. Mycol. 36: 303)
- An RNA-containing virus with isometric particles about 28 nm in diameter.
It is readily transmitted by sap inoculation and has a wide host range,
including both herbaceous and woody plants. Transmitted by the nematode
Xiphinema americanum, and also by species of thrips, spider mite,
grasshopper, flea beetle and, possibly, aphid. Commonly seed transmitted.
Causes ringspot diseases of tobacco, cucumber, Easter lily, hydrangea,
iris and Pelargonium
; also blueberry necrotic ringspot, soybean bud
blight, and chlorotic or necrotic spotting in many other annual and perennial
Occurs in the USA and Canada, field spread being confined primarily to
areas where Xiphinema americanum
is prevalent. The virus has been
distributed, probably in ornamental crops, to other parts of the world,
including the UK, Germany and Australia.
Host Range and Symptomatology
Host range wide; has been found infecting, or transmitted experimentally
to, plants of at least 38 genera, representing 17 families
anemone necrosis strain infected 58 of 103 plant spp. tested, in 21 of 32
The nematode vector, Xiphinema americanum
can transmit the virus to roots of Cupressus arizonica
- Cucumis sativus (cucumber;
Fig.1). Chlorotic local lesions, systemic
mottling and dwarfing, severe apical distortion.
- Nicotiana tabacum (tobacco;
Fig.3), N. glutinosa and N.
Necrotic local lesions that frequently develop into
rings or ringspots; systemic ring or line patterns. Leaves produced later
show no symptoms but contain virus.
- Lycopersicon esculentum (tomato). Difficult to infect by sap
inoculation; plants that are infected develop small necrotic spots.
- Phaseolus vulgaris (bean). Necrotic spots on inoculated leaves;
systemically infected leaves show spots and rings, and the growing tip becomes
- Vigna sinensis (cowpea;
Fig.2). Necrotic local lesions, systemic
necrosis, apical necrosis and wilt. Cowpea varieties may be used for
- Chenopodium amaranticolor and C. quinoa. Local necrotic dots;
usually no systemic reaction.
- Propagation species
- Cucumber or tobacco are suitable hosts for maintaining cultures. Cucumber
or bean are good sources of virus for purification.
- Assay species
- Vigna sinensis, Nicotiana tabacum, N. clevelandii and Cassia
occidentalis are useful local lesion hosts. Cucumber is a useful source
and bait plant for nematode transmission experiments
Many minor variants can be distinguished. The best known major variants are:
Tobacco green ringspot strain of
and pale yellow lesions in tobacco; recovered leaves are green. Local lesions
in cowpea are necrotic at edges only. Source USA.
Tobacco yellow ringspot strain of
yellow as well as necrotic local lesions in tobacco; recovered leaves are yellow.
Local lesions in cowpea are necrotic at edges only. Source USA.
Tobacco ringspot virus No. 1 of
Produces necrotic and
pale yellow lesions in tobacco, causes more necrosis and stunting than tobacco
green ringspot virus; recovered leaves are green. Produces solid necrotic
spots in cowpea. Source USA.
Eucharis mottle strain of
Kahn, Scott & Monroe (1962). Produces
necrotic or chlorotic rings in some tobacco varieties but is latent in others.
Ringspot lesions followed by recovery in Gomphrena globosa. Source Peru.
Anemone necrosis strain of
Produces local necrotic
spots and rings in tobacco; chronic symptoms are chlorosis, vein-banding and
dwarfing. Produces necrotic local lesions in cowpea, followed by apical necrosis
and death of plant. Source UK.
Satellite-like strain of
Non-infective alone but
multiplies in bean and cowpea when mixed with a tobacco isolate. Produces small
dark local lesions, usually surrounded by a clear zone, in inoculated leaves of
Transmission by Vectors
Transmitted by adults and three larval stages of the nematode Xiphinema americanum
Single nematodes may transmit
acquire virus within 24 h. Infective nematodes stored at 10°C for 49 weeks
could still transmit
(Bergeson et al., 1964
The virus is also transmitted in soybean by nymphs but not adults of Thrips
They acquire virus within 8 hr and remain infective
for 14 days.
The virus is transmitted less efficiently by spider mites of the genus
grasshoppers of the genus Melanoplus
and the tobacco flea beetle, Epitrix hirtipennis
There are also reports of transmission by the aphids
Myzus persicae and Aphis gossypii
(Komuro & Iwaki, 1968;
Rani, Verma & Verma, 1969),
but the aphid-transmitted virus in begonia
is probably not tobacco ringspot virus.
Transmission through Seed
Common in soybean, petunia, Nicotiana glutinosa, Gomphrena globosa
and Taraxacum officinale
; rare in tobacco, cantaloupe, cucumber,
muskmelon and lettuce. Pollen transmission not investigated.
Transmission by Dodder
Not transmitted by Cuscuta campestris
The virus is moderately immunogenic. Antiserum titres in excess of 1:2000
are readily attained. Diagnostic serological reactions can be obtained in ring
precipitin, microprecipitin, tube precipitin, or gel-diffusion tests. Antisera
prepared by intravenous or intramuscular injections give a single band of
precipitate in gel-diffusion tests. Agar gel tests on microscope slides are
not always satisfactory
The Eucharis mottle strain is serologically related but not identical to the
tobacco isolates, as shown by spur formation in agar gel-diffusion tests
(Kahn et al., 1962
Four distinct serological strains have been detected in
Also, a strain isolated from trailing blackberry is
antigenically related to, but not identical with, an isolate from tobacco
(Rush, Gooding & Ellis, 1968
In plant-protection tests, recovered tobacco plants are partially or completely
protected against invasion by related strains, Gomphrena globosa plants
that have recovered from infection with the type isolate from tobacco, are
protected against invasion by the Eucharis mottle strain but, in reciprocal
tests, plants that have recovered from infection with the Eucharis mottle strain
are not protected against invasion by the tobacco strain
(Kahn et al., 1962).
Stability in Sap
In petunia sap, diluted 1:5 with distilled water, the thermal inactivation
point (10 min) for most isolates is 65°C, although a blueberry isolate is
inactivated at 55°C
(Lister, Raniere & Varney, 1963
The dilution end
point of most isolates is c
. Sap is infective after 6-10
days at room temperature, 3 weeks at 18°C, and several months at 2°C.
Lyophilized sap containing the anemone necrosis isolate was infective after 5
years in sealed ampoules
The virus is relatively stable and many purification techniques are
satisfactory. Squash or cucumber seedlings or inoculated leaves of cowpea may
yield 50-100 mg virus per kg tissue.
The widely used butanol-chloroform procedure was developed for the
purification of this virus
It gives satisfactory yields of most
strains, but extracts containing the anemone necrosis strain are best clarified
by adding n-butanol to 8.5% (v/v)
that are rapid and give good yields involve removing impurities with activated
charcoal followed by density gradient centrifugation
(Corbett & Roberts, 1962)
or addition of ammonium sulphate (200 g/l clarified sap), which removes
host proteins with little loss of virus
(Stace-Smith, Reichmann & Wright, 1965).
Properties of Particles
Purified preparations contain three major classes of particles
empty protein shells without RNA (T), non-infectious nucleoprotein (M), and
infectious nucleoprotein (B)
(Stace-Smith et al., 1965
is a satellite-like nucleoprotein (SL) which is non-infective alone but infective
when mixed with the multi-component virus
All particles are
Sedimentation coefficients (s20,w) at infinite
dilution (svedbergs): 53 (T), 91 (M), 126 (B) and 122 (SL).
Molecular weights (daltons): 3.3 x 106 (T), 4.9 x 106
(M), 5.7 x 106 (B).
Diffusion coefficient (D20 x 10-7 cm2/sec):
Isoelectric point: between pH 4.2 and 6.1 (B).
Electrophoretic mobility: -1.39 x l0-5 cm2
volt-1 sec-1 in 0.1 ionic strength phosphate, pH 6.5.
Absorbance at 260 nm (1 mg/ml, 1 cm light path): about 10.0 (B).
A260/A280: 0.91 (T), 1.37 (M), 1.88 (B).
Particles are isometric, about 29 nm in diameter
and have 42
(Chambers, Francki & Randles, 1965
stable when mounted in phosphotungstate or uranyl acetate for electron microscopy.
Particles penetrated by negative stain do not necessarily represent particles
devoid of RNA; the proportion of particles penetrated increases with increasing
pH of the stain but staining time has no effect
(Davison & Francki, 1969
: The 126 S nucleoprotein particle may contain one infectious or two
non-infectious nucleic acid strands per particle
(Diener & Schneider, 1966
The 91 S particle contains one non-infectious strand. The infectious
strand has a molecular weight of 2.2 x 106
and a sedimentation
coefficient of c
. 32 S. The non-infectious strand has a molecular
weight of 1.2 x 106
and a sedimentation coefficient of c
S. With increasing age of infection the proportion of 126 S
particles with two non-infectious strands increases
(Schneider & Diener, 1968
The RNA of the SL nucleoprotein has a molecular weight of 86,000 and
a sedimentation coefficient of 7 S. The SL particle is thought to
contain 14 or more RNA strands of about the same size
Protein: About 60% of the particle weight. No evidence of more than one protein
species. For amino acid composition, see
Stace-Smith et al. (1965).
Relations with Cells and Tissues
No crystalline aggregates of virus particles were seen in root tip cells of
beans or leaf cells of bean, cucumber or cowpea. The virus was seen in the
terminal 0.5 mm of the root tips of infected beans - files of virus particles
occurred in tubules that passed through plasmodesmata and into the cytoplasm
of neighbouring cells
(Crowley et al., 1969
The most damaging disease caused by tobacco ringspot virus is bud blight of
soybean, and the importance of the various modes of transmission in this crop
is not resolved. Seed-transmission occurs but is not considered important in
major periodic outbreaks. Transmission by the nematode X. americanum
is considered negligible, primarily because the virus does not move readily to
the foliage of plants infected through the roots. Aerial vectors are suspected
and of these, thrips, mites, grasshoppers and beetles have been incriminated.
The geographical distribution, natural host range and vector relationships
of the virus are similar to those of
tomato ringspot virus.
reactions may be useful in distinguishing isolates of the two viruses
but serological tests are essential for positive identification. The
virus is also similar in size, shape, physical properties and host reactions
to several other
but is not serologically related to any of them.
- Bennett, Phytopathology 44: 905, 1944.
- Bergeson, Athow, Laviolette & Thomasine, Phytopathology 54: 723, 1964.
- Chambers, Francki & Randles, Virology 25: 15, 1965.
- Corbett & Roberts, Phytopathology 52: 902, 1962.
- Crowley, Davison, Francki & Owusu, Virology 39: 322, 1969.
- Davison & Francki, Virology 39: 235, 1969.
- Diener & Schneider, Virology 29: 100, 1966.
- Dunleavy, Phytopathology 47: 681, 1957.
- Fromme, Wingard & Priode, Phytopathology 17: 321, 1927.
- Fulton, Phytopathology 52: 375, 1962.
- Fulton, Phytopathology 59: 236, 1969.
- Gooding, Phytopathology 59: 114, 1969.
- Hollings, Ann. appl. Biol. 55: 447, 1965.
- Kahn, Scott & Monroe, Phytopathology 52: 1211,1962.
- Komuro & Iwaki, Ann. phytopath. Soc. Japan 34: 7, 1968.
- Lister, Raniere & Varney, Phytopathology 53: 1031, 1963.
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- McLean, Pl. Dis. Reptr 46: 877, 1962.
- Messieha, Phytopathology 59: 943, 1969.
- Price, Phytopathology 26: 665, 1936.
- Price, Am. J. Bot. 27: 530, 1940.
- Rani, Verma&Verma, Pl. Dis. Reptr 53: 903, 1969.
- Rush, Gooding & Ellis, Phytopathology 58: 1065, 1968.
- Schneider, Science, N.Y. 166: 1627,1969.
- Schneider & Diener, Virology 35: 150, 1968.
- Schuster, Pl. Dis. Reptr 47: 510, 1963.
- Semal, Nature, Lond. 182: 1688, 1958.
- Stace-Smith, Reichmann & Wright, Virology 25: 487, 1965.
- Steere, Phytopathology 46: 60, 1956.
- Thomas, Phytopathology 59: 633, 1969.
- Valleau, Bull. Ky agric. Exp. Stn. 327: 43, 1932.
Local and systemic symptoms in Cucumis sativus.
Local and systemic symptoms in Vigna sinensis.
Diffuse local lesions in inoculated leaf of Nicotiana tabacum
Virus particles from a purified preparation stained with uranyl
acetate. Bar represents 100 nm.
Systemic mottle and necrosis in Nicotiana clevelandii.
Analytical ultracentrifuge photograph taken with schlieren optics
showing relative proportion of (left to right) T, M and B components.