Tobacco yellow dwarf virus
J. E. Thomas
Department of Primary Industries, Indooroopilly, Queensland, 4068, Australia
J. W. Bowyer
Department of Plant Pathology, University of Sydney, New South Wales, 2006, Australia
- Described by Hill (1937) and Ballantyne (1968). Virus first purified by Thomas
& Bowyer (1980).
- (Bean) summer death (virus) (Rev. appl. Mycol. 48: 654)
A virus with geminate particles, 20 nm x 35 nm. It has a fairly wide host range and
is transmitted in the persistent manner by the leafhopper Orosius argentatus,
but not by mechanical inoculation. Recorded only from Australia and causes
economically significant diseases in bean (Phaseolus vulgaris) and tobacco
Causes a severe dwarfing disease in tobacco (Hill, 1937
) and a lethal, necrotic
disease in susceptible bean cultivars (Ballantyne, 1968
Reported only from Australia, where it occurs in all States.
Host Range and Symptomatology
Not transmitted by mechanical inoculation. Transmitted by the leafhopper vector
or by grafting to 30 species in seven dicotyledonous families (Helson, 1950
; Hill & Mandryk, 1954
; Thomas & Bowyer, 1979
- Diagnostic species
- Datura stramonium. Strong interveinal chlorosis and down-curling of leaf
- Phaseolus vulgaris (French bean) cvs Spartan Arrow, Bountiful. Plants
inoculated at the cotyledon stage show a reduction in the growth rate of the first
trifoliolate leaf, usually in 7 to 10 days. Down-curling of the trifoliolate leaf
margin, vascular necrosis of the upper stem and epinasty of the primary leaves and
petioles follow rapidly. Ultimately, interveinal chlorosis of the primary leaves,
leaf abscission, axillary shoot formation and finally wilting and collapse of the
plant occur (Fig.2, Fig.3). Symptom expression is more rapid in warm conditions
(c. 30°C) and plant death can occur as soon as 8 days after the first
appearance of symptoms.
- Nicotiana tabacum (tobacco). Down-curling of the tips and margins of
the youngest leaves, chlorosis and stunting (Fig.4). Small necrotic spots sometimes
occur on the older chlorotic leaves.
- Propagation species
- Lycopersicon esculentum (tomato) is useful for maintaining cultures.
Datura stramonium is a suitable host for acquisition feeding by the
leafhopper vector and as a source of virus for purification.
- Assay species
- No local lesion host is known. The virus can be assayed by inoculating seedlings
of susceptible cultivars of Phaseolus vulgaris (French bean) with
leafhoppers that have acquired virus from test plants or by feeding through membranes.
Isolates differ in the severity of symptoms produced in Datura
Transmission by Vectors
Transmitted by the leafhopper Orosius argentatus
) but not
by the leafhoppers Batracomorphus punctatus, Orosius lotophagorum
) or Austroasca alfalfae
(J. E. Thomas,
unpublished data). An isolate from Phaseolus vulgaris
had a minimum latent
period of 24-48 h in O. argentatus;
infectivity was not lost after
moulting and was retained for at least 21 days after removal from infected plants
(Bowyer & Atherton, 1971
Transmission through Seed
Not detected in Datura stramonium
Transmission by Dodder
Not transmitted by Cuscuta campestris
or eight other species of dodder
(Hill & Mandryk, 1954
Moderately immunogenic in rabbits. An antiserum with a gel diffusion titre of
1/128 was produced by injecting a total of 230 µg virus. Gel diffusion tests
are possible only with concentrated or purified virus preparations. Virus can be
detected in sap by immunosorbent electron microscopy and ELISA.
A number of isolates from bean and tobacco were shown by ELISA to be
serologically related (J. W. Bowyer & J. E. Thomas, unpublished data). In
gel diffusion serology tests with antiserum to a tobacco isolate, confluent
precipitin lines were formed between bean and tobacco isolates of the virus
(J. E. Thomas, unpublished data). No cross-protection was detected between bean
and tobacco isolates of the virus (Than, 1976
Tobacco yellow dwarf virus is distantly serologically related to beet curly top
virus, as demonstrated by gel double diffusion tests (Thomas & Bowyer, 1980)
and immunosorbent electron microscopy (B. D. Harrison & I. M. Roberts,
personal communication; J. E. Thomas, unpublished data). Many bean cultivars
selected for resistance to beet curly top virus were also resistant to tobacco
yellow dwarf virus (Ballantyne et al., 1969; Ballantyne, 1970). However,
sugarbeet cultivars susceptible to beet curly top virus could not be infected
by two isolates of tobacco yellow dwarf virus, although some plants of one
susceptible cultivar were symptomlessly infected by a third isolate (J. E.
Thomas, unpublished data).
No serological reaction was detected between tobacco yellow dwarf virus and
antiserum to either maize streak or chloris striate mosaic viruses, by gel
diffusion serology (Thomas, 1979). Electron microscope grids coated with tobacco
yellow dwarf virus antiserum did not trap particles of maize streak, wheat dwarf,
cassava latent or tomato golden mosaic viruses (B. D. Harrison & I. M.
Roberts, personal communication).
Stability in Sap
Determined by feeding leafhoppers through membranes on virus-containing
extracts. The thermal inactivation point of a partially purified preparation
from tobacco was between 50°C and 60°C and the dilution end-point in
bean sap was between 1/50 and 1/500. Infective virus was recovered from bean
tissue stored at -18°C for 11 months and from a purified preparation
stored at 4°C for 26 days.
Modifications of the methods used for beet curly top virus
maize streak virus
(Bock et al., 1974
) are suitable (Thomas & Bowyer,
). A useful increase in yield is obtained by re-extracting the fibres in
0.1 M phosphate buffer (pH 6.0) containing 0.2% (v/v) thioglycerol and 1% (w/v)
cellulase and incubating, with shaking, overnight at room temperature. Yields
are usually less than 250 µg virus/kg leaf tissue.
Properties of Particles
Geminate particles form a single band in sucrose density gradients.
Sedimentation coefficient (at 20°C in 0.01 M phosphate buffer, pH
7.7): 76 S.
A260/A280: 1.25 (not
corrected for light-scattering).
Particles are geminate c.
20 nm x 35 nm (Fig.5
consisting of two incomplete icosahedra with a T = 1 surface lattice and a total
of 22 capsomeres (Thomas, 1979
). Particles are stable in 0.5% aqueous uranyl
acetate, 2% ammonium molybdate (pH 7.0) or 1% potassium phosphotungstate
Particle CompositionNucleic acid:
The type of nucleic acid has not been determined
unequivocally. Nucleic acid extracted from a purified preparation with
SDS-Pronase had a buoyant density in CsCl of c.
suggesting the presence of DNA (J. E. Thomas, unpublished data).
Protein: A single protein species of M. Wt c. 27,500, estimated
by SDS-polyacrylamide gel electrophoresis (Thomas & Bowyer, 1980).
Relations with Cells and Tissues
In French bean, cytopathic effects are obvious only in the phloem tissue.
Crushed, necrotic sieve tubes become apparent about 8 days after inoculation,
coincident with the appearance of macroscopic symptoms in the plant. Virus
particles can be detected in some necrotic phloem cells (Fig.7
Tobacco yellow dwarf virus can be distinguished from most other viruses by
its geminate particles and leafhopper vector. Two other geminiviruses, tobacco
leaf curl virus
and beet curly top virus
, have many hosts in common with tobacco
yellow dwarf virus. Tobacco leaf curl virus, however, is transmitted by the
whitefly Bemisia tabaci.
Beet curly top virus causes similar symptoms
to tobacco yellow dwarf virus in several hosts and is also transmitted by
leafhoppers, so the two viruses are best distinguished by serological tests.
- Ballantyne, Agric. Gaz. N.S.W. 79: 486, 1968.
- Ballantyne, Pl. Dis. Reptr 54: 903, 1970.
- Ballantyne, Sumeghy & Pulver, Agric. Gaz. N.S.W. 80: 430, 1969.
- Bock, Guthrie & Woods, Ann. appl. Biol. 77: 289, 1974.
- Bowyer & Atherton, Phytopathology 61:1451, 1971.
- Helson, Aust. J. agric. Res. 1:144, 1950.
- Hill, J. Counc. scient. ind. Res. Aust. 10: 228, 1937.
- Hill, J. Counc. scient. ind. Res. Aust. 14: 181, 1941.
- Hill, Aust. J. agric. Res. 1:141, 1950.
- Hill & Mandryk, Aust. J. agric. Res. 5: 617, 1954.
- Mumford, Phytopathology 64:136, 1974.
- Than, M.Agric. Thesis, University of Sydney, 1976.
- Thomas, Ph.D. Thesis, University of Sydney, 1979.
- Thomas & Bowyer, Australas. Pl. Path. 8: 36, 1979.
- Thomas & Bowyer, Phytopathology 70: 214, 1980.
Interveinal chlorosis and leaf down-curling in Datura
Symptoms of stunting, epinasty and leaf down-curling in glasshouse
inoculated bean (right); healthy bean (left).
Symptoms of epinasty and leaf down-curling on the first trifoliolate
leaf of a glasshouse inoculated bean plant.
Symptoms of stunting and leaf down-curling in tobacco.
Purified virus particles in 0.5% uranyl acetate. Bar represents 100 nm.
Virus particles enlarged to show substructure. Bar represents 20 nm.
Geminate virus particles (arrows) in a necrotic phloem cell in bean. Bar
represents 200 nm.