Bean golden mosaic virus
R. M. Goodman
Department of Plant Pathology, University of Illinois, Urbana, Illinois, USA
Agricultural Experiment Station, University of Puerto Rico, Mayaguez, Puerto Rico, USA
- Disease first described by Costa (1965). Virus first purified by Galvez &
- Selected synonyms
- Mosaico dorado (Rev. Pl. Path. 51: 867)
- Golden-yellow mosaic virus (Rev. Pl. Path. 51: 4506)
- A DNA-containing virus with isometric particles about 19 nm in diameter
occurring predominantly in pairs. The host range is apparently restricted to
certain wild and cultivated species of the Leguminosae. Transmitted by the
whitefly, Bemisia tabaci, and by inoculation with sap from young infected
Causes bright yellow mosaic diseases of legumes, including Phaseolus
(French bean), P. lunatus
(lima bean), and closely related
Widely distributed in tropical and subtropical America (Bird &
). Similar diseases reported in tropical Africa and Asia.
Host Range and Symptomatology
Known host range includes only certain species in the legume genera
Phaseolus, Macroptilium, Vigna
(Bird et al.,
; Bird, Sanchez & Vakili, 1973
; Meiners et al., 1973
.) The virus
did not infect 21 species in 8 other families, or 6 species in the legume genera
Cassia, Cajanus, Glycine, Rhynchosia
unpublished data). The virus has been transmitted by inoculation with sap to
from P. vulgaris
and Calopogonium mucunoides
(Meiners et al., 1973
; Galvez & Castano, 1976
; Goodman, Bird &
) and to P. lunatus
and P. vulgaris
(H. Lot & J. Bird, unpublished data).
- Diagnostic species
- Phaseolus lunatus (lima bean). Bright yellow systemic vein chlorosis
developing into golden mosaic.
- Phaseolus vulgaris (French bean). Irregularly shaped chlorotic spots
develop in young systemically infected leaflets followed by vein chlorosis and,
in advanced infections, by golden mosaic (Fig.2). Leaves are usually deformed
and curled downward at the edges when infected plants are grown in growth
chambers but this symptom is not always found in the field. Plants are usually
stunted and the number of pods reduced.
- Propagation species
- Phaseolus vulgaris cv. Top Crop grown at 31°C with 14 h day length
(10,000 lux) is a good source for virus purification. Systemically infected
leaves are harvested 9-12 days after manual inoculation of expanding primary
leaves (Goodman et al., 1977; Goodman, 1977a). Yields average
1 mg per 100 g tissue.
- Assay species
- Phaseolus vulgaris cv. Top Crop sometimes shows chlorotic local lesions
on inoculated primary leaves (Fig.1). P. vulgaris cv. Top Crop and Red
Kidney have been used for assaying transmission by vectors.
Transmission by Vectors
Transmissible by the whitefly Bemisia tabaci
authors distinguish races of this species (Bird et al., 1972
is the one reported to transmit this virus (Bird et al.,
). Males and females were equally effective as vectors (Bird et al.,
). Acquisition and inoculation by adults can be effected in a total time of
less than 6 min (J. Bird, unpublished data), but efficient transmission requires
longer feeding periods (Gamez, 1971
; Bird et al., 1973
). No tests have
been reported to determine if a latent period exists or if larval forms can
transmit. Individual adult whiteflies transmit intermittently for up to 16 days
after acquisition (Gamez, 1971
Transmission through Seed
Not seed-transmitted (Costa, 1965
An antiserum has been prepared with a titre of 1/320 in Ouchterlony double
diffusion tests against sap from infected plants (Goodman, unpublished data).
The presence in infected beans of copious amounts of the highly immunogenic
), which is present in negligible amounts in healthy
plants, may complicate antiserum production and interpretation of serological
tests unless the virus is scrupulously purified.
Relationships among the whitefly-transmitted pathogens causing similar
diseases of various species and in various countries are not understood.
Disease symptoms and particle morphology suggest that bean golden mosaic
viruses from Puerto Rico, El Salvador, Colombia, Guatamala, and probably
Brazil are the same virus, although possible strain relationships are not
worked out. Causal agents of similar diseases in other tropical areas have
not been characterized.
Stability in Sap
In Phaseolus vulgaris
sap the thermal inactivation point (10 min)
is between 50° and 55°C, dilution end-point about 10-1
, and longevity in vitro
about 72 h at 23°C (Galvez
& Castano, 1975
; J. Bird, unpublished data).
Highest yields have been obtained by the following method (Goodman
et al., 1977
). Freeze systemically infected leaves (9-12 days after
inoculation of plants) in dry ice. Crush frozen leaves to a coarse powder
and grind in cold 0.1 M sodium phosphate, 10 mM disodium
ethylenediamine-tetra acetate, 1 mM cysteine (pH 7.8). Strain through cheesecloth and clarify
by centrifugation (12,000 g
, 20 min, 4°C). Add NaCl to 0.2 M
and polyethylene glycol (PEG) to 4% (w/v). Discard supernatant fluid containing
phytoferritin. Resuspend virus from PEG pellet with 0.1 M sodium phosphate,
pH 7.8. Clarify by centrifugation (12,000 g
, 20 min) and subject
to one or two cycles of high- and low-speed centrifugation, resuspending the
high-speed pellets in the sodium phosphate buffer. Final purification is by
sucrose density gradient centrifugation (Fig.6
). Work at 4°C throughout.
Properties of Particles
Sedimentation coefficient (s20,w
): 69 S (Fig.7
M. Wt: about 2.6 x 106 daltons.
Absorbance at 260 nm (1 mg/ml, 1 cm light path): 7.7.
Particles are isometric, about 19 nm diameter, and in aldehyde-fixed
negatively stained preparations are predominantly in pairs (geminate)
) (Galvez & Castano, 1976
; Goodman et al., 1977
). It is
not certain whether the pairing of the particles is a fixation/staining
artefact or real and, if real, whether it is of biological significance.
The best electron micrographs available suggest icosahedral (T = 1) symmetry
). The particles disintegrate when mounted in phosphotungstate, uranyl
acetate, or ammonium molybdate unless aldehyde-fixed (Galvez & Castano,
; Goodman et al., 1977
Particle CompositionNucleic acid:
DNA, M. Wt about 0.75 x 106
), comprising about 29% of particle mass. DNA is single-stranded
) and resistant to exonucleases (R. M. Goodman,
unpublished data). Infective DNA is easily prepared from purified virus by
treatment with 1% sodium dodecyl sulphate at pH 9.0 or 0.3 M NaOH (Goodman,
). DNA sediments as a single component under neutral or alkaline
conditions with a sedimentation coefficient (s20,w
pH 7.0, i = 0.1, of 16.0 S. Two components are resolved when analysis
is by polyacrylamide gel electrophoresis in 8 M urea (R. P. Ricciardi &
R. M. Goodman, unpublished data). Buoyant density in CsCl is 1.717 g/ml.
Protein: Subunits have M. Wt of about 3.1 x 104 daltons
(T. L. Shock & R. M. Goodman, unpublished data).
Relations with Cells and Tissues
Infection of Phaseolus vulgaris
cv. Top Crop is confined to phloem and adjacent parenchyma cells. Virus-like
particles occur in hexagonally-packed crystalline array or in loose aggregates
in the nuclei of infected cells (Fig.8
). Distinctive alterations occur in
nucleoli, including segregation of granular and fibrillar components and
formation of electron-dense rings. Electron-dense areas shown by cytochemical
tests with the electron microscope to contain deoxyribonucleoprotein may be
regions where viral DNA synthesis occurs (Kim, Shock & Goodman, 1977
Virus-like particles have been seen in disintegrating nuclei of immature
phloem and in mature phloem sieve elements.
Virus purification has been reported only for isolates from Puerto Rico,
Colombia and El Salvador (Galvez & Castano, 1976
; Goodman et al.,
). Geminate particles are associated with a similar disease in Brazil but
the virus has not been transmitted by inoculation of sap and the reported
diameter of individual particles from electron microscopy observations is
12-13 nm (Matyis et al., 1976
). Bean golden mosaic virus can be
readily distinguished from other viruses infecting Phaseolus vulgaris
by the distinctive symptoms and cytopathological alterations it causes in
infected plants, by its narrow host range, and by its transmission by whiteflies.
- Bird, Perez, Alconero, Vakili & Melendez, J. agric. Univ. Puerto Rico 56: 64, 1972.
- Bird, Sanchez & Vakili, Phytopathology 63:1435, 1973.
- Bird & Maramorosch, eds., Tropical Diseases of Legumes, Academic Press, New York, 1975.
- Costa, Pl. Prot. Bull. F.A.O. 13:123, 1965.
- Costa, A. Rev. Phytopath. 14: 429, 1976.
- Galvez & Castano, Proc. Am. Phytopath. Soc. 2: 75, 1975.
- Galvez & Castano, Turrialba 26: 205, 1976.
- Gamez, Turrialba, 21: 22, 1971.
- Goodman, Nature, Lond. 266: 54, 1977a.
- Goodman, Virology 83: 171, 1977b.
- Goodman, Bird & Thongmeearkom, Phytopathology 67: 37, 1977.
- Kim, Shock & Goodman, Proc. Am. Phytopath. Soc. 4:130, 1977.
- Matyis, Silva, Oliveira & Costa, IX Congresso Brasiliero Fitopatologia, Abstract 064, 1976.
- Meiners, Lawson, Smith & Diaz, Phytopathology 63: 803, 1973.
Local chlorotic lesions in inoculated primary leaves of Phaseolus
vulgaris Top Crop.
Bean golden mosaic symptoms in P. vulgaris.
Electron micrograph of purified particles of bean golden mosaic virus. Preparation
fixed with glutaraldehyde and
stained with sodium phosphotungstate, pH 7.0. Bar represents 100 nm.
Electron micrograph of purified phytoferritin particles from infected plants. Preparation
fixed with glutaraldehyde and
stained with sodium phosphotungstate, pH 7.0. Bar represents
Electron micrograph of a bean golden mosaic virus particle-pair at high magnification.
Preparation fixed with glutaraldehyde and stained with
sodium phosphotungstate, pH 7.0. Bar represents 20 nm.
Sucrose density gradient profile of (S) supernatant and (P) pellet
fractions following treatment of clarified extracts from infected plants with
PEG. The broad peak in (S) is phytoferritin (see Fig.4); the peak in (P) is bean
golden mosaic virus. Sedimentation from the left.
Schlieren diagram of a sedimentation velocity experiment after
8 min at 35,660 rev./min. Sedimentation from the right.
Portion from a systemically infected P. vulgaris plant cell
8 days after inoculation, showing the presence of an electron-dense crystalline
area in the nucleus. Bar represents 1 µm. (Courtesy Dr K. S. Kim.)
Enlarged view of a nuclear crystal in the cell of a systemically
infected P. vulgaris plant showing hexagonal crystalline array of
virus-like particles. Bar represents 100 nm. (Courtesy Dr K. S. Kim.)