Bean rugose mosaic virus
Centro de Investigación en Biologia Celular y Molecular, Universidad de Costa Rica, Ciudad Universitaria, Costa Rica
A virus with isometric particles c. 28 nm in diameter sedimenting as
three components, two of which contain single-stranded RNA. Transmitted by beetles
and readily by inoculation of sap. Narrow host range, mainly restricted to legumes.
Found in Costa Rica and other countries in Central America.
Causes a severe mosaic, rugosities and deformation of leaves
bean (Phaseolus vulgaris
). Mottling and malformation of pods, and
stunting are observed in susceptible varieties
Reported from Costa Rica
(Gálvez et al., 1977
Host Range and Symptomatology
Occurs naturally in bean (Phaseolus vulgaris
). Restricted host range:
only species of Leguminosae are systemically infected following mechanical
inoculation, and Chenopodium amaranticolor
is the only local lesion host
found among 15 species in 5 dicotyledonous families
- Phaseolus vulgaris. Three different types of reaction, depending on
cultivar. In some (e.g. cv. Plentiful) there is systemic infection
resulting in severe mosaic, rugosity, blistering and deformation of leaves
and mottling and malformation of pods; others (e.g. cv.
Top Crop) develop necrotic lesions in inoculated leaves
but no systemic
infection. Cv. Tendergreen is immune.
- Chenopodium amaranticolor. Local necrotic lesions. No systemic
- Cucumis sativus. Immune.
- Nicotiana tabacum cv. White Burley. Immune.
- Vicia faba. Mild mottle in systemically infected leaves.
- Phaseolus vulgaris cvs Plentiful, Col. 109-R and Méx. 27-R.
- Phaseolus vulgaris cvs Top Crop, Pinto III, Jamapa.
Three strains have been recognized; a mild and a severe strain from
Kitajima et al., 1974
severe ampollado strain from El Salvador
(Gálvez et al., 1977
Strains differ in host range, cytopathology and symptomatology, but
appear to be serologically identical or closely related.
Transmission by Vectors
Transmitted by the chrysomelid beetles Cerotoma ruficornis, Diabrotica
and D. adelpha.
Insects acquire the virus in 12 to 24 h
but differ in the length of time for which they remain viruliferous; C.
retains the virus for 9 to 10 days and D. balteata
to 4 days
(Fulton, Scott & Gámez, 1980
of transmission on the first day is much greater for C. ruficornis
than for D. balteata
(20%) or D. adeipha
(10%). Beetles may be
rendered viruliferous by intrahaemocoelic injection. The virus may be recovered
from faeces, regurgitated fluid and haemolymph of C. ruficornis
Transmission through Seed
Not seed-transmitted in Phaseolus vulgaris
The virus is very immunogenic. The ring precipitin and gel
double diffusion tests are useful. Rabbit antisera with titres of 1/1024 in
the ring precipitin test are easily obtained
specific electron microscopy has been used for the identification of the virus.
Strains from Guatemala and El Salvador are serologically closely related to
the type strain from Costa Rica
Fulton & Scott, 1979
Gálvez et al., 1977
Bean rugose mosaic virus
is a comovirus
distantly related to
bean pod mottle
cowpea severe mosaic
Antiserum to bean rugose mosaic virus reacts with
other comoviruses to give diffuse straight bands of precipitate which, following
the criteria of
Fulton & Scott (1977
suggests that it should be
regarded as a distinct member of the comovirus group.
Stability in Sap
In extracts of P. vulgaris
cv. Col. 109-R assayed in cv. Pinto III,
the thermal inactivation point (10 min) is between 65 and 70°C, the longevity
is between 2 and 4 days at 22°C, and the dilution end-point
is between 10-4
Steeres chloroform/butanol method, as modified by
bean pod mottle virus
is suitable. Extract infected P.
leaves in 3.5 ml 50% K2
/100 g of tissue,
express the juice and extract the pulp in 0.01 M phosphate buffer, pH 7.0.
Combine the extracts and clarify with a 1:1 mixture of chloroform and
butanol, followed by one cycle of differential centrifugation. Precipitate
the virus at pH 5.0 with 10% acetic acid. Resuspend in 0.5 M phosphate buffer,
pH 7.0, and give a further cycle of differential centrifugation. An alternative
method is clarification with butanol and chloroform, and precipitation by adding
polyethylene glycol (M. Wt 6000) to 4% and NaCl to 0.2 M. The precipitate is
resuspended, clarified by centrifugation at low speed, and sedimented through
a sucrose cushion, as described for
cowpea mosaic virus
(van Kammen & de Jager, 1978
Properties of Particles
The virus sediments as three components: empty protein shells (T), and
two nucleoproteins with different RNA content (M and B)
Sedimentation coefficients (s20,w ) (svedbergs) are: 59
(T), 97 (M), 113 (B) (H. A. Scott, unpublished data).
1.7 for unfractionated virus, uncorrected for light-
Buoyant densities in caesium chloride: 1.302 (T), 1.380 (M) and 1.402 (B)
(Lucía Fuentes & R. Gámez, unpublished data).
Molecular weight (x 10-6): about 3.6 (T), 5.0 (M) and 5.9 (B),
estimated from the protein and RNA composition.
Particles are isometric, c.
28-29 nm in diameter with hexagonal
Particle CompositionNucleic acid:
RNA, single-stranded, of M. Wt about 2.3 x 106
and 1.4 x 106
, estimated by polyacrylamide gel electrophoresis under
denaturing conditions (Lucía Fuentes & P. Leon, unpublished data).
Protein: Polyacrylamide gel electrophoresis of SDS-treated virus shows
two polypeptide species of M. Wt c. 38,000 and
22,000. By analogy with other comoviruses,
there are presumably 60 molecules of
each polypeptide per particle.
Relations with Cells and Tissues
Trichomal, epidermal and mesophyll cells of infected P. vulgaris
leaves show large, dense, crystalline inclusions in the cytoplasm. These
crystals are made up of virus particles, many of which are in hexagonal arrays
A less dense crystalline material, exhibiting a honeycomb-like
pattern, is occasionally observed. Particles also occur scattered in the
cytoplasm and in tubules in the plasmodesmata, associated with finger-like
outgrowths of the cell wall. The cytoplasm around virus crystals frequently
appears rich in vesicles and tubules
Strains differ in the type of
cellular alteration that is most prevalent
(Kitajima et al., 1974
cowpea severe mosaic virus
bean pod mottle virus
are the most closely related to bean rugose mosaic virus
but may be distinguished by differences in host range
and symptomatology in indicator hosts and by serological reactions. Vigna
cv. Early Ramshorn is readily infected by cowpea severe
mosaic virus but is not infected by bean rugose mosaic virus. P. vulgaris
cv. Tendergreen is susceptible to cowpea severe mosaic and bean pod mottle
viruses but not to bean rugose mosaic virus. Antigenic specificity, disease
symptoms and type of insect vector readily distinguished this virus from
other viruses occurring naturally in Phaseolus
(Fulton & Scott, 1977
Bean rugose mosaic virus is of
limited economic importance because most bean cultivars grown in Central
America are resistant
- Bancroft, Virology 16: 419, 1962.
- Bruening, CMI/AAB Descr. Pl. Viruses 199, 5 pp., 1978.
- Cartín, Ing. Agron. Thesis, Univ. of Costa Rica, 1973.
- Fulton & Scott, Fitopatol. Bras. 2: 9, 1977.
- Fulton & Scott, Phytopathology 69: 305, 1979.
- Fulton, Scott & Gámez, in Vectors of Plant Pathogens,p. 115, ed. K. Maramorosch & K. Harris, New York: Academic Press, 467pp., 1980.
- Gálvez, Cárdenas, Kitajima, Diaz & Nieto,Turrialba 27: 343, 1977.
- Gámez, Turrialba 22: 249, 1972.
- Gámez, in Problems in Bean Production, p. 241, ed. H. F.Schwartz & G. E. Gálvez, Cali, Colombia: CIAT, 424 pp., 1980.
- Kitajima, Tascón, Gámez & Gálvez, Turrialba 24: 393, 1974.
- van Kammen & de Jager, CMI/AAB Descr. Pl. Viruses 197, 6 pp., 1978.
Typical mosaic induced by type strain from Costa Rica in Phaseolus
vulgaris cv. Méx. 27-R.
Severe symptoms induced in P. vulgaris cv. Plentiful by the
severe strain from Guatemala.
Local lesions in P. vulgaris cv. Top Crop.
Virus particles in neutral phosphotungstate. Bar represents 50 nm.
Crystalline inclusions in cytoplasm of trichomal cells of P.
vulgaris infected with the type strain. Bar represents 1.25 µm.
Vesicles around crystalline inclusion in cytoplasm of trichomal
cell of P. vulgaris. Bar represents 200 nm.