Echtes Ackerbohnemosaik virus
A. J. Gibbs
John Curtin School of Medical Research, Australian National University, Canberra, Australia
H. L. Paul
Institut für Landwirtschaftliche Virusforschung, Braunschweig, Germany
- Broad bean true mosaic virus (Rev. appl. Mycol. 33: 461)
- Vicia virus 1 (Rev. appl. Mycol. 33: 461)
- Viciavirus varians (Rev. appl. Mycol. 33: 461)
A virus with angular, isometric, RNA-containing particles about 25 nm in diameter,
which sediment as two components when centrifuged. It is readily transmitted by
inoculation of sap, is seed-borne, and seems to infect only legumes. It occurs in
Europe and North Africa, but no specific vector has been found.
Common in crops of broad bean (Vicia faba
), causing mosaic symptoms.
There seem to be no varieties of broad bean or pea that escape infection with the
virus in the field
Europe and North-west Africa.
Host Range and Symptomatology
Only hosts known are legumes;
obtained symptoms in 24 of 31
species of legume inoculated, but none of 7 species belonging to 5 non-legume
genera. However, none were tested for symptomless infection by inoculating sap
to test plants.
- Vicia faba (broad bean). Characteristic systemic mottling and mosaic
evanescent in hot weather, severe, often with shoot necrosis in cool
weather. Severity of symptoms and virus concentration in the youngest leaves
throughout the growth of the plant
(Paul & Quantz, 1959).
- Pisum sativum (pea). Severe systemic chlorotic mosaic, occasionally
necrotic. Plant stunted, and leaf lamina deformed.
- Phaseolus vulgaris (bean). Some varieties are occasionally infected
by some strains of the virus, giving chlorotic flecking.
- Chenopodium amaranticolor, Gomphrena globosa, Nicotiana tabacum
(tobacco) and N. clevelandii are not susceptible.
Propagation and assay species
- Pisum sativum or Vicia faba. No local lesion host known.
Minor variants, differing in the severity of the symptoms they cause, are
Transmission by Vectors
Vectors not yet known, though the virus spreads over large distances within
broad bean crops
Gibbs, Giussani-Belli & Smith, 1968
Transmission through Seed
Common. Up to 15% of the progeny of infected plants may be infected.
Transmission by Dodder
Moderately immunogenic. Gives a single band of precipitate in Ouchterlony
gel diffusion tests, and a granular precipitate in mixed-liquid serological tests.
The physical and chemical properties of the particles of this virus are typical
of viruses in the
cowpea mosaic virus group
except that, like
radish mosaic virus
(another member of the group), preparations contain few or no RNA-free particles.
No serological relationships to other viruses in the cowpea mosaic virus group
has been established
(Gibbs et al., 1968
Stability in Sap
In pea sap, four strains of the virus lost infectivity after heating for 10
min at between 65° and 75°C, dilution to about 10-4
, or storage
at room temperature for 6-7 days
In bean sap the virus was infective
after 3 years at -20°C.
The particles of the virus are stable, and Steeres chloroform/butanol method
is convenient for extracting the virus from plant tissue, into pH 7.0 buffer
containing a reducing agent; the latter is not needed to stabilize the virus
particles, but prevents darkening of sap. The virus particles are then purified
and concentrated by differential centrifugation
Gibbs et al., 1968
Properties of Particles
The particles are all of one size but sediment as two components
Sedimentation coefficients (s20,w) at infinite dilution: 98
and 119 S.
Molecular weights (daltons): about 6.1 x 106 and 7.5 x 106.
Diffusion coefficient (D20,w x 10-7 cm2
Absorbance at 260 nm (1 mg/ml, 1 cm light path): about 7.7 (normal mixture of
98 and 119 S particles)
A260/A280: 1.76 (98 S particles), 1.81 (119 S particles).
The particles are isometric, about 25 nm in diameter with angular polygonal
The central parts of the 98 S particles are penetrated
by negative stain but those of the 119 S particles are not. The particles
show no regularly arranged morphological subunits.
RNA: Molecular weight of nucleic acid in 98 S particles 1.7 x
106, in 119 S particles 2.8 x 106 (calculated from
the molecular weights of the particles and their nucleic acid contents).
Probably single-stranded. Molar percentage of nucleotides of unfractionated
preparations: G22.8; A26.5; C18.4; U32.3. RNA is about 26% of weight of 98 S
particles and about 35% of weight of 119 S particles
Protein: Amino acid composition has been reported by
Wittmann & Paul (1961).
The size of the chemical subunits is uncertain.
Echtes Ackerbohnemosaik-Virus (EAMV) is readily confused with
broad bean stain virus
, because both cause similar leaf
symptoms in V. faba
plants, are seed-borne, and have similar particles.
However, broad bean stain virus, unlike EAMV, infects P. vulgaris
Tendergreen and Canadian Wonder, causes chlorosis and necrosis but no distortion
of infected pea plants, produces many RNA-free 60 S particles
and is serologically unrelated to EAMV.
Broad bean mottle virus
also gives symptoms in V. faba
that could be confused with
those caused by EAMV, and these viruses were thought to be the same until
Wetter et al. (1960)
showed that they are distinct. Broad bean mottle virus has
a thermal inactivation point 20°C higher than that of EAMV, causes tiny
chlorotic lesions in C. amaranticolor
leaves 5 days after inoculation
and has particles that differ in composition from those of
EAMV and sediment as a single component when centrifuged.
- Gibbs, Giussani-Belli & Smith, Ann. appl. Biol. 61: 99, 1968.
- Hollings, Pl. Path. 6: 133, 1957.
- Paul, Phytopath. Z. 43: 315, 1962.
- Paul, Phytopath. Z. 49: 161, 1963.
- Paul & Quantz, Arch. Mikrobiol. 32: 312, 1959.
- Quantz, Phytopath. Z. 20: 421, 1953.
- Wetter, Paul, Brandes & Quantz, Z. Naturf. 158: 444, 1960.
- Wittmann & Paul, Phytopath. Z. 41: 74, 1961.
Photographs: courtesy of Rothamsted Experimental Station, UK and Institut
für Landwirtschaftliche Virusforschung, Braunschweig, Germany.
Shoot of a Vicia faba plant infected with Echtes
Ackerbohnemosaik-Virus; the severity of symptoms (and virus concentration)
differs in different leaves and varies cyclically throughout the growth of
Sedimentation behaviour of the virus (lower schlieren diagram)
compared with that of broad bean stain virus (upper diagram); sedimentation
is from left to right (note that the menisci of the two diagrams are displaced).
Electron micrograph of a phosphotungstate-stained purified preparation
of the virus. Bar represents 100 nm.