Beet mosaic virus
G. E. Russell
Plant Breeding Institute, Trumpington, Cambridge, England
- Described by Lind (1915), Robbins (1921) and Smith (1957).
- Selected synonyms
- Beta virus 2 (Rev. appl. Mycol. 17: 52)
- Marmor betae (Rev. appl. Mycol. 19: 229)
- A virus with flexuous filamentous particles c. 730 nm long and 13 nm
wide. Transmitted by many species of aphids in the non-persistent manner and
fairly easily by sap inoculation. Host range moderately wide. Widely distributed
throughout the beet-growing areas of the world.
Causes a mosaic disease in Beta vulgaris
(sugar beet, red beet,
spinach beet, etc.) and in Spinacea oleracea
World-wide in major beet-growing areas, especially in temperate regions.
Host Range and Symptomatology
Host range is moderately wide, mainly in the Chenopodiaceae, Solanaceae and
Leguminosae; species in about 10 dicotyledonous families have been infected
experimentally (Bennett, 1949
). Transmitted readily by aphids or by sap
inoculation to the following species:
- Diagnostic species
- Beta vulgaris (sugar beet). Young leaves often show vein-clearing (Fig.1).
Older leaves show a pronounced light and dark green mottle and are often puckered
(Fig.3). Infected plants are sometimes stunted but severe distortion of the
leaves is uncommon.
- Spinacea oleracea (spinach). Numerous, small yellow flecks, often
coalescing to form large chlorotic areas, appear on the youngest leaves. Older
leaves become progressively chlorotic and necrotic, and infected plants are
- Propagation species
- Sugar beet is ideal for maintaining cultures.
- Assay species
- Sugar beet and spinach are good hosts for testing aphids and for whole-plant
assay using sap inoculation. Beta patellaris is a useful local lesion host,
developing a few large necrotic lesions (Fig.2). Amaranthus retroflexus
and A. caudatus also give local lesions (Bennett, 1949). Many
chlorotic local lesions are produced in Chenopodium quinoa (Fig.4) and
in Gomphrena globosa.
Many minor variants, differing in virulence towards sugar beet, have been
described (Bennett, 1964
). Beet water mottle virus (Watson, 1958
) is probably
Transmission by Vectors
Transmissible by more than 28 aphid species (Kennedy, Day & Eastop, 1962
but Myzus persicae
and Aphis fabae
are the principal vectors in
the field. Transmission is of the non-persistent type (Watson, 1946
) and is improved by starving aphids for 2-5 min before acquisition feeds.
Acquisition and inoculation thresholds are 6-10 sec; no latent period.
Persistence of the virus in the vector depends on the species of aphid
) but is probably less than 1 hr in apterae. All instars
transmit but alatae transmit more efficiently than apterae and retain virus
for up to 4 hr (Cockbain, Gibbs & Heathcote, 1963
). The virus is not
transmitted to progeny of vectors and vectors do not retain virus after
Transmission through Seed
Probably not seed-transmitted.
Transmission by Dodder
Three species of Cuscuta
did not transmit (Bennett, 1944
The virus is only moderately immunogenic (Bercks, 1960
); antisera with titres
greater than 1/1000 are difficult to obtain. Tube and droplet precipitin tests
with clarified sap or partially purified virus preparations have been used.
A member of the potato virus Y group
of viruses (Brandes & Bercks, 1965
and serologically distantly related to bean yellow mosaic virus
potato virus Y
Stability in Sap
In beet sap, thermal inactivation point (10 min) is between 55 and 60°C,
dilution end-point is up to 1/4000 and infectivity is retained for 24-48 hr at
20°C (Bennett, 1964
). In beet leaves, infectivity survived 1 year at
-20°C (Yamaguchi, 1964
The virus seems rather unstable in vitro;
preparations have been obtained using the following method (Chod &
). Extract frozen beet leaves in phosphate buffer (pH 7.8)
containing 0.01 M veronal, 0.01 M cysteine and 0.007 M ethylenediamine-tetraacetate. Centrifuge at low speed. Precipitate the virus from the supernatant
fluid by adding a 40% aqueous solution of polyethylene glycol (PEG) to reach a
final PEG concentration of about 10%, and allowing the mixture to stand for 30
min. Sediment and clarify by differential centrifugation, resuspending the
pellets obtained at high speed in 0.01 M phosphate buffer.
Properties of Particles
Extraction of leaves of infected sugar beet or Stellaria media
water-saturated phenol yielded preparations which infected Chenopodium
Flexuous, filamentous particles (Fig.5
) about 730 nm long and 13 nm in
diameter (Zimmer & Brandes, 1956
Relations with Cells and Tissues
In beet, vesicular X-bodies are produced in the cytoplasm, and crystalline
inclusions occur in the chloroplasts (Fujisawa, Matsui & Yamaguchi, 1967
nucleoli are enlarged and distorted in beet (Bos, 1969
) and in Gomphrena
(Martelli & Russo, 1969
); cytoplasm contains inclusions which
appear in section as pinwheels and bundles and are digestible by pepsin but
not by ribonuclease (Hoefert, 1969
Beet mosaic virus is usually of little economic importance in sugar beet or
spinach; its effects on yield of sugar beet are very small (Wiesner, 1959
symptoms it causes in sugar beet might be confused with the yellow mosaic and
blotching caused by tomato black ring
and tobacco rattle
viruses (Gibbs &
), though these two viruses are readily distinguished from beet
mosaic virus by their symptoms in other hosts, the morphology of their particles,
and by having nematode vectors. Among other viruses occurring in sugar beet and
spinach, cucumber mosaic
and beet ring mottle viruses (Duffus & Costa, 1963
cause mottling, pronounced chlorosis, narrowing and distortion of the leaves,
and severely stunt the plants; beet yellows
, beet mild yellowing
and beet western
viruses all cause chlorosis of the older leaves but not mottling or
chlorotic flecking; and beet curly top virus
induces leaf-curling, wart-like
protuberances on the leaves, and stunting of the plant.
- Beiss, Naturwissenschaften 50: 675, 1963.
- Bennett, Phytopathology 34: 905, 1944.
- Bennett, Phytopathology 39: 669, 1949.
- Bennett, J. Am. Soc. Sug. Beet Technol. 13: 27, 1964.
- Bercks, Virology 12: 311, 1960.
- Bos, Neth. J. Pl. Path. 75: 137, 1969.
- Brandes & Bercks, Adv. Virus Res. 11: 1, 1965.
- Chod & Polák, Biologia Pl. 11: 324, 1969.
- Cockbain, Gibbs & Heathcote, Ann. appl. Biol. 52: 133, 1963.
- Duffus & Costa, Phytopathology 53: 1422, 1963.
- Fujisawa, Matsui & Yamaguchi, Phytopathology 57: 210, 1967.
- Gibbs & Harrison, Pl. Path. 13: 144, 1964.
- Hoefert, Virology 37: 498, 1969.
- Kennedy, Day & Eastop, A conspectus of aphids as vectors of plant viruses, London, Commonwealth Institute of Entomology, 1962.
- Lind, Tidsskr. PlAvl 22: 444, 1915.
- Martelli & Russo, Virology 38: 297, 1969.
- Robbins, Phytopathology 11: 349, 1921.
- Smith, Textbook of plant viruses, London, Churchill, 1957.
- Sylvester, Phytopathology 39: 417, 1949.
- Sylvester, Phytopathology 42: 252, 1952.
- Watson, Proc. R. Soc., B 133: 200, 1946.
- Watson, Rep. Rothamsted exp. Stn, 1957: 113, 1958.
- Wiesner, Zucker 12: 266, 1959.
- Yamaguchi, Ann. phytopath. Soc. Japan 29: 52, 1964.
- Zimmer & Brandes, Phytopath. Z. 26: 439, 1956.
Photographs: courtesy of Plant Breeding Institute, Cambridge; Fig.5,
courtesy of Rothamsted Experimental Station.
Young sugar beet leaves, (left) systemically infected, showing
vein-clearing and incipient mottle symptoms; (right) virus-free.
Beta patellaris leaf showing brown necrotic local lesions.
Mature leaf from systemically infected sugar beet plant showing light
green and dark green mottle symptoms.
Chenopodium quinoa leaf showing chlorotic local lesions.
Electron micrograph of particle mounted in phosphotungstate. Bar
represents 100 nm.