Lettuce mosaic virus
J. A. Tomlinson
National Vegetable Research Station, Wellesbourne, Warwickshire, England
Described by Jagger (1921)
- Selected synonyms:
- Lactuca virus 1 (Rev. appl. Mycol. 17: 52)
- Marmor lactucae (Rev. appl. Mycol. 28: 514)
- A virus with flexuous filamentous particles approximately 750 x 13 nm. It
is sap-transmissible to a wide range of species, is seed-borne in lettuce and
is transmitted by several aphid species in the non-persistent manner. World-wide
Causes various mosaic and mottle symptoms in almost all types of lettuce
and L. sativa
World-wide. The disease is widespread in the USA, especially California,
and in Europe.
Host Range and Symptomatology
Host range is wide (Costa & Duffus, 1958
). Susceptible species occur in
20 genera (9 genera of Compositae) in 10 families. Transmissible by inoculation
with sap from young infected plants, but transmission with sap from old leaves
may be difficult.
- Diagnostic species
- Lactuca sativa (lettuce). Symptoms are variable but usually consist of
vein clearing and yellow mottling sometimes with veinal necrosis (conspicuous
in the flowering plant) and bronzing. Plants fail to heart and inner leaves
remain dwarfed and rosetted (Fig.1).
- Chenopodium amaranticolor. Pale green or chlorotic local lesions
(usually with reddish margins) after 8-10 days (Fig.2, left). Systemic
yellow veinal flecks or yellow netting of the younger leaves especially in
winter (Fig.2, right).
- C. quinoa. More sensitive than C. amaranticolor: local lesions
more numerous but without reddish margins. Conspicuous, systemic yellow
vein-net symptoms with twisting and stunting of apical leaves (Fig.3).
- Gomphrena globosa. Whitish, local necrotic dots (4-7 days) enlarging
into red-rimmed lesions.
- Propagation species
- Lettuce plants 10-15 days after inoculation are suitable sources of virus
for purification. Systemically infected safflower (Carthamus tinctorius) is also
reported (Klisiewicz, 1965) to be a good source.
- Chenopodium quinoa can be used for maintaining cultures.
- Assay species
- Chenopodium amaranticolor, C. quinoa and Gomphrena globosa are
suitable local lesion hosts.
StrainsMcLean & Kinsey (1962
) differentiated four Californian strains
by symptoms in lettuce and pea.
Transmission by Vectors
Transmissible by several species of aphid (Dickson & Laird, 1959
Kennedy, Day & Eastop, 1962
) notably Myzus persicae, Macrosiphum
and Acyrthosiphon scariolae barri.
All instars of M. persicae
alates are less efficient than apterae. Transmission efficiency increases with
increasing periods of fasting (5-240 min), but decreases with increasing
acquisition access time from 5 to 120 min (Sylvester, 1955
Transmission through Seed
The virus is seed-borne in lettuce (Newhall, 1923
), some 3-10% of the seed
giving rise to infected seedlings, depending on the time of infection of the
mother plant (Couch, 1955
) and the variety (Grogan, Welch & Bardin, 1952
Transmission occurs through both pollen and ovules of infected plants (Ryder,
). Seed transmission also occurs in Lactuca serriola
) but not in the lettuce variety Cheshunt Early Giant (Kassanis, 1947
Seed transmission was reported in Senecio vulgaris
; Kemper, 1962
), but was unconfirmed by Fry (1952)
Seed transmission is probably the major factor in the spread of the disease
(Broadbent, Tinsley, Buddin & Roberts, 1951; Grogan et al., 1952;
Tomlinson, 1962). Spread occurs (a) from seedlings infected through the seed
and (b) from neighbouring infected lettuce. The disease can be controlled by
ensuring that the crop is isolated from external sources of virus and that less
than 0.1% of the seed carries the virus (Zink, Grogan & Welch, 1956;
Tomlinson, 1962). Even where adjacent crops are infected, use of mosaic-free
seed provides some control (Tomlinson, 1962).
Transmission by Dodder
An antiserum prepared by intravenous injection of a purified preparation
had a titre of 1/256 and gave a flagellar-type precipitate in precipitin tube
tests. Agglutination tests with crude sap were about 90% reliable (Tomlinson,
The virus belongs to the potato virus Y group
. According to Brandes &
, lettuce mosaic virus may be distantly serologically related to
and sugarcane mosaic
In plant protection tests, some strains of the virus protected lettuce against
other more virulent strains (McLean & Kinsey, 1962, 1963). Lettuce mosaic
virus did not protect lettuce against dandelion yellow mosaic virus (Kassanis,
Stability in Sap
In lettuce sap, the thermal inactivation point (10 min) is 55-60°C,
dilution end-point 10-1
and infectivity is retained
at 20°C for 1-2 days. Infectivity is considerably stabilized by adding 0.5%
sodium sulphite (Ainsworth & Ogilvie, 1939
) or 0.1% thioglycollic acid
. Extract infected lettuce leaves at pH 7.5 in 0.5 M
sodium borate containing 0.1% thioglycollic acid. Filter and add n-
to 8.5% (v/v). Centrifuge twice at low speed. Sediment and clarify by high and
low speed centrifugation, resuspending the pellets obtained at high speed in
0.05 M borate (pH 7.5). Do all steps at 3°C. Preparations infective to
Properties of Particles
Particles are flexuous filaments approximately 750 x 13 nm (Fig.4
do not appear to be penetrated by phosphotungstate.
Relations with Cells and Tissues
Lettuce mosaic virus may sometimes be found in lettuce together with cucumber
and both viruses may be simultaneously transmitted in sap to
or C. quinoa.
Unlike cucumber mosaic
virus, which causes only local lesions in the inoculated leaves (2-3 days),
lettuce mosaic virus infects both these hosts systemically.
- Ainsworth & Ogilvie, Ann. appl. Biol. 26: 279, 1939.
- Brandes & Bercks, Adv. Virus Res. 11: 1, 1965.
- Broadbent, Tinsley, Buddin & Roberts, Ann. appl. Biol. 38: 689, 1951.
- Costa & Duffus, Pl. Dis. Reptr 42: 583, 1958.
- Couch, Phytopathology 45: 63, 1955.
- Dickson & Laird, J. econ. Ent. 52: 440, 1959.
- Fry, N.Z. Jl Sci. Technol. Sect. A 33: 52, 1952.
- Grogan, Welch & Bardin Phytopathology 42: 573, 1952.
- Jagger, J. agric. Res. 20: 739, 1921.
- Kassanis, Ann. appl. Biol. 34: 412, 1947.
- Kemper, Z. PflKrankh. PflPath. PflSchutz 69: 653, 1962.
- Kennedy, Day & Eastop, A conspectus of aphids as vectors of plant viruses, London, Commonwealth Institute of Entomology, 1962.
- Klisiewicz, Pl. Dis. Reptr 49: 541, 1965.
- McLean & Kinsey, Phytopathology 52: 403, 1962.
- McLean & Kinsey, Pl. Dis. Reptr 47: 474, 1963.
- Newhall, Phytopathology 13: 104, 1923.
- Ryder, Pl. Dis. Reptr 48: 522, 1964.
- Sylvester, Phytopathology 45: 357, 1955.
- Tomlinson, Pl. Path. 11: 61, 1962.
- Tomlinson, Ann. appl. Biol. 53: 95, 1964.
- Van Hoof, Tijdschr. PlZiekt. 65: 44, 1959.
- Zink, Grogan & Welch, Phytopathology 46: 662, 1956.
Photographs: courtesy of National Vegetable Research Station.
Lettuce (cv. Cheshunt Early Giant) showing (left) normal plant
and (right) plant with systemic symptoms of mosaic and vein clearing.
(Left) local lesions, (right) systemic symptoms in
Systemic symptoms in Chenopodium quinoa.
Virus particles from a purified preparation in phosphotungstate. Bar
represents 200 nm.