Carnation mottle virus
Glasshouse Crops Research Institute, Littlehampton, Sussex, England
Olwen M. Stone
Glasshouse Crops Research Institute, Littlehampton, Sussex, England
- None; carnation mosaic virus is not an acceptable name because it has been applied
to many different viruses
An RNA-containing virus with isometric particles about 28 nm in diameter, transmissible
by inoculation of sap unless prevented by inhibitors. It occurs naturally only in the
Caryophyllaceae but can be transmitted experimentally to other species. Very common and
widespread in carnation, many commercial cultivars being wholly infected. Vector unknown.
Mild mottle and loss of vigour in carnation. Symptoms often apparent only by
comparison with healthy plants.
Widespread wherever carnations are grown.
Host Range and Symptomatology
Natural host range seems restricted to species of Caryophyllaceae, but the virus
can infect over 30 spp. in 15 dicotyledonous families. Because of inhibitors in
carnation sap the virus may be transmitted readily only after purification.
- Chenopodium amaranticolor. Usually develops local chlorotic dots after 4-7
lesions may be necrotic with some strains or in older leaves. Systemic
infection rare, and usually occurs only in short day conditions.
- Chenopodium quinoa. Local chlorotic spots after 4-7 days followed by systemic
chlorotic spotting and mottle with some leaf distortion.
- Atriplex hortensis. Local chlorotic spots after 5-9 days followed by systemic
chlorotic flecks and leaf buckling.
- Gomphrena globosa. Faint fawn local necrotic dots after 7-10 days
No systemic infection; this distinguishes the virus from
carnation ringspot virus.
- Tetragonia expansa. Faint local chlorotic or necrotic spots after 5-8 days
followed by limited systemic infection.
- Dianthus barbatus (sweet william). Some clones give local fawn spots after
followed by systemic chlorotic flecking and mottling; others are immune.
- Dianthus caryophyllus (carnation) is very suitable both for maintaining the
virus and as a source of virus for purification. Chenopodium quinoa is also
useful; Dianthus barbatus should only be used where a susceptible host clone
has been selected.
- Chenopodium amaranticolor and C. quinoa are useful local lesion hosts
and will detect attenuated forms of the virus (see below).
Three minor variants are recorded:
(Hollings & Stone, 1964).
Produces necrotic local lesions in a
number of hosts which give chlorotic spots with the type strain
Fig.7). It is
serologically indistinguishable from the type strain.
(Kemp & Fazekas, 1966).
Can be distinguished from the type
strain serologically and by the smaller local necrotic lesions produced in Dianthus
(Hollings & Stone, 1962).
Found in carnation plants after
heat treatment or meristem tip culture. Very few, large local chlorotic lesions develop
in Chenopodium amaranticolor after about 21 days
(Fig.3). On serial passage,
such lesions give the typical, rapidly multiplying form with no serological difference
from the type strain.
Transmission by Vectors
Transmission through Seed
Transmission by Dodder
The virus is a good immunogen and rabbits given one intravenous and two intramuscular
injections produce antisera with specific precipitin tube titres of 1/4096 to 1/16,384.
Specific precipitates in tube tests are granular (somatic), and a single band of
precipitate forms in gel-diffusion tests. All strains of the virus, except the attenuated
form, can be detected in crude sap by gel-diffusion tests. In gel immunoelectrophoresis
the virus moves towards the cathode
(Devergne & Cardin, 1967
No relationship has been shown to any other isometric virus. The type strain and the
PSR strain protected against each other in cross-protection tests.
Stability in Sap
In carnation sap the thermal inactivation point (10 min) is
about 90°C though much infectivity is lost at 65°C; dilution end-point is
. Infectivity survives for 70 days at 20°C; the attenuated
form was recovered after 13 months. Virus lyophilized in sap of Dianthus barbatus,
stored at room temperature under vacuum, retained infectivity for over 10 years.
The method used by
Hollings & Stone (1965)
carnation ringspot virus
suitable for carnation mottle virus. Leaves minced with 0.05 M phosphate buffer, pH
7.6, containing 0.1% thioglycollic acid (w/v= 1/1.25) are squeezed through cheesecloth
and the slurry treated with n
-butanol to 8.5% of the final volume. The mixture
is stored overnight at 2°C and the virus then separated from the aqueous phase by
differential centrifugation. Preparations made with borate buffers have about half the
infectivity and serological activity of those prepared with phosphate buffer.
Precipitation with ammonium sulphate (40% saturation) or ethanol (50%) or by
acidification to pH 4.8 also gives acceptable virus preparations.
Properties of Particles
Sedimentation coefficient (s20, w
): about 122 S.
No accessory viral components are found by analytical centrifugation.
Molecular weight: 7-8 x 106.
Isoelectric point: pH 5.2.
Electrophoretic mobility: -8 x 10-5 cm2 sec-1
volt-1 at pH 7 in 0.02 ionic strength buffer (Tremaine, unpublished).
Particles are rounded, isometric and about 28 nm in diameter
). Subunit structure is not known.
Single stranded, about 20% of particle weight. Molar percentages of
nucleotides: G27; A30; C19; U24 (Tremaine, unpublished).
Protein: About 80% of particle weight, probably about 240 subunits per
particle (Tremaine, unpublished). Subunits stated to contain 382 amino acid residues
(Tremaine & Goldsack, 1968).
Relations with Cells and Tissues
The virus is found in stems, leaves, flowers
and roots, though in lower concentration in apical meristems. No reported inclusion
bodies, or association with cell organelles. There is no information on sites of
Carnation mottle virus can be eliminated from carnation and Dianthus
by meristem tip culture with or without previous heat treatment. It often
occurs together with other isometric viruses in carnation.
Carnation ringspot virus
usually induces much more damaging effects in carnation, and produces conspicuous
local necrotic concentric rings in Gomphrena globosa
and local necrotic rings
and ringspots in D. barbatus.
Carnation Italian ringspot virus
by its systemic invasion of Chenopodium amaranticolor
and by its serological
reactions; it is a serotype of
tomato bushy stunt virus
Two other small isometric
viruses have been isolated from carnation but they have not yet been fully
characterized; they do not induce symptoms in any of the diagnostic hosts of
carnation mottle virus
(Hollings & Stone, 1968
- Devergne & Cardin, Annls. Épiphyt. 18: 65, 1967.
- Hollings & Stone, Rep. Glasshouse Crops Res. Inst., 1961: 100, 1962.
- Hollings & Stone Ann. appl. Biol. 53: 103, 1964.
- Hollings & Stone, Ann. appl. Biol. 56: 73, 1965.
- Hollings & Stone, Rep. Glasshouse Crops Res. Inst., 1967: 94, 1968.
- Kassanis, Ann. appl. Biol. 43: 103, 1955.
- Kemp & Fazekas, Can. J. Bot. 44: 1261, 1966.
- Tremaine & Goldsack, Virology 35: 227, 1968.
Photographs: M. Hollings and Glasshouse Crops Research Institute.
Typical local chlorotic lesions in Chenopodium amaranticolor.
Local necrotic lesions of the PSR strain in C. amaranticolor.
Local chlorotic lesions of the attenuated form in C. amaranticolor.
Necrotic local lesions in a susceptible clone of Dianthus barbatus.
Faint local necrotic lesions in Gomphrena globosa.
Virus particles from a purified preparation stained with phosphotungstate.
Bar represents 100 nm.
Local necrotic lesions of the PSR strain in Tetragonia expansa.