Narcissus latent virus
A. A. Brunt
Glasshouse Crops Research Institute, Littlehampton, Sussex, England
Detected by Brunt & Atkey (1967)
and partially characterized by
- Irisbontvirus (Asjes & Derks, 1975)
A virus with filamentous particles c. 13 x 650 nm; found in W. Europe in
narcissus, nerine and bulbous iris, but often present with other viruses. Transmitted
in the non-persistent manner by aphids and by mechanical inoculation of sap.
Infects narcissus, nerine and bulbous iris but the virus is often present with other
viruses. In narcissus, the virus alone induces light and dark green mottling near leaf
tips of intolerant cultivars
this may initially resemble the chlorosis
induced by narcissus yellow stripe virus but, unlike the latter symptom, it occurs only
on the distal 6-10 cm of leaves. Cultivars with greater tolerance are either symptomless
or produce inconspicuous tip chlorosis which is barely discernible through the waxy
bloom on leaves. The leaf mottling is often more extensive but less conspicuous in
infected narcissus plants forced in glasshouses for early flower production. In nerine
the virus induces inconspicuous leaf mottling in some cultivars, but is virtually
symptomless in others. In bulbous irises it has been found only in complex with other
viruses, but in iris seedlings infected by sap-inoculation it induces very faint leaf
Reported in one or more hosts in Britain
(Brunt & Atkey, 1967
Brunt, Hollings & Stone, 1970
), The Netherlands
Asjes & Derks, 1975
) and Germany
(Koenig et al., 1973
R. Koenig, personal communication), but
present wherever nerine, narcissus and bulbous irises are grown.
Host Range and Symptomatology
In addition to the two natural hosts from the Amaryllidaceae and one from the
Iridaceae, narcissus latent virus infects 12 of 26 species from the Amaranthaceae,
Solanaceae and Papilionaceae but none of 23 species from 11 other families.
- Tetragonia expansa. Circular chlorotic lesions in inoculated leaves after
10-14 days, slowly enlarging to 4-8 mm in diameter and often with a green margin
(Fig.3). No systemic infection.
- Nicotiana clevelandii, N. megalosiphon and N. benthamiana. Some
isolates induce faint chlorotic lesions in inoculated leaves after 10-15 days but no
systemic infection; others induce both local chlorotic lesions and faint systemic leaf
- Phaseolus vulgaris cvs. The Prince and Canadian Wonder. Erratic production
of faint chlorotic circular lesions in inoculated primary leaves after 14 days. No
- Narcissus. In intolerant cultivars (e.g. Boswin, Dutch Master) light
and dark green leaf mottling mainly near leaf tips
- Nicotiana clevelandii and N. megalosiphon are good sources of inocula
and virus for purification, especially of those isolates inducing systemic infection.
- Although Tetragonia expansa and Phaseolus vulgaris produce local lesions,
neither is a reliable assay host. Infectivity is usually best assayed in Nicotiana
clevelandii or N. megalosiphon by recording the proportion of inoculated
plants becoming infected.
Although in Nicotiana clevelandii, N. benthamiana
and N. megalosiphon
some isolates induce local infection only and others infect systemically, all
isolates tested are serologically indistinguishable. Such isolates are probably best
considered as minor variants rather than as different strains.
Transmission by Vectors
Transmitted efficiently from narcissus and Nicotiana clevelandii
non-persistent manner by Acyrthosiphon pisum, Aphis gossypii
Transmission through Seed
Not seed-borne in narcissus or Nicotiana clevelandii.
Antisera with homologous titres of 1/4000 to 1/16,000 are readily prepared in
rabbits by one or two intramuscular injections, each of c.
0.5 mg of virus in
Freund's complete adjuvant. Antisera react with homologous antigen in tube precipitin
tests to produce typical flagellar precipitates.
Isolates from narcissus, nerine and bulbous iris are serologically indistinguishable.
Antiserum to irisbontvirus
(Asjes & Derks, 1975
reacted to its homologous titre
of 1/3200 with narcissus latent virus
Particle morphology and other properties place
narcissus latent virus in the carlavirus group
but no relationship was detected to any
of fourteen carlaviruses and it is thus probably a distinct member of the group.
Stability in Sap
Sap from Nicotiana clevelandii
is usually infective after dilution to
but not 10-4
, after 10 min at 65°C but not 70°C,
or after 16 and 4 days at 2°C and 20°C respectively.
Up to 25 mg virus/kg Nicotiana clevelandii
leaf tissue is obtainable by
the following procedure (A. A. Brunt & R. J. Barton, unpublished information):
Homogenise infected leaves (1 g/2 ml) at 2°C in an extractant at pH 7.1 containing
0.25 M phosphate, 0.2 M ascorbate and 0.1% v/v thioglycollate; add ether and carbon
tetrachloride (each 15% v/v), stir the mixture and then subject to one or two cycles
of differential centrifugation (15 min at 10,000 g
; 80 min at 65,000
). Resuspend final pellets in 0.033 M phosphate at pH 7.6 (1 ml/50-60
g leaf tissue). Separate the virus from the smaller contaminants (mainly cytoplasmic
ribosomes and fraction I protein) by chromatography on 700Å (120-200 mesh)
controlled-pore glass beads (Sigma Ltd.); when eluted with 0.05 M phosphate buffer
pH 7.6, virus is discharged in or soon after the void volume
) from which it
is then readily reconcentrated by ultracentrifugation.
Properties of Particles
Pure virus preparations contain a single sedimenting component with a sedimentation
) of 158±4 S and a buoyant
density of 1.33 g/cm3
A260/A240: 1.10 (both values corrected for light-scattering).
The virus has straight or slightly flexuous filamentous particles c.
650 nm (Fig.4
Particle CompositionNucleic acid:
RNA, probably single-stranded, c.
5 % of particle
weight (estimated spectrophotometrically).
Protein: c. 95% of particle weight. Subunit M. Wt (estimated by
polyacrylamide gel electrophoresis) c. 32,000 (R. J. Barton & A. A. Brunt,
Relations with Cells and Tissues
The common commercial exchange of flower bulbs throughout Western Europe,
together with the detection of the same but no other
in the three main
hosts in Britain, in bulbous iris in Germany (R. Koenig, personal communication) and
in narcissus in the Netherlands
), all suggested that narcissus latent
virus is also the carlavirus infecting nerine and bulbous iris in the Netherlands
Asjes & Derks, 1975
) and nerine in Germany
(Koenig et al., 1973
(Asjes & Derks, 1975
) and narcissus
latent viruses are now known to be synonyms, the serological affinities of
nerine latent virus
) have yet to be determined.
Although the virus is permanently or temporarily symptomless in some narcissus cultivars,
in others it induces definite leaf-tip mottling. Nevertheless, the name clearly indicates
its affinities with
carnation latent and allied viruses
(Harrison et al., 1971).
The virus alone is probably less damaging than most others infecting the three hosts but,
like some other carlaviruses, it probably contributes substantially to the gradual
decline of plants when present with other viruses.
The common occurrence of narcissus latent virus and other viruses in the three primary
hosts has previously caused difficulties in the separation and identification of the
individual viruses, especially when they induced similar symptoms and infected some
common indicator plants. Thus local lesions in Tetragonia expansa and systemic
chlorosis in Nicotiana clevelandii, which were previously attributed to
narcissus yellow stripe virus
(Brunt, 1971) or
iris mild mosaic virus
respectively, are now known to be induced by narcissus latent virus.
Virus-free nerine plants are readily obtained from infected bulbs by meristem-tip
culture; of 250 tips taken from infected plants, 130 produced small plants and of
56 surviving after transplanting into soil, 49 were virus-free
(Hakkaart, Maat & Quak, 1975).
- Asjes, Jversl. Lab. Bloembollen Onderz. Lisse 1968-1969: 40, 1969.
- Asjes & Derks, Jversl. Lab. Bloembollen Onderz. Lisse 1974: 41, 1975.
- Brunt, CMI/AAB Descriptions of Plant Viruses 76: 4 pp., 1971.
- Brunt, CMI/AAB Descriptions of Plant Viruses 116: 4 pp., 1973.
- Brunt, Rep. Glasshouse Crops Res. Inst. 1975: 122, 1976.
- Brunt & Atkey, Rep. Glasshouse Crops Res. Inst. 1966: 155, 1967.
- Brunt, Hollings & Stone, Rep. Glasshouse Crops Res. Inst. 1969: 138, 1970.
- Hakkaart, Jversl. Inst. plziektenk. Onderz. 1971: 105, 1972.
- Hakkaart, Maat & Quak, Acta Hort. 47: 51, 1975.
- Harrison, Finch, Gibbs, Hollings, Shepherd, Valenta & Wetter,Virology 45: 356, 1971.
- Koenig, Lesemann, Brunt & Kühne, Intervirology 1: 346, 1973.
Inconspicuous leaf chlorosis in narcissus cv. Boswin.
Leaf tip chlorosis in narcissus cv. Dutch Master.
Chlorotic local lesions in Tetragonia expansa leaf.
Virus particles in infective Nicotiana clevelandii sap mounted in
phosphotungstate. Bar represents 200 nm.
Inconspicuous systemic leaf chlorosis in N. clevelandii.
Molecular permeation chromatography elution profile on 700 Å pore size
controlled-pore glass beads of a partially purified virus preparation: Fractions 6
and 7 = virus; fractions 9, 10 and 11 = smaller debris.