Artichoke yellow ringspot virus
G. L. Rana
Istituto di Patologia vegetale, UniversitÓ di Bari, 70126 Bari, Italy
Panayota E. Kyriakopoulou
Benaki Phytopathological Institute, Kiphissia, Athens, Greece
G. P. Martelli
Istituto di Patologia vegetale, UniversitÓ di Bari, 70126 Bari, Italy
Disease described by
Kyriakopoulou & Bem (1973
Rana, Rosciglione & Cannizzaro (1978)
, virus characterized by
Rana et al. (1980)
A virus with isometric particles c. 30 nm in diameter, containing two
functional RNA species. Readily transmitted by inoculation of sap to many
herbaceous hosts and frequently transmitted through seed and pollen. No vector
known. Occurs in a range of cultivated and wild plants in Greece and Italy.
Causes chrome-yellow blotches, rings and lines (Fig.1
) on the leaves of
artichoke (Cynara scolymus
) and cardoon (Cynara cardunculus
(Kyriakopoulou & Bem, 1973
; Rana et al., 1978
rings and oakleaf patterns in tobacco (Nicotiana tabacum
) cv. Black
of Argos (P. E. Kyriakopoulou, unpublished information); stunting, diffuse
yellowing and leaf malformation in French bean (Phaseolus vulgaris
and broad bean (Vicia faba
) (P. E. Kyriakopoulou, unpublished
information). In naturally infected wild plant species, induces chlorotic
to yellow rings, mottling and, occasionally, malformation of the leaves.
Reported from north-east Peloponnesus (Greece) and Sicily (Italy).
Host Range and Symptomatology
In nature the virus was found infecting 32 different plant species in
13 dicotyledonous families, of which 5 species are cultivated (artichoke, cardoon,
tobacco, French and broad beans)
and 27 are wild (P. E. Kyriakopoulou, unpublished information). Experimental host
range is wide, including 56
species in 11 families (Rana et al., 1980
- Diagnostic species
- Gomphrena globosa. Reddish local lesions followed by systemic yellow
ringspots and line patterns.
- Chenopodium quinoa. Chlorotic/necrotic local lesions, systemic mottling
and tip necrosis.
- Phaseolus vulgaris (French bean). Reddish necrotic local lesions,
systemic mosaic and leaf deformation.
- Cucumis sativus (cucumber). Chlorotic lesions on cotyledons followed
by mosaic, malformation and enations in non-inoculated leaves.
- Nicotiana tabacum (tobacco). Local and systemic chlorotic rings,
lines and oakleaf patterns (Fig.2).
- Propagation species
- Phaseolus vulgaris, Chenopodium quinoa and Cucumis sativus
are good sources of virus for purification. G. globosa is suitable for
maintaining virus cultures.
- Assay species
- Chenopodium quinoa, Cucumis sativus and Canavalia ensiformis
(Fig.3) are satisfactory local lesion hosts.
Virus isolates from Italy and Greece differ in host range responses but
are serologically indistinguishable (Rana et al., 1980
Transmission by Vectors
No vector known. Italian and Greek isolates were not transmitted by
(Rana et al., 1980
) and an intensive search
for possible longidorid nematode vectors in Greece was unsuccessful (F. Roca
& G. L. Rana, unpublished information).
Transmission through Seed
Transmitted through seed at rates ranging from 15 to 100% in artificially
infected Chenopodium amaranticolor, C. quinoa, Datura stramonium, Nicotiana
clevelandii, N. glutinosa, N. rustica
and Petunia hybrida
, and in
naturally infected Anethum graveolens
glauca, N. tabacum, Reseda alba
and Stellaria media
Kyriakopoulou, unpublished information). Pollen transmission to seeds
occurs in D. stramonium, N. clevelandii, N. glutinosa, N. tabacum, P.
and transmission through pollen to pollinated plants was found
in N. clevelandii
(P. E. Kyriakopoulou, unpublished information).
The virus is weakly immunogenic. Antisera with titres not higher than
1/32 were obtained. The best antisera still had a titre of 1/2 to healthy
plant proteins. In gel double diffusion tests no precipitin lines form unless
virus particles are dissociated with SDS or ethanolamine (Rana et al.,
). Immunosorbent electron microscopy and antibody coating can be used for
The virus is classified in the nepovirus group
on the basis of particle
size and morphology, physico-chemical properties, transmission through seed and
intracellular behaviour. However, it was serologically unrelated to any of 26
different viruses with isometric particles, including the following 13
nepoviruses: artichoke Italian latent
(grapevine and artichoke isolates),
, cherry leaf roll
(rhubarb and walnut strains), chicory yellow
, grapevine Bulgarian latent
, cocoa necrosis
, tomato black ring
bouquet and beet ringspot strains), tomato ringspot
, grapevine fanleaf
myrobalan latent ringspot
, strawberry latent ringspot
(type, peach and olive
strains), grapevine chrome mosaic
and peach rosette mosaic
(Rana et al.,
Stability in Sap
In expressed sap of French bean the virus was still infective after
dilution to 10-3
. Infectivity was lost after heating
for 10 min at 60°C or storing at 22-24°C for 48-72 h.
Virus particles show a strong tendency to aggregate during extraction and
purification. However, the following method (Rana et al., 1980
satisfactory results: homogenise each 100 g French bean leaves, collected 10-12
days after inoculation, in 200 ml each of chloroform and neutral 0.1 M phosphate
buffer containing 0.6% sodium ascorbate, 4% Triton X-100 and 25% sucrose.
Centrifuge at low speed and precipitate the virus from the supernatant fluid
by adding polyethylene glycol to 10% (w/v) and NaCl to 1% (w/v); centrifuge at
low speed and resuspend the pellets overnight at 4°C in neutral 0.02 M
phosphate buffer. The virus particles can then be separated from most host
constituents by alternate cycles of low speed centrifugation (20 min at 7000
) in 25% sucrose and high speed centrifugation (1 h at 90,000
) in 12.5% sucrose, retaining the supernatant fluid and pellets,
respectively. Further purification can be obtained by centrifuging partially
purified preparations to equilibrium using the step isopycnic CsCl method
as modified by Sehgal et al. (1970)
Properties of Particles
Particles are of two types: empty shells (T component) and full
containing RNA. Because of the strong aggregation of particles during purification,
preparations cannot be satisfactorily fractionated. In step isopycnic CsCl
centrifugation, most of the empty shells band in the upper part of the gradients
(density 1.20-1.30 g/cm3
) whereas full particles sediment in the lower part
(density 1.40-1.53 g/cm3
) (Rana et al., 1980
Particles are isometric, c
. 30 nm in diameter and show angular
outlines. Empty particles (possibly T component) are penetrated by negative
Particle CompositionNucleic acid
: Single-stranded RNA. In polyacrylamide gel
electrophoresis the RNA migrates as two species (RNA-1 and RNA-2) with
estimated M. Wt (x 10-6
) of 2.3 and 1.9 respectively under
non-denaturing conditions (Bishop, Claybrook & Spiegelman, 1967
) or 2.17
and 1.85 respectively under denaturing conditions (Reijnders et al.,
). Both RNA species are necessary for infectivity (Rana et al.,
Protein: In polyacrylamide/SDS gels, protein preparations from
unfractionated virus contained a single polypeptide of estimated M. Wt 53,000.
Relations with Cells and Tissues
The virus is present in most plant tissues both in leaves and roots.
Cytopathological modifications (Russo et al., 1978
) consist of cytoplasmic
inclusion bodies made up of accumulations of tangled membranes (Fig.5
vesicles containing finely stranded material resembling nucleic acid. Dictyosomes
are much affected and may take part in some steps of virus multiplication
(possibly assembly of virions). Virus particles occur in the cytoplasm at the
periphery of the inclusions in stacked layers or between membranes (Fig.5
within tubular structures. Aggregates of empty particles may be present in the
nucleoplasm. Modifications of cell walls (callose deposition and wall outgrowths)
and of the cell wall-plasmalemma interface (paramural bodies) are very common.
The virus has biological, physico-chemical and ultrastructural properties of
. However, it is not serologically related to any of the known members
of this group that have been tested and it has no known vector. Because of the
M. Wt of its RNA-2, artichoke yellow ringspot virus can be assigned to the
cherry leaf roll virus
subgroup (Martelli et al., 1978
). The virus is
transmitted to plants through pollen, as may happen with cherry leaf roll
virus (Mircetich, Sanborn & Ramos, 1981
). Artichoke yellow ringspot virus
may be distinguished from other viruses occurring in the same natural hosts
by differences in artificial host range and symptomatology, by its strong
tendency to aggregate during extraction and purification, and by serological
reactions (Rana et al., 1980
). The field syndrome observed in artichoke
and cardoon plants is distinctive and unlike that shown by the same species
when infected by other viruses (Martelli, Russo & Rana, 1981
- Bishop, Claybrook & Spiegelman, J. molec. Biol. 26: 373, 1967.
- Kyriakopoulou & Bem, Symp. Agric. Res., Athens, 1973: 64, 1973.
- Martelli, Quacquarelli, Gallitelli, Savino & Piazolla, Phytopath. Medit. 17: 145, 1978.
- Martelli, Russo & Rana, Atti 3° Congr. Internaz. Carciofo, Bari, 1979: 895, 1981.
- Mircetich, Sanborn & Ramos, Phytopathology 71: 962, 1981.
- Rana, Rosciglione & Cannizzaro, Phytopath. Medit. 17: 63, 1978.
- Rana, Gallitelli, Kyriakopoulou, Russo & Martelli, Ann. appl. Biol. 96: 177, 1980.
- Reijnders, Aalbers, Van Kammen & Thuring, Virology 60: 515, 1974.
- Russo, Martelli, Rana & Kyriakopoulou, Microbiologica 1: 81, 1978.
- Sehgal, Jean, Bhalla, Soong & Krause, Phytopathology 60: 1778, 1970.
Naturally infected artichoke leaf showing yellow rings, blotches
and oakleaf patterns.
Chlorotic/necrotic rings and lines in a leaf of experimentally
infected tobacco plant.
Necrotic ring-like local lesions in Canavalia ensiformis.
Virus particles in neutral 2% potassium phosphotungstate. A few
empty shells (T component) are visible. Bar represents 100 nm.
Part of a cytoplasmic inclusion body (1B) made up of tangled
membranes and vesicles and rows of virus particles (V) enclosed in membranes
either singly or in stacked layers. Bar represents 250 nm.