Potato virus Y
S. Delgado-Sanchez
Instituto Nacional de Investigaciones Agricolas, Apdo. Postal No. 6-882, Mexico 6, D. F. Mexico
R. G. Grogan
Dept. of Plant Pathology, Univ. of California, Davis, California 95616, USA
Contents
Introduction
-
Described by Smith (1931).
-
Selected synonyms
- Potato acropetal necrosis virus (Rev. appl. Mycol. 10: 745)
- Tobacco vein-banding virus (Rev. appl. Mycol. 10: 60)
- Tobacco veinal necrosis virus (Rev. appl. Mycol. 31: 201)
- Solanum virus 2 (Rev. appl. Mycol. 17: 52)
- Marmor upsilon (Rev. appl. Mycol. 28: 514)
-
A virus with flexuous helically constructed particles, 730 x 11 nm, sap-transmissible
to a narrow
range of hosts and transmitted by several species of aphids in the non-persistent manner.
It causes
important economic diseases of solanaceous plants and has a world-wide distribution.
Main Diseases
In potato it usually causes ‘leaf-drop streak’ or necrosis along the veins
of the underside of
leaflets in the first year of infection
(
Fig.3,
Fig.4);
in combination with
potato virus X it causes the
disease called ‘rugose mosaic’ in the USA, one of the most
destructive diseases of potato. In Britain,
the term, rugose mosaic, is used to refer to disease caused by potato virus Y
in the second and subsequent
years of infection. In tobacco, pepper, and tomato the virus causes mild to
severe mottling depending on
the strain
(
Smith, 1957).
Geographical Distribution
World-wide.
Host Range and Symptomatology
Reported to infect at least 60 plant spp., mostly in the Solanaceae, but also infects members of the
Chenopodiaceae and Leguminosae
(
Thornberry, 1966).
-
Diagnostic species
- Capsicum frutescens
cv. Tabasco (pepper). Mild to severe mottle;
no wilting like that caused by
tobacco etch virus.
- Datura stramonium. Immune to infection by all tested strains of
potato virus Y, but susceptible
to tobacco etch virus; useful for separating potato virus Y from tobacco etch virus.
- Nicotiana glutinosa. Mild to severe mottling depending on the strain
(Fig.1).
- N. tabacum (tobacco). Most strains produce vein clearing followed by
mottling; an exception
is the necrotic strain. Combined infection with potato viruses X
and Y produces a synergistic ‘spot
necrosis’ reaction which has been used to detect the presence of potato virus Y
(Darby, Larson & Walker, 1951).
- Solanum tuberosum cv. Saco (potato). Some strains produce local necrotic
lesions; useful
for separating potato virus Y from potato virus X to which Saco is virtually immune
(Benson & Hooker, 1960).
-
Propagation species
- N. glutinosa
may be used to maintain the virus. N. tabacum cv. Wisconsin
Havana 425
is a good source for virus purification.
-
Assay species
- Local lesion hosts include Chenopodium amaranticolor, C. quinoa
(Fig.5),
several species
of Lycium, Nicandra physalodes, Nicotiana repanda, N. rustica, Physalis floridana,
Solanum demissum
‘Y’
(Fig.2),
S. demissum x S. tuberosum ‘A-6’, and S. tuberosum cvs. Saco
and U.S.D.A. seedling 41956.
Strains
Several strains can be distinguished on the basis of severity of systemic symptoms
in tobacco and
other hosts. The following seem the most important:
Common strains: Differentiated by the severity of symptoms in
N. glutinosa, P. floridana
and potato. Found world-wide
(Kahn & Monroe, 1963).
The necrotic or tobacco veinal necrosis strain
(Nobrega & Silberschmidt, 1944)
produces
severe veinal necrosis in tobacco. Source South America.
Potato virus C
(Bawden, 1936)
differs from others in not being transmitted by Myzus
persicae, which is an efficient vector of PVY. Source Australia and England.
Transmission by Vectors
Transmitted in the non-persistent manner by several aphid spp.
Myzus persicae is
probably
the most efficient vector; others are
Myzus ornatus, Macrosiphum euphorbiae,
Aulacorthum circumflexum,
Aphis nasturtii and
Aphis gossypii
(
Kennedy, Day & Eastop, 1962).
Young upper leaves of
infected potato plants are better sources of virus for aphids than are middle or lower leaves
(
Bagnall & Bradley, 1958).
Adult or later instar apterous aphids have usually been used in transmission
experiments and a pre-acquisition starvation period of 2-7 h aids transmission. The optimum
acquisition feeding period is from 30 sec to 5 min a period of 30-60 sec to 24 h is
satisfactory for
inoculation
(
Bradley, 1953;
Easton, Larson & Hougas, 1958).
Transmission through Seed
Not reported.
Transmission by Dodder
Not reported.
Serology
Strongly immunogenic. Emulsification of antigen with Freund’s adjuvant before
injecting it
intramuscularly into rabbits increased both the titre of the antiserum obtained
and the period of
maximum immune response
(
Wetter, 1960).
Microprecipitin tests can be done using clarified extracts of
infected tissue. The formation of non-specific precipitates can be avoided by
buffering the saline
solution with 0.05 M Tris-HCl. Serological precipitates in mixed liquids are of the
flocculent
(flagellar) type.
Relationships
Precipitin tests showed that the common, C and necrotic strains are serologically related
(
Bawden & Kassanis, 1951),
but differences were noted between the homologous and heterologous reactions,
particularly between the necrotic and the common strains
(
Bartels, 1957).
Using high titred antisera,
PVY was shown to be distantly related to at least 16 other filamentous viruses,
and these comprise the
potato virus Y group
(
Brandes & Bercks, 1965).
In cross-protection tests, several mild isolates protected against more virulent
isolates in potato,
but not in tobacco
(Darby et al., 1951).
Stability in Sap
Infectivity is lost after heating sap from infected tobacco for 10 min at 55-60°C;
dilution
end-points range from 10
-2 to 10
-3 for most isolates;
inactivated
in vitro
within 48-72 h.
Purification
Several procedures have been described, but aggregation of the particles
presents difficulties
(
Van Regenmortel, 1964;
Venekamp & Mosch, 1964).
A procedure for obtaining essentially unaggregated
preparations has been described
(
Delgado-Sanchez & Grogan, 1966).
Particle Structure
Virus particles are flexuous filaments about 11 nm wide and helically constructed,
with a pitch of
about 3.3 nm
(
Varma et al., 1968).
The normal length of particles in purified virus preparations
is about 684 nm, compared with about 730 nm for particles in
tissue-dip preparations
(
Fig.6).
Particle Composition
Not known.
Relations with Cells and Tissues
Pin-wheel inclusions
(
Fig.8)
occur in systemically infected tissue
(
Edwardson, 1966).
They are
composed of pin-wheel plates, which are easily seen in leaf-dip preparations
(
Fig.7)
and have
characteristic striations with a spacing of
c. 5 nm.
Notes
In some
Solanum species the virus may be confused with
tobacco etch and
henbane mosaic
viruses, which produce somewhat similar symptoms and have similar host ranges.
Tobacco etch virus,
however, infects
Datura stramonium and produces necrotic wilting of Tabasco pepper
and etching
of the leaves of tobacco. Henbane mosaic virus occurs less frequently in the common hosts
of potato Y
and tobacco etch viruses; it can infect
D. stramonium but not Tabasco pepper.
References
- Bagnall & Bradley, Phytopathology 48: 121, 1958.
- Bartels, Proc. 3rd Conf. on Potato Virus Diseases, Lisse-Wageningen: 13, 1957.
- Bawden, Ann. appl. Biol. 23: 487, 1936.
- Bawden & Kassanis, Ann. appl. Biol. 38: 402, 1951.
- Benson & Hooker, Phytopathology 50: 231, 1960.
- Bradley, Nature, Lond. 171: 755, 1953.
- Brandes & Bercks, Adv. Virus Res. 11: 1, 1965.
- Darby, Larson & Walker, Res. Bull. Univ. Wisc. 177, 32 pp., 1951.
- Delgado-Sanchez & Grogan, Phytopathology 56: 1397, 1966.
- Easton, Larson & Hougas, Res. Bull. Univ. Wisc. 205, 32 pp., 1958.
- Edwardson, Am. J. Bot. 53: 359, 1966.
- Kahn & Monroe, Phytopathology 53: 1356, 1963.
- Kennedy, Day & Eastop, A conspectus of aphids as vectors of plant viruses, London, Commonwealth Institute of Entomology, 1962.
- Nobrega & Silberschmidt, Arquiv. Inst. Biol. S. Paulo 15: 307, 1944.
- Smith, Proc. R. Soc., B 109: 251, 1931.
- Smith, A Text Book of Plant Virus Diseases, Churchill, London, 1957.
- Thornberry, Index of Plant Virus Diseases, Agric. Handb. U.S.D.A., 307, 285, 1966.
- Van Regenmortel, Virology 23: 495, 1964.
- Varma, Gibbs, Woods & Finch, J. gen. Virol. 2: 107, 1968.
- Venekamp & Mosch, Virology 23: 394, 1964.
- Wetter, Arch. Mikrobiol. 37: 278, 1960.
Systemic mottle in Nicotiana glutinosa.
Necrotic local lesions in inoculated leaves of Solanum demissum ‘Y’.
Symptoms of ‘leaf-drop streak’ in potato.
Systemic necrotic symptoms in potato leaf.
Chlorotic local lesions in inoculated leaves of Chenopodium quinoa.
Flexuous elongated virus particles in uranyl formate. Bar represents 200 nm.
Pinwheel plate in leaf-dip preparation mounted in phosphotungstate. Bar represents 100 nm.
Pinwheel inclusion bodies typically produced in tissues infected with potato virus Y
and other viruses in the potato virus Y group. Bar represents 200 nm.
