36
October 1970
Family: Luteoviridae
Genus: Polerovirus
Species: Potato leafroll virus
Acronym: PLRV

There is a more recent description of this virus: DPV 291

Potato leafroll virus

D. Peters
Department of Virology, State Agricultural University, Wageningen, The Netherlands

Contents

Introduction
Main Diseases
Geographical Distribution
Host Range and Symptomatology
Strains
Transmission by Vectors
Transmission through Seed
Transmission by Grafting
Transmission by Dodder
Serology
Nucleic Acid Hybridization
Relationships
Stability in Sap
Purification
Properties of Particles
Particle Structure
Particle Composition
Properties of Infective Nucleic Acid
Molecular Structure
Genome Properties
Satellites
Relations with Cells and Tissues
Ecology and Control
Notes
References
Acknowledgements
Figures

Introduction

Described by Quanjer, Van der Lek & Oortwijn Botjes (1916).

Selected synonym

Potato phloem necrosis virus (Quanjer, 1913)

A virus with isometric particles about 24 nm in diameter. It has a narrow host range, is not sap transmissible, but is transmitted by about 10 species of aphids in the persistent manner. Common wherever potatoes are grown.

Main Diseases

Causes prominent rolling of the leaves of potato and a stiff upright habit of the plants (Fig.1). There is necrosis of the phloem and accumulation of carbohydrates in the leaves.

Geographical Distribution

World wide, wherever potatoes are grown.

Host Range and Symptomatology

Hosts are mainly in the Solanaceae, but some non-solanaceous plants such as Amaranthus caudatus, Celosia argentea, Gomphrena globosa and Nolana lanceolata are susceptible (Natti, Kirkpatrick & Ross, 1953).

Diagnostic species

Physalis floridana. Leaves show interveinal chlorosis; plants show variable amounts of stunting, depending on strain and temperature (Fig.2).

Datura stramonium. Interveinal chlorosis.

Solanum tuberosum (potato). Several varieties may react with the characteristic symptoms described above.

Propagation species
Plants and tubers of Solanum tuberosum are convenient for maintaining isolates, Physalis floridana (Kojima et al., 1969) and Datura stramonium (Peters & Van Loon, 1968) are used for purification.

Assay species
Physalis floridana is used to test the transmitting ability of aphids that have acquired the virus from plants or have been infected by injection. This plant may also give interveinal chlorosis upon infection with other viruses persistent in aphids (Duffus, 1964; MacKinnon, 1965).

Strains

Strains are distinguished on the basis of severity of reaction of P. floridana. Webb, Larson & Walker (1951) and Webb (1955) distinguished five strains; Rozendaal (1952) distinguished three.

Transmission by Vectors

Transmissible by more than 10 aphid species in the persistent manner (Kennedy, Day & Eastop, 1962). Myzus persicae seems to be the most efficient vector. All instars can acquire and transmit, but nymphs transmit more efficiently than adults. Acquisition and inoculation feeding periods of 1 day are necessary to obtain high levels of infection. There is a latent period longer than half a day. Virus is retained by the vector for its whole life span. The ability of the aphid to transmit depends on the dose of virus acquired (Day, 1955; MacCarthy, 1954; MacKinnon, 1963). Multiplication of the virus in the aphid has been reported (Stegwee & Ponsen, 1958), but Harrison (1958a) failed to obtain evidence of multiplication.

Transmission through Seed

Probably does not occur.

Transmission by Dodder

Reported for Cuscuta subinclusa (Williams, 1957).

Serology

There are no reports of antisera to potato leaf roll virus having been prepared.

Relationships

In plant protection tests, infection with avirulent strains protects plants from virulent strains (Webb et al., 1952; Harrison, 1958b). In transmission experiments, single M. persicae could acquire and transmit a virulent strain after acquisition and transmission of an avirulent strain. Duffus & Gold (1969) did not detect any serological reaction between potato leaf-roll virus and beet western yellows virus antiserum using the infectivity neutralization and membrane feeding technique.

Stability in Sap

In extracts of aphids and sap of Physalis floridana, the thermal inactivation point (10 min) is about 70°C and dilution end-point about 10-4; longevity in sap is about 4 days at 2°C, and in aphid extracts between 12 and 24 h at 25°C (Murayama & Kojima, 1965; Peters, 1967b). Infectivity can be stabilized by adding reducing agents.

Purification

Two methods have been developed, one to purify the virus from aphids and the other from plant material. Both methods yield small amounts of virus, but more was obtained from plant material.

1. Peters (1967a, 1967b). Extract aphid homogenates in 0.01 M phosphate buffer with an equal volume of chloroform twice at pH 5.0 and twice at pH 7.0. Pool the two pH 7.0 extracts and sediment by high speed centrifugation. Resuspend the pellet in 0.01 M phosphate (pH 7.2) and mix with an equal volume of 2.5 M K2HPO4 - KH2PO4 (pH 7.5), and 0.8 volume of a 1:2 mixture of butoxy-ethanol and ethoxy-ethanol. Extract the virus from the interphase obtained after low speed centrifugation. Clarify the suspension and purify the virus further by centrifugation in sucrose density gradients. Do all steps at 0-4°C.

2. Kojima et al. (1969). Emulsify extracts from frozen Physalis floridana plants with a mixture of chloroform and n-butanol. Centrifuge at high speed, resuspend the pellet in 0.01 M phosphate buffer and emulsify the suspension with fluorocarbon (Daifron S-3). Centrifuge again at high speed and fractionate on a sucrose gradient. Do all steps at 0-4°C.

Properties of Particles

No information.

Particle Structure

Particles are isometric, c. 24 nm in diameter (Fig.3).

Particle Composition

No information.

Relations with Cells and Tissues

The virus seems to be restricted to the phloem, in which virus particles have been observed by electron microscopy (Kojima et al., 1969).

Notes

The virus may be confused with other viruses that are transmitted by aphids in the persistent manner and have host ranges overlapping that of potato leafroll virus (Duffus, 1964; MacKinnon, 1965). Some of these viruses were found contaminating a potato leafroll virus isolate (Peters, 1965, 1967a, 1967b).

References

  1. Day, Aust. J. biol. Sci. 8: 498, 1955.
  2. Duffus, Phytopathology 54: 736, 1964.
  3. Duffus & Gold, Virology 37: 150, 1969.
  4. Harrison, Virology 6: 265, 1958a.
  5. Harrison, Virology 6: 278, 1958b.
  6. Kennedy, Day & Eastop, A conspectus of aphids as vectors of plant viruses, London, Commonwealth Institute of Entomology, 1962.
  7. Kojima, Shikata, Sugawara & Muryama, Virology 39: 162, 1969.
  8. MacCarthy, Phytopathology 44: 167, 1954.
  9. MacKinnon, Virology 20: 281, 1963.
  10. MacKinnon, Can. J. Bot. 43: 509, 1965.
  11. Murayama & Kojima, Ann. phytopath. Soc. Japan 30: 209, 1965.
  12. Natti, Kirkpatrick & Ross, Am. Potato J. 30: 55, 1953.
  13. Peters, Virology 26: 159, 1965.
  14. Peters, Virology 31: 46, 1967a.
  15. Peters, Meded. Fonds Landbouw Export Bureau 45, 100 pp., 1967b.
  16. Peters & Van Loon, Virology 35: 597, 1968.
  17. Quanjer, Meded. LandbHoogesch. Wageningen 6: 41, 1913.
  18. Quanjer, Van der Lek & Oortwijn Botjes, Meded. LandbHoogesch. Wageningen 10: 1, 1916.
  19. Rozendaal, Meded. ned. aig. KeurDienst LandbZaken Aardappelpootg. 8: 94, 1952.
  20. Stegwee & Ponsen, Entomologia exp. appl. 1: 291, 1958.
  21. Webb, Am. Potato J. 32: 173, 1955.
  22. Webb, Larson & Walker, Am. Potato J. 28: 667, 1951.
  23. Williams, Diss. Abstr. 27: 2784, 1957.


Figure 1

Plants of Solanum tuberosum cv. Meerster, (left) infected, (right) healthy. (Photo courtesy A. Rozendaal.)

Figure 2

Physalis floridana, (left) healthy, (right) infected.

Figure 3

Virus particles from a purified preparation, stained with 2% phosphotungstate. Bar represents 100 nm. (Photo courtesy M. Kojima.)