60
June 1971
Family: Betaflexiviridae
Genus: Carlavirus
Species: Potato virus S
Acronym: PVS


Potato virus S

C. Wetter
Botanisches Institut, Universität des Saarlandes, 66 Saarbrücken, Germany

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 De Bruyn Ouboter (1952) and Rozendaal (1952).

A virus with straight to slightly curved filamentous particles c. 650 x 12 nm. It is sap-transmissible to a limited range of species. Some isolates aphid-transmissible. World-wide distribution.

Main Diseases

Causes few or no symptoms and is carried by many cultivated potato varieties. Decreases yield of potato tubers by up to 20%.

Geographical Distribution

World-wide in cultivated varieties of potato.

Host Range and Symptomatology

Host range is narrow. Susceptible species belong mainly to the families Solanaceae and Chenopodiaceae. Transmissible by inoculation with sap from young fully expanded potato leaves but not from older leaves. Infected potato leaves may show slight chlorosis, roughness of the surface and undulation of the margin (Fig.1).

Diagnostic species
Chenopodium amaranticolor, C. quinoa, C. album. Chlorotic local lesions 1-2 mm in diameter about 20 days after inoculation; lesions on old yellow leaves are surrounded by a green halo. Not systemic (Fig.3).

Solanum rostratum. Numerous small necrotic local lesions about 20 days after inoculation. Systemically infected leaves show similar symptoms (Fig.4).

Nicotiana debneyi. No symptoms in the inoculated leaves. Systemically infected leaves show vein-clearing and mottling, becoming necrotic (Fig.2).

Cyamopsis tetragonoloba (guar). Small brown necrotic local lesions on cotyledons after about 10 days. Not systemic.

Propagation species
Potato varieties. Nicotiana clevelandii (M. Hollings, pers. comm.).

Assay species
Chenopodium amaranticolor, C. quinoa, C. album.

Strains

There are no well defined strains, only minor variants. De Bokx (1968) differentiated isolates by their rate of translocation within the potato plant.

Transmission by Vectors

Isolates may differ in their transmissibility by Myzus persicae. An isolate from US seedling 41956 could not be transmitted under conditions in which the related potato virus M was transmitted (Wetter & Völk, 1960). Some other isolates were transmitted by Myzus persicae (Bode & Weideman, 1970).

Transmission through Seed

Seeds produced by systemically infected Solanum demissum plants gave healthy seedlings (Wetter, unpubl.).

Transmission by Dodder

No reports.

Serology

Antisera with titres up to 1/65,000 were obtained by primary intravenous injections of partially purified virus preparations followed by intramuscular injections with antigen mixed with Freund’s complete or incomplete adjuvant (Wetter, 1960). The precipitate in precipitin tube tests is flagellar. Several kinds of test have been used in diagnosis of infection in potato: the microprecipitin (Van Slogteren, 1955), bentonite flocculation (Kahn et al., 1967), and latex (Bercks, 1967) tests. For comparative studies with related viruses double diffusion tests in gels have been employed (Wetter, 1967). Serological tests are the best way of diagnosing the virus.

Relationships

Potato virus S is distantly serologically related to the following viruses which together form the potato virus S group (Brandes & Wetter, 1959, 1963): carnation latent (Kassanis, 1955, 1956), potato M (Bagnall, Larson & Walker, 1956; Bagnall, Wetter & Larson, 1959), chrysanthemum B (Hakkaart, Van Slogteren & De Vos, 1962), passiflora latent (Brandes & Wetter, 1963), cactus 2 (Brandes & Wetter, 1963) and red clover vein mosaic (Wetter, 1967). Other viruses which have similar particles and are possibly related include freesia mosaic, hop mosaic and poplar mosaic (Brandes, 1964).

Stability in Sap

Thermal inactivation point is 55-60°C, dilution end-point is 10-2-10-3 and infectivity is retained at 20°C for 3-4 days.

Purification

Wetter (1960). Extract sap from infected potato leaves and add ascorbic acid to 0.2% (w/v) and sodium sulphite to 0.2% (w/v). Filter, and shake filtrate with an equal volume of ether. Centrifuge, and shake clarified aqueous phase with an equal volume of carbon tetrachloride. Sediment and clarify by two cycles of high and low speed centrifugation, resuspending the pellets in 0.01 M phosphate buffer. Density gradient centrifugation can be used to free the partially purified virus from host material.

Properties of Particles

No reports.

Particle Structure

Particles are straight, sometimes curved, filaments with modal length of c. 650 x 12 nm (Fig.5) (Wetter & Brandes, 1956; De Bokx, 1969).

Particle Composition

No reports.

Relations with Cells and Tissues

No reports.

Notes

Potato virus S is found in some potato varieties together with strains of the aphid- transmissible and serologically related potato virus M. Potato virus S may be obtained from the mixture by inoculating Nicotiana debneyi which is systemically invaded by potato virus S, whereas potato virus M remains localized in the inoculated leaves.

References

  1. Bagnall, Larson & Walker, Res. Bull. agric. Exp. Stn Univ. Wis. 198, 45 pp., 1956.
  2. Bagnall, Wetter & Larson, Phytopathology 49: 435, 1959.
  3. Bercks, Phytopath. Z. 58: 1, 1967.
  4. Bode & Weideman, Proc. 4th trienn. Conf. Eur. Ass. Potato Res., Brest, 1969: 224, 1970.
  5. Brandes, Mitt. biol. BundAnst. Ld- u. Forstw. 110, 130 pp., 1964.
  6. Brandes & Wetter, Virology 8: 99, 1959.
  7. Brandes & Wetter, Phytopath. Z. 49: 61, 1963.
  8. De Bokx, Meded. Rijksfac. LandbWetensch. Gent 33: 1179, 1968.
  9. De Bokx, Neth. J. Pl. Path. 75: 144, 1969.
  10. De Bruyn Ouboter, Proc. 1st Conf. Potato Virus Diseases, Lisse- Wageningen, 1951: 83, 1952.
  11. Hakkaart, Van Slogteren & De Vos, Tijdschr. PlZiekt. 63: 126, 1962.
  12. Kahn, Scott, Bozicevich & Vincent, Phytopathology 57: 61, 1967.
  13. Kassanis, Ann. appl. Biol. 43: 103, 1955.
  14. Kassanis, J. gen. Microbiol. 15: 620, 1956.
  15. Rozendaal, Meded. ned. alg. KeurDienst LandbZaken Aardappelpootg. 8: 94, 1952.
  16. Van Slogteren, Proc. 2nd Conf. Potato Virus Diseases, Lisse-Wageningen, 1954: 51, 1955.
  17. Wetter, Arch. Mikrobiol. 37: 278, 1960.
  18. Wetter, Z. Naturf. B 22: 1008, 1967.
  19. Wetter & Brandes, Phytopath. Z. 26: 81, 1956.
  20. Wetter & Völk, Eur. Potato J. 3: 158, 1960.

Acknowledgements

The support of the ‘Deutsche Forschungsgemeinschaft’ is gratefully acknowledged.

Photographs: Figs 3 and 4 courtesy of Dr M. Vulic; Fig.5 courtesy of the late Dr J. Brandes.


Figure 1

Solanum demissum x S. tuberosum cv. Aquila (=A6 hybrid). (Right) healthy plant, (left) systematically infected plant with rough leaf surface and undulation of leaf margins.

Figure 2

Systematically infected leaves of Nicotiana debneyi.

Figure 3

Inoculated leaf of Chenopodium amaranticolor, showing local lesions.

Figure 4

Systematically infected leaf of Solanum rostratum, showing necrotic lesions.

Figure 5

Virus particles from a leaf dip preparation. Bar represents 400 nm.