Cherry rasp leaf virus
Agriculture Canada Research Station, Vancouver, B.C., Canada
A. J. Hansen
Agriculture Canada Research Station, Summerland, B.C., Canada
- Described by Bodine & Newton (1942).
- Flat apple virus (Rev. appl. Mycol. 46, 2772).
- An RNA-containing virus with isometric particles about 30 nm in diameter
occurring in western North America. It is readily transmitted by inoculation
of sap and has a wide host range, including both herbaceous and woody plants.
The virus is transmitted by the nematode Xiphinema americanum. It is
seed-transmitted in some herbaceous hosts.
The virus causes two diseases, cherry rasp leaf and flat apple. It infects
cherry (Prunus avium
and P. mahaleb
) and peach (P. persica
but does not usually become fully systemic. Causes rasp-like enations on the
underside of cherry leaves (Fig.1
), small enations, stunted growth and shortened
internodes in peach, and a general decline in cherry and peach. Affected cherry
branches become highly frost-sensitive (Bodine, Blodgett & Lott, 1951
Hansen et al., 1974
; Wagnon et al., 1968
). Also sometimes causes
enations on apple leaves (Lott & Keane, 1960
) and flattened apple fruits on
some cultivars (Parish & Cheney, 1974
). The virus does not induce symptoms
in naturally-infected balsamroot (Balsamorhiza sagittata
) and plantain (Plantago major
North America, in the foothills and west of the Rocky Mountains, from
Colorado, Utah and California to southern British Columbia.
Host Range and Symptomatology
Natural infection has been found in native balsam-root, in dandelion and
plantain under orchard trees, in scattered trees or small groups of cherry and
peach, and in several apple orchards in Washington State, USA. The virus
infected 22 out of 24 commonly-used herbaceous plants. Symptoms were generally
mild and often absent. Isolates differ in the severity of symptoms they induce,
but not in host range.
- Diagnostic species
- Cucumis sativus (cucumber). Faint chlorotic primary lesions in
cotyledons; fine systemic mottle (Fig.2).
- Cyamopsis tetragonoloba (guar). Brown necrotic lesions after 4
(summer) to 14 (winter) days in inoculated cotyledons; no systemic infection.
- Chenopodium quinoa. A fine mottle and vein clearing on the third or
fourth leaf above the inoculated leaf (Fig.3). Wilting of axillary shoots
(under winter greenhouse conditions only).
- C. amaranticolor. Systemic mottle about 7 days after inoculation
- Vigna sinensis (cowpea), Physalis floridana and Sesbania
exalta usually display lesions in inoculated leaves but are unreliable
under unfavourable greenhouse conditions (Hansen et al., 1974).
- Assay species
- Cucumis sativus is a reliable local lesion host. Cyamopsis tetragonoloba may also be useful.
- Propagation species
- C. quinoa, Cucumis sativus (cucumber).
Minor differences between strains were observed in symptom severity on
herbaceous hosts and in lesion type on guar (Hansen et al., 1974
Transmission by Vectors
Transmitted by the nematode Xiphinema americanum
from Chenopodium amaranticolor
and C. quinoa
(Nyland et al., 1969
). Transmitted to cucumber bait plants and mazzard
cherry seedlings which received viruliferous X. americanum
orchard and nursery trees (Hansen et al., 1974
Transmission through Seed
10-20% of seeds from infected Chenopodium quinoa
plants gave rise to infected plants. Seeds from infected parts
of cherry trees did not germinate. Virus can be detected in pollen from infected
cherry trees by mechanical transmission tests (Wagnon et al., 1968
Transmission by Dodder
The virus is moderately immunogenic-antisera with titres of 1/640 are
readily obtained. Antisera prepared by intravenous and intramuscular injections
give a single band of precipitate in gel-diffusion tests. Agar gel tests on
microscope slides are recommended. Virus can be detected serologically in crude
sap extracted from inoculated cucumber cotyledons.
The isolates that were studied were serologically identical. In many of its
properties it resembles nepoviruses
, tomato ringspot
, peach rosette mosaic
, raspberry ringspot
, tomato black ring
) but it is unrelated to them serologically (Hansen et al., 1974
and its protein components are anomalous in size.
Stability in Sap
In Cucumis sativus
sap, the virus loses infectivity after 10 min at
about 58°C or 7 days at 4°C. Dilution end-point is c
(Stace-Smith & Hansen, 1976
The virus is relatively unstable and is degraded by purification procedures
commonly used with nepoviruses
. Virus purifications have been attempted from
infected cucumber, C. quinoa
and N. clevelandii
and, of these,
cucumber is the preferred source. The following method has given yields of
10 mg/kg of infected tissue: homogenize tissue in cold 0.5 M borate, 0.05 M EDTA
buffer, containing 0.02 M mercaptoethanol and adjusted to pH 6.5, 2 ml/g of
tissue. Squeeze through muslin and adjust to pH 6.5 with citric acid. Centrifuge
at low speed, add granular ammonium sulphate, 15 g/100 ml, to supernatant fluid,
and stir overnight. Centrifuge at low speed, retaining supernatant fluid, and
follow with high speed centrifugation, resuspending pellet in 0.05 M borate
buffer, pH 6.5. The resuspended material may be further purified by density
gradient centrifugation (Stace-Smith & Hansen, 1976
Properties of Particles
Purified preparations contain three classes of particles, empty protein
shells without RNA (T) sedimenting at 56 S and two nucleoproteins (M
and B) sedimenting at 96 and 128 S (Stace-Smith & Hansen, 1976
Isometric, about 30 nm in diameter, usually hexagonal in outline
- Nucleic acid: RNA, single-stranded. Combined M and B components
contain two RNA species with M. Wt c. 2.0 x 106and 1.5 x 106.
- Protein: Particles contain two kinds of polypeptide molecules
of M. Wt 24,000 and 22,500 (Stace-Smith & Hansen, 1976).
Relations with Cells and Tissues
In systemically infected cucumber and C. quinoa
, rows of virus particles
enclosed within a tubular structure are found within the cytoplasm of
parenchyma cells (Fig.6
). Particles are also frequently found within the
plasmodesmata (Stace-Smith & Hansen, 1976
The virus occurs in a wide geographical area but primary outbreaks are
usually limited to one or very few trees. Secondary spread is generally slow,
due to the slow lateral movement of the nematode vector. However, in older
cherry-growing areas, rasp leaf infection can be as high as 38% (Luepschen
et al., 1974
). Cherry or apple trees planted on the site of
previously-infected trees often become infected (Wagnon et al., 1968
Parish & Cheney, 1974
). Cherry rasp leaf is unrelated to Eola rasp leaf
and other cherry diseases characterized by development of leaf enations.
- Bodine & Newton, Phytopathology 32: 333, 1942.
- Bodine, Blodgett & Lott, Handb. U.S. Dept. Agric. 10: 71-80, 1951.
- Hansen, Nyland, McElroy & Stace-Smith, Phytopathology 64: 721, 1974.
- Lott & Keane, Pl. Dis. Reptr 44: 634, 1960.
- Luepschen, Harder, Rohrback & Sisson, Pl. Dis. Reptr 58: 26, 1974.
- Nyland, Lownsbery, Lowe & Mitchell, Phytopathology 59: 1111, 1969.
- Parish & Cheney, Proc. Am. phytopath. Soc. 1: 52, 1974.
- Stace-Smith & Hansen, Acta Hort. 67: 193, 1976.
- Wagnon, Traylor, Williams & Weiner, Pl. Dis. Reptr 52: 618, 1968.
Leaf enation symptoms in sweet cherry.
Local and systemic symptoms in Cucumis sativus.
Systemic symptoms in Chenopodium quinoa.
Systemic symptoms in Chenopodium amaranticolor.
Virus particles from a purified preparation stained with uranyl
acetate. Bar represents 100 nm.
Ultrathin section of leaf parenchyma cell of infected C.
quinoa, showing tubules containing virus-like particles. Bar represents 100 nm.