Black raspberry latent virus
R. M. Lister
Dept. of Botany and Plant Pathology, Purdue University, Lafayette, lndiana, USA
R. H. Converse
USDA ARS Plant Science Research Division, Dept. Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
Converse & Lister (1969,
- New Logan-64 virus (Rev. appl. Mycol. 46: 3311n)
A virus with isometric particles about 26 nm in diameter, which occurs with no
apparent symptoms in black raspberry (Rubus occidentalis L.) cultivars in the
eastern USA, and is transmissible by sap-inoculation to a fairly wide range of
herbaceous hosts. It has no known vectors, but in black raspberry is transmitted by
pollen to pollinated plants and through seed.
The virus may be obtained from symptomless black raspberry plants, and is not
associated with any specific disease syndrome in raspberry. It has not been reintroduced
into healthy raspberry plants for observation of growth or yield effects.
In the eastern USA the virus is probably common in cultivated black raspberry
though rare in red raspberry. It was obtained from Thornless Youngberry (a Rubus
hybrid) collected in western Canada (R. M. Lister, unpublished), but is not
Host Range and Symptomatology
Experimental host range is fairly wide; about 30 species in 8 dicotyledonous
families have been infected by sap-inoculation. Many hosts produce only mild
symptoms or none.
- Chenopodium quinoa. Local vein chlorosis in inoculated leaves after 2-3 days,
followed by irregularly-shaped spreading necrotic and chlorotic lesions, and severe
systemic chlorosis, necrosis and distortion of shoot tips
infected leaves may be produced later.
- Nicotiana tabacum cvs. White Burley and Turkish. Local chlorotic and
necrotic ringspots and line patterns
(Fig.2); virus is recoverable from symptomless
- Cucumis sativus cv. National Pickling. Chlorotic lesions in inoculated
cotyledons, with severe systemic mottling, distortion and dwarfing
- Phaseolus vulgaris cvs. The Prince and Bountiful. No symptoms in inoculated
leaves. Irregular systemic red-brown veinal necrosis, especially visible on the
underside of leaves; also browning and reddening of nodes.
- Gomphrena globosa. Occasional small red rings and spots.
- Chenopodium quinoa is the best source plant for bulk propagation; Cucumis
sativus, though unproductive, is useful as a source of inoculum. Gomphrena
globosa is suitable for maintaining cultures.
- No reliable local lesion hosts are known. Some Chenopodium spp. give
- C. quinoa is the best systemic assay species.
No major variants have been distinguished. The isolate described in detail by
Converse & Lister (1969)
was from black raspberry, Rubus occidentalis,
New Logan, collected in the eastern USA
(Converse, Lister & Cadman, 1966
Transmission by Vectors
No aerial or soil-living vector is known. Not transmitted experimentally by
under conditions in which this vector transmitted
raspberry mosaic viruses. In black raspberry the virus is transmitted by pollen to
Transmission through Seed
Experimentally seed-transmitted through about 10% of open-pollinated seed of
black raspberry cultivars New Logan and Cumberland. Seed-transmission not tested
in other hosts.
Transmission by Dodder
The virus is poorly immunogenic. Antisera obtained from rabbits given various
schedules of intramuscular and intravenous injections of untreated or aldehyde-fixed
virus reacted specifically only at dilutions less than 1/8.
Lacking good antisera, testing for possible relationships between this virus
and others has been based on one-way serological tests, and cross-protection tests
(Converse & Lister, 1969
Serologically, the virus is unrelated to the following
cherry rugose mosaic
strawberry latent ringspot,
sweet cherry narrow leaf,
tomato black ring
and tobacco streak
Barnett & Murant (1970)
found no serological relationship
raspberry bushy dwarf virus
Cross-protection tests suggest no relationship to
prunus necrotic ringspot
tobacco streak viruses.
Stability in Sap
In Chenopodium quinoa
sap (1:1 w/v, in 0.1 M phosphate buffer at pH 7),
thermal inactivation point is 46-49°C, dilution end-point is up to 10-4
and longevity in vitro
is a few hours at 20°C or 3-5 days at 4°C.
Extracts made at pH 5 have lower infectivity than those made at pH 8, but it
persists longer - up to 23 days at 4°C. Freezing infected leaves or sap
drastically lowers infectivity. Reducing agents only slightly increase retention
of infectivity; therefore oxidation seems to be only a minor factor in affecting
The best method involves clarifying C. quinoa
extracts by acidification.
Extraction at pH 6 gives higher yields than extraction at pH 5 or 7, but yields are
low at best (up to 0.5 mg/100 g leaf). Component ratios (see below) are influenced
by the pH of extraction.
Blend infected leaves (1:1.5 w/v) with acetate (0.2 M) or phosphate (0.1 M) buffer
at pH 6, containing 0.1 M sodium diethyldithiocarbamate and 0.2 M sodium
thioglycollate. Squeeze through cheesecloth and adjust pH to 5 with acetic acid.
Readjust to pH 6 after 1 hr and leave overnight. Centrifuge at low speed, and
then subject the straw-coloured supernatant fluid to 2 cycles of differential
centrifugation, resuspending the high-speed pellets in 0.1 M pH 5 acetate buffer.
Concentration by precipitation with 10% polyethylene glycol (av. M. Wt
6000-7500) can be substituted for the first cycle of differential centrifugation.
Further purification can be obtained by sucrose rate-zonal density gradient
Do all steps at 4°C. Purified virus is degraded by brisk agitation.
Properties of Particles
Three nucleoprotein components occur (top, middle and bottom) with respective
values of 81, 89 and 98 S at pH 5, or 78, 88 and
93 S at pH 7 (not extrapolated to infinite dilution). Only the bottom
component particles appear to be infective, and the role of the others is unknown.
Stained in phosphotungstate at pH 5, or after pretreatment
at pH 7 with 1% glutaraldehyde
(Lister & Cathro, 1967
), the particles are roughly
isometric, about 26 nm in diameter. Size and shape is rather variable, possibly
because of distortion
Relations with Cells and Tissues
Details unknown: exposure of infected black
raspberry plants to a constant temperature of 37°C for 16 days failed to eliminate
In the absence of good antisera and definitive symptoms in its natural
host, the routine differential diagnosis of the virus is unsatisfactory. Production
of systemic necrosis in C. quinoa
by a virus from raspberry is not presumptive
evidence for infection by black raspberry latent virus because a strain of
tobacco streak virus
is common in some Rubus
cultivars (R. H. Converse, in press).
Serological tests are needed to distinguish black raspberry latent virus from other
viruses with similar herbaceous host ranges and symptomatology.
- Barnett & Murant, Ann. appl. Biol. 65: 435, 1970.
- Converse, Lister & Cadman, Rep. Scott. hort. Res. Inst. 1965: 51, 1966.
- Converse, Phytopathology 57: 97, 1967.
- Lister & Cathro, Rep. Scott. hort. Res. Inst. 1966: 63, 1967.
- Converse & Lister, Phytopathology 59: 325, 1969.
- Converse & Lister, in Virus diseases of small fruits and grapevines, Univ. Calif Div. Agr. Sci., Berkeley: 151, 1970.
Chenopodium quinoa, showing systemic necrosis.
Nicotiana tabacum cv. Turkish with ringspots on inoculated leaves.
Cucumis sativus cv. National Pickling with mottling on a systemically
A selected field from an unfractionated virus preparation, negatively
stained with phosphotungstate (pH 7) after pretreatment with glutaraldehyde. Note
variations in apparent particle shape, presumably due to distortion. Some particles
appear to be disintegrating. Bar represents 100 nm (photo by C. E. Bracker).