Peanut mottle virus
K. R. Bock
Overseas Development Administration, Crop Virology Project, EAAFRO P.O. Box 30148, Nairobi, Kenya
C. W. Kuhn
Department of Plant Pathology and Plant Genetics, University of Georgia, Athens, Georgia 30602, USA
- Described by Kuhn (1965) and Bock (1973).
- Peanut mild mosaic virus (Rev. appl. Mycol. 29: 397)
- Peanut severe mosaic virus (Rev. appl. Mycol. 29: 397)
- Groundnut mottle virus (Rev. appl. Mycol. 47: 2420)
- A serologically distinct RNA-containing virus of the
potyvirus group with
flexuous filamentous particles c. 740-750 nm long. It has a restricted
experimental host range, is transmitted by inoculation of sap and by several
common species of aphid, is seed-borne in groundnut, and probably occurs wherever
groundnuts are grown.
Causes systemic mottle and necrosis in groundnut (Arachis hypogaea
bean (Phaseolus vulgaris
), soybean (Glycine max
) and pea (Pisum
), the severity of disease being dependent on host cultivar and virus
strain. Economically significant in groundnut in USA (where Kuhn (1965)
a yield loss of 25% in greenhouse tests), and in bean in Australia (Behncken
& McCarthy, 1973
Occurs in south-east USA, East Africa and north-east Australia, and probably
in Japan, West Malaysia, South America (Venezuela) and Europe (Bulgaria).
Host Range and Symptomatology
Although the virus infects several species within the Leguminosae, its host
range outside this family is extremely limited. Readily transmissible by
inoculation of sap.
- Diagnostic species
- Phaseolus vulgaris (French bean). Local necrotic lesions which spread
dendritically along veins (Fig.1). No systemic infection in many cvs. (e.g.
The Prince, Topcrop, Tendergreen). In others (e.g. California Small White,
Gallaroy, Pinto), systemic mottle with limited or severe necrosis (Behncken, 1970;
Behncken & McCarthy, 1973).
- Arachis hypogaea (groundnut). The most commonly occurring and widespread
(mild) strains induce a mild dark-green mottle (Fig.2); leaflet margins are
crinkled with depression of interveinal tissue. For symptoms induced by other
isolates, see Strains.
- Glycine max (soybean). Chlorotic or necrotic local lesions with some
cvs; systemic chlorotic mottle, mild mosaic or mild to severe leaf-curling and
distortion with others (Fig.5).
- Cassia occidentalis. Systemic yellow mottle induced by most strains
(Fig.6), but the severe strain (S) does not infect.
- Nicotiana clevelandii. Chlorotic or necrotic local lesions; systemic
- Chenopodium amaranticolor. Apparently immune (Kuhn, 1965; Behncken,
1970; Sun & Hebert, 1972; Bock, 1973).
- Propagation species
- Cultures are best maintained in Cassia occidentalis or groundnut
(for severe strain). For purification the virus should be propagated in suitable
cvs. of pea, cowpea or bean.
- Assay species
- Phaseolus vulgaris (cv. The Prince, Tendergreen or Topcrop) is a good
local lesion host.
The American mild (type) strain (M-2) (Paguio & Kuhn, 1973a
East African groundnut and soybean isolates, and an Australian isolate from bean
are serologically indistinguishable from each other (K. R. Bock & G. W.
Behncken, unpublished data) and closely resemble each other in the symptoms they
induce in groundnut.
At present there is no evidence for different strains in Africa and Australia.
In USA, however, Paguio & Kuhn
(1973a) have differentiated five serologically indistinguishable variants,
chiefly on symptom expression in groundnut:
M-1 and M-2 (mild mottle); N (necrosis, Fig.3); S (severe mosaic = severe strain
of Sun & Hebert, 1972; Fig.4); and
CLP (chlorotic line pattern, Fig.7). The M-2 strain cross-protects against N, S,
and CLP in groundnut.
Peanut mild mosaic and peanut severe mosaic viruses (Cooper, 1950) are synonymous
with peanut mottle virus M and S strains, respectively (Sun & Hebert, 1972).
Transmission by Vectors
The virus is transmitted in the non-persistent manner by the aphids Aphis
craccivora, A. gossypii, Hyperomyzus lactucae, Myzus persicae
). A. craccivora
can transmit strains M1, M2, S, and CLP but not strain N. However,
both aphids can transmit strain N if it is in a plant simultaneously inoculated
with strain M2 (O. R. Paguio & C. W. Kuhn, unpublished data).
Transmission through Seed
Seed-transmission occurs in groundnut at low rates (0.02-2.0%) but apparently
not in cowpea, soybean, Pisum sativum
, or Cassia obtusifolia
; Paguio & Kuhn, 1973a
; C. W. Kuhn, unpublished data).
Seed-transmission (<1%) has been reported also in bean (Behncken & McCarthy,
). Twenty percent of the groundnut plants developing from pods left in
in pots were infected with virus (Bock, 1973
Transmission by Dodder
The virus is moderately to strongly immunogenic; an antiserum with a tube
precipitin titre of 1/8192 has been obtained (Bock, 1973
Peanut mottle virus does not react with antisera to the following common
: bean common mosaic
, bean yellow mosaic
, cowpea aphid-borne mosaic
, clover yellow vein
, potato Y
, tobacco severe etch
, celery mosaic
and sugarcane mosaic
; Sun & Hebert, 1972
In East Africa, viruses serologically related to peanut mottle have been obtained
from Cassia (K. R. Bock, unpublished data) and Voandzeia (Bock, 1973).
The Venezuelan (Herold & Munz, 1969), Japanese (Inouye, 1969) and European
(Schmidt & Schmelzer, 1966) viruses have not been tested serologically against
antisera to American, East African or Australian isolates, but they closely
resemble peanut mottle virus in host range and symptomatology, properties in
vitro, transmission by aphids and particle morphology.
Groundnut mosaic virus (Ting, Geh & Chuan, 1972), found in West Malaysia,
is probably the same as or closely related to peanut mottle virus. The two viruses
share many properties but particle characteristics and serological reactions have
not been determined for the Malaysian virus.
Stability in Sap
The thermal inactivation point of the East African and Australian isolates is
between 55° and 59°C; that of the American isolates is 60 to 64°C. The
dilution end-point of all isolates is between 10-3
and infectivity is retained at 20°C for 1-2 days (but less than 1 day with the
S strain). Frozen infected leaves retain infectivity for at least 12 wk at
-12°C (Bock, 1973
Two methods appear to be satisfactory.
1. Bock (1973). Homogenize systemically infected cowpea leaves at
pH 8.1 in 0.5 M sodium citrate buffer containing 1%, mercaptoethanol, (1 ml/g tissue), clarify by
treatment with equal volume of chloroform; centrifuge differentially; resuspend in 0.01 M phosphate buffer,
2. Paguio & Kuhn (1973b). Homogenize systemically infected
pea leaves at pH 8 in 0.01 M potassium phosphate buffer, containing 0.01 M DIECA, 0.01 M
sodium bisulphite (2 ml/g tissue), clarify by adding 0.1 vol chloroform and
centrifuging at 10,000 g for 10 min. Precipitate virus by adding
polyethylene glycol (PEG) to 4% and KCl to 0.2 M; centrifuge at low speed and
resuspend pellets in 0.05 M phosphate buffer containing 0.001 M dithiothreitol.
Repeat the PEG-KCl precipitation and follow with rate zonal density-gradient
Properties of ParticlesA260
: 1.24 (Paguio & Kuhn, 1973b
A260(max)/A246 (min): 1.3 (Paguio & Kuhn, 1973b).
Absorbance at 260 nm (1 mg/ml, 1 cm light path): 2.6 (C. W. Kuhn, unpublished
Particles are flexuous filaments (Fig.8
), probably c
. 740-750 nm long
(Sun & Hebert, 1972
; Bock, 1973
; Paguio & Kuhn, 1973b
estimates of length range between 704 nm (Behncken, 1970
) and 812 nm (Herold &
Particle CompositionNucleic acid:
RNA, probably single-stranded, about 6% of the particle
weight (C. W. Kuhn, unpublished data).
Protein: No information.
Relations with Cells and Tissues
Virus particles occur in the cytoplasm singly, or in loosely arranged bundles.
Pinwheel inclusions and plates typical of the potyvirus group
are seen in tissue
sections (Herold & Munz, 1969
Sun & Hebert, 1972
The following viruses important in field-grown groundnut have been described
sufficiently well to permit comparison with peanut mottle virus. Tomato spotted
) is easily differentiated from peanut mottle virus by its
low thermal inactivation point (40-46°C), its instability in sap and its
very wide host range. The two component viruses of groundnut rosette disease
are persistent in Aphis craccivora
(Storey & Ryland, 1955
) has isometric particles and a wide host range; cowpea
mild mottle virus
) has particles 650 nm long and is not
transmitted by aphids.
- Behncken, Aust. J. agric. Res. 21: 465, 1970.
- Behncken & McCarthy, Qd. agric. J. 99: 635, 1973.
- Bock, Ann. appl. Biol. 74: 171, 1973.
- Brunt, CMI/AAB Descriptions of Plant Viruses 140, 4 pp., 1974.
- Cooper, Phytopathology 40: 6, 1950.
- Herold & Munz, Phytopathology 59: 663, 1969.
- Ie, CMI/AAB Descriptions of Plant Viruses 39, 4pp., 1970.
- Inouye, Nogaku Kenkyu 52: 159, 1969.
- Kuhn, Phytopathology 55: 880, 1965.
- Mink, CMI/AAB Descriptions of Plant Viruses 92, 4 pp., 1972.
- Paguio & Kuhn, Phytopathology 63: 976, 1973a.
- Paguio & Kuhn, Phytopathology 63: 720, 1973b.
- Schmidt & Schmelzer, Phytopath. Z. 55: 92, 1966.
- Storey & Ryland, Ann. appl. Biol. 43: 423, 1955.
- Sun & Hebert, Phytopathology 62: 832, 1972.
- Ting, Geh & Chuan, Expl Agric. 8: 355, 1972.
Local lesions induced in Phaseolus vulgaris (cv. Topcrop ) by type
Systemic symptoms induced in groundnut (cv. Argentine) by mild (M-2)
Systemic symptoms induced in groundnut (cv. Argentine) by necrosis (N)
Systemic symptoms induced in groundnut (cv. Argentine) by severe (S)
Systemic symptoms induced in soybean (cv. HLS 541) by East African
Systemic symptoms induced in Cassia occidentalis by East African
Systemic symptoms induced in groundnut (cv. Argentine) by chlorotic line
pattern (CLP) strain.
Virus particles from a purified preparation of an African isolate in
phosphotungstate. Bar represents 200 nm.