Agropyron mosaic virus
J. T. Slykhuis
Ottawa Research Station, Canada Department of Agriculture, Ottawa, Ontario, Canada
First reported by McKinney (1937).
- Agropyron green mosaic virus (Rev. appl. Mycol. 24: 136)
- Agropyron streak mosaic virus (Rev. appl. Mycol. 33: 285)
- Agropyron yellow mosaic virus (Rev. appl. Mycol. 24: 136)
- Couch grass streak mosaic virus (Rev. appl. Mycol. 36: 303)
- Wheat virus 2 (McKinney, 1937)
- Marmor agropyri (Rev. appl. Mycol. 24: 136)
A virus with filamentous particles c. 717 nm long and 15 nm in diameter infecting only
species of Gramineae. It has been found naturally in Agropyron repens and wheat. It is
transmitted by an eriophyid mite, and by rubbing leaves with infective sap.
Causes light green to yellow mosaic in Agropyron repens
) and wheat. A strain
found in Ontario caused a yellow mosaic, moderate stunting and loss in yield of wheat.
Host Range and Symptomatology
Only species in the Gramineae have been reported systemically infected, generally developing light
green to yellow mosaic on the leaves. In North America, wheat (Triticum aestivum
) was reported highly susceptible and Agropyron repens, A. elongatum
were moderately susceptible. Less susceptible species included Elymus canadensis,
E. virginicus, Hordeum vulgare
cvs. Brant and Husky, Lolium multiflorum
cv. S22 and
(Slykhuis & Bell, 1966
Additional hosts reported in Europe include
and Hordeum murinum
) and Aegilops aegilopoides, Ae.
crassa, Agropyron acutum, A. caninum, A. elmeri, A. pungens, A. sibiricum, A. villosum, Apera
spicaventi, Bromus racemosus, B. secalinus, Cynosurus cristatus, Deyeuxia sylvatica, Hordeum maritimum,
Lamarkia aurea, Panicum crus-galli, Phalaris paradoxa, Poa pratensis, Setaria glauca, S. viridis
and Triticum bicorne
also reported that the virus produced
local lesions in a dicotyledonous species, Chenopodium quinoa
- Systemic mosaic symptoms develop in wheat, Lolium multiflorum cv. S22, rye and some
cultivars of barley; all these hosts are also susceptible to
wheat streak mosaic virus,
ryegrass mosaic viruses.
Agropyron mosaic virus is differentiated from these viruses, which
have similar particles, by its ability to infect Agropyron repens but not oats.
- Agropyron repens is the best host for maintaining the virus, but a number of cultivars of
wheat, e.g. Kent, are more suitable as sources of virus for purification.
- Assays based on proportion of plants infected have been done using Kent wheat. Other cultivars
of wheat should also be suitable.
Mild (green) and virulent (yellow) strains have been reported in the USA
) and in Canada
The mild strain had little apparent effect on wheat, but the virulent
strain caused significant stunting and loss of yield.
Transmission by Vectors
Eriophyid mites were usually present on Agropyron repens
or wheat found infected with
agropyron mosaic virus in the field, but mites transferred singly to test plants did not transmit
the virus. However, a low percentage of wheat test plants became infected when colonies of the
mite Abacarus hystrix
) were reared on Agropyron repens
or wheat infected
with the virus and the mites then blown to the test plants by a fan. No transmission occurred in
similar tests with Aculus mckenziei
or Aceria tulipae
Various insects (including aphids) failed to transmit the virus
Transmission through Seed
Transmission by Dodder
Antisera with precipitin titres of 1/1280 were prepared by injecting rabbits intra-muscularly
with partially purified preparations of a yellow strain of the virus emulsified with Freund's
incomplete adjuvant. The precipitin titre of clarified sap from infected Agropyron repens
was about 1/16, and from infected wheat, 1/32
(Slykhuis & Bell, 1966
The mild and virulent strains tested in Canada were indistinguishable from each other in
serological tube and micro-precipitin tests.
Staples & Brakke (1963)
suggested that agropyron
mosaic virus was a mild strain of
wheat streak mosaic virus
Slykhuis & Bell (1966)
that although the particles of agropyron mosaic virus resembled those of hordeum mosaic and wheat
streak mosaic viruses, they were slightly longer (717 nm as compared with 700 nm and 683 nm) and
appeared more flexuous in leaf dip preparations. The viruses had some antigens in common, but
were considered to be distantly related serotypes rather than closely related strains.
found no serological relationship using low-titred antisera. Despite similarities in
particle morphology and vector transmission, there is no evidence of serological relationship
between any of these viruses and
ryegrass mosaic virus
(Slykhuis & Paliwal, 1972
In plant protection tests, agropyron mosaic virus did not protect wheat against wheat streak mosaic
virus but gave partial protection against hordeum mosaic virus.
Stability in Sap
In wheat sap, the thermal inactivation point (10 min) is about 50°C, dilution end-point
, and infectivity is retained at 20°C for 2-4 days.
The following method was used to partially purify the virus for the preparation of antigen
(Slykhuis & Bell, 1966
Inoculate wheat at the 3-leaf stage, harvest leaves 12-14 days later, freeze overnight at
-20°C, thaw, grind at 4°C, express juice, acidify at pH 4.9 by adding 0.5 N HCl while
stirring, allow to stand at 4°C for 30 min, centrifuge at 8000 g for 10 min,
dilute 1:1 with 0.5 M neutral phosphate-buffered saline, centrifuge at 8000 g for
10 min, sediment and clarify by high and low speed centrifugation, resuspend pellets obtained at
high speed in neutral phosphate-buffered saline. Work at 4°C.
Properties of Particles
Sedimentation rate the same as for wheat streak mosaic
virus (Staples & Brakke, 1963) which
has a sedimentation coefficient (s20, w
) about 165 S
Particles are flexuous filaments
) about 15 nm in diameter and with a modal length of
about 717 nm (Bremer, 1964
Slykhuis & Bell, 1966
Relations with Cells and Tissues
Pinwheel inclusions, and bundles of virus particles
), are present in the parenchyma
cells of infected wheat (W. B. Langenberg, unpublished).
NotesBrome mosaic virus
might be confused with agropyron mosaic virus because it is also readily
transmitted to Agropyron repens
in which it occurs in Russia
) and Jugoslavia
(Milicic et al., 1966
It is readily distinguished because it produces severe effects on a
much wider range of hosts, including Zea mays
and oats, and induces local lesions in some
dicotyledonous plants including Chenopodium hybridum
and Datura stramonium
it has much higher thermal inactivation and dilution end-points, and has isometric particles
In wheat, agropyron mosaic virus can be confused with
wheat streak mosaic or hordeum mosaic viruses.
The symptoms can be differentiated by careful comparison under controlled conditions. Agropyron
mosaic is readily distinguished from these viruses by its transmissibility to Agropyron repens
but not to oats. Also it is not transmitted by Aceria tulipae, the efficient vector of wheat
streak mosaic virus.
Agropyron mosaic virus is widely distributed in northern USA, southern Canada, and some areas of
northern Europe. Its occurrence in wheat appears to depend on nearness to infected Agropyron
repens. It occurs together with wheat streak mosaic virus in some areas, but the two viruses
seem to spread entirely independently. Normally the symptoms in wheat are very mild and the
incidence very low, but some strains in Ontario, Canada, can cause severe stunting and loss of
yield. If such strains were to become prevalent and to spread rapidly in wheat they could cause
severe losses. The possibility of this has been demonstrated in experimental plots in which high
rates of spread occurred in immature wheat during the summer
- Brakke, CMI/AAB Descriptions of Plant Viruses 48, 4 pp., 1971.
- Bancroft, CMI/AAB Descriptions of Plant Viruses 3, 3 pp., 1970.
- Bremer, Ann. Agric. Fenn. 3: 324, 1964.
- Keifer, Bull. Calif. Insect Surv. 2, 123 pp., 1952.
- Larina, Byull. vses. nauchno-issled. Inst. Zashch. Rast. 3: 60, 1968.
- McKinney, Circ. U.S. Dep. Agric. 442, 23 pp., 1937.
- McKinney, J. Wash. Acad. Sci. 34: 322, 1944.
- Milicic et al., Zast. Bilja 17: 213, 1966.
- Schumann, Phytopath. Z. 64: 258, 1969.
- Shepard, Pl. Dis. Reptr 52: 139, 1968.
- Slykhuis, Tech. Bull. S. Dak. agric. Exp. Stn 11, 29 pp., 1952.
- Slykhuis, Can. J. Bot. 40: 1439, 1962.
- Slykhuis, Phytopathology 59: 29, 1969.
- Slykhuis & Bell, Can. J. Bot. 44: 1191, 1966.
- Slykhuis & Paliwal, CMI/AAB Descriptions of Plant Viruses 86, 4 pp., 1972.
- Staples & Brakke, Phytopathology 53: 969, 1963.
Figs 3, 4 & 5 courtesy W. G. Langenberg, United States Department of Agriculture, Lincoln,
Leaves of Agropyron repens showing various symptoms of agropyron mosaic. The leaf
on the left is from a healthy plant.
The mite vector, Abacarus hystrix, dorsal and lateral views. The adult mites are
about 250 µm long (Keifer, 1952).
Negatively stained particles of agropyron mosaic virus. Bar represents 500 nm.
Pinwheel inclusions in section of a parenchyma cell from infected Cheyenne wheat. Bar
represents 500 nm.
Bundles of virus particles in an infected wheat leaf cell. Bar represents 500 nm.