Barley yellow dwarf virus
W. F. Rochow
Plant Pathology Dept., Cornell University, Ithaca, N.Y. 14850, USA
Described by Oswald & Houston (1951
- Selected synonyms
- Cereal yellow dwarf virus (Rev. appl. Mycol. 33: 74)
- Hordeumvirus nanescens (Rev. appl. Mycol. 38: 677)
- Oat red leaf virus (Rev. appl. Mycol. 36: 238)
A virus with isometric particles c. 20-24 nm in diameter, transmitted by aphids in
the persistent (circulative) manner, but not by sap inoculation. Apparently confined to the
phloem. Many variants exist that differ in vector specificity, virulence, and serological
properties. Distributed throughout the world, probably more widely than any other virus
Causes stunting and chlorosis of a wide range of monocotyledonous species, including oats,
barley, wheat, and many grasses (Bruehl, 1961
; Rochow, 1961
; Slykhuis, 1967
). Losses may be
great if infection occurs early in the growing season.
Host Range and Symptomatology
About 100 monocotyledonous spp. are known to be susceptible. Such knowledge is limited,
however, by the great variability among virus isolates, by the necessity to use feeding aphids
for inoculation, and by genetic heterogeneity in many grass species. Symptoms are usually less
severe in barley than in oats, and mildest of all in wheat. Some infected grasses develop no
symptoms. Most infected plants are stunted (Fig.1
). Blasting of florets is common, especially
in oats. Leaves may appear water-soaked and develop chlorotic stripes, blotches, or mottle,
starting at the tip. Leaf chlorosis is often accompanied in barley by a brilliant yellow
colour; oats may become red or purple. Some leaves may be serrated. Cool temperatures and
supplementary light are often needed for development of obvious symptoms in the greenhouse.
- Diagnostic species
- Avena sativa cvs. Clintland, Clintland 64 and Blenda (spring oats).
- Avena byzantina cvs. Coast Black and California Red (winter oats).
- Hordeum vulgare cv. Black Hulless (barley).
- Propagation species
- Avena byzantina cv. Coast Black has been used as a source of virus for purification.
- Assay species
- Same as diagnostic species.
Many variants have been identified on the basis of virulence, host range, and vector
specificity. Recent evidence suggests that some of the variants are so different that they
should perhaps be considered as distinct viruses, for not only do they seem serologically
unrelated but their interactions in mixed infections and in cross-protection tests resemble
those of unrelated viruses (Aapola, 1968
). Four isolates (Fig.1
) that have been studied for
some years (Rochow, 1969b
) are as follows:
RMV - Weakly virulent in Coast Black oats, transmitted regularly by
R. maidis, but infrequently by R. padi, M. avenae, and S. graminum.
RPV - Weakly virulent in Coast Black oats, transmitted regularly by
erratically by S. graminum, but rarely by R. maidis and M. avenae.
MAV - Moderately virulent in Coast Black oats, transmitted regularly by
but rarely by R. padi, R. maidis, and S. graminum.
PAV - Strongly virulent in Coast Black oats, transmitted regularly by
and M. avenae, erratically by S. graminum, but rarely by R. maidis.
Three of these virus isolates (MAV, RPV, and PAV) have also been differentiated by
Gill (1969) described an additional vector-specific isolate:
SGV - Weakly virulent in Clintland 64 oats, transmitted regularly by
but rarely if at all by M. avenae, R. padi, or R. maidis.
Transmission by Vectors
Transmissible by about 14 spp. of aphids that feed on cereals and grasses. Some of the most
important vectors are Metopolophium (Acyrthosiphon) dirhodum, Macrosiphum avenae,
Rhopalosiphum maidis, Rhopalosiphum padi
and Schizaphis graminum
. Transmission is
in the persistent (circulative) manner and the virus persists in the vector for 2-3 weeks.
Virus transmission to nymphs does not occur. A latent period can be shown when acquisition
feeding times are shorter than 1 day (Rochow, 1963
), but transmission readily occurs when
acquisition and inoculation feeding times are 1-2 days (Watson & Mulligan, 1960
). Transmission depends greatly on many factors, including aphid species or clone, virus isolate, temperature,
test plant species, and age of source plant (Rochow, 1969a
). The marked specificity
between virus and vector is an important method of identifying variants of the virus.
Transmission is greatly affected by interactions among isolates of the virus (Jedlinski &
Brown, 1965). Studies of mixed infections of two isolates have suggested that vector
specificity is a function of the virus coat protein and that phenotypic mixing between two
isolates can be an important factor in aphid transmission (Rochow, 1970).
Transmission through Seed
Not known to occur.
Transmission by Dodder
Virus has been recovered by aphids feeding on dodder established on infected barley
(Orlob, Arny & Medler, 1961
), and virus has been transmitted from barley to barley by
The virus is strongly immunogenic but, because of its small concentration in plants,
concentrated, partially purified virus preparations must be used in all serological methods
tested so far. Antisera against MAV, PAV, and RPV have been obtained by intramuscular and
intravenous injection of rabbits (Aapola, 1968
). Three serological methods have been useful.
In one the infectivity is neutralized, thereby blocking transmissions by aphids that feed
through membranes on treated virus preparations (Rochow & Ball, 1967
; Rochow, 1970
others involve micro agar double-diffusion and latex agglutination (Aapola, 1968
; Aapola &
All three serological methods show a close relationship between MAV and PAV but suggest
that RPV is different from the other two. The apparent unrelatedness of RPV was confirmed in
cross-protection tests and other in vivo
interactions (Aapola, 1968
relationships with other viruses are not yet known.
Stability in Sap
MAV has been recovered from crude sap (diluted as much as 1/1000) by M. avenae
through membranes on sap containing added sucrose. The thermal inactivation point (10 min) for
RPV and MAV both in crude and in partially purified preparations is between 65 and 70°C
(Heagy & Rochow, 1965
MAV has been purified by chloroform clarification, differential centrifugation, and density
gradient centrifugation (Rochow & Brakke, 1964
). Yields of MAV are usually less than 100
µg/l of juice. Purified preparations of RPV, PAV and RMV have also been obtained by the
same method, but yields of virus are usually less, especially with PAV and RMV. Precipitation
by polyethylene glycol (M. Wt = 6000) (Hebert, 1963)
has shown promise in preliminary tests.
Growth of source plants at temperatures below 20°C and thorough extraction of virus from
tissue are two critical steps in purification.
Properties of Particles
Sedimentation coefficient (s20,w
) is c.
115-118 S for MAV. Other isolates studied
appear to have a similar coefficient.
A260/A280: c. 1.92 (MAV), 1.72 (RPV) (Brakke & Rochow, unpublished data).
Particles are isometric; diameter c.
30 nm in shadowed preparations (Rochow &
24 nm in thin sections of host tissue (Jensen, 1969
), and c.
20 nm in negatively stained virus preparations (Fig.2
). Particles of four isolates appear
), although RPV is less stable than MAV in phosphotungstate at pH 6.85. The
particle may be an octahedron (Israel & Rochow, unpublished).
Relations with Cells and Tissues
Particles appear to be confined to the phloem (Jensen, 1969
Because symptoms of barley yellow dwarf in the field can easily be confused with those
caused by other factors, recovery of virus by aphids is an indispensable part of diagnosis.
The disease especially resembles aster yellows in small grains (Banttari, 1965
; Gill, Westdal
& Richardson, 1969
Much effort has been directed toward breeding varieties tolerant of the virus; use of such
varieties is an important way of controlling barley yellow dwarf.
Studies on barley yellow dwarf virus have been facilitated by the relative ease with which
two bioassay techniques can be applied: injection of virus into aphids and acquisition of
virus by aphids feeding through membranes.
- Aapola, Ph.D. Thesis, Cornell Univ., 1968.
- Aapola & Rochow, Phytopathology 58: 398, 1968.
- Banttari, Phytopathology 55: 838, 1965.
- Bruehl, Monogr. Am. phytopath. Soc. 1, 1961.
- Gill, Can. J. Bot. 47: 1277, 1969.
- Gill, Westdal & Richardson, Phytopathology 59: 527, 1969.
- Hebert, Phytopathology 53: 362, 1963.
- Heagy & Rochow, Phytopathology 55: 809, 1965.
- Jedlinski & Brown, Virology 26: 613, 1965.
- Jensen, Virology 38: 83, 1969.
- Orlob, Arny & Medler, Phytopathology 51: 515, 1961.
- Oswald & Houston, Pl. Dis. Reptr 35: 471, 1951.
- Oswald & Houston, Phytopathology 43: 128, 1953a.
- Oswald & Houston, Phytopathology 43: 309, 1953b.
- Rochow, Adv. Agron. 13: 217, 1961.
- Rochow, Phytopathology 53: 355, 1963.
- Rochow, in Viruses, Vectors, & Vegetation, Ed. K. Maramorosch, Interscience, New York, p.175, 1969a.
- Rochow, Phytopathology 59: 1580, 1969b.
- Rochow, Science, N.Y. 167: 875, 1970.
- Rochow & Ball, Virology 33: 359, 1967.
- Rochow & Brakke, Virology 24: 310, 1964.
- Slykhuis, Rev. appl. Mycol. 46: 401, 1967.
- Timian, Phytopathology 54: 910, 1964.
- Watson & Mulligan, Ann. appl. Biol. 48: 711, 1960.
Symptoms caused by four isolates of barley yellow dwarf virus in single plants of Coast
Black oats 56 days after inoculation by Rhopalosiphum maidis (RMV), R. padi
(RPV and PAV) and Macrosiphum avenue (MAV). H is a comparable healthy plant
originally infested with virus-free aphids as a control. Photograph by H. H. Lyon, Jr. (From
Phytopathology 59: 1582, 1969).
Electron micrographs by H. W. Israel of preparations of each of the four virus isolates.
Those of RMV and MAV were stained with vanadatomolybdate; those of RPV and PAV were stained
with potassium phosphotungstate. Bar represents 20 nm.