Agropyron mosaic virus (Agropyron mosaic virus)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- List of Symptoms/Signs
- Air Temperature
- Means of Movement and Dispersal
- Seedborne Aspects
- Vectors and Intermediate Hosts
- Impact Summary
- Impact: Economic
- Risk and Impact Factors
- Similarities to Other Species/Conditions
- Prevention and Control
- Gaps in Knowledge/Research Needs
- Links to Websites
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Agropyron mosaic virus
Preferred Common Name
- Agropyron mosaic virus
Other Scientific Names
- Agropyron mosaic rymovirus
- Agropyron repens mosaic virus
- agropyron streak mosaic virus
- couch grass streak mosaic virus
- Marmor agropyri
International Common Names
- English: Agropyron green mosaic virus; Agropyron yellow mosaic virus; Wheat virus 2
- Agropyron mosaic mild isolate
- Agropyron mosaic PV101 isolate
- Agropyron mosaic PV75 severe isolate
Summary of InvasivenessTop of page
AgMV has been reported in North America and Europe and is not considered a major pathogen on wheat, although it has pathogenic potential if present at high incidences (Slykhuis, 1962a). AgMV is transmitted by the widely distributed eriophyid mite Abacarus hystrix and can be mechanically transmitted by rub-inoculation with infected plant sap experimentally. No clear evidence is available of AgMV increasing in distribution.
Taxonomic TreeTop of page
- Domain: Virus
- Group: "Positive sense ssRNA viruses"
- Group: "RNA viruses"
- Family: Potyviridae
- Genus: Rymovirus
- Species: Agropyron mosaic virus
Notes on Taxonomy and NomenclatureTop of page
Agropyron mosaic virus (AgMV) is a species in the genus Rymovirus, family Potyviridae. Members of the genus Rymovirus are transmitted by eriophyid mites, and other members of the genus include Ryegrass mosaic virus (RGMV) and Hordeum mosaic virus (HoMV). AgMV is most closely related to HoMV, with which their polyprotein amino acid sequences share 71.6% sequence identity (French and Stenger, 2005).
DescriptionTop of page
AgMV is a positive sense RNA virus in the genus Rymovirus, family Potyviridae with a genome of 9540 nucleotides (French and Stenger, 2005). The virion is a filamentous particle 717 nm in length and 15 nm in diameter (Bremer, 1964; Slykhuis and Bell, 1966; Slykhuis, 1973). The sedimentation coefficient of AgMV is 165 S (Staples and Brakke, 1963).
The nucleotide sequence contains one open reading frame that produces a single polyprotein that is post-translationally cleaved into several proteins (French and Stenger, 2005). It is assumed that like other closely related rymoviruses the polyprotein is cleaved into proteins P1, HC-Pro, P3, 6K1, CI, 6K2, VPg-NIa, NIb and the coat protein (French and Stenger, 2005).
AgMV strains differing in symptom severity and yield reduction have been reported, AgMV-mi (mild) and AgMV-s (severe; Slykhuis and Bell, 1966). Earlier studies defined these two strains based on differences in symptoms, with one exhibiting ‘green mosaic’ and the more severe strain exhibiting ‘yellow mosaic’ (Slykhuis, 1973; Staples and Brakke, 1963). Although the two strains can be differentiated by symptom severity, the genetic variation among strains or isolates of AgMV is unknown (Staples and Brakke, 1963; Slykhuis and Bell, 1966). AgMV can survive in a variety of environments as long as one of its hosts and its vector, Abacarus hystrix, are present (Slykhuis and Bell, 1966; Slykhuis, 1969). AgMV is dependent on its vector or mechanical transmission to move from plant to plant.
DistributionTop of page
The known distribution of AgMV includes the USA, Canada, Bulgaria, Hungary, Finland, Germany, and the UK. In the USA, it was first described in Virginia (as wheat virus 2; McKinney, 1937) and subsequently in South Dakota (as Agropyron streak mosaic virus; Slykhuis, 1952), Iowa (McKinney, 1953), Montana (Shepard, 1968); Colorado (Seifers, 1992), Oklahoma (Montana et al., 1994) and Ohio (Hodge et al., 2018). In Canada it has been described in southern Ontario, Quebec, Prince Edward Island and Saskatchewan (Slykhuis, 1962a). Bremer (1964) reported AgMV in Finland; Schumann (1969) reported AgMV in Germany; Catherall and Chamberlain (1975) reported AgMV in the UK (Wales); Gáborjányi (1991) reported AgMV in Hungary (reviewed by Mesterházy et al. (2002) in English); and Bakardjieva et al. (2004) reported AgMV in Bulgaria. Slykhuis (1962b) reported virus symptoms resembling those of AgMV in couch grass in New Zealand; however, this report was based on symptoms and host and AgMV was not confirmed. More recent reviews of experimentally confirmed viruses in New Zealand identified no further evidence of AgMV in New Zealand, thus the initial suggestion remains unconfirmed (Pearson et al., 2006; Guy, 2014).
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.Last updated: 17 Feb 2021
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Bulgaria||Present, Few occurrences|
|Finland||Present, Few occurrences|
|Germany||Present, Few occurrences|
|Hungary||Present, Few occurrences|
|United Kingdom||Present, Few occurrences||Detected in samples from Wales, Scotland and England.|
|-Prince Edward Island||Present, Few occurrences|
|-Quebec||Present, Few occurrences|
|-Saskatchewan||Present, Few occurrences|
|-Colorado||Present, Few occurrences||Loveland, Colorado|
|-Iowa||Present, Few occurrences|
|-Montana||Present, Few occurrences|
|-Oklahoma||Present, Few occurrences|
|-South Dakota||Present, Few occurrences|
|-Virginia||Present, Few occurrences|
|New Zealand||Absent, Unconfirmed presence record(s)|
History of Introduction and SpreadTop of page
AgMV was first described in 1937, then as ‘wheat virus 2’, isolated from Elymus repens, commonly known as quackgrass or couch grass, collected in Arlington, Virginia, USA (McKinney, 1937). For the next several decades it was described in other parts of the USA as well as in Canada and Europe. Although detection locations have increased over time, there is no clear evidence of movement or an increase in distribution of the virus.
Risk of IntroductionTop of page
Although AgMV is pathogenic to wheat, it has not typically been considered a major pathogen, and its currently reported distribution is probably incomplete. Its major weedy plant host, quackgrass (Elymus repens), has worldwide distribution. Its known vector is the cereal rust mite, Abacarus hystrix (Slykhuis, 1969). A. hystrix is reportedly widespread in North American and Eurasia (Frost and Ridland, 1996) and is also found in Egypt, South Africa (Meyer, 1989), Australia (Frost et al., 1990) and New Zealand (Guy, 1993). There are no reports of A. hystrix in South America or Asia. Parts of North America and Europe where AgMV has not yet been reported may already have AgMV as both the vector and plant host(s) are present. Transport of virus and/or vector such as through live plant trade to global locations where one or both are not already present poses risk of introduction. Assessment of introduction risk is confounded by distribution data that are probably not comprehensive. Based on the absence of AgMV reports, Africa, Australia or New Zealand may be at highest risk of introduction due to the presence of vector mites, while South America, Africa and Asia may be at risk of establishment of introduced virus only if vector populations are also established. Most AgMV isolates described have mild green mosaic symptoms and limited pathogenicity on wheat, but a few isolates causing stronger yellow mosaic symptoms are more pathogenic to wheat (McKinney, 1944; Slykhuis, 1962a; Slykhuis, 1973).
Hosts/Species AffectedTop of page
AgMV host range is restricted to a number of species of Poaceae, which includes a number of important crops including wheat, rye and barley (Slykhuis and Bell, 1966). Staples and Brakke (1963) suggested that green and yellow mosaic AgMV strains may differ in their host range, as the yellow strain infected Aegilops cylindrica [A. caudata], A. triuncialis and A. triaristata [A. neglecta] while the green strain did not in a small number of inoculations. Bremer (1964) demonstrated that AgMV can produce local lesions on Chenopodium quinoa similar to Brome mosaic virus. Additional host range studies by Schumann (1969) indicate that AgMV can infect a wide range of Poaeceae spp. that are primarily weedy grass species.
The experimentally demonstrated host range of AgMV includes: Agropyron repens [Elymus repens], A. elongatum [E. elongatus], A. inerme [E. spicatus], A. intermedium [E. hispidus], A. junceum [E. farctus], A. pertenue [E. tauri], A. trachycaulum [E. trachycaulus], Aegilops cylindrica [Aegilops caudata], A. squarrosa [A. triuncialis], A. triuncialis, A. triaristata [A. neglecta], Hordeum vulgare, Lolium multiflorum, Triticum aestivum, T. durum, T. monococcum, T. vulgare [T. aestivum], Festuca rubra, Elymus canadensis and E. virginicus. Tested species that were not infected include: Avena sativa, Hordeum jubatum, Panicum miliaceum, Setaria italica, Sorghum vulgare [S. bicolor], Zea mays, Agropyron cilliare [Elymus ciliaris], A. cristatum, A. dasystachyum, A. desertorum, A. trachycaulum [E. trachycaulus], A. trichophorum [E. hispidus], Bromus inermis, Phalaris arundinacea, Phleum arundinacea, P. pretense or Poa pratensis (Slykhuis, 1952; Staples and Brakke, 1963; Slykhuis and Bell, 1966; Shepard, 1968; Slykhuis, 1973). Bremer (1964) showed that AgMV could also infect Bromus japonicus, Hordeum murinum and Secale cereale.
Slykhuis (1962a) reported that A. repens [E. repens] and T. aestivum were the hosts most commonly found to be naturally infected with AgMV. It was hypothesized that A. repens acts as a virus reservoir for the spread of AgMV to wheat. However, A. repens appeared to be less susceptible to infection in mechanical inoculation compared to wheat (Slykhuis, 1962a). Under experimental mechanical inoculation, infection rates for wheat were around 100% regardless of variety; however, infection rates for A. repens, A. elongatum [E. elongatus] and A. intermedium [E. hispidus] were approximately 50% (Slykhuis, 1962a). Most other hosts of AgMV showed an infection rate around 10% (Slykhuis and Bell, 1966).
Host Plants and Other Plants AffectedTop of page
SymptomsTop of page
AgMV typically produces a mild to severe mottle with marked contrast between light and green areas early after infection which then gradually turns into very light streaks on the leaves. In wheat, mottling symptoms appear 5-19 days after inoculation, depending on temperature (Slykhuis, 1962a; Staples and Brakke, 1963). Moderate stunting is a common symptom in infected hosts. The two strains of AgMV can be differentiated on the basis of their symptoms in wheat. AgMV-mi is reported to produce a very light green mosaic in wheat with little stunting and yield reduction, whereas AgMV-s is reported to produce severe chlorosis, stunting and yield reduction in wheat (Slykhuis, 1962a).
List of Symptoms/SignsTop of page
|Fruit / discoloration|
|Growing point / dwarfing; stunting|
|Inflorescence / dwarfing; stunting|
|Inflorescence / mosaic|
|Leaves / abnormal colours|
|Leaves / abnormal patterns|
ClimateTop of page
|C - Temperate/Mesothermal climate||Preferred||Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C|
|Cs - Warm temperate climate with dry summer||Preferred||Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers|
|Cw - Warm temperate climate with dry winter||Preferred||Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)|
|Cf - Warm temperate climate, wet all year||Preferred||Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year|
|D - Continental/Microthermal climate||Preferred||Continental/Microthermal climate (Average temp. of coldest month < 0°C, mean warmest month > 10°C)|
|Ds - Continental climate with dry summer||Preferred||Continental climate with dry summer (Warm average temp. > 10°C, coldest month < 0°C, dry summers)|
|Dw - Continental climate with dry winter||Preferred||Continental climate with dry winter (Warm average temp. > 10°C, coldest month < 0°C, dry winters)|
|Df - Continental climate, wet all year||Preferred||Continental climate, wet all year (Warm average temp. > 10°C, coldest month < 0°C, wet all year)|
Air TemperatureTop of page
|Parameter||Lower limit||Upper limit|
|Absolute minimum temperature (ºC)||15|
|Mean annual temperature (ºC)||15||30|
Means of Movement and DispersalTop of page
Vector Transmission (Biotic)
Members of the genus Rymovirus, including AgMV, are transmitted by eriophyid mites. AgMV has been reported to be transmitted by the wheat rust mite Abacarus hystrix but was not experimentally transmitted by Aculus mckenziei or Aceria tulipae (Slykhuis, 1969; Slykhuis, 1973). Non-mite arthropods tested including aphid species Rhopalosiphum padi, Macrosiphum avenae [Sitobion avenae], M. dirhodum [Metoplophium dirhodum] and Myzus persicae did not transmit AgMV from wheat to wheat (Bremer, 1964). AgMV transmission by A. hystrix is inefficient (Slykhuis, 1969) but this transmission is considered to be the main mode of natural dispersal of the virus as no other vectors have been identified. AgMV is experimentally transmissible by rub-inoculation of infected plant sap (Slykhuis, 1973).
Seedborne AspectsTop of page
No data are available on seed transmissibility of AgMV.
Where measured, infection incidence is low (Slykhuis 1962a).
Effect on Seed Quality
No data on AgMV effects on seed quality are reported.
Vectors and Intermediate HostsTop of page
Impact SummaryTop of page
|Economic/livelihood||Positive and negative|
Impact: EconomicTop of page
Most AgMV identified from field plants has mild symptoms (McKinney, 1937; Slykhuis, 1962a; Bremer, 1964). However, isolates with more severe or virulent phenotypes were isolated in the USA and Canada (McKinney, 1944; Slykhuis 1962a; Slykhuis, 1973). The AgMV-severe strain has been reported to cause up to 88% yield reduction in wheat in Canada under field conditions when the incidence of infection is 100% whereas AgMV-mild causes less severe reduction in yield with a maximum of 32% reduction in yield (Slykhuis, 1962a). Yield losses were reported to be more severe under early infections during the 3-leaf stage of wheat than late infections (Slykhuis, 1962a). Despite the high potential for yield loss caused by AgMV, natural infection rates, where measured, are very low (Slykhuis, 1962a). Reports of natural infections of AgMV are associated with grassy weeds or volunteer wheat, not from samples collected within cultivated wheat fields (Slykhuis, 1962a; Seifers, 1992; Hodge et al., 2018). Thus, it is not expected that AgMV currently causes significant economic losses, although it has potential to do so if incidence becomes high.
Risk and Impact FactorsTop of page
- Has a broad native range
- Has propagules that can remain viable for more than one year
- Reproduces asexually
- Negatively impacts agriculture
- Damages animal/plant products
- Difficult to identify/detect in the field
DiagnosisTop of page
AgMV usually causes a mild green or yellow mosaic that cannot be reliably distinguished from those induced by other mosaic viruses without further testing. Host range and vector differences can be used to differentiate AgMV from other viruses, serological tests (Slykhuis and Bell, 1966) and reverse transcription-polymerase chain reaction (RT-PCR) tests can also differentiate AgMV (Hodge et al., 2018). Sequence data from deep sequencing analyses can also be used to identify AgMV. The complete sequence of ND402, a US isolate of AgMV is reported as GenBank accession no. NC_005903.1 (French and Stenger, 2005). Three near-complete AgMV genome sequences from Ohio, USA, are also reported (GenBank accession nos. MF621331-MF621333; Hodge et al., 2018), as are partial sequences from USA and Germany (GenBank accession nos. U30615, Salm et al., 1996; AJ889240, Shi et al., 2016, unpublished).
Similarities to Other Species/ConditionsTop of page
AgMV infection is not distinguishable from other mosaic-causing viruses on the basis of symptoms alone, although it can be distinguished by sequence-based or serological diagnostic tests, host range and vector transmission. Viruses that cause similar mosaic symptoms in wheat and other grasses include Brome mosaic virus (BMV), Wheat streak mosaic virus (WSMV), and Hordeum mosaic virus (HoMV). BMV is distinguishable by diagnostic tests and by its much broader host range in the family Poaceae including maize (Zea mays), which is not infected by AgMV (see Slykhuis, 1973). In addition to serological or amplification-based assays, AgMV can be distinguished from WSMV and HoMV by its transmissibility to E. repens but not to Avena sativa (Slykhuis and Bell, 1966). It is also not transmitted by Aceria tulipae, the vector for WSMV (Slykhuis, 1969).
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
Although AgMV is pathogenic on wheat, it is not considered a major threat due to low incidences reported. Thus, there are no current management or prevention recommendations specific to AgMV. Slykhuis (1962a) reported that AgMV infections in wheat fields were near diseased couchgrass, which would indicate that removing hosts near planted wheat such as couchgrass or volunteer wheat would help prevent future infections.
Infection of plants with a mild isolate is reportedly effective at preventing subsequent infection of more severe AgMV isolates (Slykhuis and Bell, 1966).
Gaps in Knowledge/Research NeedsTop of page
Although AgMV has been described since 1937 and is known to be pathogenic on wheat in North America, it does not receive much attention as it is generally found at low incidence and is not considered to be a high-risk or high-impact pathogen. Reports of AgMV indicating its distribution are sporadic and rare, suggesting its low incidence and that its full established range is probably not reported. Seed transmission and potential introduction risks are not known. The impact on yield of crops other than wheat (barley, rye, etc.) has not been studied for AgMV, and it may have impacts on forage crops with economic or societal impacts that have not been reported. There is no information available regarding the ecological impact of AgMV.
ReferencesTop of page
French, R., Stenger, D. C., 2005. Genome sequences of Agropyron mosaic virus and Hordeum mosaic virus support reciprocal monophyly of the genera Potyvirus and Rymovirus in the family Potyviridae. Archives of Virology, 150(2), 299-312. doi: 10.1007/s00705-004-0396-6
Frost, W. E., Ridland, P. M., 1996. Grasses. In: Eriophyid mites-their biology, natural enemies and control, [ed. by Lindquist, E. E., Sabelis, M. W., Bruin, J.]. Netherlands: Elsevier Science B. V. . 619-629.
Gáborjányi, R., 1991. Agropyron mosaic virus and ryegrass mosaic virus: two new cereal pathogens in Hungary. (Két új gabonapatogén vírus Magyarországon: a tarackbúza mozaik vírus (AgMV) és az angolperje mozaik vírus (RyMV)). Növénytermelés, 40, 219–225.
Hodge, B. A., Paul, P. A., Stewart, L. R., 2018. Agropyron mosaic virus detected in Ohio wheat (Triticum aestivum). Plant Disease, 102(2), 463-464. http://apsjournals.apsnet.org/loi/pdis doi: 10.1094/PDIS-08-17-1223-PDN
McKinney, HH, 1937. Mosaic diseases of wheat and related cereals. In: U. S. Department of Agriculture Circular , (No. 442) . 1-23.
Montana, J. R., Jacobs, J. L., Hunger, R. M., Sherwood, J. L., 1994. First reports of agropyron mosaic virus in wheat and mixed infection with wheat streak mosaic virus in Oklahoma. Plant Disease, 78(4), 432. doi: 10.1094/PD-78-0432D
Pearson, M. N., Clover, G. R. G., Guy, P. L., Fletcher, J. D., Beever, R. E., 2006. A review of the plant virus, viroid and mollicute records for New Zealand. Australasian Plant Pathology, 35(2), 217-252. doi: 10.1071/AP06016
Salm, S. N., Rey, M. E. C., Robertson, N. L., French, R., Rabenstein, F., Schubert, J., 1996. Molecular cloning and nucleotide sequencing of the partial genomes of agropyron and hordeum mosaic viruses, two members of the Rymovirus genus in the taxonomic family Potyviridae. Archives of Virology, 141(11), 2115-2127. doi: 10.1007/BF01718219
Schumann, K., 1969. (Nachweis des Queckenmosaikvirus (agropyron mosaic virus) in der Deutschen Demokratischen Republik). Archives of Phytopathology and Plant Protection, 3(2), 83-88.
Slykhuis, J. T., 1973. Agropyron mosaic virus. In: CMI/AAB Descriptions of Plant Viruses , (No. 118) . Wellesbourne, UK: Association of Applied Biologists.http://www.dpvweb.net/dpv/showdpv.php?dpvno=118
Slykhuis, J. T., Bell, W., 1966. Differentiation of Agropyron mosaic, Wheat streak mosaic, and a hitherto unrecognized Hordeum mosaic virus in Canada. Canadian Journal of Botany, 44(9), 1191-1208. doi: 10.1139/b66-131
Gáborjányi R, 1991. Agropyron mosaic virus and ryegrass mosaic virus: two new cereal pathogens in Hungary. (Két új gabonapatogén vírus Magyarországon: a tarackbúza mozaik vírus (AgMV) és az angolperje mozaik vírus (RyMV)). Növénytermelés. 219–225.
Hodge B A, Paul P A, Stewart L R, 2018. Agropyron mosaic virus detected in Ohio wheat (Triticum aestivum). Plant Disease. 102 (2), 463-464. http://apsjournals.apsnet.org/loi/pdis DOI:10.1094/PDIS-08-17-1223-PDN
McKinney HH, 1937. Mosaic diseases of wheat and related cereals. In: U. S. Department of Agriculture Circular, 1-23.
Montana J R, Jacobs J L, Hunger R M, Sherwood J L, 1994. First reports of agropyron mosaic virus in wheat and mixed infection with wheat streak mosaic virus in Oklahoma. Plant Disease. 78 (4), 432. DOI:10.1094/PD-78-0432D
Schumann K, 1967. Detection of Agropyron mosaic virus in the German Democratic Republic. (Nachweis des Queckenmosaikvirus (Agropyron mosaic virus) in der Deutschen Demokratischen Republik.). Arch. PflSchutz. 3 (2), 83-88.
ContributorsTop of page
29/02/20 Original text:
Lucy Stewart, USDA-ARS, Selby Hall, Wooster, Ohio, USA
Brian Hodge, Ohio State University, Selby Hall, Wooster, Ohio, USA
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