Panicum mosaic virus

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Panicum mosaic virus
Virus classification OOjs UI icon edit-ltr.svg
(unranked): Virus
Realm: Riboviria
Kingdom: Orthornavirae
Phylum: Kitrinoviricota
Class: Tolucaviricetes
Order: Tolivirales
Family: Tombusviridae
Genus: Panicovirus
Species:
Panicum mosaic virus

Panicum mosaic virus (PMV) is a positive-sense single-stranded RNA viral pathogen that infects plant species in the panicoid tribe of the grass family, Poaceae . [1] The pathogen was first identified in Kansas in 1953 and most commonly causes disease on select cultivars of turf grass, switchgrass, and millet. The disease most commonly associated with the panicum mosaic virus pathogen is St. Augustine Decline Syndrome, which infects species of turf grass and causes chlorotic mottling. [2] In addition to St. Augustine Decline, panicum mosaic virus is responsible for chlorotic streaking and mild green mosaicking in select cultivars of switchgrass and millet. [3]

Contents

History

PMV was first observed in Kansas in 1953. It was originally noted to infect switchgrass (Panicum virgatum), and was observed infecting St. Augustine grass (Stenotaphrum secundatum) in Texas in 1966. The strain specific to St. Augustine grass has since been observed in Arkansas, Louisiana, Mississippi and South Carolina in the United States, as well as in Mexico. Other strains have been identified infecting centipedegrass (Eremochloa ophiuroides). [4] Foxtail millet (Setaria italica), white proso millet (Panicum miliaceum) and pearl millet (Pennisetum glaucum) have also been used to propagate PMV and panicum mosaic satellite virus (SPMV), and mechanical transmission can occur to maize and some cultivars of common wheat (Triticum aestivum). [5]

Classification

Panicum mosaic virus is assigned to the genus Panicovirus , a member of the plant virus family Tombusviridae . [4] Members of Tombusviridae are transmitted as positive sense single-stranded non-enveloped RNA viruses, with an icosahedral capsid. [6] PMV itself has a genome of 4,326 nucleotides, encapsulated into 30-nm particles by a capsid protein of 26  kDa. [4] PMV was placed in the genus Panicovirus because of its limited monocot host range and lack of an additional 5'-ORF. PMV is serologically related to Molina streak virus and Maize mild mottle virus. [5]

Satellite panicum mosaic virus

There exists a satellite virus to panicum mosaic virus. Although little is known about the satellite panicum mosaic virus, the pathogen is believed to play a role in the infection process because when combined with panicum mosaic virus, the satellite virus causes symptoms to appear earlier in the growing season and results in a more severe infection. [7] Because of the change in disease virulence to the main viral pathogen, panicum mosaic virus and satellite panicum mosaic virus are believed to cause synergistic effects to their hosts. Satellite panicum mosaic virus cannot produce its own replication nor movement proteins, thus it depends entirely on panicum mosaic virus for replication and systemic movement in the host plant. [8]

Pathogenesis and disease characteristics

Panicum mosaic virus is a plant disease that infects monocots by invading through mechanical wounds. [9] Because panicum mosaic virus pathogen cannot create its own wound in a host plant, the pathogen must survive until a wound is formed by living epiphytically on its future host or in plant debris. [10] The virus can live up to nine years in infected plant debris. The virus is moved around the environment by wind, rain, and cultural practices such as plowing and mowing. Once the virus has successfully invaded the plant, panicum mosaic virions spread through the plant by producing three proteins (p8, p6.6, and p15) as part of their capsids. [7] The incubation period of panicum mosaic virus is fastest in warm conditions, around 29 to 35 degrees Celsius, and can take as few as 7–18 days. [10]

In regard to pathogen composition, there are two characteristic components of panicum mosaic and its related panicum satellite mosaic viruses. One characteristic of the disease is a 42S component which is isometric shaped, 17 nm in diameter, and has not been shown to be infectious by itself. [11] The second characteristic component of panicum mosaic virus is the 109S component which is approximately 30 nm in diameter, also isometric shaped, and has been shown to be infectious. From replication testing, it is believed the 109S component is the panicum mosaic pathogen and the 42S component of the pathogen is the panicum satellite virus because the 109S component replicates independently while 42S cannot replicate without the presence of the 109S component.[ citation needed ]

Hosts and symptoms

St. Augustine grass

Symptoms of St. Augustine Decline Syndrome on St. Augustine grass (Stenotaphrum secundatum) are mild green mosaics in addition to mottling and streaking of leaves. [2] In extreme cases, a turf grass crop may experience chlorosis if the disease affects susceptible plants. The disease is spread only through mechanical vectors, such as mowing. At this time, the only method of control for panicum mosaic virus is planting resistant cultivars. In turf grass, the disease is geographically centered around the southcentral and southeastern United States, due to the high prevalence of non-resistant turf species. [2]

Millet

Symptoms of panicum mosaic virus on millet—without its satellite virus—are slight chlorosis and mild stunting. [9] The synergistic effect of panicum mosaic virus and satellite panicum mosaic virus on millet cultivars is rapidly developed chlorotic streaking within several days of inoculating plants. The long-term effects of combined panicum mosaic and satellite panicum mosaic viruses on millet are severe leaf mosaicking, stunting, and failure to set seed. [12]

Switchgrass

Switchgrass is a native prairie grass that started to be bred for erosion control and forage around a century ago. [13] In the 1980s, switchgrass began to be cultivated for biofuels. Over the course of the last three decades, there has been a dramatic increase in the amount of disease research of switchgrass and other energy crops.[ citation needed ]

Similar to its symptoms on millet and turf grass, panicum mosaic virus causes switchgrass to have chlorotic mottling and stunting. [7] Unlike turf grass, there are no resistant cultivars of switchgrass available to be grown. As a result of the lack of resistance in cultivated species of switchgrass, there is a potential danger of developing large scale disease within energy cropping systems.[ citation needed ]

Management

St. Augustine decline in turf grass

The main method of controlling St. Augustine Decline Syndrome is breeding resistant varieties. This method of resistance breeding has been successful in turf grass because it has led to the production of two resistant cultivars of St. Augustine grass, FA-108 and FA-2002 (nicknamed 'Raleigh', and 'Seville'). [14] Aside from resistance genes, another option of managing St. Augustine Decline Syndrome is cultural control by cleaning tools between mowing different properties to prevent the spread of pathogen. [2] A third control option for St. Augustine Decline is to mow turf grass only during dry weather because the infected sap is not able to spread as easily. [2]

Switchgrass and millet

Although a strong strain of the pathogen is economically and aesthetically detrimental, a possible beneficial interaction with a susceptible host by panicum mosaic virus is cross-protection by inoculation of a weak panicum mosaic virus strain. The benefit of inoculation with a weak strain means that the crop will have cross-protection, which means that the crop will not have as extensive of yield loss if the crop is exposed to a more aggressive, virulent strain. [7]

One risk that comes with weak strain inoculation is increased susceptibility to other viral strains and pathogens. Additionally, there is a risk that the weak strain could mutate into a more virulent strain. Alternatively, the inoculated weak viral disease might cause synergistic effects if another viral pathogen infects the plant. [15] Despite the risks posed by cross-protection of crops using weak strains, the method has proven valuable in the control of several other viruses. Cross-protection appears to be the most promising option in the case of switchgrass because of the lack of resistance genes for pathogen control. [7]

Related Research Articles

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<i>Tomato bushy stunt virus</i> Species of virus

Tomato bushy stunt virus (TBSV) is a virus of the tombusvirus family. It was first reported in tomatoes in 1935 and primarily affects vegetable crops, though it is not generally considered an economically significant plant pathogen. Depending upon the host, TBSV causes stunting of growth, leaf mottling, and deformed or absent fruit. The virus is likely to be soil-borne in the natural setting, but can also be transmitted mechanically, for example through contaminated cutting tools. TBSV has been used as a model system in virology research on the life cycle of plant viruses, particularly in experimental infections of the model host plant Nicotiana benthamiana.

<i>Cowpea chlorotic mottle virus</i> Species of virus

Cowpea chlorotic mottle virus, known by the abbreviation CCMV, is a virus that specifically infects the cowpea plant, or black-eyed pea. The leaves of infected plants develop yellow spots, hence the name "chlorotic". Similar to its "brother" virus, Cowpea mosaic virus (CPMV), CCMV is produced in high yield in plants. In the natural host, viral particles can be produced at 1–2 mg per gram of infected leaf tissue. Belonging to the bromovirus genus, cowpea chlorotic mottle virus (CCMV) is a small spherical plant virus. Other members of this genus include the brome mosaic virus (BMV) and the broad bean mottle virus (BBMV).

<i>Alfalfa mosaic virus</i> Species of virus

Alfalfa mosaic virus (AMV), also known as Lucerne mosaic virus or Potato calico virus, is a worldwide distributed phytopathogen that can lead to necrosis and yellow mosaics on a large variety of plant species, including commercially important crops. It is the only Alfamovirus of the family Bromoviridae. In 1931 Weimer J.L. was the first to report AMV in alfalfa. Transmission of the virus occurs mainly by some aphids, by seeds or by pollen to the seed.

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<i>Apple mosaic virus</i> Species of virus

Apple mosaic virus (ApMV) is a plant pathogenic virus of the family Bromoviridae. It is named after its symptoms that were first present on apples. ApMV is a positive sense RNA based virus. The disease itself has several synonyms including Mild Apple Mosaic Virus, Hop Virus, Rose Mosaic Virus, and European Plum Line Patten Virus. It causes a severe yield reduction and decreased life-expectancy of fruit trees.

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<i>Cucumber mosaic virus</i> Species of virus

Cucumber mosaic virus (CMV) is a plant pathogenic virus in the family Bromoviridae. This virus has a worldwide distribution and a very wide host range, having the reputation of the widest host range of any known plant virus. It can be transmitted from plant to plant both mechanically by sap and by aphids in a stylet-borne fashion. It can also be transmitted in seeds and by the parasitic weeds, Cuscuta sp. (dodder).

<i>Maize dwarf mosaic virus</i> Species of plant pathogenic virus

Maize dwarf mosaic virus (MDMV) is a pathogenic plant virus of the family Potyviridae. Depending on the corn plant’s growth stage, the virus can have severe implications to the corn plant’s development which can also result in economic consequences to the producer of the crop.

<i>Pepper mild mottle virus</i> Species of virus

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<span class="mw-page-title-main">Panicum mosaic satellite virus</span> Species of virus

Panicum mosaic satellite virus (SPMV) is a plant satellite virus in genus Papanivirus, which is a member of realm Riboviria without assigned family or order. It only infects grasses which are infected by Panicum mosaic virus. One study found that 72% of Stenotaphrum secundatum infected with panicum mosaic virus was also infected with SPMV. In addition to SPMV, many plants infected with panicum mosaic virus are also infected with satellite RNAs.

<i>Soybean mosaic virus</i> Plant disease

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<i>Watermelon mosaic virus</i> Species of virus

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Cocoa necrosis virus (CoNV) is a plant pathogenic virus of the genus nepovirus that infects Theobroma cacao en natura causing cacao necrosis disease. CoNV is considered synonymous with Strain S of cacao swollen shoot virus. Unlike Cacao swollen shoot virus, it is not transmitted by mealybugs nor vectored by aphids, beetles, or leafhoppers that also commonly infest cacao. It is serologically, distantly related to Tomato black ring virus and very distantly related to Grapevine chrome mosaic virus.

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<span class="mw-page-title-main">Viral diseases of potato</span>

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References

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