Yellow dwarf virus

Yellow dwarf virus

Classification :	Viruses
Area :	Ribovirian
Empire :	Orthornavirae
Phylum :	Kitrinoviricota
Class :	Tolucaviricetes
Order :	Tolivirales
Family :	Luteoviridae
Genre :	Luteovirus , polerovirus
Type :	(see text)

Taxonomic characteristics

Genome :	(+) ss RNA linear
Baltimore :	Group 4
Symmetry :	icosahedral
Cover :	no

Scientific name

Barley yellow dwarf virus

Short name

BYDV

Left

NCBI Taxonomy:

12037

The collective term yellow dwarf virus ( English Barley yellow dwarf virus , BYDV ) summarizes a number of species of the family Luteoviridae belonging to the genera Luteovirus (subgroup I) or polerovirus (subgroup II). Together with the ryegrass mosaic virus (officially Ryegrass mosaic virus , RGMV), they are among the most widespread plant viruses in the world . Their hosts include mainly the sweet grasses , such as. B. the cereals oats , barley , wheat , triticale and rye , also grass types such. B. the ryegrass . The virus is transmitted by aphids . The susceptibility differs depending on the type of grain. Oats are the most susceptible, followed by barley, then wheat and triticale; rye has the lowest susceptibility.

Structure and genome

The yellow dwarf viruses have a single-stranded RNA and no virus envelope .

Systematics

Overall, there are the following representatives of this group in the Luteoviridae family , confirmed and proposed by the International Committee on Taxonomy of Viruses (ICTV) , which are now regarded as a separate species (respective vectors in brackets):

Subgroup I (members of the genus Luteovirus as Barley yellow dwarf virus , BYDV in the proper sense)

Species Barley yellow dwarf virus kerII (BYDV-kerII)
Species Barley yellow dwarf virus kerIII (BYDV-kerIII)
Species Barley yellow dwarf virus MAV (BYDV-MAV), vector: Sitobion avenae
Species Barley yellow dwarf virus PAS (BYDV-PAS)
Species Barley yellow dwarf virus PAV (BYDV-PAV), type species, vectors: Rhopalosiphum padi , Sitobion avenae , Metopolophium dirhodum
Species “ Barley yellow dwarf virus GAV ” (BYDV-GAV) (proposed candidate)
Species “ Barley yellow dwarf virus OYV ” (BYDV-OYV) (as proposed)

Subgroup II (members of the genus Polerovirus with the new name Cereal yellow dwarf virus , CYDV or Maize yellow dwarf virus , MYDV etc.)

Species Cereal yellow dwarf virus RPS (CYDV-RPS), obsolete Barley yellow dwarf virus RPS (BYDV-RPS)
Species Cereal yellow dwarf virus RPV (CYDV-RPV), obsolete Barley yellow dwarf virus RPV (BYDV-RPV), vector: Rhopalosiphum padi
Species Maize yellow dwarf virus RMV (MYDV-RMV), obsolete Barley yellow dwarf virus RMV (BYDV-RMV), vector: Rhopalosiphum maidis
Species “ Setaria yellow dwarf virus ” (SYDV) (as proposed)

in the same family, but not (yet) assigned to a genus by ICTV:

Species Barley yellow dwarf virus GPV (BYDV-GPV)
Species Barley yellow dwarf virus SGV (BYDV-SGV), vector: Schizaphis graminum

Assigned to other virus families and genera, but with a similar clinical picture, are for example:

Species Onion yellow dwarf virus from the genus Potyvirus , family Potyviridae .
Species Chickpea yellow dwarf virus from the genus Mastrevirus , family Geminiviridae .
Species Tobacco yellow dwarf virus ibid
Species “ Wheat yellow dwarf virus ” ibid (as proposed)

pathology

Symptoms of the infection in wheat

inhibited growth in wheat

transmission

The virus first attacks aphids , which takes one to twelve hours. After ingesting the virus, the aphids are infectious for more than 20 days. The virus is transmitted to the plants within 30 minutes to several hours when the aphids eat food: In this case, the virus is transmitted into the phloem of the plants and multiplies. An ELISA test is carried out on the leaf sap to detect the yellow dwarf virus.

Symptoms

The virus often spreads in nests in a stand. The pronounced symptoms vary depending on the type of grain, variety, temperature and nutrient supply. The first are visible after an infestation after 2–4 weeks, depending on the temperature. With early sowing, symptoms of disease can be observed as early as autumn. The color of the leaves of the affected plants is characteristic of the yellow dwarf virus. This ranges from yellow in the case of barley to orange in the case of wheat to red in the case of oats and often spreads from the leaf edge over the entire leaf. Plants infected by the yellow dwarf virus are also stunted in growth and therefore remain very small if infected early, but are heavily planted. Often the shooting and the formation of ears are inhibited, which is why inflorescences cannot develop and the plants can not reproduce. This means great economic damage. Furthermore, there is often necrosis in the vascular bundles of the plants. In addition, the plants can be more prone to abiotic stress or fungal pathogens.

Combat

Since it is impossible to fight viruses directly, the main solution is to check the vectors . Grain is preferably sown in the absence of aphids and a quick and uninterrupted emergence of the field is encouraged. Insecticides are sometimes used as a preventive measure. Dressed seeds allow the use of insecticides to be minimized. This is particularly useful after pronounced official warnings about the risk of infection. In addition, attempts are being made to make do with genetic engineering by incorporating the ryd2 gene found in an Ethiopian variety in some cultivated barley varieties.