Peanut mottle virus


Peanut mottle virus is a plant pathogenic virus of the family Potyviridae. As with other members of this virus family, PeMoV is a flexuous filamentous virus with particles 740-750 nm long. It is transmitted by several species of aphids and by mechanical inoculation. It was first given its name in 1965 when it was isolated from peanuts in Georgia, USA. This virus was found to be seed transmitted in this host.

Host species

Besides peanuts, this virus is known to infect soybeans, French beans, peas, and various weed species of Cassia. Since 1964 it has been identified in East Arica and north-east Australia and possible Venezuela, Japan, Malaysia and Bulgaria. Given the fact that PeMoV is seed transmissible in peanut, the virus could occur anywhere peanuts are grown. In the United States, for example, a survey done in 1975 found the virus in all states where peanuts were grown.

Symptoms

The symptoms of this virus in peanuts appear as irregular dark islands on young leaves. The symptoms are not as clear on older leaves and thus can be easily missed even when the virus is in epidemic proportions in the field.
In infected plant cells, the virus makes characteristic potyvirus cylindrical inclusions. that are visible in the light microscope with proper staining.

Disease control

An interesting study of the spread of this virus in Georgia showed that the virus moved from infected peanut plants to nearby soybean fields and was only present in soybeans in areas where peanuts were also grown. Thus, the recommended approach to control this virus in peanuts and other susceptible hosts such as soybean is the planting of PeMoV-free seed.
In 2007 PeMoV was reported for the first time to infect Rhizoma peanuts in Georgia. This plant is propagated by cuttings and is a perennial crop. To avoid spread, growers of this perennial plant will have to maintain virus free stock and destroy infected fields. If this virus spreads in perennial peanuts in the Southern USA, this plant could become a reservoir of the virus and increase its spread to field peanut and soybean via aphid transmission.