Potato Virus Y
Potato virus Y (PVY) is a plant pathogenic virus of the family Potyviridae. It is one of the most important plant viruses affecting potatoes. Infection results in various symptoms depending on the strain. Production loss is the most mild of the symptoms and “˜potato tuber necrotic ringspot disease’ is the worst.
Ringspot renders potatoes unmarketable and can therefore result in a major loss of income. Aphid vectors transmit PVY but it can also remain dormant in seed potatoes. The South African potato industry has seen a considerable loss due to an increase in potato plant infection. Increased infection could be attributed to chemicals used in vector control failing, infected seed potatoes in cultivation, incorrect irrigation and farming increase I the average temperature of winters.
PVY belongs to the potyvirus genus. Potyvirus genus is the largest plant virus group and is thought to be one of the most destructive families of plant virus affecting potato crops. There are more than 200 members that bring about significant losses in the agricultural arena. It infects many economically important plant species including potato, tobacco, tomato, and pepper. The strain infecting the plants usually determines the level of damage to the crops. Resistance is low in many cases and infection can lead to 10-100% loss in yield.
PVY has different isolates according to the symptoms they induce in various potato plant species. Classification is thus difficult and a better system is being researched. PVY may be transmitted through grafting, plant sap inoculation and through aphid transmission. Most common manner of PVY infection of plant material in the field is through aphids.
Plants viral defense mechanisms primarily try to restrict the movement of the virus. If this doesn’t work the plant may try to kill the cell that is infected thus preventing the spread of virions. Visual inspection was used as a basis for seed certification. Post season tests and inspections were introduced. These tests involved cultivation of previously harvested material in greenhouses. Resulting plants are inspected for a more accurate estimate of viral status. This method of screening was eventually found to be ineffective and it was replaced by enzyme-linked immunosorbent assay screenings. Use of ELISA has become a popular and cost-effective means of routine detection.