Potato leafroll virus
Encyclopedia
Potato leafroll virus is a member of the genus Polerovirus and family
Luteoviridae
. The phloem limited positive sense RNA virus
infects potato
s and other members of the family Solanaceae. PLRV was first described by Quanjer et. al. in 1916. PLRV is transmitted by aphids, primarily the green peach aphid, Myzus persicae
. PLRV is one of the most important potato viruses worldwide but particularly devastating in countries with limited resources and management. It can be responsible for individual plant yield losses of over 50%. One estimate suggests that PLRV is responsible for a global yield loss of 20 million tons. Symptoms include chlorosis, necrosis
and leaf curling.
family. The most economically important host is the Potato, Solanum tuberosum spp. In potato, symptoms of primary infection, infection in the growing season, occurs in the youngest leaves. Leaf margins become necrotic, turning brown and purplish and curl inwards towards the center of the leaf. Secondary infection, which starts from infected potato culls, produces more severe symptoms. Leaf rolling is more apparent and the entire leaf can become chlorotic and sometimes also has a purple discoloration. Necrosis of the phloem tissue particularly in the haulm is observed after onset of symptoms. Plants infected with PLRV experience stunted growth and produce smaller tubers. Infected tubers retain normal shape but experience necrosis of the vascular tissue. Necrosis of the tuber may not be apparent at harvest and can develop in storage. This usually appears as small brown spots scattered throughout the tissue.
PLRV infects other hosts including moonflower, Datura stramonium causing interveinal necrosis and hairy nightshade, Solanum villosum causing chlorosis, leafroll and leathery texture of leaves. Husk tomato, Physalis floridana symptoms include chlorosis, rolling of the leaves and stunting. PLRV infects many other plants in the family Solanacea and can also infect some non-solanaceous plants.
Because of the wide array of symptoms that occur in different hosts, diagnosis of PLRV must be done based on the infected species. In potatoes PLRV is diagnosed by stunting and leafroll. Diagnosis of other species mentioned previously is by the above mentioned symptoms. PLRV can be detected on site using PLRV AgriStrip-magnetic. This lateral flow test uses microbeads coated with an anti-body specific to PLRV. Virus particles are separated from the plant tissue using a powerful magnet. The PLRV AgriStrip-magnetic can detect low titers that were previously thought to be too low for traditional lateral flow tests.
This process takes several hours after which time the aphid will continue to transmit the virus for its remaining life.Aphids can also spread PLRV to tubers in storage, especially after they sprout. Plants that have become infected with PLRV will generally produce infected tubers. Crops planted from infected tubers will then carry the virus. Winged aphids can be carried several hundred kilometers by wind currents allowing for wide spread infection.
, Methamidophos
and Endosulfan
are commonly used in aphid control.Other management strategies include sanitation and seed certification. Cleaning any volunteer tubers from a field reduces any reservoirs that may persist. Seed certification programs test seed lots utilizing ELISA for the detection of multiple potato viruses. Seed lots can then be rated by the amount of infection. Highly infected seed lots are rejected and not used the next season.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Luteoviridae
Luteoviridae
The Luteoviridae are a family of viruses, including the following genera:*Genus Luteovirus; type species: Barley yellow dwarf virus-PAV*Genus Polerovirus; type species: Potato leafroll virus...
. The phloem limited positive sense RNA virus
RNA virus
An RNA virus is a virus that has RNA as its genetic material. This nucleic acid is usually single-stranded RNA but may be double-stranded RNA...
infects potato
Potato
The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...
s and other members of the family Solanaceae. PLRV was first described by Quanjer et. al. in 1916. PLRV is transmitted by aphids, primarily the green peach aphid, Myzus persicae
Myzus persicae
Myzus persicae, known as the green peach aphid, is a small green aphid. It is the most significant aphid pest of peach trees, causing decreased growth, shriveling of the leaves and the death of various tissues...
. PLRV is one of the most important potato viruses worldwide but particularly devastating in countries with limited resources and management. It can be responsible for individual plant yield losses of over 50%. One estimate suggests that PLRV is responsible for a global yield loss of 20 million tons. Symptoms include chlorosis, necrosis
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...
and leaf curling.
Hosts and Symptoms
PLRV infects members of the SolanaceaeSolanaceae
Solanaceae are a family of flowering plants that include a number of important agricultural crops as well as many toxic plants. The name of the family comes from the Latin Solanum "the nightshade plant", but the further etymology of that word is unclear...
family. The most economically important host is the Potato, Solanum tuberosum spp. In potato, symptoms of primary infection, infection in the growing season, occurs in the youngest leaves. Leaf margins become necrotic, turning brown and purplish and curl inwards towards the center of the leaf. Secondary infection, which starts from infected potato culls, produces more severe symptoms. Leaf rolling is more apparent and the entire leaf can become chlorotic and sometimes also has a purple discoloration. Necrosis of the phloem tissue particularly in the haulm is observed after onset of symptoms. Plants infected with PLRV experience stunted growth and produce smaller tubers. Infected tubers retain normal shape but experience necrosis of the vascular tissue. Necrosis of the tuber may not be apparent at harvest and can develop in storage. This usually appears as small brown spots scattered throughout the tissue.
PLRV infects other hosts including moonflower, Datura stramonium causing interveinal necrosis and hairy nightshade, Solanum villosum causing chlorosis, leafroll and leathery texture of leaves. Husk tomato, Physalis floridana symptoms include chlorosis, rolling of the leaves and stunting. PLRV infects many other plants in the family Solanacea and can also infect some non-solanaceous plants.
Because of the wide array of symptoms that occur in different hosts, diagnosis of PLRV must be done based on the infected species. In potatoes PLRV is diagnosed by stunting and leafroll. Diagnosis of other species mentioned previously is by the above mentioned symptoms. PLRV can be detected on site using PLRV AgriStrip-magnetic. This lateral flow test uses microbeads coated with an anti-body specific to PLRV. Virus particles are separated from the plant tissue using a powerful magnet. The PLRV AgriStrip-magnetic can detect low titers that were previously thought to be too low for traditional lateral flow tests.
Disease Cycle
Insects have a crucial part in the inoculum and spread of PLRV, in particular Myzus Persicae (green peach aphid.) PLRV present in weeds of the family Solanaceae can be transmitted to potatoes and other crops by the aphid. Aphids that feed on an infected host transmit the virus persistently to healthy plants. Aphids acquire the virus when taking up infected phloem into their digestive system. The virus crosses the membrane of the gut and enters the hemocoel where it then can cross the membrane into the salivary glands.This process takes several hours after which time the aphid will continue to transmit the virus for its remaining life.Aphids can also spread PLRV to tubers in storage, especially after they sprout. Plants that have become infected with PLRV will generally produce infected tubers. Crops planted from infected tubers will then carry the virus. Winged aphids can be carried several hundred kilometers by wind currents allowing for wide spread infection.
Environment
Because PLRV is transmitted by aphid vectors it is more prevalent in environments that are conducive to aphid development. Warm humid conditions are preferred, but aphids can thrive in a number of climates as long as it is not too hot and dry. Their soft bodies make them prone to dessication. In the tropics, aphids persist year round but the efficiency of PLRV transmission is reduced at temperatures above 26 degrees Celsius.Importance
PLRV is an economically important disease due to the yield loss it can cause. Along with other aphid vectored viruses PLRV causes an annual potato loss in the U.S. of 100 million dollars. Plants that are infected with the virus produce only small to medium tubers that are not preferable in market. When plants are grown from infected tubers yield can be reduced 33-50%. PLRV is especially problematic in seed potato production since plantings from infected tubers will not yield acceptable market quality potatoes. Thus any amount of infection is above the economic threshold. In the United States the potato industry is an important source of revenue, with the top producing states in 2009 being Idaho ($735,250,000), Washington ($627,995,000) and Wisconsin ($246,330,000)Management
Since PLRV is persistently transmitted it makes for easier means of control. In order to transmit the virus the aphid must inject its saliva into the phloem of a healthy plant. PLRV can be controlled effectively by reducing aphid vector populations. Systemic and foliar insecticides can be used to prevent aphid feeding. The virus takes several hours to be transmitted by aphids, so when systemic insecticides are utilized the aphid dies before it can transmit the virus. Foliar pesticides are utilized when colonizing aphid populations get too high and are useful as a knockdown method, to rapidly reduce aphid populations.ImidaclopridImidacloprid
Imidacloprid is a nicotine-based, systemic insecticide, which acts as a neurotoxin and belongs to a class of chemicals called the neonicotinoids. Although it is now off patent, the primary manufacturer of this chemical is Bayer CropScience,...
, Methamidophos
Methamidophos
Methamidophos is an organophosphate insecticide.Crops grown with the use of methamidophos include some Latin American rice. Many nations use methamidophos on crops, including developed nations such as Spain, US, Japan, and Australia...
and Endosulfan
Endosulfan
Endosulfan is an off-patent organochlorine insecticide and acaricide that is being phased out globally. Endosulfan became a highly controversial agrichemical due to its acute toxicity, potential for bioaccumulation, and role as an endocrine disruptor...
are commonly used in aphid control.Other management strategies include sanitation and seed certification. Cleaning any volunteer tubers from a field reduces any reservoirs that may persist. Seed certification programs test seed lots utilizing ELISA for the detection of multiple potato viruses. Seed lots can then be rated by the amount of infection. Highly infected seed lots are rejected and not used the next season.