|Tobacco streak virus|
Tobacco streak virus
asparagus stunt virus
Tobacco streak virus (TSV) is a plant pathogenic virus of the family Bromoviridae, in the genus Ilavirus. It has a wide host range, with at least 200 susceptible species.TSV is generally more problematic in the tropics or warmer climates. TSV does not generally lead to epidemics, with the exception of sunflowers in India and Australia, and peanuts in India.
TSV has been reported worldwide in North and South America, Europe, India, Japan, Australia, New Zealand and South America.TSV has a wide host range including both monocots and dicots. Economically important crop hosts include peanuts, sunflower, soybean, cranberry, cotton, chickpea and mung beans. As with many plant viruses, diagnosis is very difficult because TSV has very wide host range and has different effects depending on the host being infected. Symptoms of TSV may include black streaks on stems and leaves, stunted growth, chlorosis, leaf mosaic, lodging, and deformed growing tips, to name a few. On tobacco plants, TSV causes chlorosis, with a unique pattern of white or dark necrotic leaf tissue close to the veins of the leaf. As its name implies, necrotic streaks are found on leaf veins of infected plants. Symptoms are strongly influenced by temperature. For example, plants experiencing a temperature of 20° Celsius will develop small necrotic spots while at temperatures above 30° Celsius, necrotic spots will become large necrotic arcs. Symptoms are not sufficient to correctly identify TSV - serology and PCR techniques are required.
TSV purified from infected plants consists of a ss-RNA genome encapsulated by spheroid particles made up of coat protein subunits.The coat protein subunits play a key role in the life cycle of the virus. Once the virus has penetrated into the host cells, it uncoats and releases its viral genomic RNA into the cytoplasm and expressed proteins replicate. After replication, the dsRNA genome is synthesized from genomic ssRNA. Subgenomic RNA4 is translated producing capsid proteins and the new virus particles are assembled. The coat protein of TSV plays an important role in its life cycle. It protects the viral genome and plays a role in cell to cell movement. Once the virus becomes systemic, it can be transmitted by vectors. TSV requires a living plant to survive for a period of time. The virus may be transmitted by thrips vector, mechanical damage, pollen or dodder.
Severe outbreaks of TSV typically occur under climatic conditions that allow large thrips populations to develop and when large quantities of pollen are being produced by the host plant. These conditions generally occur in warmer months but are dependent on rainfall and weeds in the field.
Modes of Transmission:
Control for TSV is difficult, and there are no chemical controls available for the virus. The best management practices are to maintain good sanitation, purchase certified seed, control insects that serve as vectors, and provide barrier crops.
Sanitation: Remove plant debris after harvest or any plant material that may serve as a source of inoculum. Due to its wide host range, TSV may also infect many weed species, so keeping fields free of weeds is a good control strategy.
Chemical Control: Preventative control of disease dispersal may be possible if insecticide is sprayed for the trips vector. Barrier Crops: One common form of management for viruses is to plant a desirable host for thrips around the cropping system. The thrips will insert their stylet and “clean” off any virus on their stylet before moving to the target crop.
Barrier Crops: One common form of management for viruses is to plant a desirable host for thrips around the cropping system. The thrips will insert their stylet and “clean” off any virus on their stylet before moving to the target crop.
Plant viruses are viruses that affect plants. Like all other viruses, plant viruses are obligate intracellular parasites that do not have the molecular machinery to replicate without a host. Plant viruses can be pathogenic to higher plants.
Bromoviridae is a family of viruses. Plants serve as natural hosts. There are currently 36 species in this family, divided among 6 genera.
Luteoviridae is a family of viruses. Plants serve as natural hosts. There are currently 51 species in this family, divided among three genera, with seven unassigned species. Diseases associated with this family include: yellowing symptoms.
The Potyviridae are a family of viruses that encompasses more than 30% of known plant viruses, many of which are of great agricultural significance. Currently, more than 190 species are placed in this family, divided among eight genera.
Potyvirus is a genus of viruses in the family Potyviridae. Plants serve as natural hosts. There are currently 158 species in this genus including the type species potato virus Y. The genus is named after the type virus. Potyviruses account for ~30% of the currently known plant viruses. Like begomoviruses, members of this genus may cause significant losses in agricultural, pastoral, horticultural and ornamental crops. More than 200 species of aphids spread potyviruses and most are from the subfamily Aphidinae.
Nepovirus is a genus of viruses in the order Picornavirales, in the family Secoviridae, in the subfamily Comovirinae. Plants serve as natural hosts. There are currently 36 species in this genus including the type species Tobacco ringspot virus. Nepoviruses, unlike the other two genera in the subfamily Comovirinae, are transmitted by nematodes.
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 Bromoviridae family. 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.
Bean pod mottle virus, or BPMV, is a species of plant pathogenic virus in the family Secoviridae. It is known to infect soybean crops.
Cucumber mosaic virus (CMV) is a plant pathogenic virus in the family Bromoviridae. It is the type member of the plant virus genus, Cucumovirus. This virus has a worldwide distribution and a very wide host range. In fact it has the reputation of having 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).
Impatiens necrotic spot virus(INSV) is a plant pathogenic virus of the order Bunyavirales. It was originally believed to be another strain of Tomato spotted wilt virus but genetic investigations revealed them to be separate viruses. It is a single stranded RNA It has a tripartite genome and is largely spread by the insect vector of the western flower thrips. The virus infects more than 648 species of plant including important horticultural and agricultural species such as fuchsia, tomato, orchids, and lettuce. As the name implies, the main symptom on plants is necrotic spots that appear on the leaves. The INSV virus infects by injecting the RNA the virus contains into the cell which then starts using the cell resources to transcribe what the virus RNA states. Viral infection can often result in the death of the plant. The disease is mainly controlled by the elimination of the western flower thrip vector and by destroying any infected plant material.
Potato virus Y (PVY) is a plant pathogenic virus of the family Potyviridae, and one of the most important plant viruses affecting potato production.
Prunus necrotic ringspot virus (PNRSV) is a plant pathogenic virus causing ring spot diseases affecting species of the genus Prunus, as well as other species such as rose and hops. PNRSV is found worldwide due to easy transmission through plant propagation methods and infected seed. The virus is in the family Bromoviridae and genus Ilarvirus. Synonyms of PNRSV include European plum line pattern virus, hop B virus, hop C virus, plum line pattern virus, sour cherry necrotic ringspot virus, and peach ringspot virus.
Tomato yellow leaf curl virus(TYLCV) is a DNA virus from the genus Begomovirus and the family Geminiviridae. TYLCV causes the most destructive disease of tomato, and it can be found in tropical and subtropical regions causing severe economic losses. This virus is transmitted by an insect vector from the family Aleyrodidae and order Hemiptera, the whitefly Bemisia tabaci, commonly known as the silverleaf whitefly or the sweet potato whitefly. The primary host for TYLCV is the tomato plant, and other plant hosts where TYLCV infection has been found include eggplants, potatoes, tobacco, beans, and peppers. Due to the rapid spread of TYLCV in the last few decades, there is an increased focus in research trying to understand and control this damaging pathogen. Some interesting findings include virus being sexually transmitted from infected males to non-infected females, and an evidence that TYLCV is transovarially transmitted to offspring for two generations.
Soybean mosaic virus (SMV) is a member of the plant virus genus Potyvirus. It infects mainly plants belonging to the family Fabaceae but has also been found infecting other economically important crops. SMV is the cause of soybean mosaic disease that occurs in all the soybean productions areas of the world. Soybean is one of the most important sources of edible oil and proteins and pathogenic infections are responsible for annual yield losses of about $4 billion dollars in the United States. Among these pathogens, SMV is the most important and prevalent viral pathogen in soybean production worldwide. It causes yield reductions of about 8% to 35% but losses as high as 94% have been reported.
Strawberry Crinkle Virus (SCV) is a negative sense single stranded RNA virus that threatens strawberry production worldwide. This virus reduces plant rigidity, runner production, fruit size, and production, while causing distortion and crinkling of the leaves. This virus was first described in 1932 in Oregon and California with commercial strawberry varieties, and later became an issue around the world, including North America, South America, Europe, South Africa, New Zealand, Australia, and Japan. Of the family Rhabdoviridae, it is a large family of viruses that affects plants, vertebrates, and invertebrates. Specifically, this virus is transmitted through two aphid vectors that feed on strawberry plants of genus Fragaria, Chaetosiphon fragaefolii and C. jacobi. When SCV is combined with other aphid-transmitted strawberry viruses, such as mottle, mild yellow-edge, vein banding, or pallidosis, the damage becomes even more deleterious. Economically, Fragaria ananassa are those being affected by SCV.
The Orthotospoviruses are a genus of negative RNA virus found within the family Tospoviridae of the order Bunyavirales. The genus takes its name from the discovery of tomato spotted wilt virus (TSWV) in Australia in 1919. It remained the only member of the family until the early 1990s when genetic characterisation of viruses discovered in plants became more common. There are now at least twenty viral species in the family with more being recorded and described on a relatively regular basis. Together, these viruses have been documented infecting over eight hundred different plant species from 82 different families.
Idaeovirus is a genus of positive-sense ssRNA viruses that contains one species: Raspberry bushy dwarf virus (RBDV). Although the genus does not belong to any family or order, it has been proposed as a member of the family Bromoviridae due to similarities to members of that family. RBDV has two host-dependent clades: one for raspberries; the other for grapevines. Infections are a significant agricultural burden, resulting in decreased yield and quality of crops. RBDV has a synergistic relation with Raspberry leaf mottle virus, with co-infection greatly amplifying the concentration of virions in infected plants. The virus is transmitted via pollination with RBDV-infected pollen grains that first infect the stigma before causing systemic infection.
Soybean vein necrosis virus is a plant pathogenic virus of soybeans. SVNV is a relatively new virus, which was discovered in Tennessee in 2008 and has recently been found in many US states from the Southeast and East coast to some western states including CA. This pathogen initially causes intraveinal chlorosis (yellowing) in leaves. This chlorosis then spreads throughout the leaf and eventually these chlorotic areas can become necrotic. It is a member of the order Bunyavirales, family Tospoviridae and genus Orthotospovirus, which is the only genus within this virus family that infects plants. Like other members of Bunyavirales, this virus is enveloped and has a negative sense single-stranded RNA (−ssRNA) genome composed of three genomic segments. It encodes proteins on the M and S segments in an ambisense manner.
Carrot virus Y (CarVY) is a (+)ss-RNA virus that affects crops of the carrot family (Apiaceae), such as carrots, anise, chervil, coriander, cumin, dill and parsnip. Carrots are the only known crop to be infected in the field. Infection by the virus leads to deformed roots and discolored or mottled leaves. The virus is spread through insect vectors, and is currently only found in Australia.