Tomato yellow leaf curl virus

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Tomato yellow leaf curl virus
Virus classification OOjs UI icon edit-ltr.svg
(unranked): Virus
Realm: Monodnaviria
Kingdom: Shotokuvirae
Phylum: Cressdnaviricota
Class: Repensiviricetes
Order: Geplafuvirales
Family: Geminiviridae
Genus: Begomovirus
Species:
Tomato yellow leaf curl 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. [1] 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 the virus being sexually transmitted from infected males to non-infected females (and vice versa), and an evidence that TYLCV is transovarially transmitted to offspring for two generations. [2] [3]

Contents

Genome

This virus consists of a single circular single-stranded (ss) DNA molecule (2787 nt in size) which is a common distinction among viruses in the family Geminiviridae. The coat protein is an essential component for successful insect transmission of this virus. The ssDNA genome encodes for six open reading frames (ORF): two in the virion sense orientation, V1 and V2, and four in the complementary orientation, C1, C2, C3, and C4. The V1 and V2 protein encoded by the v1 and v2 gene are the coat protein and pre-coat protein, respectively. [4] The function of the V1 protein, identified as the coat protein, is to encapsulate the ssDNA and form the virus particle to protect the viral DNA, while the pre-coat protein is believed to be involved in movement of the virus. [1]

The six open reading frames encoded by the TYLCV genome are V1, V2, C1, C2, C3, and C4. V1 protein is the coat protein and its function is to protect the viral DNA by encapsulating it. V2 protein is the pre-coat protein, which function is still not clear, but it might be associated with viral movement. C1 protein is also known as the viral replication protein, which makes it essential for virus replication. C2, C3, and C4 proteins have been associated to function as a post-transcriptional gene silencing suppressor, a virus accumulation enhancer, and a symptom induction determinant, respectively. [1] In the insect vector, a study found that TYLCV had a high binding affinity to a GroEL homolog, a molecular chaperon essential for protein folding. Therefore, after feeding B. tabaci with a diet containing antiserum against GroEL, they found TYLCV transmission to be reduced. This study demonstrated that the GroEL homolog is involved in the virus transmission. [5]

Transmission

TYLCV is transmitted by the insect vector Bemisia tabaci in a persistent-circulative nonpropagative manner. The virus can be efficiently transmitted during the adult stages. This virus transmission has a short acquisition access period of 15–20 minutes, and latent period of 8–24 hours. In this plant-virus and vector system, females are more effective than males transmitting the virus. [1] A study demonstrated that TYLCV is transmitted to offspring for at least two generations. [3] Also, it has been demonstrated that a TYLCV isolate from Israel is sexually transmitted from one insect to another. In this study, they found that the virus was transmitted to males from virus-infected females and to females from virus-infected males. [2] muswar

Agricultural importance

Symptoms of TYLCV infection include severe stunting, reduction of leaf size, upward cupping/curling of leaves, chlorosis on leaves and flowers, and reduction of fruit production. This virus can cause significant yield losses from 90–100%, and it is estimated that about 7 million hectares can experience TYLCV infection or mixed virus infections annually. Treatments that are commonly used for this disease include insecticides, hybrid seeds, and growing tomatoes under greenhouse conditions. Developing countries are most affected by this crop disease due to both the climate and the high costs of treatments used in order to control it. [1] The primary plant host impacted by TYLCV infection are tomato plants, but other plant hosts used for food such as peppers ( Capsicum annuum ) and beans ( Phaseolus vulgaris ), as well as weeds/flowers ( Datura stramonium and Malva parviflora ) can be affected by TYLCV. [1]

Epidemiology

TYLCV is found in tropical and subtropical regions, and it is one of the most important pathogens against tomato crops around the world. This virus was first detected in Israel around 1930, and now it affects more than 30 countries around the world that grow tomatoes. TYLCV has been found in different countries from Africa, Asia, Australia, and Central and North America. The two isolates of TYLCV that are most commonly found in affected countries are tomato yellow leaf curl Sardinia virus (TYLCSV) and tomato yellow leaf curl virus-Israel (TYLCV-Isr). The first detection of TYLCV was confirmed through blot hybridization, PCR, and genome sequencing in the Dominican Republic in 1994. From here, it was then found in Jamaica and Cuba. One of the most effective techniques to detect geminiviruses in tomato is the visualization of inclusion bodies using a light microscope, as well as the immunological detection with antibodies. [6] Not only has the virus spread over the last few decades, but its insect vector has a wide distribution range as well. Bemisia tabaci has a wide geographical distribution, and it can be found in Asia, Africa, North, Central, and South America, and Australia. Since the insect vector has a wide distribution range, the virus can be spread to new areas where it has not been found but the insect is present.

Management

Currently, the most effective treatments used to control the spread of TYLCV are insecticides and resistant crop varieties. The effectiveness of insecticides is not optimal in tropical areas due to whitefly resistance against the insecticides; therefore, insecticides should be alternated or mixed to provide the most effective treatment against virus transmission. [6] Developing countries experience the most significant losses due to TYLCV infections due to the warm climate as well as the expensive costs of insecticides used as the control strategy. Other methods to control the spread of TYLCV include planting resistant/tolerant lines, crop rotation, and breeding for resistance of TYLCV. As with many other plant viruses, one of the most promising methods to control TYLCV is the production of transgenic tomato plants resistant to TYLCV. [1]

Resources

Related Research Articles

<span class="mw-page-title-main">Whitefly</span> Family of insects

Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise the family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than 1550 species have been described.

<i>Geminiviridae</i> Family of viruses

Geminiviridae is a family of plant viruses that encode their genetic information on a circular genome of single-stranded (ss) DNA. There are 520 species in this family, assigned to 14 genera. Diseases associated with this family include: bright yellow mosaic, yellow mosaic, yellow mottle, leaf curling, stunting, streaks, reduced yields. They have single-stranded circular DNA genomes encoding genes that diverge in both directions from a virion strand origin of replication. According to the Baltimore classification they are considered class II viruses. It is the largest known family of single stranded DNA viruses.

<span class="mw-page-title-main">Silverleaf whitefly</span> Species of true bug

The silverleaf whitefly is one of several species of whitefly that are currently important agricultural pests. A review in 2011 concluded that the silverleaf whitefly is actually a species complex containing at least 40 morphologically indistinguishable species.

<i>Begomovirus</i> Genus of viruses

Begomovirus is a genus of viruses, in the family Geminiviridae. They are plant viruses that as a group have a very wide host range, infecting dicotyledonous plants. Worldwide they are responsible for a considerable amount of economic damage to many important crops such as tomatoes, beans, squash, cassava and cotton. There are 445 species in this genus.

<span class="mw-page-title-main">Curly top</span> Viral disease that affects many crops

Curly top is a viral disease that affects many crops. This disease causes plants to become smaller in size, have shriveled petals and leaves, and are twisted and pulled out of shape. They are often caused by curtoviruses, members of the virus family Geminiviridae. This disease is important in western United States, such as California, Utah, Washington, and Idaho.

Cassava mosaic virus is the common name used to refer to any of eleven different species of plant pathogenic virus in the genus Begomovirus. African cassava mosaic virus (ACMV), East African cassava mosaic virus (EACMV), and South African cassava mosaic virus (SACMV) are distinct species of circular single-stranded DNA viruses which are transmitted by whiteflies and primarily infect cassava plants; these have thus far only been reported from Africa. Related species of viruses are found in India and neighbouring islands, though cassava is cultivated in Latin America as well as Southeast Asia. Nine species of cassava-infecting geminiviruses have been identified between Africa and India based on genomic sequencing and phylogenetic analysis. This number is likely to grow due to a high rate of natural transformation associated with CMV.

Cotton leaf curl viruses (CLCuV) are a number of plant pathogenic virus species of the family Geminiviridae.

Indian cassava mosaic virus(ICMV) is a plant pathogenic virus of the family Geminiviridae. It affects cassava (Manihot esculenta) in India and certain other countries. It is considered to be an invasive species.

<i>Carlavirus</i> Genus of viruses

Carlavirus, formerly known as the "Carnation latent virus group", is a genus of viruses in the order Tymovirales, in the family Betaflexiviridae. Plants serve as natural hosts. There are 53 species in this genus. Diseases associated with this genus include: mosaic and ringspot symptoms.

Cassava brown streak virus disease (CBSD) is a damaging disease of cassava plants, and is especially troublesome in East Africa. It was first identified in 1936 in Tanzania, and has spread to other coastal areas of East Africa, from Kenya to Mozambique. Recently, it was found that two distinct viruses are responsible for the disease: cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Both have (+)ss RNA genomes, belong to the genus Ipomovirus in the family Potyviridae, and produce generally similar symptoms in infected plants. Root rot renders the cassava tuber inedible, resulting in severe loss of economic value; therefore, current research focuses on achieving cultivars that do not develop the necrotic rot. This disease is considered to be the biggest threat to food security in coastal East Africa and around the eastern lakes.

Ipomovirus is a genus of positive-strand RNA viruses in the family Potyviridae. Member viruses infect plants and are transmitted by whiteflies. The name of the genus is derived from Ipomoea – the generic name of sweet potato. There are seven species in this genus.

<i>Abutilon mosaic virus</i> Species of virus

Abutilon mosaic virus (AbMV) is a virus of the genus Begomovirus. It infects Abutilon species, notably the flowering maple, Abutilon striatum. The mottled or variegated effect on the leaves of Abutilon striatum is sought after.

Cassava brown streak virus is a species of positive-strand RNA viruses in the genus Ipomovirus and family Potyviridae which infects plants. Member viruses are unique in their induction of pinwheel, or scroll-shaped inclusion bodies in the cytoplasm of infected cells. Cylindrical inclusion bodies include aggregations of virus-encoded helicase proteins. These inclusion bodies are thought to be sites of viral replication and assembly, making then an important factor in the viral lifecycle. Viruses from both the species Cassava brown streak virus and Ugandan cassava brown streak virus (UCBSV), lead to the development of Cassava Brown Streak Disease (CBSD) within cassava plants.

<i>Pepper leaf curl virus</i> Species of virus

Pepper leaf curl virus(PepLCV) is a DNA virus from the genus Begomovirus and the family Geminiviridae. PepLCV causes severe disease especially in pepper (Capsicum spp.). It can be found in tropical and subtropical regions such as Thailand and India, but has also been detected in countries such as the United States and Nigeria. This virus is transmitted by an insect vector from the family Aleyrodidae and order Hemiptera, the whitefly Bemisia tabaci. The primary host for PepLCV are several Capsicum spp.. PepLCV has been responsible for several epidemics and causes severe economic losses. It is the focus of research trying to understand the genetic basis of resistance. Currently, a source of resistance to the virus has been identified in the Bhut Jolokia pepper.

Chilli leaf curl virus(ChiLCV) is a DNA virus from the genus Begomovirus and the family Geminiviridae. ChiLCV causes severe disease especially in pepper (Capsicum spp.), but also affects other crops such as tomato (Solanum lycopersicum). It can be found in tropical and subtropical regions primarily in India, but has also been detected in countries such as Indonesia and Sri Lanka. This virus is transmitted by an insect vector from the family Aleyrodidae and order Hemiptera, the whitefly Bemisia tabaci. The primary host for ChiLCV are several Capsicum spp., but host species also include tomato and amaranth. ChiLCV has been responsible for several epidemics and causes severe economic losses. It is the focus of research trying to understand the genetic basis of resistance. Currently, a few sources of resistance have been discovered and used to breed resistant varieties.

Papaya leaf curl virus(PaLCuV) is a DNA virus from the genus Begomovirus and the family Geminiviridae. PaLCuV causes severe disease in papaya (Carica papaya), but can sometimes infect other crops such as tobacco or tomato. It can be found in tropical and subtropical regions primarily in India, but closely related species have also been detected in countries such as China, Malaysia, Nigeria and South Korea. This virus is transmitted by an insect vector from the family Aleyrodidae and order Hemiptera, the whitefly Bemisia tabaci. PaLCuV has been responsible for several epidemics and causes severe economic losses. Because of the broad diversity of these viruses, their characterization and control remains difficult.

<i>Sweet potato leaf curl virus</i> Species of virus

Sweet potato leaf curl virus is commonly abbreviated SPLCV. Select isolates are referred to as SPLCV followed by an abbreviation of where they were isolated. For example, the Brazilian isolate is referred to as SPLCV-Br.

Tomato yellow leaf curl China virus (TYLCCNV) is a virus which contains 25 isolates. It infects plants as different as tobacco and tomato, as well as genetically modified plants. Petunias can be infected, but show no symptoms. The microbiology of the virus has been studied in the Chinese province of Yunnan. Tomato yellow leaf curl China virus belongs to the genus Begomovirus, which also contains the tomato leaf curl China virus.

The tomato chlorosis virus (ToCV) is an RNA virus belonging to the genus crinivirus, a group of plant-infecting viruses in the family Closteroviridae.

References

  1. 1 2 3 4 5 6 7 Glick, M; Levy, Y; Gafni, Y (2009). "The Viral Etiology of Tomato Yellow Leaf Curl Disease – A Review". Plant Protection Sciences. 3: 81–97. doi: 10.17221/26/2009-PPS .
  2. 1 2 Ghanim, M; Czosnek, H (2000). "Tomato Yellow Leaf Curl Geminivirus (TYLCV-Is) Is Transmitted among Whiteflies (Bemisia tabaci) in a Sex-Related Manner". Journal of Virology. 74 (10): 4738–4745. doi:10.1128/jvi.74.10.4738-4745.2000. PMC   111996 . PMID   10775612.
  3. 1 2 Ghanim, M; Morin, S; Zeidan, M; Czosneck, H (1998). "Evidence for transovarial transmission of tomato yellow leaf curl virus by its vector, the whitefly Bemisia tabaci". Journal of Virology. 240 (2): 295–303. doi: 10.1006/viro.1997.8937 . PMID   9454703.
  4. ↑ Navot, J.E.; Pichersky, E; Zeidan, M; Zamir, D (1991). "Tomato Yellow Leaf Curl Virus: A Whitefly-Transmitted Geminivirus with a Single Genomic Component" (PDF). Journal of Virology. 185 (1): 151–161. doi:10.1016/0042-6822(91)90763-2. hdl: 2027.42/29562 . PMID   1926771.
  5. ↑ Morin, S; Ghanim, M; Zeidan, M; Czosnek, H; Verbeek, M; van den Heuvel, J (1999). "A GroEL homologue from endosymbiotic bacteria of the whitefly Bemisia tabaci is implicated in the circulative transmission of tomato yello leaf curl virus". Journal of Virology. 256 (1): 75–84. doi: 10.1006/viro.1999.9631 . PMID   10087228.
  6. 1 2 Poston, J.E.; Anderson, P.K. (1997). "The Emergency of Whitefly-Transmitted Geminiviruses in Tomato in the Western Hemisphere". Plant Disease. 81 (12): 1358–1369. doi:10.1094/pdis.1997.81.12.1358. PMID   30861786.
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