| Indian cassava mosaic virus | |
|---|---|
Virus classification  | |
| (unranked): | Virus |
| Realm: | Monodnaviria |
| Kingdom: | Shotokuvirae |
| Phylum: | Cressdnaviricota |
| Class: | Repensiviricetes |
| Order: | Geplafuvirales |
| Family: | Geminiviridae |
| Genus: | Begomovirus |
| Species: | Indian cassava mosaic virus |
| Synonyms | |
| |
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. [1]
This virus was unknown in India before the introduction of cassava into the country by the Portuguese in the seventeenth century, nor has a similar virus been reported in the New World where cassava originated. [1] It is possible that the virus is native to India, affecting some yet-to-be-identified plant host, with the virus later adopting cassava as its preferred host; once present in a crop, the virus can be spread from plant to plant by insects such as whitefly. [1]
The virus was first noticed in India in 1942. Its incidence is higher in Tamil Nadu and Kerala, the states where most cassava is grown, and it is of little consequence elsewhere in the country. Depending on the cultivar and the time of year, losses in root yield can vary from negligible to 84%. [2]
In India, the natural hosts of ICMV are Manihot esculenta and Manihot carthaginensis subsp. glaziovii. Additionally, Jatropha curcas shows mosaic symptoms similar to cassava infected by ICMV; affected leaves have been shown to react in ELISA bioassay trials to African cassava mosaic virus antiserum, but follow up with a DNA B probe has provided negative results. [2] This mosaic disease may be a new strain of ICMV affecting J. curcas, a plant with a potential as a biofuel crop, and it may become necessary to develop virus-resistant clones. [3]
The foliage of the plant exhibits the main symptoms which are yellow or green mosaic patterns appearing on the leaves, mottling, contortion, mis-shapen leaves, distorted growing points, stunting of the plant, rosetting, dwarfing and reduction in the root system. [1]
ICMV is not transmissible by seed, so cassava seedlings are initially healthy. However the crop is mainly planted by stem cuttings and these are often infected. The main vectors involved in transferring the virus between plants are whitefly, particularly the silverleaf whitefly (Bemisia tabaci). One strain of B. tabaci in India infests cassava, eggplant and tobacco, and transmits ICMV. A second biotype infests sweet potato, cotton, eggplant, tobacco and tomato but not cassava, and this seems incapable of transmitting ICMV. [2] The spiralling whitefly, Aleurodicus dispersus , also colonises cassava in India but whether it has a role in transferring the virus remains unclear. [2]
Tobacco mosaic virus (TMV) is a positive-sense single-stranded RNA virus species in the genus Tobamovirus that infects a wide range of plants, especially tobacco and other members of the family Solanaceae. The infection causes characteristic patterns, such as "mosaic"-like mottling and discoloration on the leaves. TMV was the first virus to be discovered. Although it was known from the late 19th century that a non-bacterial infectious disease was damaging tobacco crops, it was not until 1930 that the infectious agent was determined to be a virus. It is the first pathogen identified as a virus.
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.
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.
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 currently 424 species in this genus including the type species Bean golden yellow mosaic virus.
African cassava mosaic virus is a plant pathogenic virus of the family Geminiviridae that may cause either a mosaic appearance to plant leaves, or chlorosis, a loss of chlorophyll. In Manihot esculenta (cassava), a highly valuable African food crop, the virus causes severe mosaic. Cassava is a staple food crop in many places throughout the tropics and subtropics as a source of carbohydrates, but the transmission and severity of disease for cassava in Africa is greatest with ACMV.
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.
Barley stripe mosaic virus (BSMV), of genus Hordevirus, is an RNA viral plant pathogen whose main hosts are barley and wheat. The common symptoms for BSMV are yellow streaks or spots, mosaic, leaves and stunted growth. It is spread primarily through infected seed and can be spread through mechanical transfer of an infected and uninfected host. Plants infected with BSMV are more symptomatic in warmer temperatures. Resistant hosts and sterilization of equipment are the best ways to control the spread of the pathogen. BSMV has been known to reduce the yields of barley by up to 25%, but is not a major problem because of resistant varieties of barley.
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).
Sunn-hemp mosaic virus (SHMV) is a pathogenic plant virus. It is known by many names, including bean strain of tobacco mosaic virus and Sunn-hemp rosette virus. SHMV is an intracellular parasite that infects plants. It can be seen only through an electron microscope. It is a positive-sense single-stranded RNA virus that causes physical characteristics of spotting and/or discoloration. The Sunn-hemp mosaic virus is listed as a species within the genus Tobamovirus and the virus family Virgaviridae by the International Committee on the Taxonomy of Viruses, who renamed it from "Sunnhemp" to "Sunn-hemp" in 1991.
Mungbean yellow mosaic virus (MYMV) is a plant pathogenic virus of the family Geminiviridae. Of the various viral diseases inflicting legume crops, Mungbean Yellow Mosaic disease is one of the most destructive and widely distributed. The disease has been reported from various countries.
Pepper mild mottle virus (PMMoV) is a plant pathogenic virus that occurs worldwide on species of field grown bell, hot and ornamental pepper species. It is caused by members of the plant virus genus Tobamovirus- otherwise known as the tobacco mosaic virus family. Tobamovirus are viruses that contain positive sense RNA genomes that infect plants. Symptoms of the disease vary depending on the cultivar. Typical symptoms include the chlorosis of leaves, stunting, and distorted and lumpy fruiting structures. The virus is spread by mechanical transmission and infected seeds. Avoidance is the best means of controlling the disease because once a plant is infected it cannot be treated. Only seeds that have been tested and treated for the pathogen should be planted.
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.
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.
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.
Xanthomonas axonopodis pv. manihotis is the pathogen that causes bacterial blight of cassava. Originally discovered in Brazil in 1912, the disease has followed cultivation of cassava across the world. Among diseases which afflict cassava worldwide, bacterial blight causes the largest losses in terms of yield.
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.
Pepper leaf curl virus(PepLCV) is a DNA virus from the genus Begomovirus and the family Geminiviridae. PepLCV causes severe disease especially in pepper. 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.
Papaya leaf curl virus(PaLCuV) is a DNA virus from the genus Begomovirus and the family Geminiviridae. PaLCuV causes severe disease in 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.
The cardamom mosaic virus (CdMV) is a mosaic virus that affects the production of green cardamom. It is a member of the genus Macluravirus, and is transmitted through aphids and infected rhizomes, the former in a non-persistent manner.