Production of tungroresistant cul ti vars is a major breeding objective. Rice tungro disease rtd is known to be one of the most economically important viral diseases of rice. Disease cycle transmission mainly by the leaf hopper vector nephotettix virescens males, females and nymphs of the insect can transmit the disease. Tungro disease viruses are transmitted from one plant to another by leafhoppers that feed on tungro infected plants. Pararetroviruses show similarities with retroviruses in molecular organization and replication. In nature, rice tungro disease is caused by an rna and a dna virus complex, but we have obtained an independently infectious clone of rice tungro bacilliform virus rtbv dna. Characterization of the protease domain of rice tungro.
Rice tungro bacilliform virus an overview sciencedirect. Green leafhopper adults tungro disease affected rice field both nymphs and adults suck the sap from the leaves and tillers with their sucking mouth parts resulting yellowing of the leaves which later become brown and dry up from the tip downwards. Spot a spot is a localized necrotic or dead area photo 4. Development of a rice tungro epidemiological model for. Complete genome sequence of rice tungro bacilliform virus. Stunting was severe in susceptible rice oryza saliva l. Asia describe rice tungro disease as a cancer disease because of the severe damage it causes and the difficulty of controlling it 121. From identification to disease control article pdf available in world applied sciences journal 316. Tungro virus disease is transmitted by leafhoppers, wherein the most efficient vector is the green leafhopper, nephotettix virescens distant.
This bacterium is of bacillus and gram negative type. Dec 20, 2017 citrus canker, tungro virus disease of rice pathogen symptoms control. Sample it6801 question bank service oriented architecture 19. Rice sheath blight disease resistance identified in oryza spp. The biology, epidemiology, and management of rice tungro disease in asia article pdf available in plant disease 862. Based on field evaluation trial and greenhouse reaction, the rice cultivars cr1467003, cr 260157, cr 2606321 and cr 319644 had high degree of resistance to tungro with high yielding ability. Yet, little is known about the genetic makeup of this important system for plant pathology. Here we report the development of two serological based assays for ease of detection. Dry rot is firm or dry decay, while soft rot is soft, watery decomposition. The disease complex is associated with rice tungro baciliform virus rtbv and rice tungro spherical virus rtsv.
Apr 14, 2005 rice tungro is a major rice disease in southeast asia and is caused by a double infection by two viruses 8, 9. Apart from direct feeding both nymphs and adults act as vectors of rice tungro virus disease. The first and only genome of rice tungro bacilliform virus rtbv isolated from rice in malaysia was sequenced in 1999. Tungro infects cultivated rice, some wild rice relatives and other grassy weeds commonly found in rice paddies.
Green leafhopper glhplays an important role in tungro disease epidemics. Abstract rice tungro, the most important virus disease of rice in south and southeast asia, is caused by a complex of two. Download fulltext pdf download fulltext pdf weed host range of rice tungro virus disease article pdf available in plant archives 181 june 2018 with 228 reads. Rtd is routinely detected based on visual observation of the plant. Overexpression of rf2a in transgenic rice plants cultivar ir64. Southern blot analysis demonstrated that the rice genome contains a single copy of the rf2b gene fig. Agroinoculation was used to introduce rtbv into the test plants. Identification of field resistant rice cultivars for tungro. Bakanae disease is an important fungal disease caused by gibberella fujikuroi. Severely infected nursery and field appear as burnt. Feb 28, 2018 what it does rice tungro disease is caused by the combination of two viruses, which are transmitted by leafhoppers. Rice tungro bacilliform virus rtbv is a reversetranscribing dna virus which, in association with an rna virus, rice tungro spherical virus rtsv, is responsible for rice tungro disease, the most important viral disease of rice in south and southeast asia. Epidemiological studies of rice tungro disease in paddy fields were conducted with a view to.
After nearly two decades, here, we present the complete genome sequence of an rtbv isolate in rice from seberang perai, malaysia. The success of a monitoring system can be measured by its ability to provide early detection of pests for prevention of a serious outbreak of rice tungro. Two host transcription factors, rf2a and rf2b, regulate expression of the rtbv promoter and are important for plant development. Identification of field resistant rice cultivars for. However, it is not always easy to identify the disease in the field as it is often confused with other diseases or physiological disorders.
Rice tungro disease is caused by an infection of two different viruses, rice. Pdf the biology, epidemiology, and management of rice. Akhigbe today and be free from your diseases because he is very good and honest doctor and he is also called the godfather of herbal root contact him via email. Transgenic rice plants that overexpress transcription. All diazinontreated plots had significantly lower leafhopper and plamhopper populations and low tungro virus infection in comparison with untreated plots. Production of tungro resistant cul ti vars is a major breeding objective. Staggered planting under the doublecropping rice systems is the major reason why tungro disease predominated after the 1960s. Balimau putih an indonesian cultivar tolerant to rice tungro bacilliform virus rtbv was crossed with ir64 rtbv, susceptible variety to produce the three filial generations f 1, f 2 and f 3. Tungro is polycyclic and complex disease of rice associated by dual infection with rice tungro bacilliform virus rtbv and rice tungro spherical virus rtsv.
The vector population, both adult and nymph, was efficiently controlled by these insecticides in. Rice tungro bacilliform virus rtbv is a pararetrovirus, and a member of the family caulimoviridae in the genus badnavirus. Fine mapping of qbk1, a major qtl for bakanae disease. The spots coalesce as the disease progresses and large areas of the leaves dry up and wither. Tungro, the most important virus disease of rice in south east asia, effects. Rice tungro disease is the most important viral disease of rice in south and southeast asia. Nov, 2008 fourteen rice cultivars were identified as field resistant. Information is given on the geographical distribution in asia. Incidence of rice bakanae disease creates serious problems in the foremost rice growing countries, and no rice variety has been found to be completely resistant to this disease. Coexistence of multiple endemic and pandemic lineages of. Tungrovirus is a genus of viruses, in the family caulimoviridae order ortervirales. Infectivity could be demonstrated only when a more than unitlength copy was cloned in the agrobacterium binary vector bin19 and agroinoculated into rice plants. They are mainly caused by bacteria, viruses, or fungi. Rice tungro, which means degenerated growth in a philippine dialect, is a devastating disease caused by coinfection with two morphologically and genetically different viruses, rice tungro spherical virus rtsv and rice tungro bacilliform virus rtbv, depicted in fig.
In rice tungro, rtbv induces most of the symptoms yellowing and reddening of the leaves, stunting of rice plants and rtsv is mainly. It may be circular, angular, or irregular in shape. Transgenic rice plants that overexpress transcription factors. Tungro disease viruses are transmitted from one plant to another by leafhoppers that feed on tungroinfected plants. The proximity of virusinfected plants and the insects ability to alternately. Genetic analysis of tolerance to rice tungro bacilliform. What it does rice tungro disease is caused by the combination of two viruses, which are transmitted by leafhoppers. Dec 30, 2008 rice tungro disease rtd is a significant yield constraint in rice growing areas of south and southeast asia. This is a leafhopper cicadellidae, nephotettix spp.
Biological control of rice tungro disease rtd springerlink. Expression of a dominant negative mutant of these factors in. High incidences of rtd have been reported across south and southeast asia 2, 3. A laboratory manual, cold spring harbor laboratory, cold. However, breeding rice varieties resistant to bakanae disease may be a costsaving solution preferable to the application of fungicides. Farmers lose an estimated average of 37% of their rice crop to pests and diseases every year. Virus diseases of rice rice tungro virus y asuo saito 11, hirovuki hibin0 21, toshihiro omura 31, and h.
Rice tungro bacilliform virus rtbv 10, 11, a member of the genus badnavirus in the family caulimoviridae, and rice tungro spherical virus rtsv, a singlestranded rna virus and member of the genus waikivirus in the family. Rf2b was predicted to encode a bzip protein of 329 aa fig. This virus disease is transmitted by nephotettix impicticeps ishihara and is nonpersistant in the vector. Rf2b, a rice bzip transcription activator, interacts with.
Planting a resistant variety is the simplest and, often, the most cost effective management for diseases. Rice sheath blight disease resistance identified in oryza. Rtbv has a long open reading frame that encodes a large polyprotein p3. Tungro became a serious problem after the release of highyielding rice cultivars which are short statured and photoinsensitive, have shorter growth duration, and allow rice growers two crops of rice in a year. Risk assessment for rice planthopper and tungro disease outbreaks article pdf available in crop protection 154. Service oriented architecture it6801 question bank pdf free download. This is the authors version of a work that was submitted. Citrus canker, virus tungro disease of rice pathogen. However, tungro, which means degenerated growth in a filipino. Fourteen rice cultivars were identified as field resistant. Rice tungro disease rtd is a significant yield constraint in ricegrowing areas of south and southeast asia. Citrus canker, tungro virus disease of rice pathogen symptoms control.
It calculates the rate of rice hill infection or how many rice hills are infected with rice tungro virus through its vector, green leafhopper glh, based on weather conditions over the. A mathematical model of transmission of rice tungro. Rice tungro disease transmitted by the green leafhopper jircas. Tungro disease is caused by a combination of an rna virus, rice tungro spherical virus rtsv and a. Diagnosis of common diseases of rice home irri rice. Common leafhopperplanthopper populations and incidence of. The viruses are common in mixed infections in south and south. Pdf the biology, epidemiology, and management of rice tungro. Abstract rice tungro, the most important virus disease of rice in south and southeast asia, is caused by a complex of two viruses, rice tungro bacilliform virus rtbv and rice tungro spherical virus rtsv. A mathematical model of transmission of rice tungro disease.
P3 contains a putative movement protein mp, the capsid protein cp, the aspartate. During flower emergence, the fungus attacks the peduncle. Grain discolouration of rice has become a serious problem in recent years especially when there is postflowering rain. One of the major threats in rice agriculture is the tungro virus, which is transmitted semipersistently to rice plants via green rice leafhoppers called nephotettix virescens. A suite of new techniques to tackle the devastating rice losses caused by tungro is now helping smallscale farmers in indonesia, the philippines and india. Crop protection center vii denpasar, bali, indonesia. Pathogen two morphologically unrelated viruses present in phloem cells. The vector population, both adult and nymph, was efficiently controlled by these insecticides in the respective rice cultivars.
Pyricularia oryzae causes the most damaging rice disease. It causes leaf discoloration, stunted growth, reduced tiller numbers and sterile or partly filled grains. Rice tungro disease rtd is one of the most destructive diseases of rice in south and southeast asia. Use of cypermethrin, a synthetic pyrethroid, in the control. Rice tungro disease, the most important viral disease of rice, is widespread in south and southeast asia and is believed to be responsible for annual losses nearing 10 billion us dollars worldwide. Reduce the activity of glhsuckasvectorsof tungro virus was effective to limit transmission of the virus. In 1975, rtbv was first recognized and then identified as a component member along with rice tungro spherical virus rtsv of the virus complex that is responsible for causing rice tungro disease. Rice tungro bacilliform virus rtbv bacilliform capsid, circular ds dna genome and rice tungro spherical virus rtsv isometric capsid ss rna genome. Rice tungro disease perhaps the most important disease affecting rice is rice tungro disease rtd. In cytoplasmic male sterile lines a lines where the emergence of the panicles is poor, the incidence of sheath rot is very high. A new distribution map is provided for rice tungro disease viruses hosts. Pdf as the most devastating viral disease of rice in south and southeast asia, rice tungro disease remains one of the. Rotting is disintegration and decomposition of host tissue photo 3.
Seasonal patterns of immigration and population development for the three major leafhopper vectors of rice tungro viruses were examined in relation to tungro. Rice tungro bacilliform virus dna independently infects. Rice tungro disease is the most important viral disease. Rice tungro disease rtd consists of a spherical virus rtsv and a bacilliform virus rtbv and the disease is a. Cypermethrin, acephate, fmc 35001, phosphamidon and demeton. This book on biological control of rice diseases deals with microorganisms and cultural practices as the nonchemical alternatives developed and used to manage devastating rice diseases such as blast, sheath blight, bacterial blight and rice tungro disease in asia.
The withinfield dynamics of rice tungro disease in relation to the. Monocots and family poaceae serve as natural hosts. It is found to occur in ortyza sativa and ortyza sp. Rice tungro, the most important virus disease of rice in south and southeast asia, is caused by a complex of two viruses, rice tungro bacilliform virus rtbv and rice tungro spherical virus rtsv. Molecular biology of rice tungro viruses and strategies for their. The tungro epidemiological model developed in this study is named rtdsim rice tungro disease simulation and is created in the r programming language r version 3. Better understanding of the leafhopper insect that spreads the virus has led to better growing practices, especially late. Rice tungro disease rtd is one of the most important virus diseases of rice in south and southeast. Rtbv is a plant pararetrovirus with bacilliform particles, the structure of which is based on t 3 icosahedral symmetry cut across the threefold axis. Characterization of the genome of rice tungro bacilliform virus. Using whole genome resequencing of a worldwide collection of isolates, we identified four major m. The disease results from an infection by two distinct viruses, rice tungro bacilliform virus rtbv and rice. Rice plants thus agroinfected with cloned rtbv dna. In major ricegrowing rtbv and rice tungro spherical virus rtsv 4.
The rice tungro bacilliform virus gene ii product interacts. Rice tungro disease rtd consists of a spherical virus rtsv and a bacilliform virus rtbv and the disease is a significant yield constraint in ricegrowing areas of south and southeast asia. Plant virus disease problems in the developing world. Disease symptoms are caused largely by infection by the rice tungro bacilliform virus rtbv. In the face of international and national food security, being a major constraint to stable rice production in south and. Citrus canker, virus tungro disease of rice pathogen symptoms. The purpose of this chapter is to introduce the reader to the major or devastating diseases of rice. Jan, 2004 the similarity between the abnormal phenotype caused by an antisense gene of rf2b and the rice symptoms of rice tungro disease may indicate that infection by rtbv reduces the availability of rf2a, rf2b, and perhaps related factors for expression of endogenous genes that are important for plant development through quenching andor titration. Pdf risk assessment for rice planthopper and tungro. Rtbv cannot be transmitted by leafhoppers unless rtsv is present. As the most important of the 14 rice viral diseases, tungro was first recognized as a leafhoppertransmitted virus disease in 1963 88.
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