Beighley encyclopedia of life support systems eolss 2. Symptoms of tungro include orange yellow coloring of leaves, stunting, reduction in tiller number, and poor panicle emergence. 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. Tungro virus disease is transmitted by leafhoppers, wherein the most efficient vector is the green leafhopper, nephotettix virescens distant. Rice tungro is a composite disease caused by rice tungro. 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. The disease complex is associated with rice tungro baciliform virus rtbv and rice tungro spherical virus rtsv. The compendium of rice diseases and pests, second edition, is a useful tool for academics and professionals involved with rice crops, including researchers, diagnosticians, extension personnel, crop consultants, farm managers, and growers. From 2005 to 2006, more than 485,000 ha of rice production area in southern vietnam were severely affected by viral diseases seemingly spread by bph, resulting in the loss of 828,000 tons of rice. Rice tungro and tungrolike diseases are distributed in south and southeast. Since 1984, more women than men have died each year from heart disease. 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. Monocots and family poaceae serve as natural hosts.
Combining genes that overexpress rf2a and rf2b with genes that provide resistance to the insect vector could generate new rice varieties with significantly improved resistance to rice tungro disease in vulnerable regions in the world. The spatial distribution spatial distribution subject category. The tungro disease, fairly widespread in this region is caused by the joint infection with two dissimilar viruses. Rf2b, a rice bzip transcription activator, interacts with. Risk assessment for rice planthopper and tungro disease. Rice tungro disease rtd is one of the destructive and prevalent diseases in the tropical region. Technology identified could reduce the spread of rice. Potential candidate genes for improving rice disease. Average tungro incidence in monthly planted fields was higher in plots planted in the. Heart disease reversal diets south denver cardiology.
The initial lesions are small, ellipsoid or ovoid, and greenishgray photo. Southern blot analysis demonstrated that the rice genome contains a single copy of the rf2b gene fig. After removal of the rice grain from the chaff, the rice can be used as brown rice or further processed to remove the bran to produce white rice. Spot a spot is a localized necrotic or dead area photo 4. Quantitative estimation of seed microflora of rices. Plant pathology question answers bank for competitive exams. 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. Properties see more details of rice rice subject category. Aphids are exquisitely designed for their roles as vector. Rtbv has a long open reading frame that encodes a large polyprotein p3.
Integrated management of rice tungro disease in south. It causes leaf discoloration, stunted growth, reduced tiller numbers and sterile or partly filled grains. Characterization of the protease domain of rice tungro. Organism groups see more details ir26, ir62, ir64, ir68305181, utri merah, balimau putih, t11602, t12180 and t12357 was studied during. Farmers lose an estimated average of 37% of their rice crop to pests and diseases every year. Depending on the part of the plant affected, the disease is often called leaf blast, rotten neck, or panicle blast.
The disease is caused by rice tungro virus rtv, which is transmitted by the green leafhopper, nephotettix virescens. Rice types and products there are two main types of rice, japonica and indica, differentiated by the area where they are grown and by their traits when cooked. Krishnaveni principal scientist plant pathology breeding elite rice lines resistant against rice tungro virus disease directorate of rice research hyderabad, andhra pradesh. By controlling high blood pressure, quitting smoking, maintaining a healthy diet and by maintaining low cholesterol levels heart diseases can be prevented. Information is given on the geographical distribution in asia. Bacterial and viral diseases of rice linkedin slideshare. Rtd is caused by rice tungro spherical virus rtsv and rice tungro bacilliform virus. Insects glh were released on infected plants for 24 h to acquire the. Planting a resistant variety is the simplest and, often, the most cost effective management for diseases.
The spots may merge leading to a complete drying of the infected leaf. Commodities and products see more details tungro virus rtv disease on 9 rice cultivars cultivars subject category. Complex virus rtbv and rtsv transmitted by green leafhopper nephotettix spp. Pecky rice kernel spotting feeding injury by rice stink bug, oebalus pugnax. Blast fungus pyricularia grisea this disease can cause serious losses to susceptible varieties during periods of weather conditions favorable to growth of blast. Tungro virus disease of rice has been a serious problem in rice production in south sulawesi, indonesia. Tungro infects cultivated rice, some wild rice relatives and other grassy weeds commonly found in rice paddies. Rice technology bulletin series pinoy rice knowledge bank.
International conference on integrated plant disease. Tungro disease management in organic basmati rice agropedia. Brown and white rice may be consumed after cooking or may be ground into rice flour. 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.
Rice tungro is one of the most destructive viral disease particularly in north eastern and eastern coastal regions of peninsular india. Chaudbary and ghildyal 1969 and ahilja and rkhie f991 incucate that 1 minimum temperaturesfor rice gcmination and development are. Pdf as the most devastating viral disease of rice in south and southeast asia. Disease cycle transmission mainly by the leaf hopper vector nephotettix virescens males, females and nymphs of the insect can transmit the disease. During 19771981, the annual population fluctuation pattern of the vectors nephotettix virescens and n.
The term heart disease is often interchanged with the term cardiovascular disease. Spatial distribution of rice tungro virus on some rice. Tungrovirus is a genus of viruses, in the family caulimoviridae order ortervirales. Dry rot is firm or dry decay, while soft rot is soft, watery decomposition. Symptoms the lesions are usually observed on the leaf sheaths although leaf blades may also be affected. The biology, epidemiology, and management of rice tungro. Rice seeds imbibe water at adequate tcmptrsture in the pmence of oxygen yoshida, 198 i. What it does rice tungro disease is caused by the combination of two viruses, which are transmitted by leafhoppers. Rice tungro bacilliform virus rtbv bacilliform capsid, circular ds dna genome and rice tungro spherical virus rtsv isometric capsid ss rna genome. In cytoplasmic male sterile lines a lines where the emergence of the panicles is poor, the incidence of sheath rot is very high.
Before 1970s, it was relatively common but minor rice disease in the midsouth riceproducing area of the usa. Growth and production of rice encyclopedia of life. This is a leafhopper cicadellidae, nephotettix spp. Diagnosis of common diseases of rice home irri rice.
Arsenic induced, unknown physiological disorder white tip see nematodes aphelenchoides besseyi. Pararetroviruses show similarities with retroviruses in molecular organization and replication. Rtbv, or when they acquire rtsv first and then rtbv. Tungro is the most serious virus disease of rice and the major constraint to rice production in south and southeast asia. It is a composite disease caused by rice tungro bacilliform virus rtbv and rice tungro spherical virus rtsv 10. Compendium of rice diseases and pests, second edition. Rice tungro disease perhaps the most important disease affecting rice is rice tungro disease rtd. Beating tungro virus disease in rice riu validated rnrrs output. They are mainly caused by bacteria, viruses, or fungi. In major ricegrowing rtbv and rice tungro spherical virus rtsv 4. It is a valuable tool for the field, lab, or classroom.
Tungro disease viruses are transmitted from one plant to another by leafhoppers that feed on tungroinfected plants. Many farmers in south and southeast asia describe rice tungro disease as a cancer disease because of the severe damage it causes and the difficulty of controlling it 7 and 8. Diseases caused by fungal and bacterial pathogens like magnaporthe oryzae and xanthomonas oryzae pv. Tungro stunts rice plants and changed the leaf colour to shades of yellow or orange. Rice tungro disease is caused by the combination of two viruses, which are transmitted by leafhoppers. Mechanisms of transmission are best understood by considering the routes of virus movement in the aphid circulative versus non. Pdf on feb 1, 2002, osmat azzam and others published the biology, epidemiology, and management of rice tungro. Tungro is a disease complex associated with rice tungro bacilliform rtbv and spherical. Staggered planting under the doublecropping rice systems is the major reason why tungro disease predominated after the 1960s. Suppression of symptoms of rice tungro virus disease by. Transmission of rice tungro bacilliform virus rtbv and rice tungro spherical virus rtsv to rice and weeds by nephotettix virescens, n. Their viral carrier is the green leafhopper, nephotettix virescens. Rotting is disintegration and decomposition of host tissue photo 3. July 1995 planthopper bph, nilaparvata lugens, which causes damage mainly by sucking the sap of the rice plant although it also carries the virus diseases rice ragged stunt and rice grassy stunt, and secondly, rice tungro virus disease rtvd which is transmitted by the leafhoppers, nephotettix spp.
Rf2b was predicted to encode a bzip protein of 329 aa fig. Biological control of rice tungro disease rtd springerlink. Which one of the following fertilizers contain water soluble p. Pdf the biology, epidemiology, and management of rice tungro. Infected plants usually have somewhat fewer tillers than healthy plants. Rice tungro disease or yellow orange leaf disease, an important rice disease in asia, is caused by two types of viruses, rice tungro bacilliform vlrus rtbv and rice tungro spherical vlras rtsv. Physical interaction of rtbv orfi with d1 protein of oryza sativa. Top most important plant pathology question answers bank are useful for general agriculture for icar and other jrf, srf, ars, ph. Rtbv cannot be transmitted by leafhoppers unless rtsv is present. Rice is the most important food crop in india and plays a key role in delivering global food security. Plants affected by tungro exhibit stunting and reduced tillering. In the philippines, the disease used to attack rice plants in the upland and rainfed rice ecosystem. The symptoms and severity of this disease depends on these two types of viral.
Pathogen two morphologically unrelated viruses present in phloem cells. It was recognized as the most economically important rice disease in the midsouth lee and rush, 1983. Transmission of plant viruses by aphid vectors ng 2004. Rice blast is the worlds most prevalent disease as it reduces yield by 50 to 85%. Added to asia describe rice tungro disease as a can since the peak that was. Better understanding of the leafhopper insect that spreads the virus has led to better growing practices, especially late. Rice diseases and pests, description, uses, propagation. It may be circular, angular, or irregular in shape. Asia describe rice tungro disease as a can cer disease. Discoloration begins from leaf tip and extends down to the blade or the lower leaf portion.
The purpose of this chapter is to introduce the reader to the major or devastating diseases of rice. Grain discolouration of rice has become a serious problem in recent years especially when there is postflowering rain. Rice tungro spherical virus resistance into photoperiod. Unesco eolss sample chapters soils,plant growth and crop production vol. The disease is transmitted through spores scattered in the air, affecting rice growing areas that were once free from the disease. Glh retained the ability to acquire rtbv longer than rts\ itself. P3 contains a putative movement protein mp, the capsid protein cp, the aspartate.
Up to now, in rice, the modification of the expression of more than 60 genes from diverse origins has shown beneficial effects with respect to disease resistance. In rice tungro, rtbv induces most of the symptoms yellowing and reddening of the leaves, stunting of rice plants and rtsv is mainly. Piercing sucking mouthparts facilitate the delivery of virions into plant cells. Rice tungro disease stunting and reduced tillering. Presence of bacteria in the rice paddy and irrigation. Absence of symptoms at early growth stage of the disease development is one of limitation in the way of tungro management 6. In this case of rice tungro disease, viral infection is commonly transmitted by the green leafhopper. Rice tungro disease is caused by the combined action of rice tungro. Relations of rice tungro bacilliform and rice tungro. It generally refers to the conditions that involve narrowed or blocked blood vessels that can lead to a heart attack, chest pain or stroke. Their leaves become yellow or orangeyellow, may also have rustcolored spots. Disease symptoms are caused largely by infection by the rice tungro bacilliform virus rtbv. Genetic analysis of tolerance to rice tungro bacilliform. Insects are the most common of the vectors and, among these, aphids account for the transmission of 50% of the insectvectored viruses brunt et al.
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