Plant Protection from Tobacco Mosaic Virus

Plant disease resistance give protection the plants from pathogens in the two ways :by performes structures and chemicals and to the induced response of immune system. Disease resistance is the reduction from the pathogens that are growing into are onto the plant. it elaborate the plants that having little disease at pathogens level. Three-way interaction of pathogens is used to determine the disease outcome, environmental condition and the plant.

Defence activating compound can move from cell to cell and by to the plant vascular system. Infect the plant are not having circulating immune cell. Different cell types having vast antimicrobial defense. There are about 450 species there are plants pathogenic viruses that causes the limitation of disease. Plants have adapted detailed actual and defence mechanism to prevent or limit the viral infection. rna silencing has prominent gained and it’s an important pathway. These steps are result in effectively protection against plant viruses. Plant developed various approaches for the resistance of viruses, while differ viruses have overcome these resistance barriers. Resistance to plant viruses show different level and different mechanisms. Different isolated genes are involved in resistance. For getting a virus resistant host plant the scope of operational strategy are uses todays. infect for a centuries plant breeders are able to invent natural genes in a suitable genotypes unknowing the resistance traits that were knowing growing mostly resistance genes that are dominant, and analyzed I has not only describe the natural system of plant defenses but also give a proper way to use a gene far from the species border. Beside using the trait that are natural we also used some ‘engineered type of viruses resistance that has been established over the last fifteen years. The very first success that were getting from the principle of pathogen delved resistance by transferring the host plant with to the genes that are viral and or with a sequences purpose to block a specific step. plants are involved with the environment that are rich with the keen to exploit with the plant biosynthetic and energy producing capacity. The concept of virus was discovered with the Tobacco mosaic virus in the late nineteenth century. In this section I highlighted those discoveries. We have to divided the plant viruses researches into the “Classical Discovery Period” from 1883–1951 in which the searches were very descriptive; an “Early Molecular Era” from 1952 to about 1983, in which informative knowledge was flourish that described further premises of the viruses, assist by the enlargement of a numbers of important craftsmanship, and “Recent eras” from 1983 to the present days, when crafts have been developed to modified type of plant virus genomes, to detect a nonstructural gene products, to identify the functionality of viral gene products, and to transmute plants to bring out original formation of resistance to viral diseases. In this era, plant virology has influence a notable role in developing a comprehension of the mechanisms of gene silencing and recombination, plasmodesmatal function, systemic acquired resistance, and in progressing methodology for bacterial diagnosis. We also make an effort to speculate the regulation of plant virology will take in the coming years.

Mosaic viruse infect the plants in several ways. This virus is infected over and beyond 150 types of plants, including many vegetables, fruits, and flowers. It is characterized by leaves mottled with white, yellow, and dark and light green spots or stripe. Some of the mostly commonly infected plants including tomatoes, squashes, cauliflower, and cucumbers. Cucumber mosaic virus is one of the most unsuual types of mosaic viruses, and it is commonly spread by aphids. As can be deduce from its name, cucumber mosaic virus frequently affects cucumbers, but it is also a common problem for melons tomatoes, squashes, and some other plants. Tobacco mosaic virus spread by the way of seeds and direct contact, and the best direction to avoid it is to growing resistant varieties.

Viral diseases are hardly to identify because mark or indication are different from plant to plant and may also differ depending on the age limit of the plant and its growing circumstances. However, the most common ways of recognizing mosaic viruses are given below. The leaves are spotted with to the white. yellow and dark and light green spots, that are appear to be upraised. These are provide the leaves to be a blister- like appearance.

Plants are often stunted, or they grow very poorly. Plants may have other deformed parts and their leaves may be crumpled or wavy. Cucumber mosaic virus; Infected plants are retard and frequenly exhibit “shoestring syndrome, ” which is a characteristic abnormality in which the boundaries of the leaves are fail to develop, with the leaf veins developing as long, restricted strips. Tomatoes are small and deformed.

Tobacco mosaic virus; Infected plants have deformed and yellowed leaves and twisted wrinkled or deformed young growth. Once the plants are affected, there are no controls. Remove all the infected plants and damaged them. Also, be sure to that sterile your gardening gadgets. Plant resistant plants when obtainable in your garden. Resistant varieties of tomatoes have yet to be discovered for cucumber mosaic virus, but tomatoes that are resistant to tobacco mosaic virus may have some modest resistance to cucumber mosaic virus as well. Mosaic viruses are commonly spread by insects, importantly aphids and leafhoppers. You can your best try to covering up your plants with a floating row cover or aluminum foil mulches to prevent these insects from infecting your plants. Look at our other tips for controlling aphids. Control your weeds. Some types may serve as diseases for the host.

To prevent a tobacco mosaic virus, soak seeds in a 10 percent bleach solution before planting and avoid grasping tobacco near plants. Plants that are mostly affected these are Tomatoes, Cucumbers, Cauliflower, Squash (Zucchini). Tobacco mosaic virus (TMV) infects commercially grown tobacco (Nicotiana tabacum L. ) worldwide, lowering both yield and quality. The RNA plant virus is mechanically spread and causes a mottling pattern of light and dark green areas to develop on the infected leaves. Good sanitation and cultural practices are the best means of preventing the disease. Resistance provides the best means of TMV management once the disease infects a crop. The N gene is the most widely used gene conferring resistance to TMV. The N gene was transferred into N. tabacum from N. glutinosa. Once a plant containing the N gene is inoculated with TMV, a hypersensitive reaction occurs at the viral points of entry. The interaction of the N gene product with the TMV virus causes the plant to kill its own cells at any point where virus entered. Subsequently, lesions form on any inoculated leaf, restricting the movement of the virus to other plant parts and more importantly, to other plants. The N gene is effective in burley tobacco and keeps the incidence of TMV very low. The N gene has also been transferred to flue-cured tobacco, but plants containing the gene generally have lowered yield and quality.

There may be negative linkage factors associated with the N gene that are very hard to break in flue-cured tobacco. The N gene has been incorporated into flue-cured tobacco in the homozygous as well as the heterozygous state. Cultivars deriving resistance from the N gene in the heterozygous state also have reduced yield and quality, but the effect is not as great as in plants containing the N gene in the homozygous state. Plant breeders have begun to develop more tobacco hybrids that incorporate the N gene in the heterozygous state so that TMV may still be controlled, but with fewer deleterious agronomic effects. The N gene in the heterozygous state may be the answer for farmers who need to plant tobacco in fields where high incidences of TMV are known to occur. The N gene induces a very reliable and satisfactory defense mechanism against TMV; however, the disadvantages to using the N gene have not been completely overcome. Identification of TMV resistance in N. tabacum germplasm may be less likely to have negative linkage traits associated with resistance. Chaplin and Gooding (1969) screened tobacco introductions from the N. tabacum germplasm and found some accessions that induce a hypersensitive response when inoculated with TMV. The N gene may be responsible for controlling the resistance found in these tobacco introductions, or a different resistance source altogether may be responsible.

Significance

In 1898, Martinus W. Beijerinck, of the Netherlands, put forth his concepts that TMV was small and infectious. Furthermore, he showed that TMV could not be cultured, except in living, growing plants. This report, suggesting that 'microbes' need not be cellular, was to forever change the definition of pathogens. In 1946, Wendall Stanley was awarded the Nobel Prize for his isolation of TMV crystals, which he incorrectly suggested were composed entirely of protein. Research by F. C. Bawden and N. Pirie, in England, during the same period correctly demonstrated that TMV was actually a ribonucleoprotein, composed of RNA and a coat protein. By the mid-1950s, scientists in Germany and the United States proved that the RNA alone was infectious. This discovery ushered in the modern era of molecular virology.

TMV is known for several 'firsts' in virology, including the first virus to be shown to consist of RNA and protein, the first virus characterized by X-ray crystallography to show a helical structure, and the first virus used for electron microscopy, solution electrophoresis and analytical ultracentrifugation. TMV also was the first RNA virus genome to be completely sequenced, the source of the first virus gene used to demonstrate the concept of coat protein mediated protection (Figure 11), and the first virus for which a plant virus resistance gene (the N gene) was characterized. Today, TMV is still at the forefront of research leading to new concepts in transgenic technology for virus resistance and developing the virus to act as a 'work horse' to express foreign genes in plants for production of pharmaceuticals and vaccines Literature Review Tobacco mosaic virus Tobacco mosaic virus (TMV) is an economically important disease infecting tobacco (Nicotiana tabacum L. ) and other Solanaceous crops worldwide. TMV infects 199 different species from 30 families; however Solanaceous crops incur the most dramatic losses from the disease. Commercially grown tobacco in Virginia includes fluecured, burley, dark fire-cured, and sun-cured tobacco. Flue-cured and burley are the most widely grown with losses incurred from TMV most devastating in flue-cured tobacco; all currently grown burley tobacco is resistant.

Tobacco mosaic virus is a very difficult disease to control because it is spread so easily. The disease is mechanically transmitted, resulting in quick and effective infection. Once a susceptible plant is infected, symptoms show up in 7 to14 days past infection (dpi). The first symptom to occur in newly infected plants is vein clearing. A plant exhibiting vein clearing allows the veins in a leaf to be more clearly seen. The vein clearing is seen in the new upper leaves and can be seen more clearly at 40°C than 25°C.

No known mechanisms for vein clearing have been reported. Soon after vein clearing, mosaic symptoms occur in the newer leaves. This mottling consists of irregularly shaped dark green areas of tissue surrounded by light green areas of tissue. The dark green areas are called green islands and contain no virus, while the lighter green areas have virus. The young leaves infected by TMV often are deformed and wrinkled. TMV infection may also cause the production of nonviable seed. Even though mosaic symptoms are only seen in the new growth of a plant, virus movement is not restricted to symptomatic leaves. Virus has been found in the roots, leaves, and corollas of susceptible plants even when no visible symptoms are seen on the 4 plant part sampled. Likewise tobacco mosaic virus is also known to move into the stamens and pistils of plants infected with the disease.

Tobacco mosaic virus (TMV) has had an illustrious history for more than 100 years, dating to Beijerinck's description of the mosaic disease of tobacco as a contagium vivum fluidum and the modern usage of the word "virus. " Since then, TMV has been acknowledged as a preferred didactic model and a symbolic model to illuminate the essential features that define a virus. TMV additionally emerged as a prototypic model to investigate the biology of host plants, namely tobacco. TMV also exemplifies how a model system furthers novel, and often unexpected, developments in biology and virology. Today, TMV is used as a tool to study host-pathogen interactions and cellular trafficking, and as a technology to express valuable pharmaceutical proteins in tobacco. The history of TMV illustrates how pragmatic strategies to control an economically important disease of tobacco have had unexpected and transforming effects across platforms that impinge on plant health and public health.

Conclusions

There has not yet been found a chemical treatment that effectively protects plants from TMV. In fact, the virus has been known to survive for up to 50 years in dried plant parts. All plant d Reducing and eliminating sources of the virus and the spread of insects can keep the virus kept under control. Sanitation is the key to success. Garden tools should be kept sterilized.

Any small plants that appear to have the virus should be removed immediately from the garden. All plant debris, dead and diseased, should be removed as well to prevent the spread of the disease. In addition, it is always best to avoid smoking while working in the garden, as tobacco products can be infected and this can spread from gardener’s hands to plants. Crop rotation is also an effective way to protect plants from TMV. Virus-free plants should be purchased to help avoid bringing the disease into the garden. Tobacco mosaic virus continues to cause tobacco losses worldwide. Resistance has become the most effective defense mechanism for control of the disease. The N gene has been successfully transferred from N. glutinosa into N. tabacum cultivars. Historically, the commercially grown flue-cured tobacco cultivars deriving resistance from the N gene have poorer agronomic characters than do those cultivars not containing the N gene. These resistant cultivars have been predominantly inbred lines homozygous for the N gene.

Currently, hybrids heterozygous for the N gene have been developed which still have a reduction in yield, but it is not as great as the traditional homozygous inbred lines. These inbred lines may work well for farmers who have a high incidence of TMV in a particular field, where the reduction in yield due to the virus may have outweighed the reduction in yield due to the N gene.