For this reason, viruses are not disseminated as such by wind or water, and even when they are carried in plant sap or debris they generally do not cause infections unless they come in contact with the contents of wounded living cell. Chikara masuta, hokkaido university, japan deputy section editor. Because plant virologists realized that vector transmission of plant viruses is specific, and well before we were able to analyze virus genomes so readily by contemporary sequencing and bioinformatics analysis, vector transmission properties were used as critical criteria for plant virus taxonomy. Most plant viruses are transmitted by hemipteroid insects. Virus particles blue cannot spread through normal plasmodesmata plant viruses express movement. Transovarial transmission of a plant virus is mediated by. The structural differences between plant and animal cells have resulted in a variety of transmission routes being exploited, enabling the virus to be passed between different host plants.
Horizontal and vertical transmission of viruses in the honey. Mechanical transmission and virus isolation springerlink. Virus resistant plants consist of some special inhibitory substance that prevent the transmission of viruses. Noncirculative viruses bind to the insect stylet see inset or foregut.
By serving as vectors of transmission, insects play a key role in the infection cycle of many plant viruses. This spread or transmission will be considered under the following headings. Fungal zoospores of olpidium species transmit several viruses in the family tombusviridae as well as in the ophio. The method is useful for assessing fungal transmissibility of a given virus as well as for further studies on molecular and biological aspects of virus vector interaction. All viruses that spread within their host tissues systemically can be transmitted by grafting branches or buds from diseased plants on healthy plants. Pea seedborne mosaic virus psbmv, a seedtransmitted virus in pea and other legumes, invades pea embryos early in development. Seed transmission of plant viruses not all viruses are transmitted via seed seed transmission has been reported for approximately 20% of plant viruses. Common plant viruses include mosaic viruses, spotted wilt viruses, and leaf curl viruses. Such viruses are not transmitted in the fungal resting spores. Much of the early work on plant virusinsect vector associations was related to timing events. A12 disruption of insect transmission of plant viruses.
Aug 26, 2004 because hc and virus particles can be acquired sequentially, it is possible for one virus to assist in the transmission of a second virus. Ten polyhedral viruses, of which nine are in the family tombusviridae, are acquired in the in vitro manner and do not occur within the resting spores of their vectors, and. Plant virus transmission by insects camv p2 potyvirus cmv hcpro salivary canal food canal cuticular lining common canal figure 1 model describing the different strategies for virusvector interaction in noncirculative transmission by aphids. When viruses are transmitted by seeds, the seed is infected in the generative cells and the virus is maintained in the germ cells and sometimes, but less often, in the seed coat. Plant viruses are obligate parasites, often causing the death of their host, so it is necessary for them to spread from plant to plant and to be introduced into living cells. Seed transmission of the high plains virus in sweet corn. Broad bean mottle virus in morocco variability, interaction with food legume species, and seed transmission in faba bean, pea, and chickpea. Aphids are renowned plant parasites of agriculture, horticulture and forestry, causing direct physical damage by sucking phloem and especially by transmission of plant pathogenic viruses. Cucumber mosaic virus plant virus citrus tristeza virus barley yellow dwarf virus. Katis and others published transmission of plant viruses find, read and cite all the research you need on researchgate. The transmission of a virus from infected to healthy tissues is a procedure fundamental to the study of virus diseases. Hepatitis b virus sexual transmission hiv animal or insect vectors rabies virus targeting of the virus. It highlights recent advances in the field and identifies areas of desirable progress.
Much of the early work on plant virus insect vector associations was. Smith skip to main content accessibility help we use cookies to distinguish you from other users and to provide you with a better experience on our websites. Acquisition and transmission by an insect vector is central to the infection cycle of the majority of plant pathogenic viruses. Insect vectormediated transmission of plant viruses. The success of modern agriculture depends on pathogen free seed with high yielding character and in turn disease management. The transmission of a plant virus complex by aphides volume 37 issue 34 kenneth m. Pdf transmission of plant viruses by aphid vectors. Many plant diseases in the field or in harvested plant produce become much more serious and. Viroids are singlestranded molecules of rna that cause plant diseases that lead to underdevelopment.
Genetic and structural analyses of pea embryo lnvasion by pea seedborne mosaic virus daowen wang and andrew j. Mechanisms of transmission are best understood by considering the routes of virus. This is important for virus transmission, as viruses require a living cell to reproduce. Plant virus transmission from the insect point of view pnas. Transmission of viruses by dodder several plant virus can be transmit ted from one plant to another plant through the bridge formed between the two plants by twining the stem of parasitic plant, dodder cuscuta species, green strain of cucumber mosaic virus on n. Some viruses can be transmitted from female parent to offspring usually through eggs, but the mechanism of this transovarial transmission remains unclear. Aphid has a negative impact on crop yield through direct feeding injury, through transmission of plant viruses between different plants, and express development of resistance against insecticides. In terms of epidemiology, insects are the most important factors in plant virus disease. It is shown that the mottle virus can only be transmitted by the aphis when it is accompanied in the plant by the other component of the rosette disease, the veindistorting virus.
Approximately 80% of the plant viruses depend on insect vectors for transmission other vectors can be nematodes and fungi, and the plant virus vector interactions are very specific. Mechanisms of arthropod transmission of plant and animal. Rate of seed transmission vary depending on host plant, cultivar, stage. Nov, 2007 although much is known about the proteins and processes within the plant cell required for efficient virus transmission, up to now, little was known about the requirements and mechanisms from the insect point of view. Like other viruses, a plant virus particle, also known as a virion, is an extremely small infectious agent. A protein key to plant virus transmission at the tip of the insect vector stylet. The evolution of plant virus transmission pathways usda forest. Plant virus transmission advanced article by insects. Seed transmission of plant viruses the resistvir consortium. Plant virus transmission from generation to generation occurs in about 20% of plant viruses. Insectvectored pathogens pose one of the greatest threats to plant and animal, including human, health on a global scale.
Insects, mites, nematodes and protists all mediate the transmission of plant viruses. Occurs when plant come in contact with other plant and leaves rub together. Mechanisms of transmission are best understood by considering the routes of virus movement in the aphid circulative versus non. Plant viruses can interact with their insect host in a variety of ways including both nonpersistent and circulative transmission. Virus transmission and grafting practices marc fuchs section of plant pathology and plant microbe biology, school of integrative plant science, cornell university, newyork state agricultural experiment station, geneva, ny viruses can have a devastating effect on apple growth and productivity.
The transmission of pathogens from current to future host follows a repeating. Leafhopper and planthopper transmission of plant viruses. A majority of plant viruses are dependent on vectors for their transmission and survival. The programmed degeneration of the suspensor during embryo development may provide a transient window for embryo invasion by the virus and could explain the inverse relationship between the age of the mother plant for virus infection and the extent of virus seed transmission.
Plant virus transmission from the insect point of view. Specificity between viruses and vector species may reflect the preference of the vector to the plant species. Only susceptible plants act as indicator plant but not the virus resistant plants. Vectormediated transmission of plant pathogens spans the disciplines of plant pathology, virology, bacteriology, mycology, entomology, and ecology. Mechanisms of arthropod transmission of plant and animal viruses. Details of these breakthroughs can be found in hull 2002. Plant virus transmission advanced article by insects article. Thirty soilborne viruses or virus like agents are transmitted by five species of fungal vectors. Plant viruses demonstrate a high level of specificity for the group of insects that may transmit them a virus that is transmitted by one type of vector. Epidemics occur when a new virus or a new vector invade a new ecological niche.
This process is controlled by maternal genes and, in a cultivar that shows no seed transmission, is prevented through the action of multiple host genes segregating as quantitative trait loci. Mechanical transmission of plant viruses sciencedirect. Horizontal transmission by a direct route includes airborne infection, foodborne infection, and venereal. This process is controlled by maternal genes and, in a cultivar that shows no seed transmission, is prevented through the action. It is an ideal textbook and reference for students, professors, and all those who study or specialize in vector biology in generalor in relation to any of these disciplines. Bacterial diseases can be grouped into four broad categories based on the extent of damage to plant tissue and the symptoms that they cause, which may include vascular wilt, necrosis, soft rot, and tumours. Two systems of terminology have been devised to describe and group.
The latter virus is easily transmitted by the aphis, either alone or in combination with the mottle virus. Much of the early work on plant virus insect vector associations was related to timing events. Interactions among insect vectors, viruses, and host plants mediate transmission by integrating all organizational levels, from molecules to populations. Fungal vectors for other viruses in the family should be sought even though tombusviruses are reputed to be soil transmitted. So it is a dependent virus and second virus is referred as the helper virus virus helper virus vector type of transmission potato aucuba mosaic virus pva or y m. Most have negative impacts on the environment and human health and are unsustainable.
The main difference, from the point of view of a virus, is the cell wall. There is a serious scientific concern about the transmission of plant viruses sexually through seed and asexually through plant propagules. Transmission of plant viruses by aphid vectors ng 2004. Disruption of insect transmission of plant viruses. A aphid transmit can transmit the virus only if the source plant is infected by second virus. This unit describes procedures for virus transmission by olpidium sp. What are the implications of horizontal virus transmission via passive plant vectors on the patterns of cripavirus spread within herbivorous insect. Moreover, a recent analysis by mink 83 of viruses reported to infect mother plants via infected pollen casts doubt on unassisted pollentoplant virus transmission. All these insects have piercingsucking mouthparts that allow them to feed on plants while causing minimal damage. Department of plant pathology, university of california, davis, ca 95616, usa 2 department of plant pathology, cornell university, ithaca, ny 14853, usa summary aphids are the most common vector of plant viruses. Introduction plant viruses can cause severe yield losses to the cere.
Nonpropagative circulative yellow circles viruses are generally phloem limited and move through the insect body via the midgut or hindgut. There are three methods for viral transmission to a host plant. In the laboratory this is usually accomplished by grinding the leaf of a diseased plant, and rubbing the infectious sap on to the leaf of a healthy plant. Pdf disruption of insect transmission of plant viruses. Specificity of transmission is defined as the specific relationship between a plant virus and one or a few vector species but not others. Seeds provide an efficient means in disseminating plant virus and viroid diseases. Horizontal transmission can be further classiwed as direct or indirect. Aphids are the most common vector of plant viruses. The importance of insect transmission of plant diseases has generally been overlooked and greatly underestimated. The following points highlight the eight chief methods used for the transmission of plant viruses.
In this village it looks as if frosting continuously for, the plant i saw in the field of summer the colour of the leaves were yellowing the plant, which has since been identified as eupatorium lindleyanum, has been found to be. Virus transmission an overview sciencedirect topics. Plant virus, vector, transmission, specificity, virus ligand interaction. Transmission specificity can be broad or narrow but it is a prominent feature for numerous viruses and vectors. Plant pathogen transmission by insect vectors involves a combination of. Control of plant viruses is of great economic importance worldwide, because these viruses cause diseases that destroy commercial crops. Figure a122 viruses localize to different sites in the plant feeding insect vector depending on their modes of transmission.
Transmission of plant viruses plant virus transmission. Insects are the most common of the vectors and, among these, aphids account for the transmission of 50% of the insect. Many plant diseases in the field or in harvested plant produce. View the article pdf and any associated supplements and figures for a period of 48 hours. The insects use paired maxillary stylets to form a suction tube that is inserted into plant cells. Behavioural aspects influencing plant virus transmission by homopteran insects. Plant viruses are typically spread by either horizontal or verticle transmission. Plant viruses take advantage of the host plant s transport system. Mechanical transmission involves the introduction of infective virus or biologically active virus into a suitable site in the living cells through wounds or abrasions in the plant. With the exception of tobacco mosaic virus, relatively few viruses or viroids are spread extensively in the field by contact between diseased and healthy leaves. Product detail vectormediated transmission of plant pathogens.
Pdf by serving as vectors of transmission, insects play a key role in the infection cycle of many plant viruses. Few effective control strategies have been developed to thwart the transmission of any insecttransmitted pathogen. Virus vector interactions mediating nonpersistent and semipersistent transmission of plant viruses james c. Usually the cotyledons of cucumber and primary leaves of cowpea and beans are inoculated by viruses, because older plants are less susceptible. This seems to be under the genetic control of both the virus via its coat protein and the vector. Mechanical transmission of plant viruses 247 that these local necrotic lesions actually represent local centers of virus increase, and the only centers, is clearly supported by much indirect evidence, but published reports of virus content of local lesion areas, in comparison with the virus content of adjacent nonlesion areas on the same. Viruses use sophisticated transmission strategies to overcome the spatial barrier separating plants and the impediment imposed by the plant cell wall. The transmission of a plant virus complex by aphides. Clearly, horizontal virus transmission via passive vector plants constitutes an important and fascinating arena for future insect virus research. In horizontal transmission, viruses are transmitted among individuals of the same generation. Specific interactions between virus and host factors are required for efficient transmission through seed. Viruses that lost the ability to be transmitted by vectors serve to identify protein motifs that are associated with transmission.
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