Impact of abiotic stresses on plant virus transmission by. The higher the viral concentration, the higher the chances of transmission. Transmission of tobacco mosaic virus by the dodder,cuscuta japonica and its inhibitory effect on the virus activity. It highlights recent advances in the field and identifies areas of desirable progress. Mink, 1993, and yet very little is known about the mechanisms involved.
This spread or transmission will be considered under the following headings. Given increasing global temperatures and elevated atmospheric co2 levels and the occurrence of water stress episodes driven by climate change, plant biochemistry, in particular, plant defence responses, may be altered significantly. However, this situation is highly complex when one examines all the possible elements that can influence these interactions. This process is controlled by maternal genes and, in a cultivar that shows no seed transmission, is prevented through the action. Generally the infection cycle begins with the vector encountering the virus in the plant and the virus is acquired by the vector. Symptoms will vary depending on the virus and the plant. Aphids and whiteflies are by far the most important insects transmitting plant viruses. Virus binds to a specific location in the stylet or foregut virus produces a protein that binds to vector cuticle in a specific location and binds to virus coat protein, released with saliva insect feeds on infected plant to acquire virus can transmit. Much of the early work on plant virusinsect vector associations was related to. Plant virus transmission from the insect point of view pnas. Most plant viruses rely on insect vectors for survival, transmission and spread. Most vectors are piercingsucking insects that transmit plant viruses in either the circulative virus cv or noncirculative virus ncv. 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. Therefore, it seems justified to predict a very low rate of virus transmission to or from m.
The knowledge of virus transmission is important to. 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. Plant virus transmission from generation to generation occurs in about 20% of plant viruses. Evidence of first virus that infects both plants and. Nucleic acid represents the genetic material, indispensable for replication. Transmission specificity can be broad or narrow but it is a prominent feature for numerous viruses and vectors. It is the viruses of cultivated crops that have been most studied because of the financial implications of the losses they incur. It occurs in those plants in which virus are present in high concentration. Cvs cross the vectors gut, move internally to the salivary glands sg, cross the sg membranes to be ejected upon feeding. Specificity between viruses and vector species may reflect the preference of the vector to the plant species. Seasonality of interactions between a plant virus and its.
Articles are characterized by their novelty, innovativeness, and the hypothesisdriven nature of their. Many plant viruses have vec tors, providing the means for. 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. Behavioural aspects influencing plant virus transmission by homopteran insects. 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. Transovarial transmission of a plant virus is mediated by. Viruses can be transmitted horizontally from individual to individual and vertically from parents to offspring.
Since then many studies have examined the specificity of insect vectormediated plant virus transmission and clearly demonstrated that there are specific molecular determinants required e. The availability of the pathogen is affected by its quantity, location, and the strain within the plant. Transmission of plant viruses by aphid vectors ng 2004. Most vectors are piercingsucking insects that transmit plant viruses in. In horizontal transmission, viruses are transmitted among individuals of the same generation. Plant virus, vector, transmission, specificity, virusligand interaction. Although these insect viruses cannot multiply within. Broad bean mottle virus in morocco variability, interaction with food legume species, and seed transmission in faba bean, pea, and chickpea. Seed from recipient plants can carry virus leading to virus transmission. Transmission by this means consists of the removal of the plant sap from a diseased plant by artificial or natural means and its transfer to a healthy plant by rubbing or injecting. Seed transmission of the high plains virus in sweet corn. Vertical transmission in vertical transmission, the virus is inherited from a parent. Introduction approximately 20% of plant viruses are transmitted from gener ation to generation in the seed matthews, 1991.
A majority of plant viruses are dependent on vectors for their transmission and survival. Passing through the insect hemolymph is an essential step for both kinds of viral transmission. Plant virus transmission advanced article by insects. Pollen and seedtransmission of tobacco streak virus in okra pollen from an infected plant used for hybridization can carry virus and infect embryo of a recipient plant during fertilization. In other cases the vector remains permanently infective persistent transmission. Chikara masuta, hokkaido university, japan deputy section editor. Plant viruses have been studied primarily as important pathogens of crops. About 190 aphid species are known to transmit plant viruses, with many species capable of transmitting more than one virus species 18, 19 including potato viruses. Insects, mites, nematodes and protists all mediate the transmission of plant viruses. However, this situation is highly complex when one examines all the.
The evolution of plant virus transmission pathways usda forest. Horizontal transmission can be further classiwed as direct or indirect. Author summary rice stripe virus rsv, which is completely dependent on laodelphax striatellus for transmission between host plants, can also be vertically transmitted from the mother insect to its offsprings. Most plant viruses depend on insect vectors for their survival, transmission and spread. 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. Cucumber mosaic virus plant virus citrus tristeza virus barley yellow dwarf virus. The epidemiology of plant diseases caused by insectcarried plant pathogens involves four main components. Ncv are carried on the lining cuticle of vectors stylets. Repeating subunits, identical for each virus type but varies from virus to virus and even from strain to strain. Horizontal and vertical transmission of viruses in the. The effectiveness of viral transmission depends on the virus concentration and the route of transmission. Thus, the transmission of a plant pathogen by an insect to a plant appears relatively simple. Cultural, physical and novel biotechnological tools can provide virus control by interfering with vector landing and the retention of viruses in their vectors.
A aphid transmit can transmit the virus only if the source plant is infected by second virus. Pdf most plant viruses depend on vectors for their survival and spread. Plant viruses affect many plants and cause a wide range of discolourations and distortions in leaves, shoots, stems and flowers, but rarely kill the plant. Many viruses, especially plant viruses, are transmitted by insects. 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. Pdf transmission of plant viruses by aphid vectors. Mechanisms of arthropod transmission of plant and animal. The biology of plant virus transmission has been studied for more than 100 years ando, 1910, gutierrez et al. Horizontal transmission by a direct route includes airborne infection, foodborne infection, and venereal. The following points highlight the eight chief methods used for the transmission of plant viruses.
In asexual reproductive methods such as vegetative propagation, the offspring develop from and are genetically identical to a single plant. Epidemics occur when a new virus or a new vector invade a new ecological niche. Virus interactions with these vectors are diverse, but there are some commonalities. The threat of transmission of semi persistent and persistent plant viruses appears to be restricted to plants where the pea aphid probed as far as the sieve elements and ingested the phloem sap katis et al.
Recognize a virus as cause of the disease if transmitted from infected to healthy plant how virus spread in field help in its control establish biological relationship of interaction between virus and its vector. Pea seedborne mosaic virus psbmv, a seedtransmitted virus in pea and other legumes, invades pea embryos early in development. Supriya chakraborty, jawaharlal nehru university, india the plant viruses section of virology journal covers studies on all aspects of plant viruses including viral structure, gene function, genetics, virushost interactions, viral pathogenesis, epidemiology, host resistance, rna silencing and so on. 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. Transmission of plant viruses by dodder springerlink. Because hc and virus particles can be acquired sequentially, it is possible for one virus to assist in the transmission of a second virus. Virtually all plants that humans grow for food, feed, and fiber are affected by at least one virus. Plants regularly encounter abiotic constraints, and plant response to stress has been a focus of research for decades. The virus needs to be spread so that it can continue reproducing and ensuring the survival of the virus species. They trans mit plant viruses by two principal modes. Specificity of transmission is defined as the specific relationship between a plant virus and one or a few vector species but not others. More than 200 plant viruses are transmitted by specific arthropod vectors.
In spite of the ongoing debate regarding tool sterilization, there is surprisingly little information in the scientific literature that addresses this issue. Evidence of first virus that infects both plants and humans. The requirement for helper components hc facilitating virus transmission by living organisms, termed vectors, is characteristic of plant viruses in several genera, potyviruses genus potyvirus. Insect vectormediated transmission of plant viruses. Very graphical video with easy language to understand easily how virus transmits in plants. Plantinfecting viruses are transmitted by a diverse array of organisms including insects, mites, nematodes, fungi, and plasmodiophorids. They cause various diseases characterised by a combination of severe symptoms and high transmission rates 1,2,3. If validated, this would mark the first time a plant virus has been found to cause problems in people. Plant viruses naturally spread through three main transmission pathways. This type of transmission occurs in both asexual and sexual reproduction.
Viruses that lost the ability to be transmitted by vectors serve to identify. Introduction plant viruses can cause severe yield losses to the cere. These genes control the ability of psbmv to spread into andor multiply in. Plant viruses are widespread and economi cally important plant pathogens. Virus transmission an overview sciencedirect topics. Plant viruses are obligate parasites, often causing the death of their host, so it is necessary for them to spread from plant.
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