Plant viruses have some of the smallest genomes of any organism 420 kb. In susceptible hosts, plant viruses often manipulate biochemical events and molecular interactions required for their replication and movement, leading to misregulation and disruption of hormone signalling alazem and lin, 2015. The movement protein of tobacco mosaic virus tmv has been most. There are several distinct stages including intracellular movement from sites of virus replication to plasmodesmata pd plant. Celltocell movement of plant viruses through plasmodesmata involves specific viral factors movement proteins, mp and is inevitably assisted by cellular mechanisms in mp targeting, plasma membrane pm anchoring and transport of the mp through the plasmodesmal pore. Many plant virus genera encode a triple gene block tgb, a specialized evolutionarily conserved gene module involved in the celltocell and longdistance movement of viruses. Archaea, bacteria, and viruses prokaryotes, viruses, and the study of plants. Virusencoded movement proteins mediate this process and appear to use two. Here, we investigated the interaction of two tgb proteins tgb2 and tgb3 of potato moptop virus pmtv, with components of the secretory and endocytic pathways when expressed as nterminal fusions to green fluorescent protein or monomeric red fluorescent protein mrfp. Deryabina and others published molecular aspects of plant viruses movement through plants find, read and cite.
Guidelines for identification and management of plant disease. Viral and cellular factors involved in phloem transport of plant viruses. Guidelines for identification and management of plant disease problems. The virus injects its genetic material into the cell and uses the cells organelles to replicate. Plant viruses are grouped into 73 genera and 49 families. Mechanical and insect vector transmission are the two most important means by which plant viruses spread.
Virushost interactions during movement processes plant. Amelia sanchezpina and jose antonio navarro writing in recent advances in plant virology the incorporation of non invasive techniques has allowed remarkable progress in our understanding of the vascular transport of plant viruses. Two plantviral movement proteins traffic in the endocytic. Celltocell movement of plant viruses sciencedirect. Pdf key checkpoints in the movement of plant viruses. Jun 16, 2014 plant viruses need to overcome the barrier of the cell wall to spread from the initially infected cells to the rest of the plant. A general view of virus celltocell and longdistance movement in plant tissues. The plant cellular systems for plant virus movement ncbi. Pdf molecular aspects of plant viruses movement through plants.
Like other viruses, a plant virus particle, also known as a. The arabidopsis synaptotagmin syta regulates the cellto. Movement proteingfp fusions can be expressed from the parental virus or, in the absence of a fulllength infectious clone, using an alternative expression vector. Celltocell and longdistance transport of viruses in. This document is pp249, one of a series of the plant pathology department, ufifas extension. In viruses, the movement protein mp is responsible for the. Once in a wounded cell, the virus particle sheds its protein coat and the nucleic acid then directs the production of multiple copies of itself and related proteins leading to the development of new virus particles. Most plant viruses are singlestranded rna or doublestranded rna viruses. In viruses, the movement protein mp is responsible for the pd gating that. Studying the movement of plant viruses using green.
Like other viruses, a plant virus particle, also known as a virion, is an extremely small infectious agent. Genetic analysis of a piezolike protein suppressing systemic. Movement of plant viruses short distance movement long distance movement cell to cell movement movement of plant viruses as nucleoprotein e. Common plant viruses include mosaic viruses, spotted wilt viruses, and leaf curl viruses. Nucleic acid in protein capsid no membrane envelop. The tgbbased transport system exploits the coordinated action of three polypeptides to deliver viral genomes to plasmodesmata and to accomplish virus entry into neighbouring cells. Diagnosing plant diseases caused by fungi, bacteria and viruses1 ken pernezny, monica elliott, aaron palmateer, and nikol havranek2 1. Plant viruses are particles of rna or dna that infect plants and cause disease. Potyviruses represent the largest group of plant viruses and studies particularly using turnip mosaic virus tumv have strongly advanced our knowledge how these important plant viruses spread infection. It is suggested that plant viruses move from cell to cell and over long distances by exploiting and modifying these preexisting endogeneous pathways for macromolecular movement 1, 8. Differing requirements for actin and myosin by plant viruses.
Restrictions on plant virus genome size are imposed by several factors. This superfamily combines proteins of viruses belonging to all principal. Plant virus movement is the process of the spread of virus genetic material from the initially infected cells to the rest of the plant. The study of plant viruses has led the overall understanding of viruses in many aspects. This has been taken to indicate that individual cells are perfectly able to support viral replication but that the virus is unable to move to adjacent cells. The ins and outs of nondestructive celltocell and systemic. Finally, in tissues distant from the initially inoculated leaf, viruses unload from the vascular. In viruses, the movement protein mp is responsible for the pd gating that allows the intercellular movement of viral genomes. Viruses are usually spread from diseased to healthy plants. Rigid plant cell walls force most plant viruses to use plasmodesmata as a means of establishing systemic infections lucas, 2006. Guidelines for identification and management of plant. Plant viruses spread from the initially infected cells to the rest of the plant in several distinct stages. Viruses move around in plants by manipulating the plant s own systems.
Finally, we update the current research on cellular organelles as key regulator checkpoints in the longdistance movement of plant viruses. Harriesa, jongwon parkb, nobumitsu sasakic, kimberly d. Plant viruses are a persistent threat to production of vegetable crops in india. The arabidopsis synaptotagmin syta regulates the celltocell. The genome of potyviruses consists of a single, roughly 10 kb long, rna molecule that codes. Viruses do not produce any kind of reproductive structure, they. Chikara masuta, hokkaido university, japan deputy section editor. Studying the movement of plant viruses using green fluorescent protein opo,o, o,o boevink and simon santa cruz recent studies with green fluorescent protein gfp are providing new insights into the mechanisms of virus movement in plants. Although plant viruses do not have an immediate impact on humans to the extent that human viruses do, the damage they do to food supplies has a significant indirect effect.
A movement protein is a nonstructural protein which is encoded by some plant viruses to allow their movement from one infected cell to neighbouring cells. The genome of potyviruses consists of a single, roughly 10 kb long, rna molecule that codes for a polyprotein, which is processed into ten mature proteins. Genetic analysis of a piezolike protein suppressing. Plant viruses must invade and infect as much of their hosts as possible to maximize their chances of successful perpetuation. The level of diversity in single plant infections varies dramatically with. Nelsona,1 aplant biology division, the samuel roberts noble foundation, inc. Department of agriculture, agricultural research service u. The discoveries obtained by studying viruses can be used to guide plant research.
A plant virusencoded protein facilitates longdistance. In many viruses, the movement function is secured by specific virusencoded proteins. 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. This protein is expressed from a subgenomic mrna and its function is to modify plasmodesmata. Prokaryotes obtain energy for movement and metabolism and carbon for growth and reproduction from various sources. Many, if not all, plant viruses encode a movement protein, and some express more than one. Movementrestricted interactions can result in lim iting of the virus to initially infected cells or primary infection foci. To establish an infection, most plant viruses move from cell to cell in the plant.
Amino acid sequence comparisons of these proteins revealed a vast superfamily containing a conserved sequence motif that may comprise a hydrophobic interaction domain. Systemic movement of viruses via the plant phloem from vicente pallas, ainhoa genoves, m. One of the best known examples of this is the 30k protein of tobacco mosaic virus tmv. Viruses should be studied by plant biologists for many of the same reasons that prokaryotes should be studied. Various host factors interact with mp to regulate complicated.
The below mentioned article provides quick notes on plant viruses. In order for viral replication to occur, the virus must first infect a host cell. Plant virus replication and movement sciencedirect. 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. Differing requirements for actin and myosin by plant.
Plant viruses can develop high levels of variation in their populations, but this is not always the case. These tethers are part of erpm contact sites that occur at the pd as well as at other cortical sites of the cell and which may be targeted by viruses for both replication and movement. With few exceptions, virus particles are initially intro duced into host cells. Tobacco mosaic virus and potexviruses are the most extensively studied viruses. Although severe outbreaks of viral diseases tend to occur on a sporadic basis, many plant viruses are ubiquitous in nature and can result in severe outbreaks under the right conditions. Plant viruses take advantage of the host plants transport system. Jul 29, 2019 viruses are not capable of replicating their genes by themselves.
The fundamental characteristic is their absolute dependence on a living host organism for their reproduction. After inoculation, mostly into epidermal or mesophyll cells, virions. Many of the basic properties of genes and proteins can be investigated using viruses. There is no evidence that plant viruses have evolved mechanisms that specifically shut down translation of cellular mrnas. Plant virus movement tilsner major reference works. In fact, plant virologists use grafting and budding procedures to transmit and detect viruses in their studies. Celltocell movement is a crucial step in plant virus infection. Many plant viruses are known to use movement proteins to assist in their transit through plasmodesmata.
Roossinck, in origin and evolution of viruses second edition, 2008. Control of plant viruses is of great economic importance worldwide, because these viruses cause diseases that destroy commercial crops. Nov 06, 2014 to determine whether syta has a central role in regulating the celltocell trafficking of a wider range of diverse plant viruses, we extended our studies here to examine the role of syta in the celltocell movement of additional plant viruses that employ different modes of movement, namely the potyvirus turnip mosaic virus tumv, the. Through their life cycle, from virus accumulation to intracellular, local, and systemic movement, viruses utilize plant proteins, normally. Pierce, florida, usa the principal families of insect vectors which cause the most damage to agricultural crops through the spread of plant diseases are in the order hemiptera, and include the aphids. The activity of humans in propagating plants by budding and grafting or by cuttings is one of the chief ways viral diseases spread. The tgbbased transport system exploits the coordinated action of three polypeptides to deliver viral genomes to plasmodesmata and to accomplish virus entry into. Many plant viruses exploit a conserved group of proteins known as the triple gene block tgb for celltocell movement. Although plant viruses are not as well understood as their animal counterparts, one plant virus has become iconic.
Celltocell and systematic movement of plant viruses 197 cross the boundary into the vascular system of the plant to exploit the phloem stream for socalled longdistance or systemic movement throughout the plant. One of the constraints to plant virology was the lack of a quantitative assay, until holmes in. Most of plant virus infect a limited number of different plant species and a few have a wide host range. Differing requirements for actin and myosin by plant viruses for sustained intercellular movement phillip a. Viruses that associate with the er for replication and movement form replication factories at specific localized sites of the er. However, the use of non conventional translation mechanisms that compete with cellular mrnas for the cells translation machinery is a very common strategy among plant viruses. Also this section publishes studies involving useful methodological application such as diagnostic.
Celltocell and longdistance transport of viruses in plants. Systemic movement is a key process in the viral life cycle, as plants in which viral infection is limited to the initially infected cells or even leaves are functionally. Here, we investigated the interaction of two tgb proteins tgb2 and tgb3 of potato moptop virus pmtv, with components of the secretory and endocytic pathways when expressed as nterminal fusions to green fluorescent protein or. When viruses are transmitted by seeds, the seed is infected in the. There are currently over 360 species in this family, divided among 9 genera. Plant viruses are obligate parasites being largely dependent on their host for translation, replication, encapsidation, movement, and longdistance infection. Pdf the plant cellular systems for plant virus movement.
Virus particles blue cannot spread through normal plasmodesmata plant viruses express movement. Viruses move around in plants by manipulating the plants own systems. They move cell to cell via plasmodesmata pd, which they modify to a greater or lesser extent, and to distant parts of the plant through the vascular system. Virus is a nucleoprotein having rna or dna as a genetic material. Seed and pollen borne viruses plant virus transmission from generation to generation occurs in about 20% of plant viruses. To determine whether syta has a central role in regulating the celltocell trafficking of a wider range of diverse plant viruses, we extended our studies here to examine the role of syta in the celltocell movement of additional plant viruses that employ different modes of movement, namely the potyvirus turnip mosaic virus tumv, the. History although many early written and pictorial records of diseases caused by.
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