DOCSLIB.ORG

Structural Transitions of Satellite Tobacco Mosaic Virus Particles

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Structural Transitions of Satellite Tobacco Mosaic Virus Particles Virology 284, 223–234 (2001) doi:10.1006/viro.2000.0914, available online at http://www.idealibrary.com on Structural Transitions of Satellite Tobacco Mosaic Virus Particles Yurii G. Kuznetsov, Steven B. Larson, John Day, Aaron Greenwood, and Alexander McPherson1 University of California, Irvine, Department of Molecular Biology and Biochemistry, Room 560, Steinhaus Hall, Irvine, California 92697-3900 Received November 6, 2000; returned to author for revision January 15, 2001; accepted March 15, 2001 Satellite tobacco mosaic virus (STMV) can undergo at least two physical transitions that significantly alter its mechanical and structural characteristics. At high pH the 17-nm STMV particles expand radially by about5Åtoyield particles having diameters of about 18 nm. This pH-induced transition is further promoted by aging of the virions and degradation of the RNA, so that swollen particles ultimately appear even at neutral pH. While the native 17-nm particles crystallize as orthorhombic or monoclinic crystals which diffract to high resolution (1.8 Å), the enlarged 18-nm particles crystallize in a cubic form which diffracts to no better than 5 Å. In the transition, not only do the capsid protein subunits move radially outward, but the helical RNA segments with which they interact do as well. This is noteworthy because it demonstrates that the RNA and the protein shell are capable of coordinated movement, and that neither structure is rigidly defined or independent of the other. Using atomic force microscopy, it can be shown that STMV particles, upon drying, lose their mechanical rigidity and undergo deformation. Virions initially 17 nm in diameter shrink to more uniform final sizes than do 18 nm, initially swollen particles. This transition appears to be irreversible, as the particles do not reassume their former size nor structural rigidity upon rehydration. Evidence is also presented that preparations of native virus and their crystals are naturally somewhat heterogeneous and contain a variety of particles of anomalous size. © 2001 Academic Press INTRODUCTION the particle (Caspar and Klug, 1962; Horne, 1974). From the 1.8 Å resolution, refined STMV structure (Larson et al., ϭ Satellite tobacco mosaic virus (STMV) is a T 1 1998), it was possible, with a high degree of certainty, to particle of about 17 nm diameter containing a single- describe the distribution of solvent molecules both in- stranded RNA genome of 1058 bases (Mirkov et al., 1989) side and outside the capsid and to define their roles in inside a capsid composed of 60 identical copies of a maintaining intermolecular interactions. In addition, the ϭ coat protein having 159 amino acids and Mr 17,542 structural association between the capsid protein and (Valverde and Dodds, 1986, 1987; Valverde et al., 1991). the visible portions of the RNA were delineated in detail. The structure of STMV was solved by X-ray crystallog- In the course of additional X-ray diffraction and atomic raphy and reported at 1.8 Å resolution (Larson et al., force microscopy (AFM) studies of STMV, it became 1998) for the orthorhombic form. The coat protein was evident that the virus particles could undergo certain shown to be a “Swiss roll” beta barrel of 123 carboxyl- structural transitions. These occurred as a consequence terminal residues and a long, extended amino terminal of age, alteration of the pH, and as a consequence of strand of 36 amino acids. The first 12 amino terminal drying. The transitions in structure are accompanied by residues were not visible and apparently in the interior of changes in the mechanical properties of the particles as the virus. well as their sizes. Structural changes of this nature have An unanticipated feature of the STMV structure was long been known to occur in T ϭ 3 icosahedral plant the appearance of nearly 45% of the total viral RNA in the viruses (Kaper, 1975). electron density maps. This was visualized as 30 double- helical segments of seven base pairs with an additional base stacked at either 3Ј terminus (Larson et al., RESULTS 1993a,b). The double-helical RNA segments were closely If freshly prepared STMV samples are deployed for associated with dimers of coat protein and were oriented crystallization at 12–20% saturated ammonium sulfate so that viral twofold axes were perpendicular to the using vapor diffusion below pH 8.0, they consistently helical axes of the segments and coincident with their form orthorhombic crystals above 12°C, and monoclinic central dyad. Thus the RNA segments were disposed in crystals at colder temperatures. Above pH 8.0, at any a manner consistent with the icosahedral symmetry of temperature greater than 2°C, cubic crystals grow. Or- thorhombic crystals of STMV diffract to at least 1.8 Å resolution, and the structure of STMV was refined to that 1 To whom correspondence and reprint requests should be ad- resolution limit (Larson et al., 1998). The monoclinic dressed. Fax: (949) 824-1954. E-mail: [email protected]. STMV crystals diffract to about 2.7 Å, possibly higher, 0042-6822/01 $35.00 223 Copyright © 2001 by Academic Press All rights of reproduction in any form reserved. 224 KUZNETSOV ET AL. STRUCTURAL TRANSITIONS OF STMV PARTICLES 225 FIG. 2. Central cross section of STMV based on the model refined at 1.8 Å resolution by X-ray crystallography (Larson et al., 1998). This model is derived from the orthorhombic crystal form which yields a 17-nm particle by AFM and quasi elastic light scattering. The protein is shown in ribbon format in red, and the RNA as all atoms in white. Tabulated below are relevant values for the native and swollen particles. FIG. 1. (a) Variation of the correlation coefficient (CC) and R value as a function of radial displacement from the particle center based on 5–20 Å data cut at F Ն 5␴F. The darker curves are for the orthorhombic STMV model placed in the cubic cell and rotated 10.8° about the body diagonal and then expanded in 10 Å by 0.1 Å increments. Clearly, the optimum radial expansion is slightly more than 5 Å. For comparison (light curves), a similar expansion of the STMV model in the orthorhombic cell was performed starting from a particle shrunken by 5 Å and then expanded 10 Å by 0.1 Å increments. (b) Variation of CC and R as a function of the rotation angle about the body diagonal of the cubic cell using 10–20 Å data (dark curves) and 5–20 Å data (light curves), both with F Ն 5␴F. The particle was expanded by 5 Å from the original orthorhombic model and then rotated 120° in 0.1° increments about the diagonal. The optimum rotation is about 10.8°, which further refinement showed to be 11.19°. (c) Variation of CC and R as a function of particle translation along the body diagonal using 5–20 Å data cut at F Ն 5␴F. The particle was expanded by 5.38 Å and rotated by 11.11° before the 5 Å translation along the diagonal was executed using 0.1 Å increments. Clearly the correct particle position is the origin. 226 KUZNETSOV ET AL. and their structure is now also solved (unpublished STMV model composed of protein, helical RNA, and data). Cubic STMV crystals, however, diffract to no more sulfate anion was placed at the origin in the orthorhom- than 5 Å resolution even in the best of cases (Koszelak et bic orientation and noncrystallographic symmetry oper- al., 1995). ators with a variable skew matrix and skew translation As the STMV ages through storage or standing, how- were employed. The model was expanded along the ever, the pH at which cubic crystals appear decreases, radial vector through the centers of mass of the model so that after several years, when the RNA is fragmented, components, rotated about, and translated along the as clearly shown by polyacrylamide gel electrophoresis, body diagonal. The search was monitored by the corre- cubic crystals appear even at pH 7. Often in aged prep- lation coefficient based on F. Figure 1 illustrates the arations, near neutral pH, both orthorhombic and cubic variation in CC and R with respect to these operations. crystals coexist in the same crystallization samples. The Clearly the particle is centered at the origin and ex- RNA of STMV, although it does eventually break down, is panded by about 5 Å. The skew angle (equivalent to the remarkably stable. If, for example, STMV particles are rotation angle) was estimated to be about 10.8°. Contin- exposed to pH 9.0 for 24 to 36 h, their RNA, when ued refinement of these parameters with rigid body re- analyzed by agarose gel electrophoresis, is almost en- finement of the model gave final values of 11.19° for the tirely intact. Other experiments (Day et al., 2001) show skew angle and ϳ5.7 Å for the expansion. Figure 2 is an that even heating to 90°C produces little disruption of the illustration of the STMV virion showing the protein coat encapsidated RNA conformation in particles extensively and the double-helical RNA inside. The change in parti- digested with proteinase K. cle size is also tabulated as are results from the rigid ϭ Cubic STMV crystallizes in space group P213 with a body refinement. It should be noted that the 5.7 Å radial 257.25 Å. This implies that the STMV particle must have expansion of the particle is a 7.8% change in the mean its center on the body diagonal (a threefold axis) with an radius and translates directly to a 7.8% increase in tan- icosahedral threefold axis coincident with the body di- gential surface distances at the mean radii.
Load more

Recommended publications
  • Effectiveness of Seed Treatments in Reducing TMV Infection Tanner A
    Effectiveness of Seed Treatments in Reducing TMV Infection Tanner A. Robison Mentor: Claudia Nischwitz Department of Biology, Utah State University, Logan, Utah, USA Abstract Germination Rate Tobacco mosaic virus (TMV), named for the plant it was first discovered in, 1 can infect hundreds of different species. It has no known invertebrate 0.9 vectors, but TMV is spread mechanically through contact with other plants, 0.8 clothes, tools, contaminated soil and seedborne. While TMV is known to be 0.7 exceptionally stable, it has been reported that treatment of tools with 0.6 powdered milk can significantly reduce the infection rate of the virus. While 0.5 there is a seed treatment available for conventional agriculture, there is no 0.4 seed treatment available for organic production. Organic growers, who grow 0.3 heirloom tomatoes experience the highest rates of TMV infection. Since 0.2 powdered milk has been reported as an effective means of treatment in 0.1 tools, the purpose of this research is to determine whether it can be an 0 Almond Soy Rinsed Unrinsed Control effective seed treatment. To test this, tomato seeds were treated with powdered milk, soy milk, almond milk and water. A grow out test was then Results/Discussion conducted in a greenhouse and plants were tested for infection using In the grow out trial little effect was seen. The infection rate for Polymerase Chain Reaction and antibody based ELISA testing. In the first grow powdered milk, almond milk, soy milk and control treatments out trial treatment little effect was seen, with infection rate for the powdered were 61%, 34%, 32% and 47%, respectively.
    [Show full text]
  • Induction of Plant Resistance Against Tobacco Mosaic Virus Using the Biocontrol Agent Streptomyces Cellulosae Isolate Actino 48
    agronomy Article Induction of Plant Resistance against Tobacco Mosaic Virus Using the Biocontrol Agent Streptomyces cellulosae Isolate Actino 48 Gaber Attia Abo-Zaid 1 , Saleh Mohamed Matar 1,2 and Ahmed Abdelkhalek 3,* 1 Bioprocess Development Department, Genetic Engineering and Biotechnology Research Institute (GEBRI), City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab City, Alexandria 21934, Egypt; [email protected] (G.A.A.-Z.); [email protected] (S.M.M.) 2 Chemical Engineering Department, Faculty of Engineering, Jazan University, Jazan 45142, Saudi Arabia 3 Plant Protection and Biomolecular Diagnosis Department, ALCRI, City of Scientific Research and Technological Applications, New Borg El Arab city, Alexandria 21934, Egypt * Correspondence: [email protected] Received: 8 September 2020; Accepted: 19 October 2020; Published: 22 October 2020 Abstract: Viral plant diseases represent a serious problem in agricultural production, causing large shortages in the production of food crops. Eco-friendly approaches are used in controlling viral plant infections, such as biocontrol agents. In the current study, Streptomyces cellulosae isolate Actino 48 is tested as a biocontrol agent for the management of tobacco mosaic virus (TMV) and inducing tomato plant systemic resistance under greenhouse conditions. Foliar application of a cell pellet suspension of Actino 48 (2 107 cfu. mL 1) is performed at 48 h before inoculation with TMV. Peroxidase activity, × − chitinase activity, protein content, and the total phenolic compounds are measured in tomato leaves at 21 dpi. On the other hand, the TMV accumulation level and the transcriptional changes of five tomato defense-related genes (PAL, PR-1, CHS, PR-3, and PR-2) are studied.
    [Show full text]
  • The Cell Biology of Tobacco Mosaic Virus Replication and Movement
    REVIEW ARTICLE published: 11 February 2013 doi: 10.3389/fpls.2013.00012 The cell biology ofTobacco mosaic virus replication and movement Chengke Liu and Richard S. Nelson* Plant Biology Division, The Samuel Roberts Noble Foundation, Inc., Ardmore, OK, USA Edited by: Successful systemic infection of a plant by Tobacco mosaic virus (TMV) requires three Jean-François Laliberté, Institut processes that repeat over time: initial establishment and accumulation in invaded cells, National de la Recherche Scientifique, Canada intercellular movement, and systemic transport. Accumulation and intercellular movement of TMV necessarily involves intracellular transport by complexes containing virus and Reviewed by: Xueping Zhou, Zhejiang University, host proteins and virus RNA during a dynamic process that can be visualized. Multiple China membranes appear to assist TMV accumulation, while membranes, microfilaments and Yule Liu, Tsinghua University, China microtubules appear to assist TMV movement. Here we review cell biological studies *Correspondence: that describe TMV-membrane, -cytoskeleton, and -other host protein interactions which Richard S. Nelson, Plant Biology influence virus accumulation and movement in leaves and callus tissue. The importance Division, The Samuel Roberts Noble Foundation, Inc., 2510 Sam Noble of understanding the developmental phase of the infection in relationship to the observed Parkway, Ardmore, OK 73401, USA. virus-membrane or -host protein interaction is emphasized. Utilizing the latest observations e-mail: [email protected] of TMV-membrane and -host protein interactions within our evolving understanding of the infection ontogeny, a model forTMV accumulation and intracellular spread in a cell biological context is provided. Keywords: membrane transport, microfilaments, microtubules, plant virus, vesicle trafficking, tobamovirus INTRODUCTION of the observed outcome on the mechanism of virus movement is Viruses, as obligate organisms, utilize host factors to accumu- noted.
    [Show full text]
  • Diversity of Plant Virus Movement Proteins: What Do They Have in Common?
    processes Review Diversity of Plant Virus Movement Proteins: What Do They Have in Common? Yuri L. Dorokhov 1,2,* , Ekaterina V. Sheshukova 1, Tatiana E. Byalik 3 and Tatiana V. Komarova 1,2 1 Vavilov Institute of General Genetics Russian Academy of Sciences, 119991 Moscow, Russia; [email protected] (E.V.S.); [email protected] (T.V.K.) 2 Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia 3 Department of Oncology, I.M. Sechenov First Moscow State Medical University, 119991 Moscow, Russia; [email protected] * Correspondence: [email protected] Received: 11 November 2020; Accepted: 24 November 2020; Published: 26 November 2020 Abstract: The modern view of the mechanism of intercellular movement of viruses is based largely on data from the study of the tobacco mosaic virus (TMV) 30-kDa movement protein (MP). The discovered properties and abilities of TMV MP, namely, (a) in vitro binding of single-stranded RNA in a non-sequence-specific manner, (b) participation in the intracellular trafficking of genomic RNA to the plasmodesmata (Pd), and (c) localization in Pd and enhancement of Pd permeability, have been used as a reference in the search and analysis of candidate proteins from other plant viruses. Nevertheless, although almost four decades have passed since the introduction of the term “movement protein” into scientific circulation, the mechanism underlying its function remains unclear. It is unclear why, despite the absence of homology, different MPs are able to functionally replace each other in trans-complementation tests. Here, we consider the complexity and contradictions of the approaches for assessment of the ability of plant viral proteins to perform their movement function.
    [Show full text]
  • Tomato, Tobacco Mosaic Virus
    Problem: Tobacco Mosaic Virus of Tomato Host Plants: Tomato, pepper, eggplant, tobacco, spinach, petunia, marigold. Description: Several virus diseases to tomato occur in Kansas, although they generally are not as prevalent as the wilt and foliar diseases. Three of the more common virus diseases are tobacco mosaic, cucumber mosaic, and spotted wilt. The tobacco mosaic virus can attack a wide range of plants, including tomato, pepper, eggplant, tobacco, spinach, petunia and marigold. On tomato, virus infection causes light and dark green mottled areas on the leaves. The dark green areas tend to be somewhat thicker than the lighter portions of the leaf. The leaf mottling is seen more easily if the affected plant surface is partially shaded. Stunting of young plants is common and often is accompanied by a distortion and fern-like appearance of the leaves. Older leaves curl downward and may be slightly distorted. Certain strains of the virus can cause a mottling, streaking and necrosis of the fruits. Infected plants are not killed, but they produce poor quality fruit and low yields. Tobacco mosaic, is incited by a virus. The tobacco mosaic virus is very stable and can persist in contaminated soil, in infected tomato debris, on or in the seed coat, and in manufactured tobacco products. The virus is transmitted readily from plant to plant by mechanical means. This may simply involve picking up the virus while working with infected plant material, then inoculating healthy plants by rubbing or brushing against them with contaminated tools, clothing, or hands. Aphids are not vectors of the virus, although certain chewing insects may transmit the pathogen.
    [Show full text]
  • The Isolation and Properties of Crystalline Tobacco Mosaic Virus
    W ENDELL M . S T A N L E Y The isolation and properties of crystalline tobacco mosaic virus Nobel Lecture, December 12, 1946 Although the idea that certain infectious diseases might be caused by in- visible living agents was expressed by Varro and Columella about 100 B. C., there was no experimental proof and the idea was not accepted. The cause of infectious disease remained a mystery for hundreds of years. Even the won- derful work of Leeuwenhoek and his description of small animals and bacte- ria during the years from 1676 to 1683 failed to result in proof of the relation- ship between bacteria and infectious disease. There was, of course, much speculation and during the latter half of the 19th century great controversies arose over the germ theory of disease. Then, through the brilliant work of Pasteur, Koch, Cohn, Davaine and others, it was proved experimentally, for the first time, that microorganisms caused infectious diseases. The Golden Era of bacteriology followed and the germ theory of infectious disease was accepted so completely that it became heresy to hold that such diseases might be caused in any other way. Thus, when, in 1892 Iwanowski discovered that the juice of a plant diseased with tobacco mosaic remained infectious after being passed through a filter which retained all known living organisms, he was willing to conclude that the disease was bacterial in nature, despite the fact that he could not find the causative bacteria. As a result, his observations failed to attract attention. However, six years later, the filtration experiment was repeated and extended, independently, by Beijerinck, who immediately recognized the significance of the results and referred to the infectious agent, not as being bacterial in nature, but as a contugium vivum fluidum.
    [Show full text]
  • Beijerinck's Work on Tobacco Mosaic Virus: Historical Context and Legacy
    Beijerinck's work on tobacco mosaic virus: historical context and legacy L. Bos DLO Research Institute for Plant Protection (IPO-DLO), PO Box 9060, 6700 GW Wageningen,The Netherlands Beijerinck's entirely new concept, launched in 1898, of a ¢lterable contagium vivum £uidum which multiplied in close association with the host's metabolism and was distributed in phloem vessels together with plant nutrients, did not match the then prevailing bacteriological germ theory. At the time, tools and concepts to handle such a new kind of agent (the viruses) were non-existent. Beijerinck's novel idea, therefore, did not revolutionize biological science or immediately alter human understanding of contagious diseases. That is how bacteriological dogma persisted, as voiced by Loe¥er and Frosch when showing the ¢lter- ability of an animal virus (1898), and especially by Ivanovsky who had already in 1892 detected ¢lterability of the agent of tobacco mosaic but kept looking for a microbe and ¢nally (1903) claimed its multiplication in an arti¢cial medium. The dogma was also strongly advocated by Roux in 1903 when writing the ¢rst review on viruses, which he named `so-called ``invisible'' microbes', unwittingly including the agent of bovine pleuropneumonia, only much later proved to be caused by a mycoplasma. In 1904, Baur was the ¢rst to advocate strongly the chemical view of viruses. But uncertainty about the true nature of viruses, with their similarities to enzymes and genes, continued until the 1930s when at long last tobacco mosaic virus particles were isolated as an enzyme-like protein (1935), soon to be better character- ized as a nucleoprotein (1937).
    [Show full text]
  • Tobacco Mosaic Virus (TMV)
    Tobacco mosaic virus (TMV) Tobacco mosaic virus is the type member of the genus Tobamovirus, family Virgaviridae: consisting of rigid rods with single-stranded positive-sense RNA, and monomeric coat protein. Symptoms: TMV can cause symptoms including: stunting, mosaic, malformation of leaves and growing points, rugosity, yellow streaking (especially in monocots), yellow spotting, vein-clearing, and necrotic leaf spots. Many hosts are symptomless. TMV is systemic in many hosts, with particles found in roots as well as aerial portions of plant, often at very high titres. Host Range: Over 200 plant species in 11 families known to be hosts. Hosts include: tobacco, tomato, potato, pepper, other Solanaceae, Chenopodium, beet, melon, cucumber, squash, lettuce, horsenettle, Anemone, Begonia, Calibrachoa, Chrysanthemum, Coleus, Delphinium, Geranium, Impatiens, Lobelia, marigold, Petunia, plantain, poppy and Verbena. Many hosts (including several Petunia varieties) are symptomless. Epidemiology: TMV is transmitted mechanically by handling plants, as well as by tools (as many as 20 plants after cutting an infected one). Historically, tobacco products often contained TMV particles, less in flue-cured products; workers were thought to introduce and spread throughout plantings on contaminated hands. Though not considered transmissible by insects, chewing insects such as grasshoppers or flea beetles may very rarely spread by contaminated mouthparts. Is not seed transmitted, but can infect from contaminated seed coats or soil. Root fragments left in soil and leaf litter can serve as an inoculum source. TMV is graft transmissible. Virus particles are very stable, even in unpurified sap. There are records of dried leaf material remaining infectious for 30 to 50 years at room temperature.
    [Show full text]
  • The Discovery of the Causal Agent of the Tobacco Mosaic Disease
    From the book Discoveries in Plant Biology, 1998, pp.: 105-110. S.D Kung and S. F. Yang (eds). Reprinted with permission from the World Publishing Co., Ltd. Hong Kong. Chapter 7 The Discovery of the Causal Agent of the Tobacco Mosaic Disease Milton Zaitlin Cornell University Ithaca, New York 14853, USA ABSTRACT The discovery of the causal agent of the disease causing mosaic and distortion on tobacco plants, with the concomitant realization that the etiologic agent was something unique - a virus - came at the end of the 19th century. This marked the beginning of the science of virology, although many diseases now known to be caused by viruses were described much earlier. This review documents the contributions of the three men who were the pioneers in this work, namely, Adolph Mayer, Dmitrii Iwanowski and Martinus Beijerinck. To appreciate the discovery of the new infectious agent, the virus, at the end of the 19th century, we must think within the context of what was known about disease etiology at that time. It had only been appreciated for a short time that many diseases were caused by infectious entities. The work of pioneers like Pasteur, Lister and Koch had brought an appreciation of the causal agents of anthrax and tuberculosis. The dogma of the day was firmly entrenched in the postulates of Koch, who described in detail what was essential in order to establish the causal organism for a disease: 1) The organism must be associated with the pathological relationship to the disease and its symptoms; 2) The organism must be isolated and obtained in pure culture; 3) Inoculation of the organism from the pure culture must reproduce the disease; and 4) The organism must be recovered once again from the lesions of the host.
    [Show full text]
  • Tobamoviruses-Tobacco Mosaic Virus
    Agri-Science Queensland Employment, Economic Development and Innovation and Development Economic Employment, Tobamoviruses—tobacco mosaic virus, tomato mosaic virus and pepper mild mottle virus Department of Departmentof Integrated virus disease management Tobamoviruses—tobacco mosaic virus (TMV), tomato mosaic virus (ToMV) and pepper mild mottle virus Key points (PMMV)—are stable and highly infectious viruses • Tobacco, tomato and pepper mild mottle that are very easily spread from plant to plant by viruses (tobamoviruses) are highly infectious contact. These viruses can survive for long periods and are easily spread by contact (leaves in crop debris and on contaminated equipment. touching and people handling plants). Although these viruses affect field crops, they are • The viruses can be carried on seed. more often a problem in greenhouse crops where • The viruses survive in crop debris, including plants are generally grown at a higher density and roots in soil and on contaminated equipment handled more frequently. and clothing. • Healthy seedlings and strict hygiene form Host plants and symptoms the basis of effective management. TMV infects a wide range of hosts, including crop plants, weeds and ornamentals. ToMV also infects a wide range of host plants, but is most frequently Survival and spread found in tomato and capsicum. PMMV is largely restricted to capsicums, including chilli types. Unlike most plant viruses, tobamoviruses are not transmitted by insects. The symptoms caused by TMV and ToMV can vary considerably with the strain of virus, time of Tobamoviruses are very stable in the environment infection, variety, temperature, light intensity and and can survive on implements, trellis wires, stakes, other growing conditions.
    [Show full text]
  • Preventing Tobacco Mosaic Virus Infection
    Tom Ford [email protected] Volume 8 Number # 15 March 2019 Preventing Tobacco Mosaic 2019 Sponsors Virus Infection Tobacco Mosaic Virus (TMV) outbreaks are frequently blamed on the shipment of infected plugs or cuttings into area greenhouses. While this may be accurate in some cases, there are many more instances of localized TMV outbreaks that can be linked to our employees and growing practices. While it now seems like a century ago, I once served as an assistant grower for a mid-sized wholesale/retail greenhouse operation in the Maryland area. We had approximately 20 full time employees on the books, but over 200 workers would pass through our operation in a given year. The vast majority of these employees were tobacco users and even though we had defined break areas and handwashing facilities we would frequently catch our best workers using tobacco products in and around our greenhouse facilities. Tobacco Mosaic Virus is a very stable virus that can exist in its infectious state for 40 years or longer. During my tenure as assistant grower, workers would wear sweatshirts and jackets to and from the various greenhouse ranges. Because of employee turnover, sweatshirts and jackets would remain behind in the breakroom and in the greenhouse for years after an employee left our operation. Any jacket or sweatshirt left in a greenhouse or breakroom was deemed community property and was considered fair game to be worn by anyone that currently worked at the operation. Unfortunately, the innocently hanging jacket in the corner of the greenhouse that was once worn by a tobacco user could now serve as the source of TMV inoculum from a non-smoker who grabbed the coat on their way to the lower greenhouse range.
    [Show full text]
  • Tomato Virus Diseases: Various Introduction Lettuce, Pepper) and Ornamentals (E.G
    Plant Disease Diagnostic Clinic Plant Pathology and Plant‐Microbe Biology Section 334 Plant Science Building Ithaca, NY 14853‐5904 Tomato Virus Diseases: Various Introduction lettuce, pepper) and ornamentals (e.g. Delphinium, Fresh tomatoes are a hallmark of summer and a staple Geranium, Petunia, Zinnia). These alternate hosts in many home gardens. Identification and may serve as a source of inoculum for tomato management of tomato diseases is an important step infection. Symptoms on tomato may vary depending in obtaining a successful tomato harvest. Viral on severity and time of infection but typically include diseases can negatively affect tomatoes by drastically plant stunting and yellowing and/or mottling of reducing yield and/or fruit quality. This fact sheet leaves. The most characteristic feature of this disease is highlights 3 viral diseases of tomato that are wrinkling of leaves such that stems appear prominent, commonly encountered by home gardeners: forming a ‘shoestring’ appearance. Cucumber Mosaic Virus (CMV), Tobacco Mosaic Virus (TMV) and Tomato Spotted Wilt Virus Tobacco Mosaic and Tomato Mosaic Viruses are (TSWV). Information designed to aid in diagnosis closely related viruses causing similar symptoms and and management of these viral diseases is provided. so will be covered together. These viruses are common in home gardens, affecting a number of flowers, weeds, and vegetables such as tomato, pepper, and eggplant. Infected tomato plants are characterized by a light- and dark-green mottling and possibly upward curling and malformation of leaves. Mottling is best viewed by partially shading a leaf. Other symptoms may include plant stunting, uneven fruit ripening, and reduced fruit set.
    [Show full text]