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1
Ratcliff, Frank Giles. "Novel aspects of plant-virus interactions." Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302040.
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Chewachong, Godwill Mih. "Engineering Plant Virus " Vaccines" Using Pepino mosaic virus as a Model." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1384203201.
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Tungadi, Trisna Dewi. "Cucumber mosaic virus modifies plant-aphid interactions." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708288.
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van, Zyl Albertha R. "Development of plant-produced Bluetongue virus vaccines." Doctoral thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/28248.
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Bluetongue is a disease of domestic and wild ruminants caused by Bluetongue virus (BTV). It has caused several serious outbreaks, the most recent occurring in Northern Europe in 2006 during which high mortality rates of livestock were reported. The only vaccines currently approved and commercially available for use are live-attenuated or inactivated virus strains and although these are effective, there is the risk of reversion in the case of live-attenuated strains to more virulent forms by recombination. Another drawback associated with the use of live-attenuated virus vaccines is that they are not DIVA (differentiate infected from vaccinated animals) compliant, this means that naturally infected animals cannot be distinguished from vaccinated animals. Recombinantly produced vaccines would be preferable to minimize the risks associated with live-attenuated virus vaccines and also enable the development of candidate vaccines that are DIVA-compliant. A number of recombinant vaccine candidates have been developed against BTV, with the most promising vaccine consisting of BTV virus-like particles (VLPs). BTV VLPs were successfully produced in insect cells by the co-expression of the four BTV capsid proteins (VP2, VP3, VP5 and VP7). Sheep vaccinated with insect cell-produced BTV VLPs were shown to be protected against challenge with wild type virus. However, the high costs associated with the production and scale-up of BTV VLPs in insect cells has possibly limited their widespread application. Plants – such as N. benthamiana – provides a safe, efficient and cost effective system for the production of recombinant proteins. In this study the best plant expression vector with which to co-express the four BTV serotype 8 (BTV-8) VPs – which direct formation of BTV-8 VLPs – was identified. Expression and purification of the BTV-8 VLPs was optimised with the aim of producing a VLP-based vaccine for BTV-8. It was further undertaken to develop two novel second generation plant-produced protein body (PB) vaccines that are DIVA compliant. Mice were immunised with the plantproduced VLP and PB vaccines in order to analyse their ability to elicit humoral immune responses.
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Murray, Abner A. "Plant Virus Nanoparticle In Situ Cancer Immunotherapies." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1532370850718292.
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Aitken, Angus Iain. "Membrane interactions of plant virus movement proteins." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/15617.
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Plant viruses post a significant risk to both global food security, and industrial agriculture, however very little is known regarding their molecular mechanisms. Despite intensive study since the discovery of a multitude of plant virtual movement proteins, it remains unknown how they transverse the plasmodesmata, and thus move between cells. The CMV virus is widespread, infecting over a thousand plant species, and yet the means by which the movement protein CMV 3a associates to cellular membranes, targets itself and viral genomes to plasmodesmata have not been described. This study initially attempted to purify the CMV 3a protein from bacterial expression for structural and biophysical studies to examine viral protein and host membrane interactions. The study also began mapping the CMV 3a protein surface to investigate protein localisation and membrane attachment in planta, identifying structural features, including two potentially amphipathic helices which bear further investigation for potential roles in membrane association. Finally, this thesis examined the potential for the lipid modification S-acylation (Palmitoylation) as a membrane anchor, across a range of viral movement proteins. Describing this modification of viral movement proteins for the first time, S-acylation was demonstrated to not only be widespread, but potentially play different roles across a range of plant virus movement systems. This information is vital for the advancement of the field's understanding of the cell to cell movement of plant viruses, and the potential development of control strategies; and hence the safeguarding of global food security.
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Soards, Avril Jacqueline. "The Cucumber mosaic virus 2b protein : influences on the plant-virus interaction." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619971.
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Gaafar, Yahya Zakaria Abdou [Verfasser]. "Plant virus identification and virus-vector-host interactions / Yahya Zakaria Abdou Gaafar." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://d-nb.info/1220909262/34.
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Chun, Elizabeth M. "Developing a Recombinant Plant Virus Nanoparticle Vaccine for Rift Valley Fever Virus." Scholarship @ Claremont, 2019. https://scholarship.claremont.edu/scripps_theses/1345.
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Rift Valley Fever (RVF) is an emerging infectious disease found in both livestock and humans. RVF is associated with high abortion and mortality rates in livestock and can be fatal in humans. As such, RVF is economically and socially significant to affected smallholder and subsistence farmers, those infected, and national livestock industries. However, Rift Valley Fever virus (RVFV) vaccines are not commercially available outside of endemic areas or for humans, and current vaccines are limited in their safety and efficacy. A plant-based, viral nanoparticle vaccine offers a more affordable alternative to conventional vaccines that is safe, rapidly producible, and easily scalable, better meeting the needs of impacted communities. This project focuses on assessing the potential of using a Nicotiana benthamiana plant expression system to generate recombinant tobacco mosaic virus (TMV) nanoparticles displaying RVFV glycoprotein epitopes. Eight TMV-RVFV glycoprotein constructs were designed. Five TMV-RVFV constructs were successfully cloned, and four recombinant TMV constructs were successfully expressed in planta. The antigenicity of these constructs was examined for their possible use in RVFV vaccine development.
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Chare, Elizabeth R. "Recombination in RNA viruses and plant virus evolution." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433381.
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Westwood, Jack Henry. "Cucumber mosaic virus infection and plant-aphid interactions." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608811.
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Li, Hua. "Molecular approaches to plant virus resistance in lupins." Thesis, Li, Hua (2000) Molecular approaches to plant virus resistance in lupins. PhD thesis, Murdoch University, 2000. https://researchrepository.murdoch.edu.au/id/eprint/52579/.
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Narrow-leafed lupin (L. angustifolius) is the main legume crop grown in Western Australia. Yellow lupin (L. luteus) is a new crop for Western Australia which can tolerate more marginal acid soils than narrow-leafed lupin. Because lupins as crop plants are relatively undeveloped, there is potential to introduce additional traits into lupin species by conventional breeding or by gene transfer technology. Resistance to bean yellow mosaic virus (BYMV) and tolerance to herbicides are of commercial and environmental value.
The aim of this work was to optimise conditions for tissue culture and regeneration of transgenic lupin plants, specifically to introduce the NIa gene derived from BYMV for BYMV resistance, and the bar gene for tolerance to the herbicide glufosinate. Two existing L. angustifolius regeneration and transformation methods were assessed, and improved methods were developed to regenerate and transform L. angustifolius and L. luteus.
Experiments were carried out to determine optimal conditions for culture and gene transfer to examine the most effective A. tumefaciens strain, the period of precultivation, the period of cocultivation, the best method to wound the meristem, the optimum time of incubation before transfer to selection medium and the concentration of glufosinate in the selection medium.
Results from the above experiments were combined into a standard transformation procedure. The embryonic axes from mature seeds were excised and punctured 10-15 times with a fine needle. The explants were co-cultivated with A. tumefaciens strain AgL0, or LBA4404 for 4 days on IL medium without selection. Explants were then transferred to IL medium with antibiotic for shoot regeneration. After four days a drop of glufosinate (2000 mg/l) was applied on the apical region of the explant. Two to three weeks later, shoots that developed were excised individually from the shoot apices and placed on IL medium with 20 mg/L glufosinate and Timentin™.
After subculture every 10-14 days for 4-6 months, induction of roots in both lupin species was achieved by incubation in medium containing either NAA (2mg/l) or IBA (3 mg/l) (rooting medium). Thirty to fifty percent of L. angustifolius explants and 10 % of L. luteus explants developed roots in vitro. Those explants that did not develop roots were grafted onto 10-14-day old L. angustifolius Merrit or Myallie seedlings in vitro. This technique was successful in about 98% of cases. T0 plants were matured in liquid medium with a hydroponics system or in sand in the glasshouse.
A total of 13,460 L. angustifolius explants from 7 genotypes were cocultivated with A. tumefaciens with 9 different gene constructs. Twenty-four independent L. angustifolius primary transformants of 5 genotypes, transformed with one of 4 constructs were obtained. A total of 35,034 L. luteus explants from 9 genotypes were cocultivated with A. tumefaciens with 14 different constructs. Forty-eight independent L. luteus primary transformants of 4 genotypes, transformed with one of 6 constructs were obtained.
Southern analysis of 14 T. angustifolius primary transformants showed that they contained 1-4 copies of a transgene. Three L. luteus transformants contained 3-4 copies of the transgene.
All 24 L. angustifolius events and 26 of the 34 L. luteus events tested expressed PAT and acetylated glufosinate in PAT assays. Plants that expressed PAT usually tolerated leaf application of 100 mg/1 glufosinate. In 8 L. luteus T0 events, the bar gene was inactivated. Two L. luteus transformants were highly tolerant to glufosinate and showed no tissue damage after application of 1000 mg/1 glufosinate.
A PCR product from a T1 L. luteus plant, of part of the virus-resistance transgene (Nla) was sequenced. It was 3 nucleotides shorter than expected, 417 vs 420, because of a deletion. A 1,939 bp PCR product consisting of the regulatory elements 35S promoter, CMV 5’UTR and CaMV 3’UTR, and the full-length Nla gene, was similarly isolated from a T3-generation L. angustifolius plant. There were 4 nucleotide substitutions in the Nla gene, but no changes to the regulatory elements.
Plant lines derived from 17 different L. angustifolius transformation events were challenged by sap inoculation of BYMV-Mi in the glasshouse, 5 events were challenged by aphid inoculation of BYMV-Mi in a screenhouse. Manual inoculation was more effective than aphid inoculation as determined by the infection rate of non-transgenic controls. In glasshouse trials, nine transgenic events showed no resistance to systemic infection. The rates of systemic virus infection in plant lines from 6 primary transformants ranged from 60-94%. After aphid inoculation in screenhouse trials, 77-100% of non-transgenic controls became infected, and 50-100% of transgenic plants became infected. Conclusive results were therefore not obtained from aphid inoculation experiments.
Twenty six lines from 5 L. luteus transformation events were challenged by manual sap inoculation of BYMV-Mi in a glasshouse, 6 lines from 4 transformation events were challenged by aphid inoculation in a screenhouse, and 8 lines from 5 transformation events by aphid inoculation in a small field trial. In the glasshouse trials, 90-100% the nontransgenic control plants became infected after 5 virus inoculations. The rates of systemic virus infection in plant lines from 20 lines ranged from 18-86%. After aphid inoculation of the virus in the screenhouse trials, 28-57% of non-transgenic controls were infected, and 0- 70% of transgenic events were infected. In the line without systemic infection, only 28% of controls became infected. In a small field trial, 37-69% of control plants and 36-64% of the transgenic plants became infected. As with aphid inoculation experiments with L. angustifolius, conclusive results were not obtained from aphid inoculation of L luteus.
In conclusion, an improved system for in vitro culture, selection and regeneration of transgenic plants of L. angustifolius has been developed and applied to generate a series of transgenic plants with different synthetic virus resistance constructs. A similar L. luteus transformation procedure has been developed, with production for the first time of transgenic plants of L. luteus. Some individual plants from both species were highly resistant to BYMV. However, other plants within the same lines were susceptible. Transgenic plants tolerant to high levels to glufosinate, and of potential commercial use, were obtained for both species. Inheritance of transgenes was followed up to the T5 generation.
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Shamandi, Nahid. "Functional analysis of plant RNaseIII enzymes." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112157/document.
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Chez la majorité des eucaryotes, les petits ARN (miRNA et siRNA) jouent des rôles essentiels au cours du développement, dans les réponses adaptatives aux stress, et dans la maintenance de la stabilité génétique. Les plantes codent quatre enzymes RNaseIII de type DICER-LIKE (DCL). DCL1, produit les miRNAs, tandis que DCL2, DCL3 et DCL4 produisent des siRNAs des tailles diverses. Les plantes codent également des enzymes appelées RNASE-THREE-LIKE (RTL) auxquelles il manque certains domaines spécifiques aux DCLs, et dont la fonction est largement inconnue.Des plantes sur-exprimant RTL1 montrent des défauts morphologiques, et n'accumulent pas les siRNAs produits par DCL2, DCL3 ou DCL4, indiquant que RTL1 est un suppresseur général des voies de siRNA chez les plantes. L’activité de RTL1 nécessite un domaine RNaseIII fonctionnel. RTL1 ne s'exprime naturellement que faiblement dans les racines, mais l'infection virale induite fortement son expression dans les feuilles, ce qui suggère que l’induction de RTL1 est une stratégie générale utilisée par les virus pour contrer la défense antivirale basée sur siRNAs. En accord avec cette hypothèse, les plantes transgéniques sur-exprimant RTL1 sont plus sensibles à l'infection par le TYMV que des plantes de type sauvage, probablement parce que RTL1 empêche la production des siRNAs dirigés contre les RNA viraux. Cependant, les plantes transgéniques sur-exprimant RTL1 ne sont pas plus sensibles à l'infection par le TCV, TVCV ou le CMV, qui codent les suppresseurs de RNA silencing (VSR) plus puissants que le TYMV. En effet, le VSR de TCV inhibe l'activité de RTL1, suggérant que l'induction de l’expression de RTL1 par les virus et l’amortissement de l’activité de RTL1 par leurs VSRs est une double stratégie permettant d’établir une infection avec succès. Des plantes sur-exprimant RTL2 ou des mutants rtl2 ne montrent aucun défaut morphologique, et ne montrent pas de changement majeur du répertoire des petits ARNs endogènes. Toutefois, la sur-expression de RTL2 augmente l’accumulation des petits ARNs exogènes dans des essais d’expression transitoire, et cette activité nécessite un domaine RNaseIII fonctionnel. Il est donc possible que RTL2 clive certains substrats pour faciliter l’action des enzymes DCL<br>Small RNAs, including miRNA and siRNA, play essential regulatory roles in genome stability, development and stress responses in most eukaryotes. Plants encode four DICER-LIKE (DCL) RNaseIII enzymes. DCL1 produces miRNAs, while DCL2, DCL3 and DCL4 produce diverse size classes of siRNA. Plants also encode RNASE THREE-LIKE (RTL) enzymes that lack DCL-specific domains and whose function is largely unknown. Arabidopsis plants over-expressing RTL1 exhibit morphological defects and lack all types of small RNAs produced by DCL2, DCL3 and DCL4, indicating that RTL1 is a general suppressor of plant siRNA pathways. RTL1 activity requires a functional RNaseIII domain. RTL1 is naturally expressed only weakly in roots, but virus infection strongly induces its expression in leaves, suggesting that RTL1 induction is a general strategy used by viruses to counteract the siRNA-based plant antiviral defense. Accordingly, transgenic plants over-expressing RTL1 are more sensitive to TYMV infection than wild-type plants, likely because RTL1 prevents the production of antiviral siRNAs. However, TCV, TVCV and CMV, which encode stronger suppressors of RNA silencing (VSR) than TYMV, are insensitive to RTL1 over-expression. Indeed, TCV VSR inhibits RTL1 activity, suggesting that inducing RTL1 expression and dampening RTL1 activity is a dual strategy used by viruses to establish a successful infection. Plants over-expressing RTL2 and rtl2 mutants do not exhibit morphological defects and do not show major changes in the endogenous small RNA repertoire. However, RTL2 over-expression enhances the accumulation of exogenous siRNAs in transient assays, and this activity requires a functional RNaseIII domain. Therefore, it is possible that plant RTL2 processes certain substrates to facilitate the action of DCL enzymes
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Chingandu, Nomatter, and Nomatter Chingandu. "Genomic Characterization of the Cacao Swollen Shoot Virus Complex and other Theobroma Cacao-Infecting Badnaviruses." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621859.
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The cacao swollen shoot disease of Theobroma cacao L. (cacao) is caused by Cacao swollen shoot virus (CSSV; genus, Badnavirus, family, Caulimoviridae). The virus is endemic to West Africa, where it poses a serious threat to cocoa production. Despite efforts to control CSSV spread by replacement of infected trees with tolerant cultivars and mealybug vector management, the disease is widespread in West Africa. In Trinidad, leaf mosaic and vein-banding symptoms have been observed in cacao plants in the field since the 1940s, and recently at the International Cocoa Genebank (ICGT), a custodian of cacao germplasm resources. The strains A and B of the suspect Cacao Trinidad virus (CTV) caused the symptoms, and were thought to be related to CSSV, however, viral causality was not demonstrated, until now. To develop molecular detection methods for CSSV in infected plants, polymerase chain reaction (PCR) amplification of eight regions of the CSSV genome was implemented. The PCR results showed variable amplification frequencies of 19 - 42% at each region, for 124 isolates collected in Cote d'Ivoire and Ghana. Pairwise nucleotide (nt) analyses of the eight regions showed 66-99% shared identities, indicating that CSSV isolates exhibit extensive variability with respect to primer design. The results provided preliminary evidence for the existence of a CSSV complex consisting of four divergent species. The full length genome of 14 CSSV isolates from cacao determined using the Illumina HiSeq platform showed 70-99% shared nt identities. The pairwise nt identities placed CSSV sequences into a group of four distinct species, one of which represented a previously undescribed species. Moreover, the full-length genomes grouped phylogenetically with other badnaviruses and revealed two CSSV subclades with three types of genome arrangements; four, five or six open reading frames (ORFs). Predicted functional protein domains were conserved on each ORF. Two distinct, full-length genome sequences were determined using the Illumina HiSeq platform, from DNA isolated from cacao leaves exhibiting distinct symptoms in Trinidad. The sequences were validated by PCR-amplification and sequencing of overlapping viral genome fragments. Pairwise nt analysis indicated that each genome shared 52-62% nt identities with CSSV and other badnaviruses, suggesting that the two are distinct species. Phylogenetic analysis indicated that the two sequences are not strains of the same virus, as supposed, but they represent two previously undescribed species in the genus, Badnavirus, and they have been named Cacao mild mosaic virus (CaMMV) and Cacao yellow-vein-banding virus (CYVBV). Despite sharing the same host and causing similar symptoms in cacao, CSSV, CaMMV, and CYVBV are phylogenetically-distinct species. The discovery of a CSSV species complex and the identification of three new cacao-infecting badnavirus species will support the development of molecular detection tools using the partial and complete genome sequences determined in this study. The ability to develop validated molecular tools for the detection of CSSV and related viruses, CaMMV and CYVBV, in cacao will aid quarantine efforts and safe movement of germplasm from the ICGT in Trinidad to cacao-growing countries, worldwide. Also, molecular diagnostics tools are expected to be useful in efforts underway to develop CSSV-resistant planting material for countries in West Africa, which are currently experiencing continued or new disease outbreaks.
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Harker, C. L. "The detection of virus coded proteins in cauliflower mosaic virus infected plants and protoplasts." Thesis, Bucks New University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376417.
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Jeffries, Alex Craig. "The study at the molecular level of the New Zealand isolate of Lucerne transient streak sobemovirus and its satellite RNA." Title page, contents and summary only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09phj47.pdf.
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Carr, Tyrell. "Genetic and molecular investigation of compatible plant-virus interactions." [Ames, Iowa : Iowa State University], 2007.
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Brown, J. K., D. Goldstein, and M. R. Nelson. "Plant Virus Diseases that Threaten Cucurbit Production in Arizona." College of Agriculture, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/214137.
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A number of plant viruses were isolated from diseased cucurbits in Arizona during 1982 -85. Watermelon mosiac virus 2, cucumber mosaic virus, and squash mosaic virus are previously recognized viral pathogens in Arizona and in most years are not considered economically threatening to cucurbit production. Three newly described plant viruses (lettuce infectious yellows, watermelon curly mottle and zucchini yellow mosaic) however, have the potential to, or already have, incited serious epidemics in Arizona. Losses are heaviest with these diseases when insect vector levels build up early in the growing season and plants become infected during critical developmental stages.
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Cole, Anthony Blaine Thomas. "Investigations into the hypersensitive response of Nicotiana species to virus infections /." free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3012960.
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Asare-Bediako, Elvis. "Brassicaceae : Turnip yellows virus interactions." Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/44041/.
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Turnip yellows virus (TuYV) is the most common and important virus infecting oilseed rape (Brassica napus) in the UK. It causes reductions in growth and seed yield in oilseed rape. Between 2007 and 2010, the prevalence of TuYV in oilseed rape crops in Lincolnshire, Warwickshire and Yorkshire was determined; incidences of infection ranged from 0 and 100%. The highest levels of infection were detected in Lincolnshire and the lowest in Yorkshire. Highest incidences were recorded during 2009-10 and the lowest in 2008-9. Incidences of TuYV were closely related to the flight activities Myzus persicae vector. Most fields showed slightly aggregated pattern of infection during autumn but spring sampling revealed more random patterns. Phylogenetic analysis of both nucleotide and amino acid sequences of the P0 and P3 genes of TuYY revealed three and two genetic groups of TuYV respectively, infecting oilseed rape in Lincolnshire, Warwickshire and Yorkshire. The P0 gene was more variable than the P3 gene and both were under purifying selection. TuYV populations in the three regions were highly structured with limited gene flow between them. Analysis of molecular variance (AMOVA) indicated 96- 97% of the observed variation was due to the variation between isolates within fields. Three RT-PCR assays were developed to differentiate the three genotypes. They successfully detected and discriminated isolates of the two major genotypes from oilseed rape in Lincolnshire. Twenty seven accessions of a B. napus Diversity Fixed Foundation Set (DFFS) screened for resistance against TuYV infections varied in their susceptibility to the virus. An accession Yudal had partial resistance to some but not all the isolates of the two major genetic groups tested. TuYV caused yield losses of up to 44.7% in a glasshouse experiment. A major QTL for the partial TuYV resistance was detected on chromosome C4 (N14), explaining up to 50.5% of the observed resistance.
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Vaitkunas, Katrina Emilee. "The genetics of TCV resistance." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0428103-102720.
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Moshref, Mahmood. "Investigation of plant extracts for antimicrobial activity." Thesis, University of Sheffield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388711.
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Al-Kaff, Nadia Saleh Ahmed. "Biological and molecular diversity of cauliflower mosaic virus." Thesis, University of East Anglia, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240834.
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Gronnier, Julien. "Function of Plant Plasma Membrane Nanodomains : Study of Group 1 REMORINs during Plant-Virus Interactions." Electronic Thesis or Diss., Bordeaux, 2016. http://www.theses.fr/2016BORD0327.
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L’organisation par compartimentalisation est une propriété générale des systèmes naturels coordonnant les évènements biologiques dans l’espace et le temps. Au cours des trente dernières années, il a pu être démontré qu’à l’échelle d’une membrane de nombreux sous-compartiments coexistent. Une telle organisation semble cruciale pour l’ensemble des activités biologiques cellulaires et par conséquent prépondérante pour le développement et la survie des organismes vivants. La membrane plasmique présente une grande diversité de compartiments, néanmoins leurs fonctions et les mécanismes moléculaires régissant leur organisation ne sont pas très bien compris. Afin d’apporter de nouvelles informations sur comment et pourquoi la membrane plasmique des plantes est souscompartimentée, nous étudions les nanodomaines des REMORINEs du groupe 1 au cours de l’infection de N. benthamiana par le Potato Virus X (PVX). En menant une approche multidisciplinaire, nous avons décortiqué un mécanisme moléculaire impliqué dans l’organisation en nanodomaine de REMORIN à la membrane plasmique. Via la génération de mutants nous présentons des liens fonctionnels entre l’organisation en domaine de REMORIN, son statut de phosphorylation, sa capacité à réguler la perméabilité des plasmodesmes et la propagation de cellule à cellule du PVX. Nous présentons également des éléments montrant qu’au cours de la perception de PVX par N. benthamiana, l’organisation de la membrane plasmique est cruciale pour la mise en place des mécanismes de défense de la plante. Cette étude met en avant pour la première fois chez les plantes l’importance de la régulation spatio-temporelle des protéines à la membrane plasmique dans l’identité et la fonction de domaines membranaires<br>Organization by compartmentalization is a general property of natural systems coordinating biological events in space and time. Over the past three decades, it has been demonstrated that multiple micrometric to nano-metric sub-compartments co-exist at a single membrane level. Such membrane organization seems critical for most all cell bioactivities and therefore critical for development and survival of potentially all living organisms. Plants respond to pathogens by activating highly regulated plasma membrane-bound signalling pathways. Plant plasma membrane (PM) displays a great diversity of compartments, but underlying functions and molecular mechanisms governing such organization are not well understood. To get insight in how and why plant PM is compartmentalized, we choose to study the plant PM nanodomain goup 1 REMORIN during the interaction between N. benthamiana and the Potato Virus X (PVX). Using a multidisciplinary approach we decipher a molecular mechanism involved in defining REMORIN PM domains localization. Making mutants we provide a functional link between REMORIN PM organization at single molecule level, its phosphostatus, regulation of plasmodesmata permeability and PVX cell-to-cell movement restriction. We then provide evidences that during N.benthamiana PVX sensing, PM organization appears critical for the modulation plant defence mechanisms and cell signaling. This study provides a unique mechanistic insight into how tight control of protein spatio-temporal organization at PM level is crucial to confer membrane domains identity and functionality
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Balcı, Evrim Doğanlar Sami. "Genetic characterization of cucumber mosaic virus(CMV)resistance in tomato and pepper." [s.l.]: [s.n.], 2005. http://library.iyte.edu.tr/tezler/master/biyoloji/T000388.pdf.
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Chapman, Sean Nicholas. "A molecular analysis of potato virus X." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386398.
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Wasswa, Peter. "Sweet potato viruses in Uganda : identification of a new virus, a mild strain of an old virus and reversion." Thesis, University of Greenwich, 2012. http://gala.gre.ac.uk/9091/.
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In 2009, a sweet potato begomovirus (sweepovirus) was detected for the first time in Uganda. An isolate was sequenced, providing the first full sequence of a sweepovirus from mainland Africa which differed from other sweepoviruses by at least 13%, discriminating this isolate as a new species, ‘Sweet potato leaf curl Uganda virus’ (SPLCUV). SPLCUV was quite common in cultivars (cvs) Ejumula, New Kawogo and 318L having uneven distribution in infected plants and reversion to healthy occurred, especially in cv New Kawogo. SPLCUV was observed not to be synergised by Sweet potato chlorotic stunt virus (SPCSV), apparently making it the first report of a sweet potato virus not synergised by SPCSV. Besides SPLCUV, a ‘mild’ SPCSV strain that induced purpling symptoms and 50% yield reduction similar to wild type SPCSV when infecting alone was identified from Busia district, Uganda. ‘Mild’ SPCSV was never observed to be co-infected with Sweet potato feathery mottle virus (SPFMV) in farmers’ fields. Experimentally, ‘mild’ SPCSV induced mild symptoms in Ipomoea setosa and sweet potato plants and SPFMV titre was greater in co-infections of SPFMV and wild type SPCSV than in co-infections of SPFMV and ‘mild’ SPCSV. Both RNase3 (accession No. HE575406) and p22 (accession No. HE575409) genes on RNA1 of ‘mild’ SPCSV compared closely to those reported previously. Instead, RNA1 region appears to be expressed less in the ‘mild’ SPCSV infection than in the wild type SPCSV infection though RNA2 continues to be more expressed in the ‘mild’ SPCSV infection than in the wild type SPCSV infection. Recovery from SPVD symptoms and reversion from SPFMV were observed in cv Kampala White co-infected with ‘mild’ SPCSV and SPFMV. Reversion from SPFMV single infections occured in several landraces with higher rates observed in shoots of resistant than susceptible cultivars. Overall, cv NASPOT 11 was the fastest to revert while cv Beauregard was the slowest.
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Freitas, Debora Maria Sansini. "Novas observações sobre a proteção com estirpes fracas do Papaya ringspot virus - type W e do Zucchini yellow mosaic virus em plantas de abobrinha-de-moita." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/11/11135/tde-17082007-095734/.
Full textAbstract:
O Papaya ringspot virus - type W (PRSV-W) e o Zucchini yellow mosaic virus (ZYMV) são as duas espécies de potyvírus que mais causam danos em cucurbitáceas no estado de São Paulo e no Brasil. Uma boa alternativa de controle para as doenças causadas por esses vírus é o emprego da premunização. O principal objetivo desse trabalho foi estudar a competição por sítios de replicação como possível mecanismo de proteção entre a estirpe fraca PRSV-W-1 e a estirpe severa PRSV-W-C em plantas de abobrinha-de-moita. Além disso, procurou-se também conhecer o período mínimo necessário para a proteção de plantas de abobrinha-de-moita premunizadas com a estirpe fraca ZYMV-M, só e em dupla premunização com a estirpe fraca PRSV-W-1, para fornecer subsídios para o uso em condições de campo. O estudo da competição por sítios de replicação como mecanismo de proteção foi feito inoculando-se plantas de abobrinha-de-moita ‘Caserta‘ com a estirpe fraca PRSV-W-1 e desafiando-as com a estipe severa PRSV-W-C. As inoculações de proteção foram feitas nas folhas cotiledonares e as de desafio na folha nova verdadeira, e vice-versa, aos 3, 6 e 9 dias após a primeira inoculação. Plantas infectadas com a estirpe fraca e não desafiadas e plantas infectadas com a estirpe severa foram usadas como controles. As avaliações foram feitas com base na manifestação dos sintomas 30 dias após o desafio. Também foi feito teste de recuperação da estirpe desafiante e detecção desta por RT-PCR, com primers específicos, aos 8 dias após o desafio. Os resultados sugerem que, independente do local onde foi realizada a inoculação de proteção (folha cotiledonar ou folha nova expandida), de uma maneira geral parece haver alguns sítios livres para a superinfecção com a estirpe severa. Quando esta foi inoculada aos três dias após a proteção, ela se estabeleceu em algumas plantas, moveu-se sistemicamente e sobrepôs a estirpe fraca, uma vez que as plantas exibiram sintomas severos. Com o passar do tempo (seis e nove dias após a proteção), todas as plantas ficaram protegidas contra a expressão dos sintomas severos da estirpe desafiante, porém esta foi capaz de se estabelecer nas folhas inoculadas e até mesmo mover sistemicamente em algumas plantas. No caso da proteção com a estirpe fraca ZYMV-M, só ou em mistura com a estirpe fraca PRSV-W-1, contatou-se que plantas de abobrinha-de-moita premunizadas e desafiadas sete dias depois ficaram protegidas contra a infecção e/ou manifestação dos sintomas das respectivas estirpes severas usadas no desafio.<br>Papaya ringspot virus - type W (PRSV-W) and Zucchini yellow mosaic virus (ZYMV) are two potyviruses associated with severe yield losses on cucurbit crops in the State of São Paulo and other parts of the Brazilian territory. Preimmunization with mild strains has proved to be a good alternative for the control of both viruses in susceptible cultivars. The main purpose of this work was to evaluate the competition for infectable sites as a possible mechanism of cross protection between the mild strain PRSV-W-1 and the severe strain PRSV-W-C in zucchini squash (Cucurbita pepo cv. Caserta). Protective inoculation with the mild strain was done at the cotyledon and the challenge inoculation with the severe strain was applied on the first true expanded leaf, and viceversa. Different plants were challenged at three, six and nine days, respectively. No challenge protected plants and healthy plants infected with the severe strain were used as controls. Evaluations were based on the expression of the symptoms at 30 days after challenge inoculation. Attempts to recover the challenge strain from challenge inoculated and new developed leaves were also done at eight days after challenge inoculation. RT-PCR with specific pairs of primers was also used to detect both stains in some of these samples. Regardless the leaf on which the protective strain was applied (cotyledon or first true expanded leaf) there appear to be some infectable sites available for superinfection with the severe strain. When the challenge inoculation was done at three days after preimmunization, the severe strain was able to superinfect some plants, move systemically and overcome the mild strain, since these plants expressed severe symptoms. All plants become protected against the expression of the symptoms induced by the severe strain when the challenge inoculation was done at six and nine days after preimmunization. However, the severe strain was still detected in the inoculated and upper leaves of few test-plants, eight days after challenge inoculation. In addition to this, it was also determined the period of time necessary to protect zucchini squash plants with a mild strain of ZYMV, named ZYMV-M, alone and in mixture with mild strain PRSV-W-1. The results indicated that single and double preimmunized plants were protected against infection and/or expression of the homologous severe strain seven days after protective inoculation.
29
Lin, Junyan. "NONHOST RESISTANCE TO BEAN POD MOTTLE VIRUS IN NICOTIANA BENTHAMIANA." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1372723537.
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George, Gavin M. (Gavin Mager). "Virus induced gene silencing for the study of starch metabolism." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4024.
Full textAbstract:
Thesis (PhD (Plant Biotechnology))--University of Stellenbosch, 2010.<br>ENGLISH ABSTRACT: Virus Induced Gene Silencing (VIGS) was optimized to allow for the study of starch
metabolism. The plastidial inorganic pyrophosphatase gene, for which a mutant has
never been identified, was studied using VIGS and it was found to have a broad role
in this subcellular compartment. The accumulation of inorganic pyrophosphate
limited the production of starch, carotenoids, chlorophyll, and increased the plants
susceptibility to drought stress. These effects highlight the importance of this enzyme
in maintaining a low intraplastidial concentration of PPi providing an environment
which facilitates these anabolic processes. Several genes involved in starch
synthesis and degradation were also targeted with the aim of establishing a system
of multiple gene silencing for the study of metabolic pathways. One, two and three
genes were successfully silenced using this system which was validated based on
previously published data. Interestingly, simultaneous silencing of the two isoforms
of disproportionating enzyme led to a novel phenotype as a large reduction in starch
instead of the expected increase was observed.<br>No Afrikaans abstract available
31
Bustamante-Gallardo, Pedro. "Molecular studies on Rice hoja blanca virus (RHBV)." Thesis, University of East Anglia, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338096.
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Maree, H. J. (Hans Jacob). "The expression of Dianthin 30, a ribosome inactivating protein." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53633.
Full textAbstract:
Thesis (MSc)--Stellenbosch University, 2003.<br>ENGLISH ABSTRACT: Ribosome inactivating proteins (RIPs) are currently classified as rRNA N-glycosidases, but
also have polynucleotide: adenosine glycosidase activity. RIPs are believed to have anti-viral
and anti-fungal properties, but the exact mechanism of these proteins still need to be
elucidated.The mechanism of resistance however, appears to be independent of the pathogen.
For resistance the RIP terminates virus infected plant cells and stops the reproduction and
spread of the virus. Transgenic plants containing RIPs should thus be resistant to a wide
range of viruses. The ultimate goal of the larger project of which this forms part is the
development of virus resistant plants. To monitor the expression of a RIP in a transgenic
plant a detection method had to be developed. Antibody detection of the RIP was decided
upon as the most cost effective method. The RIP, Dianthin 30 from Dianthus caryophyllus
(carnation), was used and expressed in bacterial and insect expression systems. The bacterial
expression experiments were done using the pET expression system in BL21(DE3)pLysS
cells. The expression in this system yielded recombinant protein at a very low concentration.
Expression experiments were also performed in insect tissue culture with the baculovirus
vector BAC-TO-BAC™.With this system the expression was also too low to be used for the
production of antibodies. A Dianthin 30 specific peptide was then designed and then
produced by Bio-Synthesis. This peptide was then used to raise antibodies to detect Dianthin
30. These antibodies were tested on Dianthus caryophyllus proteins. To establish if this
detection method was effective to monitor the expression in plants, tobacco plants were
transformed with Agrobacterium tumefaciens containing Dianthin 30 in the pART27 plant
expression vector. The putative transformed plants were analysed with peR and Southern
blots.<br>AFRIKAANSE OPSOMMING: Tans word Ribosomale-inaktiverende proteïene (RIPs) geklassifiseer as rRNA N-glikosidase
wat ook polinukleotied: adenosien glikosidase aktiwiteit bevat. Daar word geglo dat RIPs
anti-virale en anti-fungus eienskappe bevat, maar die meganisme van beskerming word nog
nie ten volle verstaan nie. Dit is wel bewys dat die meganisme van weerstand onafhanklik is
van die patogeen. Virus geinfekteerde plantselle word deur die RIP gedood om die
voortplanting en verspreiding te bekamp en sodoende word weerstand bewerkstellig.
Transgeniese plante wat dan 'n RIP bevat sal dus weerstandbiedend wees teen 'n wye
spektrum virusse. Die hoofdoel van die breër projek, waarvan die projek deel uitmaak: is die
ontwikkeling van virusbestande plante. Om die uitdrukking van die RIP in die transgeniese
plante te kontroleer, moes 'n deteksie metode ontwikkel word. Die mees koste effektiewe
deteksie metode is met teenliggame. Die RIP, Dianthin 30 from Dianthus caryophyllus
(angelier) was gebruik vir uitdrukking in bakteriele- en insekweefselkultuur. Die bakteriele
uitdrukkingseksperimente was gedoen met die pET uitdrukkings sisteem III
BL21(DE3)pLysS selle. Die uitdrukking in die sisteem het slegs rekombinante proteïene
gelewer in uiters lae konsentrasies. Uitdrukkingseksperimente was ook gedoen in
insekweefselkultuur met die baculovirus vektor BAC-To- BACTM. Met die sisteem was die
uitdrukking ook veels te laag om bruikbaar te wees vir die produksie van teenliggame. Daar
is toe 'n peptied ontwerp wat Dianthin 30 kan verteenwoordig vir die produksie van
teenliggame. Die teenliggame is getoets teen Dianthus caryophyllus proteïene. Om vas te stel
of die deteksiemetode wel die uitdrukking van Dianthin 30 sal kan monitor, is tabak ook
getransformeer met Dianthin 30. Die transformasies is gedoen met die hulp van
Agrobacterium tumefaciens en die pART27 plant uitdrukkings vektor. Die plante is getoets
met die polimerase ketting reaksie en Southern klad tegnieke.
33
Escaler, Margarita. "Changes in host gene expression associated with plant virus replication." Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302215.
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Seymour, Maile Elizabeth Kahawaluiaakalani. "Process considerations in the extraction and recovery of plant virus." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398938.
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Zhang, Xu-Sheng. "Mathematical models of plant disease epidemics that involve virus interactions." Thesis, University of Greenwich, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327341.
Full text
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Takeda, Atsushi. "Analysis of Plant Virus Movement Proteins and RNA Silencing Suppressors." Kyoto University, 2004. http://hdl.handle.net/2433/147760.
Full textAbstract:
Kyoto University (京都大学)<br>0048<br>新制・課程博士<br>博士(農学)<br>甲第10911号<br>農博第1417号<br>新制||農||891(附属図書館)<br>学位論文||H16||N3922(農学部図書室)<br>UT51-2004-G758<br>京都大学大学院農学研究科応用生物科学専攻<br>(主査)教授 奥野 哲郎, 教授 遠藤 隆, 教授 西岡 孝明<br>学位規則第4条第1項該当
37
Giampan, José Segundo. "Infectividade e proteção de três estirpes fracas do Papaya ringspot virus em plantas de melancia." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/11/11135/tde-25022003-134805/.
Full textAbstract:
Este trabalho teve como objetivo avaliar a infectividade de estirpes fracas do Papaya ringspot virus - type W (PRSV-W) em plantas de melancia (Citrullus lanatus), em função da origem da estirpe fraca, da concentração e da espécie doadora do inóculo e da idade da planta-teste de melancia, inoculada mecanicamente. Também foi avaliado o efeito protetor dessas estirpes em plantas de melancia em casa de vegetação e em campo. A seleção de estirpes fracas do PRSV-W foi feita a partir de bolhas de folhas de melancia infectadas naturalmente em campo. A infectividade da estirpe fraca selecionada foi comparada com a das estirpes fracas PRSV-W-1 e PRSV-W-2, previamente selecionadas de bolhas de folhas de abobrinha de moita (Cucurbita pepo) 'Caserta' com mosaico. Como controle foi utilizada uma estirpe severa do vírus obtida de abobrinha de moita (PRSV-W-C). A avaliação do efeito da concentração e da espécie da planta fonte do inóculo na infectividade de plantas de melancia foi feita com extratos de 4, 8, 12 e 16 discos de folhas de abobrinha de moita e de melancia, infectadas separadamente com as estirpes fracas e severa, e diluídos em 2 mL de tampão fosfato. O efeito da idade da planta-teste de melancia na infectividade das estirpes fracas foi estudado comparando-se plantas inoculadas em quatro estádios de desenvolvimento, a partir do estádio cotiledonar, com inóculos das diferentes estirpes do PRSV-W extraídos de 12 discos foliares/2 mL de tampão. O efeito protetor da estirpe fraca obtida de bolhas de folhas de melancia com mosaico foi avaliado em plantas premunizadas e desafiadas com a estirpe PRSV-W-C, em casa de vegetação e em campo. Plantas de melancia premunizadas com as estirpes fracas PRSV-W-1 e PRSV-W-2 e plantas não protegidas também foram avaliadas no teste em campo. Foram avaliadas a proteção, com base nos sintomas, a produção e o conteúdo de açúcares (grau brix) dos frutos colhidos das plantas premunizadas e não premunizadas. Uma estirpe fraca do vírus, denominada PRSV-W-3, foi selecionada de bolhas de folhas de melancia com mosaico. Em todos os testes de infectividade em plantas de melancia, independente da concentração e da planta fonte do inóculo e do estádio de desenvolvimento da planta-teste inoculada, a estirpe fraca PRSV-W-3 apresentou taxas de infectividade semelhantes as das estirpes PRSV-W-1 e PRSV-W-2, chegando a 100% em alguns casos. A infectividade da estirpe severa PRSV-W-C foi de 100% em todos os testes. Aparentemente, a infectividade das três estirpes fracas foi mais diretamente afetada pela intensidade de fricção das folhas no momento da inoculação mecânica do que pelas variáveis estudadas. A estirpe fraca PRSV-W-3 protegeu as plantas de melancia contra a infecção e/ou manifestação da estirpe PRSV-W-C em casa de vegetação. Em campo, todas as plantas de melancia premunizadas com as três estirpes fracas também ficaram protegidas contra a estirpe severa utilizada no desafio. A produção das plantas premunizadas não diferiu estatisticamente entre si, nem mesmo daquelas inicialmente sadias infectadas em campo. O conteúdo de açúcares e a aparência da polpa dos frutos também foram semelhantes em todos os tratamentos.<br>The purpose of this work was to evaluate the infectivity of three mild strains of Papaya ringspot virus - type W (PRSV-W) on watermelon (Citrullus lanatus). The effect of the origin of the mild strain, the concentration of the inoculum, the species of the source of the inoculum and the age of the test-plant on the infectivity of mechanically inoculated watermelon were also evaluated. The protective effect of these mild strains on preimmunized watermelon plants was evaluated under greenhouse and field conditions. Mild strains were selected from blisters formed on mosaic leaves of naturally infected watermelon plants. The infectivity of the selected mild strain was compared with that of mild strains PRSV-W-1 and PRSV-W-2, which were previously obtained from blisters formed on mosaic leaves of zucchini squash (Cucurbita pepo cv. Caserta). A severe strain isolated from zucchini squash (PRSV-W-C) was used as control. The effect of the concentration and the species source of inoculum of the mild strains on the infectivity of watermelon plants was studied with inoculum extracted from 4, 8, 12 and 16 leaf discs of zucchini squash and watermelon plants, separately infected with the mild and severe strains, diluted in 2 mL of phosphate buffer. Four stages of development of watermelon plants, starting at the cotyledonal stage, were tested for the infectivity with the mild strains. Inocula were prepared with extracts of 12 leaf discs diluted in 2 mL of phosphate buffer. The protective effect of the mild strain selected from blisters on mosaic leaves of watermelon plants was evaluated on preimmunized plants challenge inoculated with severe strain PRSV-W-C, under greenhouse and field conditions. Watermelon plants preimmunized with mild strains PRSV-W-1 and PRSV-W-2 and unprotected plants were also included in the field trial. Protection was evaluated based on plant simptons, yield and sugar content in the fruits. One mild strain, named PRSV-W-3, was obtained from blisters on mosaic leaves of watermelon plants. The rate of infection of watermelon plants with mild strain PRSV-W-3 was similar to that with mild strains PRSV-W-1 and PRSV-W-2 in all infectivity tests, independently of the concentration of the inoculum, species source of the inoculum and stage of development of the inoculated test-plant, reaching 100% in some cases. Rate of infectivity with severe strain PRSV-W-C was always 100%. Apparently, the infectivity of the mild strains on watermelon was more directly related with the intensity of the abrasion produced by mechanical inoculation than with the above studied variables. The selected mild strain PRSV-W-3 protected watermelon plants against superinfection with the severe strain in the greenhouse tests. Protection was also effective under field conditions. Yield of plants preimmunized with all three mild strains and unprotected plants were statistically similar. The sugar content and the quality of the pulp of the fruits were similar for all treatments.
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Shih, Sharon Min-Hsuan Biotechnology & Biomolecular Sciences Faculty of Science UNSW. "Transient viral infection of plant tissue culture and plants for production of virus and foreign protein." Awarded by:University of New South Wales, 2007. http://handle.unsw.edu.au/1959.4/34967.
Full textAbstract:
This work was aimed to investigate the basic viral infection protocols mainly focusing on Nicotiana benthamiana hairy root cultures and wild-type tobacco mosaic virus (TMV). The application of transgenic virus containing the gene for green fluorescent protein (GFP) for foreign protein production in plant tissue cultures and whole plants was also studied. The effect on viral accumulation of the form of plant tissue culture used, such as hairy roots, shooty teratomas and suspended cells, was investigated. Viral infection was shown to have no effect on culture growth and morphology. Hairy root cultures are a superior host for viral propagation and production in vitro. The maximum specific rate of viral accumulation occurred mainly during the root growth phase. The average maximum virus concentration in the hairy roots was 0.82 ?? 0.14 mg g-1 dry weight and virus protein represented a maximum of approximately 6% of total soluble protein in the root biomass. Proportional scale-up of TMVinfected hairy roots in shake flasks and bioreactors can be achieved without changing the average virus concentration accumulated in the hairy roots. The level of viral accumulation was much lower in N. benthamiana hairy roots infected with transgenic virus containing GFP (TMVGFPC3) compared with TMV and low levels or no GFP was detected. Viral accumulation and GFP production in whole plants was studied using different generations of transgenic TMV-GFPC3 virus. Hybrid viruses with the foreign gene GFPC3 deleted may have been formed in successive TMV-GFPC3 generations, resulting in the loss of GFP production and enhanced viral infectivity. In vitro generated RNA transcript and first generation TMV-GFPC3 were found to be more suitable for infection than the second generation TMV-GFPC3. However, the accumulation of GFP and virus concentration did not occur at the same ratio. Provided a more genetically stable transgenic viral vector is used for infection, transient viral infection of hairy roots can be a potential alternative system for foreign protein production than plants grown in the field as the containment or safety issues can be addressed.
39
Pinto, Yvonne Maria. "Characterization of a Nigerian isolate of rice yellow mottle virus." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243556.
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Perbal, Marie-Christine. "A functional analysis of the cauliflower mosaic virus movement protein." Thesis, University of East Anglia, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359335.
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Weng, Ziming. "Replication and recombination of the Red clover necrotic mosaic virus." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/280079.
Full textAbstract:
In this study, Red clover necrotic mosaic virus (RCNMV) was used to better understand the functions of replication proteins and to identify the terminal promoter element involved in viral replication. RCNMV genome contains two positive-sense, single-stranded RNAs. RNA-1 encodes two proteins essential for viral replication: p27 and p88. p88 is a fusion protein containing p27 at its N terminus and RNA dependent RNA polymerase motifs at its C-terminal domain. The function of p27 is not known. In this work, studies of RNA-1 chimerical clones between a highly infectious clone and a poorly infectious clone and subsequent mutagenesis demonstrated that the N-terminal 14 amino acids of p27 and p88 were required for efficient RNA replication. Sequence analysis indicated that it is possibly involved in membrane interaction. Another important aspect of viral replication is template recognition by the replicase at the 3' promoter. The 3' -29 nucleotides of both RCNMV RNA-1 and RNA-2 can be predicted to form an identical stem-loop structure (SLS). Mutational analysis of the SLS indicated that both the structure and the loop sequence were required for viral replication. Within the 5-nt loop region, three discontinuous nucleotides were identified as critical nucleotides for RNA-replicase interaction. The functional groups in these key nucleotides involved in replicase recognition are predicted. The 3' promoter element of RCNMV not only affects viral RNA replication but also influences transgenic recombination. RCNMV RNA-2 encodes a movement protein (MP) that is required for viral cell-to-cell movement and systemic infection. Transgenic Nicotiana benthamiana plants expressing different versions of MP mRNA neither resisted RCNMV nor complemented RNA-1 infection. However, systemic infection was observed in transgenic lines expressing 5' truncated MP mRNA when only RNA-1 was inoculated. Further analysis showed that the infection was resulted from nonhomologous RNA recombination events between infecting RNA-1 and MP transgene mRNA. A replicase-mediated template switch model of the transgenic recombination was proposed. The presence of the 3' promoter element in the transgene mRNA thus was a major factor determining transgenic recombination frequencies. As predicted from the model, transgene mRNA lacking the 3' promoter element would not be a good donor RNA for transgenic recombination. Consequently, no transgenic recombination was detected in transgenic plants expressing the 3' truncated MP mRNA upon inoculation with RCNMV RNA-1.
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Brigneti, Gianinna. "Molecular and genetical analysis of the Ry-mediated resistance to potato virus Y in potato." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389221.
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Hamdollah-Zadeh, Akram. "Transgenic resistance to pollen transmission of tobacco ringspot virus." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364912.
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Lutz, Lindy Michelle. "Cauliflower mosaic virus P6 protein interactions: a complex story." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1393863253.
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Sisco, Daniel. "Adeno-associated virus rep78 expression in Arabidopsis thaliana." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/9706.
Full textAbstract:
Adeno-associated virus type 2 (AAV-2) integrates preferentially into a defined site on human chromosome 19, and has been developed as a gene therapy vector. We propose to use this unique recombination event for site-specific integration of transgenes in plants. This strategy would alleviate problems associated with current plant transformation methods that integrate transgenes randomly. The AAV-2 gene encoding the enzyme that catalyzes the insertion (rep78) was introduced into Arabidopsis thaliana via Agrobacterium-mediated transformation. PCR and sequence analysis confirmed the presence of rep78 in two plant lines. RT-PCR demonstrated rep78 transcription in one plant line, but protein could not be detected in either line.<br>Master of Science
46
Zhan, Ye. "Molecular analysis of turnip crinkle virus coat protein mutations." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0430102-142639.
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Cruz, Luisa Fernanda. "Resistance to Wheat streak mosaic virus and Triticum mosaic virus in wheat mediated by RNAi." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1653.
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Pitzalis, Nicolas. "Plant-virus interactions : role of virus- and host-derived small non-coding RNAs during infection and disease." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAJ103.
Full textAbstract:
Dans cette thèse, j'ai étudié le rôle des sRNAs dérivés de l'hôte et du virus lors de l'infection du colza (Brassica napus, Canola) par la souche UK1 du virus de la mosaïque du navet (TuMV-UK1). En utilisant un dérivé de TuMV fusionné avec un gène codant pour la protéine fluorescente verte (TuMV-GFP), deux cultivars de colza (‘Drakkar’ et ‘Tanto’) qui diffèrent par leur susceptibilité à ce virus ont été identifiés. Le profil transcriptionnel des foyers d'infection locale, dans les feuilles de Drakkar et de Tanto, par séquençage nouvelle génération (NGS) a révélé de nombreux gènes exprimés de manière différentielle. Les mêmes échantillons d'ARN provenant de feuilles de Drakkar et de Tanto, traitées par des virus ou utilisées en contrôle, ont également servi à établir le profil NGS des sRNAs (sRNAseq) et de leurs cibles potentielles d'ARN (PAREseq). Les analyses bioinformatiques et leur validation in vivo, ont permis d’identifier les événements de clivage de transcrits impliquant des micro ARN (miRNA) connus et encore inconnus. Fait important, les résultats indiquent que TuMV détourne la voie du RNA silencing de l’hôte avec des siRNAs issus de son propre génome (vsiRNA) pour cibler les gènes de l’hôtes. Le virus déclenche également le ciblage à grande échelle des ARN messagers (ARNm) de l’hôte par l’activation de la production de siRNAs secondaires en phase, à partir de locus PHAS. À leur tour, les vsiRNAs et les siRNAs dérivés de l'hôte (hsRNAs) ciblent et clivent l'ARN viral par le complexe RISC. Ces observations éclairent le rôle des siRNAs dérivés de l'hôte et du virus dans la coordination de l'infection virale. Un autre chapitre de cette thèse est consacré à l'analyse des maladies induites par des virus en utilisant comme modèle de plante Arabidopsis, infectée par un tobamovirus, le virus de la mosaïque du colza (ORMV). De plus, ces observations ont permis de proposer un modèle dans lequel cette guérison dépend d’un adressage important de vsiRNAs secondaires antiviraux depuis leur source de production jusqu’à leurs tissus de destination, et l'établissement d'un apport en vsiRNAs capable de bloquer l'activité VSR impliquée dans la formation des feuilles symptomatiques<br>In this thesis, I investigated the role of host- and virus-derived sRNAs during infection of Rapeseed (Brassica napus, Canola) by the UK1 strain of Turnip mosaic virus (TuMV-UK1). By using a TuMV derivative tagged with a gene encoding green fluorescent protein (TuMV-GFP), two rapeseed cultivars (‘Drakkar’ and ‘Tanto’) that differ in susceptibility to this virus were identified. Transcriptional profiling of local infection foci in Drakkar and Tanto leaves by next generation sequencing (NGS) revealed numerous differentially expressed genes. The same RNA samples from mock- and virus- treated Drakkar and Tanto leaves were also used for the global NGS profiling of sRNAs (sRNAseq) and their potential RNA targets (PAREseq). The bioinformatic analysis and their in vivo validation led to the identification of transcript cleavage events involving known and yet unknown miRNAs. Importantly, the results indicate that TuMV hijacks the host RNA silencing pathway with siRNAs derived from its own genome (vsiRNAs) to target host genes. The virus also triggers the widespread targeting of host messenger RNAs (mRNAs) through activation of phased, secondary siRNA production from PHAS loci. In turn, both vsiRNAs and host-derived siRNAs (hsRNAs) target and cleave the viral RNA by the RISC-mediated pathway. These observations illuminate the role of host and virus-derived sRNAs in the coordination of virus infection. Another chapter of this thesis is dedicated to the analysis of virus-induced diseases by using Arabidopsis plants infected with the Oilseed rape mosaic tobamovirus (ORMV) as a model. Initially, the infected plants develop leaves with strong disease symptoms. However, at a later stage, disease-free, “recovered” leaves start to appear. Analysis of symptoms recovery led to the identification of a mechanism in which the VSR and virus derived-siRNAs play a central role. I used Arabidopsis mutants impaired in transcriptional and post-transcriptional silencing pathways (TGS and PTGS respectively) and a plant line carrying a promoter-driven GFP transgene silenced by PTGS (Arabidopsis line 8z2). Using various techniques able to monitor virus infection, small and long viral RNA molecules, VSR activity, as well as phloem-mediated transport with in these lines, this study led to the identification of genes required for disease symptoms and disease symptom recovery. Moreover, the observations allowed to propose a model in which symptoms recovery occurs upon robust delivery of antiviral secondary vsiRNAs from source to sink tissues, and establishment of a vsiRNA dosage able to block the VSR activity involved in the formation of disease symptoms
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Király, Lóránt. "Interactions between cauliflower mosaic virus isolates and nicotiana species that determine systemic necrosis /." free to MU campus, to others for purchase, 1997. http://wwwlib.umi.com/cr/mo/fullcit?p9841160.
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Mohammed, Ibrahim Umar. "Virus-host interactions in the cassava brown streak disease pathosystem." Thesis, University of Greenwich, 2012. http://gala.gre.ac.uk/8765/.
Full textAbstract:
The research seeks to understand the virus-host plant interactions for cassava brown streak disease (CBSD) caused by two viruses, Cassava brown streak virus (CBSV) and Ugandan Cassava brown streak virus (UCBSV) of the genus Ipomovirus, family Potyviridae. The diversity of six CBSD isolates from the endemic (Kenya, Malawi, Mozambique and Tanzania) and the recently developed epidemic areas (Uganda) of the disease in eastern Africa was studied. Five cassava varieties differing in virus resistance levels; Albert, Columbian, Ebwanateraka, TMS60444 (all susceptible) and Kiroba (tolerant) were graft-inoculated with the UCBSV and CBSV isolates. Based on a number of parameters, the isolates can be grouped into two main categories; severe and milder forms. Transmission of viruses using non-vector modes confirmed that CBSV was sap transmissible from cassava to cassava. Graft-inoculation of infected scions onto CBSD-free cassava plants was the most efficient mode of transmission which resulted in 80 and 100% rate for UCBSV and CBSV respectively. The two virus isolates were not transmitted through contaminated tools and hands. The effect of host-tolerance on virus was investigated in a long-term experiment where three cassava varieties Albert, Kiroba and Kaleso (field-resistant to CBSD) were graft-inoculated with UCBSV and CBSV. The three cassava varieties showed differences in virus movement, symptom development, severity and relative virus titres. The mechanisms of resistance to CBSD were investigated by making cuttings, from various parts of the plants, and a greater number of disease-free plants were generated from cuttings made from Kaleso than Kiroba and Albert. The fecundity of B. tabaci and its ability to transmit the virus were determined and results indicated no significant differences in the ability of the three cassava varieties to support whitefly development. Finally, thermal and chemical treatments of tissue cultured plants were conducted and the combinations of both treatments produced the greatest number of disease-free plants in all three varieties; Kaleso (50%), Kiroba (44%) and Albert (35%). The information generated in this thesis has greatly improved our understanding of the interactions between the three biotic factors; the host, virus and vector in the CBSD-pathosystem, which would be highly useful in designing effective disease management strategies.