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1
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.
Testo completo
2
Mcmenemy, Lindsay Sara. "Raspberry viruses manipulate plant–aphid interactions". Thesis, University of Sussex, 2011. http://sro.sussex.ac.uk/id/eprint/7465/.
Testo completoAbstract (sommario):
Plants come under attack by a variety of organisms, including insects and pathogenic microorganisms such as viruses. Plant viruses can interact indirectly with their vectors by inducing changes to plant chemistry which may alter its attractiveness as a host for herbivore vectors. Using red raspberry as a study system, this study aimed to investigate the host plant mediated interactions occurring between the large raspberry aphid, Amphorophora idaei, and two of the viruses that it transmits, Black raspberry necrosis virus (BRNV) and Raspberry leaf mottle virus (RLMV). In whole plant bioassays, BRNV and RLMV-infected plants were shown to be initially more attractive to A. idaei and aphids remained on the initially selected host plant for a period of approximately 30 minutes. In addition, A. idaei took three days longer to reach reproductive maturity compared with those feeding on non-infected plants, suggesting a virally-induced manipulation of aphid behaviour whereby a deceptive attraction of the vector to a host plant found to be nutritionally poor, presumably acts to promote virus transmission. Investigations of the underlying plant chemistry revealed that raspberry viruses may be capable of facilitating aphid feeding by reducing leaf phenolic concentration when aphids are feeding and that infection with BRNV and RLMV resulted in significantly elevated levels of carbon and free amino acids in the leaves. While increased concentrations of amino acids might be expected to promote aphid performance, the amino acid composition was dominated by glutamate (77% of total content of infected plants), a previously suggested indicator of reduced host-plant suitability for aphids. Volatile entrainments from virus-infected plants showed elevated levels of the green leaf volatile (Z)-3-hexenyl acetate. Bioassays subsequently revealed that this compound acted as an aphid attractant at a concentration of 50 ng ml-1 but that aphid behaviour was unaffected by lower concentrations. The combined utilisation of PCR diagnostics developed from newly sequenced viral genomes and the implementation of a non-invasive, targeted method of sampling plant headspace volatiles enabled this study to provide novel insights into the nature of host plant mediated interactions between aphids and the viral pathogens that they transmit.
3
Groen, Simon Cornelis. "Manipulation of plant-insect interactions by insect-borne plant viruses". Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648187.
Testo completo
4
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.
Testo completo
5
Segwagwe, Amogelang Thethe. "Characterization of a tymovirus causing disease in diascia ornamental plants". Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Spring2007/A%5FSegwagwe%5F032007.pdf.
Testo completo
6
Afsharifar, Alireza. "Characterisation of minor RNAs associated with plants infected with cucumber mosaic virus". Title page, table of contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09pha2584.pdf.
Testo completoAbstract (sommario):
Bibliography: leaves 127-138. This thesis studies the minor double stranded RNAs (dsRNA) and single stranded RNAs (ssRNA) which are consistently associated with plants infected with Q strain of cucumber mosaic virus (Q-CMV). The investigations are focused on the structural elucidation of new RNAs which have been observed in single stranded and double stranded RNA profiles of Q strain of CMV.
7
Keese, Paul Konrad. "Structures of viroids and virusoids and their functional significance". Title page, contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phk268.pdf.
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8
Fu, S. F. "Salicylic acid induced resistance to plant viruses". Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599252.
Testo completoAbstract (sommario):
Mitochondrial alternative oxidase (AOX) plays a role in protecting plant cells against reactive oxygen species. The SA-inducible RNA-directed RNA polymerase 1 (RDR1), contributes to viral RNA degradation via RNA interference. Previous data suggested that these enzymes comprise separately regulated, redundant elements in SA-induced resistance to viruses. To test this hypothesis, I constructed transgenic tobacco (Nicotiana tabacum) and N. benthamiana plants compromised simultaneously in AOX function and RDR1 activity. Transgenic tobacco and N. benthamiana plants were characterised by measuring alternative respiratory pathway (AP) capacity and RDR enzyme activity. The resistance/susceptibility status of the transgenic plants was assessed by analysing Tobacco mosaic virus (TMV) accumulation in the chemically treated, directly-inoculated tissues. Antimycin A (AA)-induced resistance to TMV was inhibited in transgenic N. benthamiana with increased AP capacity, and SA- and AA-induced resistance was enhanced in transgenic N. benthamiana with decreased AP capacity. However, SA-induced resistance to TMV in directly-inoculated leaves was still unaffected in transgenic tobacco and N. benthamiana compromised in AOX function and RDR1 activity. This suggests that SA-induced resistance to viruses involves additional, unknown mechanisms. Surprisingly, SA can enhance RDR activity in transgenic 35S-MtRDR1 N. benthamiana but not wild-type and vector-control plants (natural mutants of RDR1). This SA-enhanced RDR activity resulted from increased MtRDR1 protein level, indicating the post-transcriptional regulation of MtRDR1 enzyme activity. SA-induced resistance to systemic movement was enhanced in transgenic 35S-MtRDR1 N. benthamiana plants, suggesting that SA-induced increase in RDR1 activity plays a role in induced resistance to systemic movement of viruses. Basal resistance to viruses was studied in transgenic tobacco (nn or NN genotype) and N. benthamiana plants with modified AP capacity or RDR activity. Modification of AP capacity had no effect on TMV accumulation in HR lesions from transgenic tobacco plants overexpressing the Aoxla construct (NN background). Notably, transgenic N. benthamiana plants with increased AP capacity were more susceptibility to Potato virus X (PVX) than non-transgenic plants. This was seen in the transgenic plant with increased AP capacity that PVX accumulated to higher level in both directly-inoculated and systemic leaf tissues. It was also nearly discovered that transgenic 35S-MtRDR1 N. benthamiana plants were more resistant to Potato virus Y ordinary strain. The results suggest that altering AP capacity has effect on basal resistance to some viruses and confirms that RDR1 plays a role on basal resistance.
9
Aw, D. W. J. "Analysis of methods for screening plant viruses". Thesis, University of Glasgow, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328786.
Testo completo
10
Bonfiglioli, Roderick. "Studies on the ultrastructural localisation of viroids and other plant pathogens". Title page, contents and summary only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phb713.pdf.
Testo completoAbstract (sommario):
Bibliography: leaves 78-90. Designed to localize viroids at the histological and subcellular level and to determine with which cellular compartments the different viroids are associated. The majority of the work, in both the viroid and the phytoplasma studies involved the development of different methods and techniques.
11
Nagano, Hideaki. "Studies on Plant-Virus Cell-to-Cell Movement Using Chimeric Viruses". Kyoto University, 2000. http://hdl.handle.net/2433/78105.
Testo completoAbstract (sommario):
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第8438号
農博第1122号
新制||農||801(附属図書館)
学位論文||H12||N3395(農学部図書室)
UT51-2000-F342
京都大学大学院農学研究科農林生物学専攻
(主査)教授 古澤 巌, 教授 泉井 桂, 教授 津田 盛也
学位規則第4条第1項該当
12
Chingandu, Nomatter, e 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.
Testo completoAbstract (sommario):
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.
13
Kallender, Howard. "Characterisation and molecular biology of two plant viruses". Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46375.
Testo completo
14
Perkins, Colin J. "A study of some viruses and virus-like agents infecting woody ornamentals". Thesis, University of Bath, 1987. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376333.
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15
Ali, Akhtar. "Pathology and molecular comparison of a range of pea seed-borne mosaic virus isolates". Title page, contents and summary only, 1999. http://web4.library.adelaide.edu.au/theses/09ACP/09acpa398.pdf.
Testo completoAbstract (sommario):
Copies of author's previously published articles inserted. Bibliography: leaves 128-143. This thesis describes the development of serological and nucleic acid based diagnostic methods for pea-seed borne mosaic virus (PSbMV), the isolation of specific effects on infected pea plants, the collection and biological comparison of new PSbMV isolates from Pakistan, the cloning and sequencing of specific parts of the genome of selected isolates, nucleotide and amino acid sequence comparisons between selected isolates, and the development of a ribonuclease protection assay (RPA) for identifying genomic differences among the PSbMV isolates. It is the first comparison of a range of geographically different isolates of PSbMV on the basis of both biological and molecular properties.
16
Haley, Ann. "Characterisation of the movement proteins of two plant viruses". Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308317.
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17
Naylor, Martin. "The effects of salicylic acid on RNA plant viruses". Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624519.
Testo completo
18
Murray, Rose Rebecca. "Investigating the interactions between plant viruses and host stomata". Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.686167.
Testo completoAbstract (sommario):
Stomata are microscopic pores located in the epidermis of most terrestrial plants. As well as serving as gateways for gas exchange and transpiration, stomata have recently become known to have increasingly complex relationships with pathogens, with many pathogens utilising stomata as entry portals. However, the research so far has largely focussed on bacterial and fungal pathogens, leaving a gap in the knowledge about the interactions between plant viruses and stomata. This study aims to investigate the interactions and relations between stomata and viruses by investigating potential for stomata to act as entry portals for viruses and the developmental changes which occur under virus infection. In order to test the hypothesis that stomata can act as entry portals for plant viruses, a series of experiments was performed which altered stomatal apertures before applying purified virus suspended in solution in an aerosol. It was found that Nicotiana tabacum plants were more likely to become infected when TMV virus solution was applied when stomata were open. Natural and chemical factors were used to manipulate stomatal apertures prior to virus application. Stomatal development was investigated following a virus infection. A range of host-virus systems was used and it was found that susceptible host types had a general reduction in stomatal index and density when infected with a virus. Transcripts of genes involved in stomatal development were also tested for changes in healthy and infected plants and were found to vary upon infection. Knock-out mutants of various stomatal developmental or functional genes showed varying developmental responses to a virus infection, with notable changes in rin4 which resulted in an increase in stomatal development post infection. The results presented in this project provide an insight into a relatively new field of research which has so far been neglected in the field of plant pathology.
19
Luo, Hao. "Using new tools to detect and characterise plant viruses". Thesis, Luo, Hao (2012) Using new tools to detect and characterise plant viruses. PhD thesis, Murdoch University, 2012. https://researchrepository.murdoch.edu.au/id/eprint/12381/.
Testo completoAbstract (sommario):
Executive summary:
The overall aim of this study was to develop new methods to detect and characterise plant viruses. Generic methods for detection of virus proteins and nucleic acids were developed to detect two plant viruses, Pelargonium zonate spot virus (PZSV) and Cycas necrotic stunt virus (CNSV), neither of which were previously detected in Australia. Two new approaches, peptide mass fingerprinting (PMF) and next-generation nucleotide sequencing (NGS) were developed to detect novel or unexpected viruses without the need for previous knowledge of virus sequence or study. In this work, PZSV was found for the first time in Australia and also in a new host Cakile maritima using one dimensional electrophoresis and PMF. The second new virus in Australia, CNSV, was first described in Japan and then in New Zealand. In this work it was detected and characterised as a new strain in Australia using NGS analysis and was found in a lily plant (Lilium. longiflorum) with symptoms. Patterns of infection of a native virus Hardenbergia mosaic virus (HarMV) and the introduced virus Cucumber mosaic virus (CMV) were studied in natural and recent host plants using real-time reverse transcription polymerase chain reaction. For different virus isolates and symptoms, the virus concentration in plants varied and interaction between two co-infected viruses (such as HarMV and CMV) altered the accumulations of both viruses. Field studies were done to measure the potential impact of natural infection by HarMV on an economically-important legume crop plant, Lupinus 4
angustifolius (narrow-leafed lupin). In field studies, HarMV was spread by naturally occurring aphids, with up to 31% of the lupin plants infected. Grain yield of affected lupin plants was substantially reduced, but seed-borne infection of HarMV was not detected.
Summary
Peptide mass fingerprint (PMF) analysis of plant viruses
A generic assay to detect and partially characterise viruses from plants was developed. Proteins extracted from virus-infected and uninfected plants were separated by one dimensional SDS polyacrylamide gel electrophoresis. Expressed coat protein bands not presented in uninfected plants were eluted after trypsin digestion and resulting peptide fragments separated according to their masses by matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). Resulting PMFs were compared with those present or predicted in protein databases. This assay strategy was used to identify four known viruses: the potyviruses Zucchini yellow mosaic virus (ZYMV) and Turnip mosaic virus (TuMV), an alfamovirus Alfalfa mosaic virus (AMV), and a cucumovirus (CMV). It was also used to identify a virus that manifested symptoms in wild C. maritima plants, tentatively identified as PZSV (genus Anulavirus) by its PMF, which was subsequently confirmed by Reverse transcription polymerase chain reaction (RT-PCR) and nucleotide sequencing. The detection of PZSV constitutes a first record of this virus in Australia and in this host. It is proposed that this simplified assay is a useful approach for analysis of plant samples known to harbour viruses, particularly for viruses which cannot be identified readily using antisera or nucleic acid-based assays. Although five viruses from different families and genera were identified successfully by this method, it was not a high-throughput and low cost 5 technique for sample screening, since protein extraction procedures were time-consuming, and protein identification based on PMF requires access to a high quality MALDI-TOF mass spectrometer. Nevertheless, this assay is a valuable complementary detection technique to support the identification of unexpected viruses to the species level, with further characterisation by other methods.
Detection and characterisation of CNSV by NGS
A lily plant (L. longiflorum), growing locally in Perth, Western Australia, with symptoms of chlorosis and streaking of leaves, was collected. Total RNA was extracted and sequenced using Illumina GA IIx technology. After assembly of reads, contigs representing the partial genome of CNSV RNA 1 and RNA2 were identified using Blastn and Blastx software. This virus was also found in bulb tissues of infected lily plants by RT-PCR and nucleotide sequencing (primers designed from the NGS sequences). This indicates that the virus can be transmitted through vegetatively propagated plant materials. Phylogenetic analysis suggested that the virus was a new strain of CNSV (family Secoviridae, genus Nepovirus). Comparison of the sequences of this virus to the CNSV (cycas strain) showed homology with identity of 88% and 96% at the nucleotide and amino acid levels, respectively, and to CNSV (gladiolus strain) of 88% and 94%, respectively; also provided in this work is a new strain of CNSV (lily strain). Another ten lily plants and nineteen cycas plants were tested for the virus by RT-PCR but none appeared to be infected. This virus has been recorded to be transmitted by seeds, nematodes and vegetative propagation, and has a very wide host range in ornamental and crop plants. This result is the 6 first record of this virus in Australia, which indicates that screening for CNSV and other nepoviruses in imported ornamental plants is essential to protect the Australian horticulture industry from incursion of new non-indigenous viruses.
Natural spread of HarMV to narrow-leafed lupin
Two field experiments were undertaken to study the potential threat of the Australian indigenous potyvirus, HarMV, to spread from its natural host, Hardenbergia comptoniana into narrow-leafed lupin (L. angustifolius) crops. Plants were grown in field conditions in two different years. Field plots of narrow-leafed lupin were established and interplanted with H. comptoniana plants infected with HarMV. Wild aphids were allowed to colonise the plots and spread the virus. Plants were monitored for aphids and symptoms of virus infection. Infection was confirmed by enzyme-linked immunosorbent assay (ELISA), RT-PCR and nucleotide sequencing. The first year established a pilot study, and this showed that HarMV spread naturally to 4.7% of L. angustifolius plants in the field. All infected lupin plants died within 20 days after virus symptoms became visible. In the second year a full field experiment was undertaken, and 30.7% of lupins became infected with HarMV. The majority of infected plants remained alive during this growing season, but showed symptoms of stunting, necrotic stem streaking and tip wilting. Three species of aphids were identified on plants during the experiment, including Myzus persicae (green peach aphid), Acyrthosiphon kondoi (bluegreen aphid) and Rhopalosiphon padi (oat aphid). A total of 761 seeds collected from infected plants were sown, and seedlings were tested for virus infection by ELISA. However, none of them were 7 found to be infected with HarMV, indicating that the virus was possibly not seed-borne in L. angustifolius. This aspect should be verified further by testing more seeds for HarMV from infected plants. The conclusion is that HarMV, a virus confined largely to a single native wild host, is capable of naturally extending its host range to an introduced grain legume under field conditions. Since adaption to an alternative host, as the case of HarMV invading lupin crops, is likely to be a driver of virus evolution, this pathosystem represents an ideal opportunity to study evolution of this virus in real time as it encounters new hosts, at the interface between an ancient ecosystem and a recent agroecosystem.
Virus quantification using real-time quantitative PCR
In this study, virus quantification by real-time quantitative PCR was used to titrate HarMV (isolate WHP-1, WHP-2 and MU-4) and CMV (Sn strain, subgroup II) expression in host L. angustifolius, H. comptoniana and Nicotiana benthamiana. A glasshouse experiment was done that showed HarMV isolate WHP-1 induced a non-necrotic (NN) response, while WHP-2 induced systemic necrosis (N) on lupin plants. Lupin cv Belara infected with WHP-2 isolate harboured a virus at a concentration of 1.34×108 copies/μl, approximately 18% higher than WHP-1 (1.13×108 copies /μl). Although typical symptoms caused by HarMV on wild H. comptoniana include: chlorosis, leaf mosaic, leaf distortion, yellow spots and blotches, the symptom severity is variable on different plants, and even different branches of the same plant show inconsistent symptoms. Their within-plant titres varied, and the highest concentration (1.75×108 copies /μl) was more than 19-fold that of the lowest (9.16×106 copies /μl). The interaction between two co-infecting viruses (HarMV and CMV) infecting N. benthamiana plants was studied. In doubly-infected N. benthamiana plants there was a strong synergistic increase in symptoms, with severe yellowing, stunting and chlorosis, and a higher overall virus titre (2.24×108 copies/μl) than for single virus infected plants (at 6.89×107 copies/μl for HarMV single infection and 4.05×107 copies/μl for CMV single infection). Compared to the single infection, CMV accumulation was enhanced (at 2.18×108 copies/μl in doubly-infected plants and 4.05×107 copies/μl in single-infected plants four weeks after inoculation), while HarMV was suppressed (at 5.66×106 copies/μl in doubly-infected plants and 6.89×107 copies/μl in single-infected plants four weeks after inoculation) in mixed infection. This study used real-time quantitative PCR to investigate the virus within-plant titre, and showed that the virus concentrations were variable in hosts depending on the virus isolate, symptoms and interaction with co-infected viruses.
20
Sheldon, Candice Claire. "Hammerhead mediated self-cleavage of plant pathogenic RNAs /". Title page, contents and summary only, 1992. http://web4.library.adelaide.edu.au/theses/09PH/09phs544.pdf.
Testo completo
21
Zambrano, Mendoza Jose Luis. "Genetic Architecture of Resistance to Phylogenetically Diverse Viruses in Maize". The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1373285155.
Testo completo
22
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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23
Yu, Weichang. "CAMV gene VI protein : a virulence factor and the host responses in Arabidopsis /". free to MU campus, to others for purchase, 2002. http://wwwlib.umi.com/cr/mo/fullcit?p3075411.
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24
Torok, Valeria Anna. "Biological and molecular variation among isolates of pea seed borne mosaic virus". Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09pht686.pdf.
Testo completoAbstract (sommario):
Corrigendum inserted at the back. Includes bibliographical references (leaves 133-158). Ch. 1. General introduction -- ch. 2. General materials and methods -- ch. 3. Biological characterisation of Australian PSbMV isolates -- ch. 4. Developing nucleic acid based diagnostics for PSbMV -- ch. 5. Detection of PSbMV isolates by RT-PCR and RFLP analysis -- ch. 6. Developing an internal control for PSbMV RT-PCR -- ch. 7. Molecular analysis of the PSbMV VPG -- ch. 8. PSbMV sequence and phylogenetic analysis -- ch. 9. General discussion Sixteen pea seed borne mosaic virus (PSbMV) isolates were collected between 1995 and 1998. These isolates were biologically distinct yet serologically indistinguishable. The conclusion is that PSbMV is widespread and occurs at a low incidence in Australia. Reports sequence information on new isolates of PSbMV which has allowed genomic regions to be identified which distinguish PSbMV pathotypes and isolates; and, to the development of PSbMV nucleic acid hybridisation and RT-PCR assays.
25
Rohozinski, J. "Studies of velvet tobacco mottle virus RNA replication by enzyme-template complexes in extracts from infected leaves /". Title page, contents and summary only, 1985. http://web4.library.adelaide.edu.au/theses/09PH/09phr738.pdf.
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26
Liu, Yuan Yi. "A study of a satellite RNA from arabis mosaic nepovirus". Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335830.
Testo completo
27
Meehan, Brian Martin. "Inter-relationships of members of the carlavirus group". Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335598.
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28
Clark, Anthony James. "Production and characterisation of hybrid comoviruses". Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267319.
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29
Taylor, Kathryn. "Structure-based refinement of peptide presentation on the surface of cowpea mosiac virus". Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389325.
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30
Lucy, Andrew P. "Pathways to systemic invasion of plants by maize streak and other viruses". Thesis, University of East Anglia, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338088.
Testo completo
31
Zhang, Shulu. "Molecular biology studies on rice tungro spherical virus with emphasis on the coat protein genes". Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358309.
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32
Wang, Daowen. "A study of the genetic and structural basis of pea seed-borne mosaic virus seed transmission in pea". Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357245.
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33
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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34
Massumi, Hossain. "Investigation into the mechanism of virus transmission in a non-persistent manner without helper factors". Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299070.
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35
Powell, Glen. "Stylet activities and potyvirus transmission by aphids". Thesis, King's College London (University of London), 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283709.
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36
Mackenzie, Susan. "Reciprocal transplantations to study local specialisation and the measurement of components of fitness". Thesis, Bangor University, 1985. https://research.bangor.ac.uk/portal/en/theses/reciprocal-transplantations-to-study-local-specialisation-and-the-measurement-of-components-of-fitness(6227a52b-adc9-4a40-9404-b8978b480027).html.
Testo completoAbstract (sommario):
Reciprocal transplant experiments have been made to investigate the .intra-specific variation in two clonal species, Primula vulgaris and RBDUDculus repens. Primula transplants performed best when returned to their native populations, indicating that they were differentia~ed in response to local conditions. There was marked variation in the degree of local specialisation of plants in different primrose populations and possible causes of this variation are discussed. Although buttercup transplants also showed great variability, there was no evidence that they were specialised, either between, or within, local populations. The lack of genetic specialisation in RBDUDculus repens may be due to its spreading growth form, widespread distribution and low level of seedling recruitment. In glasshouse experiments, the presence or absence of neighbours affected many parameters of buttercup growth. Within a genet the effect of edaphic and biotic heterogeneity was integrated, so that ramets in favourable conditions supported interconnected ramets in less favourable sites. Plants of R. repens vary phenotypically in different environments but appear to respond to heterogeneous local conditions by phenotypic plasticity of individual ramets rather than genetic specialisation. The assumption that differences between transplants are solely indicative of genetic specialisation has been questioned. Virus infection was detected in 7 of 14 primrose populations surveyed. Infected plants showed no symptoms of disease, yet they produced significantly fewer but larger leaves than uninfected plants. Differences between transplants which could easily be attributed to genetic variation may be due to differential virus infection. Furthermore, viruses may ultimately contribute to genetic differentiation and have a role as selective forces in the environment. Phenotypic differences between ramets of the same genet of R. repens were maintained and even increased after 26 week's growth in a cammon environment. It is clearly imPortant in transplant experiments to use comparable phenotypes and virus-free plants when determining the role of genotype in the match between organism and environment.
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Hodge, Brian Allen. "Occurrence, Diversity, and Impact of Viruses in Ohio". The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1606307407425512.
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Chauhan, Ramola. "A study of filamentous viruses in maize and smallgrains". Master's thesis, University of Cape Town, 1985. http://hdl.handle.net/11427/22013.
Testo completoAbstract (sommario):
Bibliography: pages 175-184.The occurrence of maize dwarf mosaic virus (MDMV) in field grown maize was investigated. For this purpose, maize showing mosiac symptoms was collected from different maize growing areas in South Africa by Prof. M.B. von Wechmar. These samples from Transvaal, Orange Free State and Natal were then investigated for the presence of MDMV and possible strains of this virus. Three virus isolates were purified and partially characterised. These isolates were serologically compared together with a fourth isolate SCMV 4975, obtained from the U.S., to establish strain relationships.
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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/.
Testo completoAbstract (sommario):
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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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.
Testo completoAbstract (sommario):
Thesis (MSc)--Stellenbosch University, 2003.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.
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.
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com, cwebster82@gmail, e Craig Graham Webster. "Characterisation of Hardenbergia mosaic virus and development of microarrays for detecting viruses in plants". Murdoch University, 2008. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20081021.103144.
Testo completoAbstract (sommario):
A virus causing chlorosis and leaf distortion in the Western Australian endemic legume Hardenbergia comptoniana was detected by biological indexing to Chenopodium quinoa and Nicotiana benthamiana. Enzyme linked immuno-sorbent assay (ELISA) using general Potyvirus antiserum and amplification by reverse transcription polymerase chain reaction (RT-PCR) with degenerate primers indicated that it was a species of Potyvirus. It was confirmed as an unknown member of the genus Potyvirus by comparing its coat protein sequence with those of other potyviruses. The name Hardenbergia mosaic virus (HarMV) is proposed for this new virus species. Isolates of HarMV were collected from 13 sites, covering much of the natural range of its host. An experimental host range was determined using nine virus isolates tested against plants from 11 species in three families. Its infectivity on three leguminous species important in agriculture (Lupinus angustifolius, L. luteus and Trifolium subterraneum) was established.
The nucleotide (nt) sequences of the coat proteins (CP) of 28 isolates determined there was 24.1- 27.6% diversity with the closest known relative, Passion fruit woodiness virus (PWV). Studies of the nucleotide sequences of the CP showed that there was considerable intra-species divergence (mean 13.5%, maximum 20.5%) despite its relatively small geographical distribution and single known natural host. The observed broad diversity strongly suggests long genetic isolation and that HarMV evolved in the region where it was collected. An examination of its phylogeny showed that 28 isolates clustered into eight clades with high bootstrap support (6.2-20.5% inter-clade diversity). Isolates collected at locations distant to the Perth metropolitan area (Margaret River and Seabird) diverged more from isolates collected in the metropolitan area (15.4-21.1% nucleotide sequence diversity). This virus represents the first endemic species to be characterised from Western Australia.
Differences in pathogenicity and symptoms induced on key host species were seen between isolates belonging to different phylogenetic clades. Phylogenetic analysis confirmed the inclusion of HarMV within the Bean common mosaic virus group of the potyviruses and also defined a previously unreported subgroup of six previously described Potyvirus species (Clitoria virus Y, Hibbertia virus Y, PWV, Siratro 1 virus Y, and Siratro 2 virus Y), from Australia, which is further evidence for a prolonged period of genetic isolation.
Both in relation to detection of strains of HarMV, and considering the broader issues of biosecurity and parallel detection of plant viruses, a microarray based detection system was established. To optimise conditions for the development of microarrays for virus detection poly-L-lysine (PLL) coated microscope slides produced in the laboratory were compared to commercially produced PowerMatrix slides (Full Moon BioSystems). Variables tested for PLL slide production were: choice of printing buffer, probe concentration, method of immobilisation and slide blocking; and in particular the print buffer and immobilisation method had the greatest effect on the quality of PLL microarray slides. Slides printed on PLL surfaces in a high salt buffer (3x Saline sodium citrate) supplemented with 1.5M betaine and immobilised at 42oC overnight retained the highest amounts of probe DNA of the methods tested. Qualitative comparisons of the two showed more probe was retained on PowerMatrix slides which were also more reliable and consistent than the PLL slides.
Probes were designed for eight different virus species and six distinct strains of HarMV to test the potential to use microarrays to distinguish between them. Probes were designed to detect potyviruses at the genus, species and strain levels. Although there was evidence of non-specific hybridisation, the Potyvirus array was used to identify six strains of HarMV by hybridisation to species specific probes. Additionally the array was used to identify three other species of Potyvirus: Bean yellow mosaic virus, PWV and Passiflora foetida virus Y, following amplification with polyvalent PCR primers.
In further microarray tests, using labelled first strand cDNA of Potato virus X (PVX) and Potato virus Y (PVY) on an array, PVX was strongly detected in leaves known to be infected, but PVY was only weakly detected in infected leaves. Three methods of pre-amplification of virus nucleic acid before hybridisation to the array were investigated to improve the sensitivity of the assay. Two of the methods, Klenow amplification and randomly primed PCR, amplified the target virus; as confirmed by real time PCR. Of the methods tested only randomly primed PCR improved the sensitivity of the microarray. The best amplification method used genus-specific primers with adaptor sequences. This method when tested by real time PCR showed a 3.7Ct reduction for PVX and 16.8Ct for PVY. The microarray correctly identified both viruses.
In this work the first virus (HarMV) endemic to Western Australia was identified, and microarray methods were developed both to identify HarMV and other plant viruses of economic importance. The microarray approach, with further development, may be applicable as a means of identifying incursions of new viruses in a biosecurity situation.
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Liu, Zun Kearney Christopher Michel. "New viral vectors for the expression of antigens and antibodies in plants". Waco, Tex. : Baylor University, 2009. http://hdl.handle.net/2104/5341.
Testo completo
43
Bendahmane, Abdelhafid. "Analysis of a gene-for-gene interaction associated with Rx-mediated resistance to potato virus X". Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389350.
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44
Williams, Iain S. "Aphid plant interactions and the epidemiology of sugar beet yellowing viruses". Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389388.
Testo completo
45
Kekarainen, Tuija. "Enhanced utilisation of an infectious plant viral cDNA clone /". Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-5781-5.pdf.
Testo completo
46
Sadeq, Al-Kuwaiti Nawres A. "Molecular characterization of viruses infecting potato and vegetables in Iraq". Thesis, University of Greenwich, 2013. http://gala.gre.ac.uk/11375/.
Testo completoAbstract (sommario):
Due to the lack of published molecular information concerning plant viruses from Iraq, this study was initiated to investigate the diversity of viruses infecting potato and vegetables in Iraq on a molecular basis. Based on the economic importance and incidence worldwide, eight virus genera were investigated in 175 potato and vegetable samples collected from fields in Baghdad, Anbar and Najaf provinces in Iraq. Using genus/family specific primers, published in the literature, polymerase chain reaction (PCR) and reverse transcription-polymerase chain reaction (RT-PCR) were performed to screen samples for potyviruses, begomoviruses, carlaviruses, tombusviruses, potexviruses, cucumoviruses, tobamoviruses and alfamoviruses. Circular DNA viruses were screened by rolling circle amplification (RCA). Products resulting from PCR/RT-PCR and RCA were cloned and sequenced and data obtained were used for sequence analyses. The above approach led to the first molecular characterisation of three potyviruses; Potato virus Y (PVY), Bean yellow mosaic virus (BYMV) and Zucchini yellow mosaic virus (ZYMV), one begomovirus; Tomato yellow leaf curl virus, two carlaviruses, Potato virus S (PVS) and Cowpea mild mottle virus (CPMMV) and one tombusvirus; Grapevine Algerian latent virus (GALV) in Iraqi potato and vegetable samples. Based on nucleotide (nt) sequence analyses, BYMV from broad bean and ZYMV from zucchini were 97% and 99% identical to equivalent sequences from the GenBank sequences, respectively. Two PVY strains were distinguished when sequences from potato and tomato showed 99% maximum nt identity to equivalent PVYO: N and PVYNTN GenBank sequences, respectively. Full-length sequence from tomato amplified by RCA showed 99% maximum nt identity to equivalent TYLCV sequences from the GenBank. Sequence comparison of carlavirus sequences isolated from potato and cowpea were 99% and 96% identical to equivalents PVS and CPMMV sequences from the GenBank, respectively. All tombusvirus sequences amplified from tomato and eggplant showed 93% maximum nt identity to equivalent GALV GenBank sequences. The high similarities (93-99%) of virus sequences isolated suggest, viruses isolated may have been introduced into Iraq from other countries, through international trading of plant materials used for cultivation as Iraq import most of plant materials for agriculture.
47
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.
Testo completo
48
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.
Testo completo
49
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.
Testo completo
50
Linnik, Volha. "Functional analysis of a plant virus replication 'factory' using live cell imaging". Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4639.
Testo completoAbstract (sommario):
Plant viruses have developed a number of strategies that enable them to become obligate intracellular parasites of many agricultural crops. Potato virus X (PVX) belongs to a group of positive-sense, single-stranded plant RNA viruses that replicate on host membranes and form elaborate structures known as viral replication complexes (VRCs) that contain viral RNA (vRNA), proteins and host cellular components. VRCs are the principal sites of viral genome replication, virion assembly and packaging of vRNA for export into neighbouring cells. For many animal viruses, host membrane association is crucial for RNA export. For plant viruses, it is not yet known how vRNA is transported to and through plant plasmodesmata. PVX encodes genetic information required for its movement between cells; three viral triple gene block (TGB) movement proteins and a viral coat protein are essential for viral trafficking. This research project studies the relationship between PVX and its host plants, Nicotiana benthamina and Nicotiana tabacum. A particular focus of this project is exploration of the structural and functional significance of the PVX VRC and how the virus recruits cell host components for its replication and movement between cells. The role of specific viral proteins in establishing the VRC, and the ways in which these interact with host organelles, was investigated. A combination of different approaches was used, including RNA-binding dyes and a Pumilio-based bimolecular fluorescence complementation assay for detection of the vRNA, fluorescent reporters for virusencoded proteins, fluorescent reporters for host organelles involved in viral replication, and also transgenic tobacco plants expressing reporters for specific plant components (endoplasmic reticulum, Golgi, actin, microtubules and plasmodesmata). In addition, mutagenesis was used to study the functions of individual viral proteins in replication and movement. All of these approaches were combined to achieve live-cell imaging of the PVX infection process. The PVX VRC was shown to be a highly compartmentalised structure; (+)-stranded vRNA was concentrated around the viral TGB1 protein, which was localised in discrete circular compartments within the VRC while coat protein was localised to the external edges of the VRC. The vRNA was closely associated with host components (endoplasmic reticulum and actin) shown to be involved in the formation of the VRC. The TGB2/TGB3 viral proteins were shown to colocalise with the host endomembranes (ER) and to exit these compartments in the form of motile granules. vRNA, TGB1, TGB2 and CP localised to plasmodesmata of the infected cells. TGB1 was shown to move cell-to-cell and recruit ER, Golgi and actin in the absence of viral infection. In the presence of virus, TGB1 targeted the VRCs in several neighbouring cells. A model of PVX replication and movement is proposed in which TGB1 functions as a key component for recruitment of host components into the VRC to enable viral replication and spread.