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Full-Text Articles in Plant Pathology

Sag101 Forms A Ternary Complex With Eds1 And Pad4 And Is Required For Resistance Signaling Against Turnip Crinkle Virus, Shifeng Zhu, Rae-Dong Jeong, Srivathsa C. Venugopal, Ludmila Lapchyk, Duroy Navarre, Aardra Kachroo, Pradeep Kachroo Nov 2011

Sag101 Forms A Ternary Complex With Eds1 And Pad4 And Is Required For Resistance Signaling Against Turnip Crinkle Virus, Shifeng Zhu, Rae-Dong Jeong, Srivathsa C. Venugopal, Ludmila Lapchyk, Duroy Navarre, Aardra Kachroo, Pradeep Kachroo

Plant Pathology Faculty Publications

EDS1, PAD4, and SAG101 are common regulators of plant immunity against many pathogens. EDS1 interacts with both PAD4 and SAG101 but direct interaction between PAD4 and SAG101 has not been detected, leading to the suggestion that the EDS1-PAD4 and EDS1-SAG101 complexes are distinct. We show that EDS1, PAD4, and SAG101 are present in a single complex in planta. While this complex is preferentially nuclear localized, it can be redirected to the cytoplasm in the presence of an extranuclear form of EDS1. PAD4 and SAG101 can in turn, regulate the subcellular localization of EDS1. We also show that the Arabidopsis genome …


Widespread Horizontal Gene Transfer From Circular Single-Stranded Dna Viruses To Eukaryotic Genomes, Huiquan Liu, Yanping Fu, Bo Li, Xiao Yu, Jiatao Xie, Jiasen Cheng, Said A. Ghabrial, Guoqing Li, Xianhong Yi, Daohong Jiang Sep 2011

Widespread Horizontal Gene Transfer From Circular Single-Stranded Dna Viruses To Eukaryotic Genomes, Huiquan Liu, Yanping Fu, Bo Li, Xiao Yu, Jiatao Xie, Jiasen Cheng, Said A. Ghabrial, Guoqing Li, Xianhong Yi, Daohong Jiang

Plant Pathology Faculty Publications

BACKGROUND: In addition to vertical transmission, organisms can also acquire genes from other distantly related species or from their extra-chromosomal elements (plasmids and viruses) via horizontal gene transfer (HGT). It has been suggested that phages represent substantial forces in prokaryotic evolution. In eukaryotes, retroviruses, which can integrate into host genome as an obligate step in their replication strategy, comprise approximately 8% of the human genome. Unlike retroviruses, few members of other virus families are known to transfer genes to host genomes.

RESULTS: Here we performed a systematic search for sequences related to circular single-stranded DNA (ssDNA) viruses in publicly available …


An Effective Virus-Based Gene Silencing Method For Functional Genomics Studies In Common Bean, Claudia Díaz-Camino, Padmanaban Annamalai, Federico Sanchez, Aardra Kachroo, Said A. Ghabrial Jun 2011

An Effective Virus-Based Gene Silencing Method For Functional Genomics Studies In Common Bean, Claudia Díaz-Camino, Padmanaban Annamalai, Federico Sanchez, Aardra Kachroo, Said A. Ghabrial

Plant Pathology Faculty Publications

BACKGROUND: Common bean (Phaseolus vulgaris L.) is a crop of economic and nutritious importance in many parts of the world. The lack of genomic resources have impeded the advancement of common bean genomics and thereby crop improvement. Although concerted efforts from the "Phaseomics" consortium have resulted in the development of several genomic resources, functional studies have continued to lag due to the recalcitrance of this crop for genetic transformation.

RESULTS: Here we describe the use of a bean pod mottle virus (BPMV)-based vector for silencing of endogenous genes in common bean as well as for protein expression. This BPMV-based vector …


Characterization Of Viral And Host Proteins And Rna Elements In Tombusvirus Replication, Kunj Bihari Pathak Jan 2011

Characterization Of Viral And Host Proteins And Rna Elements In Tombusvirus Replication, Kunj Bihari Pathak

Theses and Dissertations--Plant Pathology

Two thirds of plant viruses are positive-strand RNA viruses including the family Tombusviridae. One of the best-studied members of this family is Tomato bushy stunt virus (TBSV). Like many other viruses, TBSV has much fewer genes when compared to its hosts’ genome. Nevertheless, TBSV utilizes its genome very judiciously. To compensate for a lack of many proteins of its own, it codes for multi-functional replication protein p33 and also co-opts host factors to facilitate its replication.

By using recombinant replication proteins p33 and p92 containing single amino acid changes in protein-protein interaction domains (S1 and S2), I demonstrated that the …


Role Of The Sexual Cycle In Development Of Genotypic And Phenotypic Diversity In Gibberella Zeae, Sladana Bec Jan 2011

Role Of The Sexual Cycle In Development Of Genotypic And Phenotypic Diversity In Gibberella Zeae, Sladana Bec

Theses and Dissertations--Plant Pathology

Gibberella zeae (anamorph Fusarium graminearum) is a homothallic ascomycete pathogen that is responsible for causing Fusarium head blight (FHB) of wheat and small grains. In addition to causing a reduction in yield, harvested grain is frequently contaminated with trichothecene mycotoxins that are harmful for human and animal health. Use of wheat varieties with resistance to FHB is an important strategy to lower its impact. In order to produce varieties with durable resistance, we must understand the origin and degree of genetic diversity present in the pathogen population. In my research, I focused my efforts on an investigation of the …


Role Of Lipids In Tombusvirus Replication, Monika Sharma Jan 2011

Role Of Lipids In Tombusvirus Replication, Monika Sharma

University of Kentucky Doctoral Dissertations

Positive-strand RNA virus group are the most abundant among viruses affecting plants and animals. To successfully achieve replication, these viruses usurp or co-opt host proteins. To facilitate the discovery of host factors involved in Tomato bushy stunt virus (TBSV), yeast has been developed as a surrogate model host. Genome-wide approaches covering 95% of yeast genes, has revealed approximately hundred factors that could affect virus replication. Among the identified host factors, there are fourteen yeast genes, which affect/regulate lipid metabolism of the host.

One of the identified host gene is ERG25, which is an important factor for sterol biosynthesis pathway, affecting …


Molecular, Genetic And Biochemical Characterization Of Resistance Protein-Mediated Signaling Against Turnip Crinkle Virus, Rae-Dong Jeong Jan 2011

Molecular, Genetic And Biochemical Characterization Of Resistance Protein-Mediated Signaling Against Turnip Crinkle Virus, Rae-Dong Jeong

University of Kentucky Doctoral Dissertations

Infection of the resistant Arabidopsis ecotype Di-17 with Turnip Crinkle Virus (TCV) elicits hypersensitive response (HR), accompanied by increased expression of defense genes. HR to TCV is conferred by HRT, which encodes a coiled-coil (CC)-nucleotide-binding site (NBS)-leucine-rich repeat (LRR) class of resistance (R) protein. In contrast to HR, resistance requires HRT and a recessive locus designated rrt. Unlike most CC-NBS-LRR R proteins, HRT-mediated resistance is dependent on EDS1 and independent of NDR1. Resistance is also dependent on salicylic acid (SA) pathway and light. A dark treatment, immediately following TCV inoculation, suppresses HR, resistance and activation of a majority of the …


Comparison Of Plant‐Adapted Rhabdovirus Protein Localization And Interactions, Kathleen Marie Martin Jan 2011

Comparison Of Plant‐Adapted Rhabdovirus Protein Localization And Interactions, Kathleen Marie Martin

University of Kentucky Doctoral Dissertations

Sonchus yellow net virus (SYNV), Potato yellow dwarf virus (PYDV) and Lettuce Necrotic yellows virus (LNYV) are members of the Rhabdoviridae family that infect plants. SYNV and PYDV are Nucleorhabdoviruses that replicate in the nuclei of infected cells and LNYV is a Cytorhabdovirus that replicates in the cytoplasm. LNYV and SYNV share a similar genome organization with a gene order of Nucleoprotein (N), Phosphoprotein (P), putative movement protein (Mv), Matrix protein (M), Glycoprotein (G) and Polymerase protein (L). PYDV contains an additional predicted gene between N and P, denoted as X, that has an unknown function. In order to gain …


Abundant Degenerate Miniature Inverted-Repeat Transposable Elements In Genomes Of Epichloid Fungal Endophytes Of Grasses, Damien J Fleetwood, Anar K Khan, Richard D Johnson, Carolyn A Young, Shipra Mittal, Ruth E Wrenn, Uljana Hesse, Simon J Foster, Christopher L. Schardl, Barry Scott Jan 2011

Abundant Degenerate Miniature Inverted-Repeat Transposable Elements In Genomes Of Epichloid Fungal Endophytes Of Grasses, Damien J Fleetwood, Anar K Khan, Richard D Johnson, Carolyn A Young, Shipra Mittal, Ruth E Wrenn, Uljana Hesse, Simon J Foster, Christopher L. Schardl, Barry Scott

Plant Pathology Faculty Publications

Miniature inverted-repeat transposable elements (MITEs) are abundant repeat elements in plant and animal genomes; however, there are few analyses of these elements in fungal genomes. Analysis of the draft genome sequence of the fungal endophyte Epichloë festucae revealed 13 MITE families that make up almost 1% of the E. festucae genome, and relics of putative autonomous parent elements were identified for three families. Sequence and DNA hybridization analyses suggest that at least some of the MITEs identified in the study were active early in the evolution of Epichloë but are not found in closely related genera. Analysis of MITE integration …


Making Of Viral Replication Organelles By Remodeling Interior Membranes, Zsuzsanna Sasvari, Peter D. Nagy Nov 2010

Making Of Viral Replication Organelles By Remodeling Interior Membranes, Zsuzsanna Sasvari, Peter D. Nagy

Plant Pathology Faculty Publications

Positive-stranded RNA (+RNA) viruses exploit host cell machinery by subverting host proteins and membranes and altering cellular pathways during infection. To achieve robust replication, some +RNA viruses, such as poliovirus (PV), build special intracellular compartments, called viral replication organelles. A recent work from the Altan-Bonnett laboratory [1] gave new insights into the formation of poliovirus replication organelles, which are unique subcellular structures containing many individual replication complexes as a result of dynamic cellular membrane remodeling.


Translation Elongation Factor 1a Facilitates The Assembly Of The Tombusvirus Replicase And Stimulates Minus-Strand Synthesis, Zhenghe Li, Judit Pogany, Steven Tupman, Anthony M. Esposito, Terri Goss Kinzy, Peter D. Nagy Nov 2010

Translation Elongation Factor 1a Facilitates The Assembly Of The Tombusvirus Replicase And Stimulates Minus-Strand Synthesis, Zhenghe Li, Judit Pogany, Steven Tupman, Anthony M. Esposito, Terri Goss Kinzy, Peter D. Nagy

Plant Pathology Faculty Publications

Replication of plus-strand RNA viruses depends on host factors that are recruited into viral replicase complexes. Previous studies showed that eukaryotic translation elongation factor (eEF1A) is one of the resident host proteins in the highly purified tombusvirus replicase complex. Using a random library of eEF1A mutants, we identified one mutant that decreased and three mutants that increased Tomato bushy stunt virus (TBSV) replication in a yeast model host. Additional in vitro assays with whole cell extracts prepared from yeast strains expressing the eEF1A mutants demonstrated several functions for eEF1A in TBSV replication: facilitating the recruitment of the viral RNA template …


The Combined Effect Of Environmental And Host Factors On The Emergence Of Viral Rna Recombinants, Hannah M. Jaag, Peter D. Nagy Oct 2010

The Combined Effect Of Environmental And Host Factors On The Emergence Of Viral Rna Recombinants, Hannah M. Jaag, Peter D. Nagy

Plant Pathology Faculty Publications

Viruses are masters of evolution due to high frequency mutations and genetic recombination. In spite of the significance of viral RNA recombination that promotes the emergence of drug-resistant virus strains, the role of host and environmental factors in RNA recombination is poorly understood. Here we report that the host Met22p/Hal2p bisphosphate-3'-nucleotidase regulates the frequency of viral RNA recombination and the efficiency of viral replication. Based on Tomato bushy stunt virus (TBSV) and yeast as a model host, we demonstrate that deletion of MET22 in yeast or knockdown of AHL, SAL1 and FRY1 nucleotidases/phosphatases in plants leads to increased TBSV recombination …


Distinct Evolutionary Histories Of The Dna-A And Dna-B Components Of Bipartite Begomoviruses, Rob W. Briddon, Basavaprabhu L. Patil, Basavaraj Bagewadi, Muhammad Shah Nawaz-Ul-Rehman, Claude M. Fauquet Mar 2010

Distinct Evolutionary Histories Of The Dna-A And Dna-B Components Of Bipartite Begomoviruses, Rob W. Briddon, Basavaprabhu L. Patil, Basavaraj Bagewadi, Muhammad Shah Nawaz-Ul-Rehman, Claude M. Fauquet

Plant Pathology Faculty Publications

BACKGROUND: Viruses of the genus Begomovirus (family Geminiviridae) have genomes consisting of either one or two genomic components. The component of bipartite begomoviruses known as DNA-A is homologous to the genomes of all geminiviruses and encodes proteins required for replication, control of gene expression, overcoming host defenses, encapsidation and insect transmission. The second component, referred to as DNA-B, encodes two proteins with functions in intra- and intercellular movement in host plants. The origin of the DNA-B component remains unclear. The study described here was initiated to investigate the relationship between the DNA-A and DNA-B components of bipartite begomoviruses with a …


Systematic Overrepresentation Of Dna Termini And Underrepresentation Of Subterminal Regions Among Sequencing Templates Prepared From Hydrodynamically Sheared Linear Dna Molecules, Sherri L. Schwartz, Mark L. Farman Feb 2010

Systematic Overrepresentation Of Dna Termini And Underrepresentation Of Subterminal Regions Among Sequencing Templates Prepared From Hydrodynamically Sheared Linear Dna Molecules, Sherri L. Schwartz, Mark L. Farman

Plant Pathology Faculty Publications

BACKGROUND: Analysis of fungal genome sequence assemblies reveals that telomeres are poorly represented even though telomeric reads tend to be superabundant. We surmised that the problem might lie in the DNA shearing conditions used to create clone libraries for genome sequencing.

RESULTS: A shotgun strategy was used to sequence and assemble circular and linear cosmid DNAs sheared using conditions typical for a genome project. The DNA sheared in circular form assembled into a single sequence contig. However, the linearized cosmid produced an incomplete assembly because the two DNA termini, though greatly overrepresented in the clone library used for sequencing, were …


A Unique Role For The Host Escrt Proteins In Replication Of Tomato Bushy Stunt Virus, Daniel Barajas, Yi Jiang, Peter D. Nagy Dec 2009

A Unique Role For The Host Escrt Proteins In Replication Of Tomato Bushy Stunt Virus, Daniel Barajas, Yi Jiang, Peter D. Nagy

Plant Pathology Faculty Publications

Plus-stranded RNA viruses replicate in infected cells by assembling viral replicase complexes consisting of viral- and host-coded proteins. Previous genome-wide screens with Tomato bushy stunt tombusvirus (TBSV) in a yeast model host revealed the involvement of seven ESCRT (endosomal sorting complexes required for transport) proteins in viral replication. In this paper, we show that the expression of dominant negative Vps23p, Vps24p, Snf7p, and Vps4p ESCRT factors inhibited virus replication in the plant host, suggesting that tombusviruses co-opt selected ESCRT proteins for the assembly of the viral replicase complex. We also show that TBSV p33 replication protein interacts with Vps23p ESCRT-I …


Viral Vectors Useful In Soybean And Methods Of Use, Said A. Ghabrial, Chunquan Zhang, Honcgang Gu Nov 2009

Viral Vectors Useful In Soybean And Methods Of Use, Said A. Ghabrial, Chunquan Zhang, Honcgang Gu

Plant Pathology Faculty Patents

The invention provides Bean pod mottle virus (BPMV) vectors useful for expression of heterologous proteins in plants such as soybean. The BPMV vectors are also useful for virus-induced gene silencing. The invention also provides methods for expressing a heterologous polypeptide in a plant such as soybean. The invention additionally provides methods for virus-induced gene silencing, particularly in a soybean plant, which can be used to determine the function of a gene of interest.


Defective Interfering Rnas: Foes Of Viruses And Friends Of Virologists, Kunj Bihari Pathak, Peter D. Nagy Nov 2009

Defective Interfering Rnas: Foes Of Viruses And Friends Of Virologists, Kunj Bihari Pathak, Peter D. Nagy

Plant Pathology Faculty Publications

Defective interfering (DI) RNAs are subviral RNAs produced during multiplication of RNA viruses by the error-prone viral replicase. DI-RNAs are parasitic RNAs that are derived from and associated with the parent virus, taking advantage of viral-coded protein factors for their multiplication. Recent advances in the field of DI RNA biology has led to a greater understanding about generation and evolution of DI-RNAs as well as the mechanism of symptom attenuation. Moreover, DI-RNAs are versatile tools in the hands of virologists and are used as less complex surrogate templates to understand the biology of their helper viruses. The ease of their …


Inhibition Of Rna Recruitment And Replication Of An Rna Virus By Acridine Derivatives With Known Anti-Prion Activities, Zsuzsanna Sasvari, Stéphane Bach, Marc Blondel, Peter D. Nagy Oct 2009

Inhibition Of Rna Recruitment And Replication Of An Rna Virus By Acridine Derivatives With Known Anti-Prion Activities, Zsuzsanna Sasvari, Stéphane Bach, Marc Blondel, Peter D. Nagy

Plant Pathology Faculty Publications

BACKGROUND: Small molecule inhibitors of RNA virus replication are potent antiviral drugs and useful to dissect selected steps in the replication process. To identify antiviral compounds against Tomato bushy stunt virus (TBSV), a model positive stranded RNA virus, we tested acridine derivatives, such as chlorpromazine (CPZ) and quinacrine (QC), which are active against prion-based diseases.

METHODOLOGY/PRINCIPAL FINDINGS: Here, we report that CPZ and QC compounds inhibited TBSV RNA accumulation in plants and in protoplasts. In vitro assays revealed that the inhibitory effects of these compounds were manifested at different steps of TBSV replication. QC was shown to have an effect …


The Genome Of Nectria Haematococca: Contribution Of Supernumerary Chromosomes To Gene Expansion, Jeffrey J. Coleman, Steve D. Rounsley, Marianela Rodriguez-Carres, Alan Kuo, Catherine C. Wasmann, Jane Grimwood, Jeremy Schmutz, Masatoki Taga, Gerard J. White, Shiguo Zhou, David C. Schwartz, Michael Freitag, Li-Jun Ma, Etienne G. J. Danchin, Bernard Henrissat, Pedro M. Coutinho, David R. Nelson, Dave Straney, Carolyn A. Napoli, Bridget M. Barker, Michael Gribskov, Martijn Rep, Scott Kroken, István Molnár, Christopher Rensing, John C. Kennell, Jorge Zamora, Mark L. Farman, Eric U. Selker, Asaf Salamov, Harris Shapiro, Jasmyn Pangilinan, Erika Lindquist, Casey Lamers, Igor V. Grigoriev, David M. Geiser, Sarah F. Covert, Esteban Temporini, Hans D. Vanetten Aug 2009

The Genome Of Nectria Haematococca: Contribution Of Supernumerary Chromosomes To Gene Expansion, Jeffrey J. Coleman, Steve D. Rounsley, Marianela Rodriguez-Carres, Alan Kuo, Catherine C. Wasmann, Jane Grimwood, Jeremy Schmutz, Masatoki Taga, Gerard J. White, Shiguo Zhou, David C. Schwartz, Michael Freitag, Li-Jun Ma, Etienne G. J. Danchin, Bernard Henrissat, Pedro M. Coutinho, David R. Nelson, Dave Straney, Carolyn A. Napoli, Bridget M. Barker, Michael Gribskov, Martijn Rep, Scott Kroken, István Molnár, Christopher Rensing, John C. Kennell, Jorge Zamora, Mark L. Farman, Eric U. Selker, Asaf Salamov, Harris Shapiro, Jasmyn Pangilinan, Erika Lindquist, Casey Lamers, Igor V. Grigoriev, David M. Geiser, Sarah F. Covert, Esteban Temporini, Hans D. Vanetten

Plant Pathology Faculty Publications

The ascomycetous fungus Nectria haematococca, (asexual name Fusarium solani), is a member of a group of >50 species known as the "Fusarium solani species complex". Members of this complex have diverse biological properties including the ability to cause disease on >100 genera of plants and opportunistic infections in humans. The current research analyzed the most extensively studied member of this complex, N. haematococca mating population VI (MPVI). Several genes controlling the ability of individual isolates of this species to colonize specific habitats are located on supernumerary chromosomes. Optical mapping revealed that the sequenced isolate has 17 chromosomes ranging from 530 …


Evolution Of A Subtilisin-Like Protease Gene Family In The Grass Endophytic Fungus Epichloë Festucae, Michelle K. Bryant, Christopher L. Schardl, Uljana Hesse, Barry Scott Jul 2009

Evolution Of A Subtilisin-Like Protease Gene Family In The Grass Endophytic Fungus Epichloë Festucae, Michelle K. Bryant, Christopher L. Schardl, Uljana Hesse, Barry Scott

Plant Pathology Faculty Publications

BACKGROUND: Subtilisin-like proteases (SLPs) form a superfamily of enzymes that act to degrade protein substrates. In fungi, SLPs can play either a general nutritive role, or may play specific roles in cell metabolism, or as pathogenicity or virulence factors.

RESULTS: Fifteen different genes encoding SLPs were identified in the genome of the grass endophytic fungus Epichloë festucae. Phylogenetic analysis indicated that these SLPs belong to four different subtilisin families: proteinase K, kexin, pyrolysin and subtilisin. The pattern of intron loss and gain is consistent with this phylogeny. E. festucae is exceptional in that it contains two kexin-like genes. Phylogenetic analysis …


Enhanced Disease Susceptibility 1 And Salicylic Acid Act Redundantly To Regulate Resistance Gene-Mediated Signaling, Srivathsa C. Venugopal, Rae-Dong Jeong, Mihir Kumar Mandal, Shifeng Zhu, A. C. Chandra-Shekara, Ye Xia, Matthew Hersh, Arnold J. Stromberg, Duroy Navarre, Aardra Kachroo, Pradeep Kachroo Jul 2009

Enhanced Disease Susceptibility 1 And Salicylic Acid Act Redundantly To Regulate Resistance Gene-Mediated Signaling, Srivathsa C. Venugopal, Rae-Dong Jeong, Mihir Kumar Mandal, Shifeng Zhu, A. C. Chandra-Shekara, Ye Xia, Matthew Hersh, Arnold J. Stromberg, Duroy Navarre, Aardra Kachroo, Pradeep Kachroo

Plant Pathology Faculty Publications

Resistance (R) protein-associated pathways are well known to participate in defense against a variety of microbial pathogens. Salicylic acid (SA) and its associated proteinaceous signaling components, including enhanced disease susceptibility 1 (EDS1), non-race-specific disease resistance 1 (NDR1), phytoalexin deficient 4 (PAD4), senescence associated gene 101 (SAG101), and EDS5, have been identified as components of resistance derived from many R proteins. Here, we show that EDS1 and SA fulfill redundant functions in defense signaling mediated by R proteins, which were thought to function independent of EDS1 and/or SA. Simultaneous mutations in EDS1 and the SA-synthesizing enzyme SID2 compromised hypersensitive response and/or …


Phylogenetic Analyses Reveal Monophyletic Origin Of The Ergot Alkaloid Gene Dmaw In Fungi, Miao Liu, Daniel G. Panaccione, Christopher L. Schardl Jun 2009

Phylogenetic Analyses Reveal Monophyletic Origin Of The Ergot Alkaloid Gene Dmaw In Fungi, Miao Liu, Daniel G. Panaccione, Christopher L. Schardl

Plant Pathology Faculty Publications

Ergot alkaloids are indole-derived mycotoxins that are important in agriculture and medicine. Ergot alkaloids are produced by a few representatives of two distantly related fungal lineages, the Clavicipitaceae and the Trichocomaceae. Comparison of the ergot alkaloid gene clusters from these two lineages revealed differences in the relative positions and orientations of several genes. The question arose: is ergot alkaloid biosynthetic capability from a common origin? We used a molecular phylogenetic approach to gain insights into the evolution of ergot alkaloid biosynthesis. The 4-γ,γ-dimethylallyltryptophan synthase gene, dmaW, encodes the first step in the pathway. Amino acid sequences deduced …


A Discontinuous Rna Platform Mediates Rna Virus Replication: Building An Integrated Model For Rna-Based Regulation Of Viral Processes, Baodong Wu, Judit Pogany, Hong Na, Beth L. Nicholson, Peter D. Nagy, K. Andrew White Mar 2009

A Discontinuous Rna Platform Mediates Rna Virus Replication: Building An Integrated Model For Rna-Based Regulation Of Viral Processes, Baodong Wu, Judit Pogany, Hong Na, Beth L. Nicholson, Peter D. Nagy, K. Andrew White

Plant Pathology Faculty Publications

Plus-strand RNA viruses contain RNA elements within their genomes that mediate a variety of fundamental viral processes. The traditional view of these elements is that of local RNA structures. This perspective, however, is changing due to increasing discoveries of functional viral RNA elements that are formed by long-range RNA-RNA interactions, often spanning thousands of nucleotides. The plus-strand RNA genomes of tombusviruses exemplify this concept by possessing different long-range RNA-RNA interactions that regulate both viral translation and transcription. Here we report that a third fundamental tombusvirus process, viral genome replication, requires a long-range RNA-based interaction spanning approximately 3000 nts. In vivo …


Identification And Characterization Of Host Factors Involved In Tombusvirus Replication, Yi Jiang Jan 2009

Identification And Characterization Of Host Factors Involved In Tombusvirus Replication, Yi Jiang

University of Kentucky Doctoral Dissertations

Positive strand RNA viruses are intracellular parasites, and their genome replication and infection involves complex virus-host interactions. Therefore, identification of host factors and dissection of their functions during virus replication could facilitate our understanding of the mechanism of virus infection. Those host factors may also provide new targets for viral disease control. Tomato bushy stunt virus (TBSV) has recently become one of the model viruses to study positive strand RNA virus replication and hostvirus interactions. To identify host factors involved in TBSV replication we used yeast as a model host. Co-expression of the replication proteins and a replicon RNA (DI …


Role Of P33 In Tombusvirus Replication, Jozsef Stork Jan 2009

Role Of P33 In Tombusvirus Replication, Jozsef Stork

University of Kentucky Doctoral Dissertations

Replication of the nonsegmented, plus-stranded RNA genome of Cucumber necrosis tombusvirus (CNV) requires two essential overlapping viral-coded replication proteins, the p33 replication co-factor and the p92 RNA-dependent RNA polymerase. In my thesis I describe (i) the effect of phosphorylation of p33, (ii) the RNA chaperone-like activity of p33, and (iii) the role of HSP70s a host proteins in the viral replication. To test the effect of phosphorylation on p33 function, I used in vitro phosphorylated p33. I found that phosphorylation inhibited the ability of p33 to bind to the viral RNA. Phosphorylation-mimicking mutations rendered p33 nonfunctional in plant protoplasts and …


Towards Elimination And Genetic Manipulation Of Ergot Alkaloid Production In Fungal Endophytes, Simona Florea Jan 2009

Towards Elimination And Genetic Manipulation Of Ergot Alkaloid Production In Fungal Endophytes, Simona Florea

University of Kentucky Doctoral Dissertations

Clavicipitaceous fungal endophytes provide several ecological benefits to their hosts. Besides improving host’s growth characteristics, Neotyphodium coenophialum, the endophyte of tall fescue (Lolium arundinaceum), produces ergot alkaloids that have been proposed to be involved in fescue toxicosis. One approach to address the toxicosis problem is to genetically manipulate and modify N. coenophialum by knocking out a pair of homologous genes, (dmaW1 and dmaW2), encoding dimethylallyltryptophan synthase, the enzyme for the first and determinant step in ergot-alkaloid biosynthesis. In this study, disruption of dmaW2 was attempted using several disruption methods. Out of 1522 transformants screened, three …


Molecular, Genetic And Biochemical Characterization Of Oleic Acid- And Glycerol-Mediated Signaling In Plant Defense, Srivathsa C. Venugopal Jan 2008

Molecular, Genetic And Biochemical Characterization Of Oleic Acid- And Glycerol-Mediated Signaling In Plant Defense, Srivathsa C. Venugopal

Theses and Dissertations--Plant Pathology

Oleic acid (18:1) is one of the important monounsaturated fatty acids, which is synthesized upon desaturation of stearic acid and this reaction is catalyzed by the SSI2 encoded stearoyl-acyl-carrier-protein-desaturase. A mutation in SSI2 leads to constitutive activation of salicylic acid (SA)-mediated defense responses. Consequently, these plants accumulate high levels of SA and show enhanced resistance to bacterial and oomycete pathogens. Replenishing 18:1 levels in ssi2 plants, via a second site mutation in GLY1 encoded glycerol-3-phosphate (G3P) dehydrogenase, suppresses all the ssi2-triggered phenotypes. Study of mechanism(s) underlying gly1-mediated suppression of ssi2 phenotypes showed that 18:1 levels are regulated via …


Roles Of Micrornas In Plant Abiotic Stress, Development And Viral Infection, Venugopal Mendu Jan 2008

Roles Of Micrornas In Plant Abiotic Stress, Development And Viral Infection, Venugopal Mendu

University of Kentucky Doctoral Dissertations

Plant microRNAs play important roles in plant growth and development. Here we investigated the roles of miRNAs in the plant abiotic stress, development and viral infection. MicroRNA membrane array analysis using five different abiotic stress treatments resulted in the identification of 8 novel stress inducible miRNA-families. Functional studies on novel stress inducible miR168 revealed its functional relation with abiotic stress. Over expression of miR168 in Arabidopsis showed upregulation of four stress related miRNAs (miR163, miR167, miR398 and miR408). Analysis of 9 independent transgenic lines showed induction of miR398, an oxidative stress responsive miRNA with a corresponding down regulation of its …


Loline Alkaloid Gene Clusters Of The Fungal Endophyte Neotyphodium Uncinatum, Christopher L. Schardl, Heather H. Wilkinson, Martin J. Spiering Feb 2007

Loline Alkaloid Gene Clusters Of The Fungal Endophyte Neotyphodium Uncinatum, Christopher L. Schardl, Heather H. Wilkinson, Martin J. Spiering

Plant Pathology Faculty Patents

Loline alkaloids (LA), which are 1-aminopyrrolizidines with an oxygen bridge, are produced by Epichloë (anamorph=Neotyphodium) species, endophytes of grasses. LA are insecticidal, thus helping protect host plants from insect herbivory. Suppression subtractive hybridization PCR was used to isolate transcripts up-regulated during loline alkaloid production in cultures of Neotyphodium uncinatum. Subtracted cDNAs were cloned, and a λ-phage cDNA library from an LA-expressing N. uncinatum culture was screened with subtracted cDNA. In BLAST searches, several cDNAs identified had sequence similarities to aspartate kinases, and another with O-acetylhomoserine-(thiol)lyase. Differential expression of these two genes in LA-producing cultures of N. uncinatum …


'Paclims': A Component Lim System For High-Throughput Functional Genomic Analysis, Nicole Donofrio, Ravi Rajagopalon, Douglas Brown, Stephen Diener, Donald Windham, Shelly Nolin, Anna Floyd, Thomas Mitchell, Natalia Galadima, Sara Tucker, Marc J. Orbach, Gayatri Patel, Mark Farman, Vishal Pampanwar, Cari Soderlund, Yong-Hwan Lee, Ralph A. Dean Apr 2005

'Paclims': A Component Lim System For High-Throughput Functional Genomic Analysis, Nicole Donofrio, Ravi Rajagopalon, Douglas Brown, Stephen Diener, Donald Windham, Shelly Nolin, Anna Floyd, Thomas Mitchell, Natalia Galadima, Sara Tucker, Marc J. Orbach, Gayatri Patel, Mark Farman, Vishal Pampanwar, Cari Soderlund, Yong-Hwan Lee, Ralph A. Dean

Plant Pathology Faculty Publications

BACKGROUND: Recent advances in sequencing techniques leading to cost reduction have resulted in the generation of a growing number of sequenced eukaryotic genomes. Computational tools greatly assist in defining open reading frames and assigning tentative annotations. However, gene functions cannot be asserted without biological support through, among other things, mutational analysis. In taking a genome-wide approach to functionally annotate an entire organism, in this application the approximately 11,000 predicted genes in the rice blast fungus (Magnaporthe grisea), an effective platform for tracking and storing both the biological materials created and the data produced across several participating institutions was required.

RESULTS: …