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Department of Plant Pathology: Faculty Publications

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Articles 361 - 390 of 410

Full-Text Articles in Plant Biology

Fungal Biology And Agriculture: Revisiting The Field, O. Yarden, D. J. Ebbole, S. Freeman, R. J. Rodriguez, M. B. Dickman Jan 2003

Fungal Biology And Agriculture: Revisiting The Field, O. Yarden, D. J. Ebbole, S. Freeman, R. J. Rodriguez, M. B. Dickman

Department of Plant Pathology: Faculty Publications

Plant pathology has made significant progress over the years, a process that involved overcoming a variety of conceptual and technological hurdles. Descriptive mycology and the advent of chemical plant-disease management have been followed by biochemical and physiological studies of fungi and their hosts. The later establishment of biochemical genetics along with the introduction of DNA-mediated transformation have set the stage for dissection of gene function and advances in our understanding of fungal cell biology and plant–fungus interactions. Currently, with the advent of high-throughput technologies, we have the capacity to acquire vast data sets that have direct relevance to the numerous …

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Transcription Strategy In A Closterovirus: A Novel 5'-Proximal Controller Element Of Citrus Tristeza Virus Produces 5'- And 3'-Terminal Subgenomic Rnas And Differs From 3' Open Reading Frame Controller Elements, Siddarame Gowda, Maria A. Ayllon, Satyanarayana Tatineni, Moshe Bar-Joseph, William O. Dawson Jan 2003

Transcription Strategy In A Closterovirus: A Novel 5'-Proximal Controller Element Of Citrus Tristeza Virus Produces 5'- And 3'-Terminal Subgenomic Rnas And Differs From 3' Open Reading Frame Controller Elements, Siddarame Gowda, Maria A. Ayllon, Satyanarayana Tatineni, Moshe Bar-Joseph, William O. Dawson

Department of Plant Pathology: Faculty Publications

Citrus tristeza virus (CTV) produces more than thirty 3'- or 5'-terminal subgenomic RNAs (sgRNAs) that accumulate to various extents during replication in protoplasts and plants. Among the most unusual species are two abundant populations of small 5'-terminal sgRNAs of approximately 800 nucleotides (nt) termed low-molecular-weight tristeza (LMT1 and LMT2) RNAs. Remarkably, CTV replicons with all 10 3' genes deleted produce only the larger LMT1 RNAs. These 5'-terminal positive-sense sgRNAs do not have corresponding negative strands and were hypothesized to be produced by premature termination during plus-strand genomic RNA synthesis. We characterized a cis-acting element that controls the production …

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Evaluation Of Resistance Screening Methods For Sclerotinia Stem Rot Of Soybean And Dry Bean, Linda S. Kull, Tri D. Vuong, Kris S. Powers, Kent M. Eskridge, James R. Steadman, Glen L. Hartman Jan 2003

Evaluation Of Resistance Screening Methods For Sclerotinia Stem Rot Of Soybean And Dry Bean, Linda S. Kull, Tri D. Vuong, Kris S. Powers, Kent M. Eskridge, James R. Steadman, Glen L. Hartman

Department of Plant Pathology: Faculty Publications

Three methods to identify levels of resistance to Sclerotinia sclerotiorum in soybean (Glycine max) and dry bean (Phaseolus vulgaris) were compared using multiple data analyses. The three methods were mycelial plug inoculations of cotyledons, cut stems, and detached leaves. Six S. sclerotiorum isolates of known relative aggressiveness were inoculated on each of three soybean and dry bean cultivars with varied response to S. sclerotiorum. For soybean, all three inoculation methods accurately identified isolate aggressiveness irrespective of cultivar, but identification of susceptible and partially resistant soybean cultivars was influenced by isolate. For dry bean, the cotyledon and cut …

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Selected Soybean Plant Introductions With Partial Resistance To Sclerotinia Sclerotiorum, D. D. Hoffman, B. W. Diers, G. L. Hartman, C. D. Nickell, R. L. Nelson, W. L. Pedersen, E. R. Cober, George L. Graef, J. R. Steadman, C. R. Grau, B. D. Nelson, L. E. Del Rio, T. Helms, T. Anderson, V. Poysa, University Of Guelph, W. C. Stienstra Jan 2002

Selected Soybean Plant Introductions With Partial Resistance To Sclerotinia Sclerotiorum, D. D. Hoffman, B. W. Diers, G. L. Hartman, C. D. Nickell, R. L. Nelson, W. L. Pedersen, E. R. Cober, George L. Graef, J. R. Steadman, C. R. Grau, B. D. Nelson, L. E. Del Rio, T. Helms, T. Anderson, V. Poysa, University Of Guelph, W. C. Stienstra

Department of Plant Pathology: Faculty Publications

Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, is a major soybean (Glycine max) disease in north-central regions of the United States and throughout the world. Current sources of resistance to Sclerotinia stem rot express partial resistance, and are limited in number within soybean germ plasm. A total of 6,520 maturity group (MG) 0 to IV plant introductions (PIs) were evaluated for Sclerotinia stem rot resistance in the United States and Canada in small plots or in the greenhouse from 1995 to 1997. Selected PIs with the most resistance were evaluated for resistance in the United States and …

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Greenhouse And Field Evaluation Of Biological Control Of Fusarium Head Blight On Durum Wheat, D. A. Schisler, N. I. Khan, Michael J. Boehm, P. J. Slininger Jan 2002

Greenhouse And Field Evaluation Of Biological Control Of Fusarium Head Blight On Durum Wheat, D. A. Schisler, N. I. Khan, Michael J. Boehm, P. J. Slininger

Department of Plant Pathology: Faculty Publications

Fusarium head blight (FHB) is a devastating disease that causes extensive yield and quality losses to wheat and barley. In durum wheat, the pathogen-produced toxin deoxynivalenol (DON) is retained in semolina at ~50%, and the causal agent of FHB, Gibberella zeae, has a strong adverse effect on pasta color. Two bacteria and two yeast strains with known efficacy against G. zeae on hexaploid wheats were produced in liquid culture and assayed on two cultivars of durum wheat in greenhouse bioassays. All antagonists reduced FHB severity on cultivar Renville, and three of the four reduced severity on cultivar Ben, with …

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The P23 Protein Of Citrus Tristeza Virus Controls Asymmetrical Rna Accumulation, Satyanarayana Tatineni, Siddarame Gowda, Maria A. Ayllon, Maria R. Albiach-Marti, Shailaja Rabindran, William O. Dawson Jan 2002

The P23 Protein Of Citrus Tristeza Virus Controls Asymmetrical Rna Accumulation, Satyanarayana Tatineni, Siddarame Gowda, Maria A. Ayllon, Maria R. Albiach-Marti, Shailaja Rabindran, William O. Dawson

Department of Plant Pathology: Faculty Publications

Citrus tristeza virus (CTV), a member of the Closteroviridae, has a 19.3-kb positive-stranded RNA genome that is organized into 12 open reading frames (ORFs) with the 10 3' genes expressed via a nested set of nine or ten 3'-coterminal subgenomic mRNAs (sgRNAs). Relatively large amounts of negative-stranded RNAs complementary to both genomic and sgRNAs accumulate in infected cells. As is characteristic of RNA viruses, wild-type CTV produced more positive than negative strands, with the plus-to-minus ratios of genomic and sgRNAs estimated at 10 to 20:1 and 40 to 50:1, respectively. However, a mutant with all of the 3' genes …

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First Report Of Columbia Root Knot Nematode (Meloidogyne Chitwoodi) In Potato In Texas, A. L. Szalanski, P. G. Mullin, T. S. Harris, T. O. Powers Apr 2001

First Report Of Columbia Root Knot Nematode (Meloidogyne Chitwoodi) In Potato In Texas, A. L. Szalanski, P. G. Mullin, T. S. Harris, T. O. Powers

Department of Plant Pathology: Faculty Publications

Columbia root-knot nematode, Meloidogyne chitwoodi Golden et al. (1) was identified from potatoes, Solanum tuberosum L., collected from Dallam County, Texas in October 2000. Seed potatoes are the most likely source for this introduction. This nematode is currently found infecting potatoes grown in California, Colorado, Idaho, New Mexico, Nevada, Oregon, Utah, and Washington. Some countries prohibit import of both seed and table stock potatoes originating in states known to harbor M. chitwoodi. Lesions on the potatoes had discrete brown coloration with white central spots in the outer 1 cm of the tuber flesh. Female nematode densities averaged 3 per square …

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Virulence Of Puccinia Triticina On Wheat In Nebraska During 1997 And 1998, J. E. Watkins, J. Schimelfenig, P. Stephen Baenziger, Kent M. Eskridge Feb 2001

Virulence Of Puccinia Triticina On Wheat In Nebraska During 1997 And 1998, J. E. Watkins, J. Schimelfenig, P. Stephen Baenziger, Kent M. Eskridge

Department of Plant Pathology: Faculty Publications

Urediniospore isolates of Puccinia triticina were obtained from wheat leaf collections made in three wheat-growing regions in Nebraska in 1997 and in four regions in 1998. Using 16 Thatcher lines that are near-isogenic for leaf rust resistance, 17 virulence phenotypes were found among 121 single uredinial isolates in 1997, and 42 virulence phenotypes were found among 178 isolates in 1998. The most prevalent phenotype in 1997 was MDRR (virulent on Lr1, 3, 3ka, 10, 11, 18, 23, 24, and 30). In 1998, virulence phenotypes MDRR and MDRM (virulent on Lr1, 3, 3ka, 10, 11, 23, 24, and 30 …

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Bacillus Species For Reducing Fusarium Head Blight In Cereals, David A. Schisler, Naseem I. Khan, Michael J. Boehm Jan 2001

Bacillus Species For Reducing Fusarium Head Blight In Cereals, David A. Schisler, Naseem I. Khan, Michael J. Boehm

Department of Plant Pathology: Faculty Publications

Microbial antagonists that will suppress Fusarium head blight (head scab) in cereals, particularly in wheat and barley have been identified. Two superior antagonists include NRRL B-30210 and NRRL B-30211.

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Selection And Evaluation Of Microorganisms For Biocontrol Of Fusarium Head Blight Of Wheat Incited By Gibberella Zeae, N. I. Khan, D. A. Schisler, Michael J. Boehm, P. J. Slininger, R. J. Bothast Jan 2001

Selection And Evaluation Of Microorganisms For Biocontrol Of Fusarium Head Blight Of Wheat Incited By Gibberella Zeae, N. I. Khan, D. A. Schisler, Michael J. Boehm, P. J. Slininger, R. J. Bothast

Department of Plant Pathology: Faculty Publications

Gibberella zeae incites Fusarium head blight (FHB), a devastating disease that causes extensive yield and quality losses to wheat and barley. Of over 700 microbial strains obtained from wheat anthers, 54 were able to utilize tartaric acid as a carbon source when the compound was supplied as choline bitartrate in liquid culture. Four tartaric acid–utilizing and three nonutilizing strains reduced FHB in initial tests and were selected for further assays. Antagonists were effective against three different isolates of G. zeae when single wheat florets were inoculated with pathogen and antagonist inoculum. All seven antagonists increased 100-kernel weight when applied simultaneously …

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The Aspergillus Nidulans Snt Genes Are Required For The Regulation Of Septum Formation And Cell Cycle Checkpoints, Peter R. Kraus, Steven D. Harris Jan 2001

The Aspergillus Nidulans Snt Genes Are Required For The Regulation Of Septum Formation And Cell Cycle Checkpoints, Peter R. Kraus, Steven D. Harris

Department of Plant Pathology: Faculty Publications

In Aspergillus nidulans, germinating conidia undergo multiple rounds of nuclear division before forming a septum. Previous genetic results suggest that the ability to separate nuclear division and septum formation depends upon a threshold level of activity of the cyclin-dependent kinase NIMXcdk1. Mutations in nimX and nimT, the gene encoding the NIMXcdk1-activating phosphatase, have revealed that Tyr-15 phosphorylation is important for determining the timing of the formation of the first septum. Here, we describe a screen for suppressors of nimT23 (snt), designed to identify additional components of the pathway regulating septum formation. We show that a subset …

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Age-Related Resistance In Bell Pepper To Cucumber Mosaic Virus , Hernan Garcia-Ruiz, John F. Murphy Jan 2001

Age-Related Resistance In Bell Pepper To Cucumber Mosaic Virus , Hernan Garcia-Ruiz, John F. Murphy

Department of Plant Pathology: Faculty Publications

We demonstrated the occurrence of mature plant resistance in Capsicum annuum 'Early Calwonder' to Cucumber mosaic virus (CMV) under greenhouse conditions. When Early Cal wonder plants were sown at 10 day intervals and transplanted to 10-cm square pots, three distinct plant sizes were identified that were designated small, medium and large. Trials conducted during each season showed that CMV accumulated in inoculated leaves of all plants of each size category. All small plants (with the exception of the winter trial) developed a systemic infection that included accumulation of CMV in uninoculated leaves and severe systemic symptoms. Medium plants had a …

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Sequences Of Citrus Tristeza Virus Separated In Time And Space Are Essentially Identical, Maria R. Albiach-Marti, Munir Mawassi, Siddarame Gowda, Satyanarayana Tatineni, Mark E. Hilf, Savita Shanker, Ernesto C. Almira, Maria C. Vives, Carmelo Lopez, Jose Guerri, Ricardo Flores, Pedro Moreno, Steve M. Garnsey, William O. Dawson Aug 2000

Sequences Of Citrus Tristeza Virus Separated In Time And Space Are Essentially Identical, Maria R. Albiach-Marti, Munir Mawassi, Siddarame Gowda, Satyanarayana Tatineni, Mark E. Hilf, Savita Shanker, Ernesto C. Almira, Maria C. Vives, Carmelo Lopez, Jose Guerri, Ricardo Flores, Pedro Moreno, Steve M. Garnsey, William O. Dawson

Department of Plant Pathology: Faculty Publications

The first Citrus tristeza virus (CTV) genomes completely sequenced (19.3-kb positive-sense RNA), from four biologically distinct isolates, are unexpectedly divergent in nucleotide sequence (up to 60% divergence). Understanding of whether these large sequence differences resulted from recent evolution is important for the design of disease management strategies, particularly the use of genetically engineered mild (essentially symptomless)-strain cross protection and RNA-mediated transgenic resistance. The complete sequence of a mild isolate (T30) which has been endemic in Florida for about a century was found to be nearly identical to the genomic sequence of a mild isolate (T385) from Spain. Moreover, samples of …

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Utility Of The Mitochondrial Cytochrome Oxidase Ii Gene For Resolving Relationships Among Black Flies (Diptera: Simuliidae), K. P. Pruess, B. J. Adams, T. J. Parsons, X. Zhu, Thomas O. Powers Aug 2000

Utility Of The Mitochondrial Cytochrome Oxidase Ii Gene For Resolving Relationships Among Black Flies (Diptera: Simuliidae), K. P. Pruess, B. J. Adams, T. J. Parsons, X. Zhu, Thomas O. Powers

Department of Plant Pathology: Faculty Publications

The complete mitochondrial cytochrome oxidase II gene was sequenced from 17 black flies, representing 13 putative species, and used to infer phylogenetic relationships. A midge (Paratanytarsus sp.) and three mosquitoes (Aedes aegypti, Anopheles quadrimaculatus, and Culex quinquefasciatus) were used as outgroup taxa. All outgroup taxa were highly divergent from black flies. Phylogenetic trees based on weighted parsimony (a priori and a posteriori), maximum likelihood, and neighbor-joining (log-determinant distances) differed topologically, with deeper nodes being the least well-supported. All analyses supported current classification into species groups but relationships among those groups were poorly resolved. The majority of phylogenetic …

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Condition Of Green Ash, Incidence Of Ash Yellows Phytoplasmas, And Their Association In The Great Plains And Rocky Mountain Regions Of North America, J. A. Walla, W. R. Jacobi, N. A. Tisserat, M. O. Harrell, J. J. Ball, G. B. Neil, D. A. Reynard, Y. H. Guo, L. Spiegel Mar 2000

Condition Of Green Ash, Incidence Of Ash Yellows Phytoplasmas, And Their Association In The Great Plains And Rocky Mountain Regions Of North America, J. A. Walla, W. R. Jacobi, N. A. Tisserat, M. O. Harrell, J. J. Ball, G. B. Neil, D. A. Reynard, Y. H. Guo, L. Spiegel

Department of Plant Pathology: Faculty Publications

About 50% of 1,057 green ash (Fraxinus pennsylvanica) systematically sampled in the Great Plains and Rocky Mountain regions had substantial dieback (>10% of crown branches with dieback), and the average growth ring width during the last 20 years was 2.9 mm. The overall condition of the population was rated fair. Ash yellows phytoplasmas were identified at 102 of 106 sites throughout six U.S. states (North Dakota, South Dakota, Wyoming, Nebraska, Colorado, Kansas) and three Canadian provinces (Alberta, Saskatchewan, Manitoba). These phytoplasmas had not previously been known in Alberta, Saskatchewan, Manitoba, Wyoming, Colorado, or Kansas. Incidence of phytoplasmal …

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Soybean Cyst Nematode Reproduction In The North Central United States, J. Wang, P. A. Donald, T. L. Niblack, G. W. Bird, J. Faghihi, J. M. Ferris, C. Grau, D. J. Jardine, P. E. Lipps, A. E. Macguidwin, H. Melakeberhan, G. R. Noel, P. Pierson, P. M. Riedel, P. R. Sellers, W. C. Stienstra, T. C. Todd, G. L. Tylka, T. A. Wheeler, D. S. Wysong Jan 2000

Soybean Cyst Nematode Reproduction In The North Central United States, J. Wang, P. A. Donald, T. L. Niblack, G. W. Bird, J. Faghihi, J. M. Ferris, C. Grau, D. J. Jardine, P. E. Lipps, A. E. Macguidwin, H. Melakeberhan, G. R. Noel, P. Pierson, P. M. Riedel, P. R. Sellers, W. C. Stienstra, T. C. Todd, G. L. Tylka, T. A. Wheeler, D. S. Wysong

Department of Plant Pathology: Faculty Publications

An experiment was conducted in Heterodera glycines–infested fields in 40 north central U.S. environments (21 sites in 1994 and 19 sites in 1995) to assess reproduction of this nematode. Two resistant and two susceptible soybean cultivars from each of the maturity groups (MG) I through IV were grown at each site in 6.1 m by 4 row plots. Soil samples were collected from each plot at planting and harvest and processed at Iowa State University to determine H. glycines initial (Pi) and final (Pf) population densities as eggs per 100 cm3 of soil. Overall, reproduction (Pf/Pi) of H. glycines …

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Phylogeny Of Calostoma, The Gelatinous-Stalked Puffball, Based On Nuclear And Mitochondrial Ribosomal Dna Sequences, Brandi D. Hughey, Gerard C. Adams, Tom D. Bruns, David S. Hibbett Jan 2000

Phylogeny Of Calostoma, The Gelatinous-Stalked Puffball, Based On Nuclear And Mitochondrial Ribosomal Dna Sequences, Brandi D. Hughey, Gerard C. Adams, Tom D. Bruns, David S. Hibbett

Department of Plant Pathology: Faculty Publications

Nucleotide sequence of the nuclear small and large subunit and the mitochondrial small and large ribosomal genes of Calostoma were used to investigate evolutionary relationships with other Basidiomycetes. In separate analyses with each gene, Calostoma was placed within the Boletales and outside the clades containing most gilled mushrooms, puffballs, stalked puffballs, earthstars, stinkhorns, and nonboletalean Gasteromycetes. This contradicted previous taxonomic hypotheses. Calostoma was most closely related to Gyroporus, Pisolithus, and Scleroderma based on maximum parsimony and maximum likelihood analysis of the mitochondrial large ribosomal gene database, which contained several representatives of most genera of the Boletales. In three …

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Biological Control Of Bipolaris Sorokiniana On Tall Fescue By Stenotrophomonas Maltophilia Strain C3, Z. Zhang, G. Y. Yuen Sep 1999

Biological Control Of Bipolaris Sorokiniana On Tall Fescue By Stenotrophomonas Maltophilia Strain C3, Z. Zhang, G. Y. Yuen

Department of Plant Pathology: Faculty Publications

Stenotrophomonas maltophilia strain C3 was evaluated for control of leaf spot on tall fescue (Festuca arundinacea) caused by Bipolaris sorokiniana. In growth chamber experiments, C3 inhibited conidial germination on leaf surfaces and reduced lesion frequency and percent diseased leaf area compared with nontreated controls. The amount of leaf spot suppression was related to the C3 dose applied. The highest dose tested, 109 CFU/ml, prevented nearly all B. sorokiniana conidia from germinating on treated leaf surfaces and provided nearly complete suppression of lesion development. When colloidal chitin was added to C3 cell suspensions of 107 or …

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Dnak And The Heat Stress Response Of Pseudomonas Syringae Pv. Glycinea, Lisa M. W. Keith, James E. Partridge, Carol L. Bender Jul 1999

Dnak And The Heat Stress Response Of Pseudomonas Syringae Pv. Glycinea, Lisa M. W. Keith, James E. Partridge, Carol L. Bender

Department of Plant Pathology: Faculty Publications

The dnaK gene from Pseudomonas syringae pv. glycinea PG4180 was cloned and sequenced. The dnaK coding region was 1,917 bp and contained a putative O32 heat shock promoter 86 bp upstream of the translational start site. grpE, another heat shock gene, was found immediately upstream of the putative dnaK promoter. The predicted amino acid sequence of dnaK showed relatedness to the ATPase and substrate binding domains commonly found in heat shock proteins, as well as the highly conserved signature sequence motifs belonging to the Hsp70 protein family. Furthermore, the PG4180 dnaK gene complemented an Escherichia coli dnaK mutant …

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An Engineered Closterovirus Rna Replicon And Analysis Of Heterologous Terminal Sequences For Replication, Satyanarayana Tatineni, Siddarame Gowda, V. P. Boyko, Maria R. Albiach-Marti, Munir Mawassi, J. Navas-Castillo, Alexander V. Karasev, V. Dolja, Mark E. Hilf, D. J. Lewandowski, P. Moreno, Moshe Bar-Joseph, S. M. Garnsey, William O. Dawson Jun 1999

An Engineered Closterovirus Rna Replicon And Analysis Of Heterologous Terminal Sequences For Replication, Satyanarayana Tatineni, Siddarame Gowda, V. P. Boyko, Maria R. Albiach-Marti, Munir Mawassi, J. Navas-Castillo, Alexander V. Karasev, V. Dolja, Mark E. Hilf, D. J. Lewandowski, P. Moreno, Moshe Bar-Joseph, S. M. Garnsey, William O. Dawson

Department of Plant Pathology: Faculty Publications

Citrus tristeza virus (CTV) populations in citrus trees are unusually complex mixtures of viral genotypes and defective RNAs developed during the long-term vegetative propagation of the virus and by additional mixing by aphid transmission. The viral replication process allows the maintenance of minor amounts of disparate genotypes and defective RNAs in these populations. CTV is a member of the Closteroviridae possessing a positive-stranded RNA genome of ≈20 kilobases that expresses the replicase-associated genes as an ≈400-kDa polyprotein and the remaining 10 3' genes through subgenomic mRNAs. A full-length cDNA clone of CTV was generated from which RNA transcripts capable of …

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Identification And Characterization Of Genes Required For Hyphal Morphogenesis In The Filamentous Fungus Aspergillus Nidulans, Steven D. Harris, Amy F. Hofmann, Hugo W. Tedford, Maurice P. Lee Jan 1999

Identification And Characterization Of Genes Required For Hyphal Morphogenesis In The Filamentous Fungus Aspergillus Nidulans, Steven D. Harris, Amy F. Hofmann, Hugo W. Tedford, Maurice P. Lee

Department of Plant Pathology: Faculty Publications

In the filamentous fungus Aspergillus nidulans, germination of an asexual conidiospore results in the formation of a hyphal cell. A key feature of spore germination is the switch from isotropic spore expansion to polarized apical growth. Here, temperature-sensitive mutations are used to characterize the roles of five genes (sepA, hypA, podB–podD) in the establishment and maintenance of hyphal polarity. Evidence that suggests that the hypA, podB, and sepA genes are required for multiple aspects of hyphal morphogenesis is presented. Notably, podB and sepA are needed for organization of the cytoskeleton at sites of …

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A Sensitive Elisa For Pythium Ultimum Using Polyclonal And Species-Specific Monoclonal Antibodies, G. Y. Yuen, J. Q. Xia, C. L. Sutula Sep 1998

A Sensitive Elisa For Pythium Ultimum Using Polyclonal And Species-Specific Monoclonal Antibodies, G. Y. Yuen, J. Q. Xia, C. L. Sutula

Department of Plant Pathology: Faculty Publications

A double-antibody sandwich indirect enzyme-linked immunosorbent assay (ELISA) was developed for the detection and quantification of Pythium ultimum. A polyclonal antibody produced to cell walls of P. ultimum was used as the capture antibody, while a P. ultimum-specific monoclonal antibody (MAb E5) was used for recognition of the fungus. In the ELISA, culture extracts of 7 isolates of P. ultimum exhibited strong positive reactions, whereas none of the 37 isolates of other Pythium spp. and fungal genera had positive reactions. P. ultimum was detected by ELISA in roots of bean, cabbage, and sugar beet seedlings grown in pathogen-infested …

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A Partial Host Range Of The High Plains Virus Of Corn And Wheat, Dallas L. Seifers, Tom L. Harvey, T. J. Martin, Stanley G. Jensen Aug 1998

A Partial Host Range Of The High Plains Virus Of Corn And Wheat, Dallas L. Seifers, Tom L. Harvey, T. J. Martin, Stanley G. Jensen

Department of Plant Pathology: Faculty Publications

Barley (Hordeum vulgare), cheat (Bromus secalinus), corn (Zea mays), oat (Avena sativa), rye (Secale cereale), and wheat (Triticum aestivum) were infected by a Kansas isolate of the High Plains virus (HPV) in greenhouse experiments, but several other grass species were not. Infection of a host was dependent upon wheat curl mite numbers. Although both green foxtail (Setaria viridis) and yellow foxtail (S. glauca) are found naturally infected by HPV, only yellow foxtail could be infected in greenhouse experiments. Field sampling (1994 to 1996) of …

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Physiologic Specialization Of Puccinia Recondita F. Sp. Tritici In Nebraska During 1995 And 1996, J. E. Watkins, S. S. Rutledge, P. Stephen Baenziger, W. Youngquist Jun 1998

Physiologic Specialization Of Puccinia Recondita F. Sp. Tritici In Nebraska During 1995 And 1996, J. E. Watkins, S. S. Rutledge, P. Stephen Baenziger, W. Youngquist

Department of Plant Pathology: Faculty Publications

Field samples of Puccinia recondita f. sp. tritici, collected from four wheat-growing regions in Nebraska in 1995 and from three in 1996, were characterized for virulence. Twenty virulence phenotypes were identified in 1995 and 18 in 1996. Virulence phenotypes MBR-10,18 (virulent on Lr genes, 1, 3, 3ka, 10, 11, 18, and 30) and MDR-10,18 (virulent on Lr genes 1, 3, 3ka, 10, 11, 18, 24, and 30) were the most prevalent, with each phenotype comprising 21.6% of the isolates characterized in 1995. Of the 1995 isolates, 24% were virulent on 10 or more host genes. No virulence to Lr16 and …

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Polymerase Chain Reaction Detection And Phylogenetic Characterization Of An Agent Associated With Yellow Vine Disease Of Cucurbits, Francisco J. Avila, Benny D. Bruton, Jacqueline Fletcher, J. L. Sherwood, Sam D. Pair, Ulrich Melcher May 1998

Polymerase Chain Reaction Detection And Phylogenetic Characterization Of An Agent Associated With Yellow Vine Disease Of Cucurbits, Francisco J. Avila, Benny D. Bruton, Jacqueline Fletcher, J. L. Sherwood, Sam D. Pair, Ulrich Melcher

Department of Plant Pathology: Faculty Publications

Diagnosis of yellow vine disease (YVD) in cucurbits, an important disease in the south-central United States, relies on external symptom appearance, phloem discoloration, and the presence of bacterium-like organisms (BLOs) in phloem. Polymerase chain reaction (PCR) amplification of BLO nucleotide sequences was explored as a means to improve diagnostic techniques. PCR, using a primer pair based on sequences of the citrus-greening BLO, amplified a 0.15-kilobase (kb) fragment from the DNA of symptomatic plants, but not from that of asymptomatic plants. Its nucleotide sequence suggested that the DNA amplified was of prokaryotic origin. A primer pair, designed to amplify nonspecific prokaryotic …

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Characterization Of The Large (L) Rna Of Peanut Bud Necrosis Tospovirus, S. Gowda, Satyanarayana Tatineni, R. A. Naidu, A. Mushegian, W. O. Dawson, D. V. R. Reddy Jan 1998

Characterization Of The Large (L) Rna Of Peanut Bud Necrosis Tospovirus, S. Gowda, Satyanarayana Tatineni, R. A. Naidu, A. Mushegian, W. O. Dawson, D. V. R. Reddy

Department of Plant Pathology: Faculty Publications

The nucleocapsids purified from peanut plants systemically infected with peanut bud necrosis virus (PBNV), a member of the genus Tospovirus, contained both viral(v) and viral complementary(vc) sense L RNAs. Defective forms of L RNA containing ‘core polymerase region’ were observed. The full length L RNA of PBNV was sequenced using overlapping cDNA clones. The 8911 nucleotide L RNA contains a single open reading frame (ORF) in the vc strand, and encodes a protein of 330 kDa. At the 50 and 30 termini of the v sense RNA there were 247 and 32 nt untranslated regions, respectively, containing an 18 …

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Peanut Yellow Spot Virus Is A Member Of A New Serogroup Of Tospovirus Genus Based On Small (S) Rna Sequence And Organization, Satyanarayana Tatineni, S. Gowda, K. Lakshminarayana Reddy, S. E. Mitchell, W. O. Dawson, D. V. R. Reddy Jan 1998

Peanut Yellow Spot Virus Is A Member Of A New Serogroup Of Tospovirus Genus Based On Small (S) Rna Sequence And Organization, Satyanarayana Tatineni, S. Gowda, K. Lakshminarayana Reddy, S. E. Mitchell, W. O. Dawson, D. V. R. Reddy

Department of Plant Pathology: Faculty Publications

Peanut yellow spot virus (PYSV) represents a distinct tospovirus species based on serology and nucleic acid hybridization. The sequence of the S RNA was 2 970 nucleotides with 22 nucleotide long inverted repeats (with three mismatches) at the termini. The coding was ambisense with a long open reading frame (ORF) in each strand. The 5'-large ORF (1 440 nucleotides in the viral sense (v) strand) encoded a protein with a predicted size of 53.2 kDa that was identified as the nonstructural (NSs) protein based on 16–21% sequence identity and 42– 48% sequence similarity with other tospoviruses. A 3' ORF (741 …

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Identification Of The Wheat Curl Mite As The Vector Of The High Plains Virus Of Corn And Wheat, Dallas L. Seifers, Tom L. Harvey, T. J. Martin, Stanley G. Jensen Oct 1997

Identification Of The Wheat Curl Mite As The Vector Of The High Plains Virus Of Corn And Wheat, Dallas L. Seifers, Tom L. Harvey, T. J. Martin, Stanley G. Jensen

Department of Plant Pathology: Faculty Publications

Wheat with virus-like symptoms (extracts containing a 33-kDa protein in sodium dodecyl sulfate- polyacrylamide gel electrophoresis, negative in enzyme-linked immunosorbent assay to wheat streak mosaic virus, and not infectious in a backassay to other wheat) reacted positively to antiserum made against a protein purified from symptomatic corn infected with the High Plains virus (HPV), indicating a serological relationship between the corn and wheat pathogens. The wheat curl mite (WCM, Aceria tosichella Keifer) was identified as the vector of the virus and caused persistent infection of barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) in greenhouse experiments. The …

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Comparison Of Avrd Alleles From Pseudomonas Syringae Pv. Glycinea, Lisa Wolfson Keith, Carol Boyd, Noel T. Keen, J. E. Patridge Apr 1997

Comparison Of Avrd Alleles From Pseudomonas Syringae Pv. Glycinea, Lisa Wolfson Keith, Carol Boyd, Noel T. Keen, J. E. Patridge

Department of Plant Pathology: Faculty Publications

Avirulence gene D alleles resided on indigenous plasmids in races 0, 2, 3, 4, 5, and 6 of Pseudomonas syringae pv. glycinea (Psg), but the allele in race 1 appeared to be chromosomal. These were all nonfunctional avirulence genes because they neither induced the avirulence phenotype on Rpg4 soybean cultivars nor directed the production of syringolide elicitors when expressed in Escherichia coli cells. The predicted proteins encoded by the seven Psg avrD genes were very similar to that of a functional class II allele from P. syringae pv. phaseolicola G50 race 2, but contained mutations collectively …

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Genetic Variability Among Maize Inbred Lines For Resistance To The High Plains Virus–Wheat Streak Mosaic Virus Complex, A. Marçon, S. M. Kaeppler, S. G. Jensen Feb 1997

Genetic Variability Among Maize Inbred Lines For Resistance To The High Plains Virus–Wheat Streak Mosaic Virus Complex, A. Marçon, S. M. Kaeppler, S. G. Jensen

Department of Plant Pathology: Faculty Publications

High plains virus (HPV) is a pathogen that causes a severe disease, especially in susceptible corn genotypes. The virus is transmitted by the eriophyid mite Aceria tosichella, which also transmits wheat streak mosaic virus (WSMV). This often results in a mixed infection by these two viruses. Genetic variability for resistance to the HPV exists among maize inbred lines but has not been characterized. The disease reaction of 30 maize inbred lines to the mixed infection and to WSMV alone was characterized in this study. Evaluation was based on symptom expression and virus titer (HPV and WSMV), as measured by …

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