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Cross-Polarized Magic-Angle Spinning 13c Nuclear Magnetic Resonance Spectroscopic Characterization Of Soil Organic Matter Relative To Culturable Bacterial Species Composition And Sustained Biological Control Of Pythium Root Rot, Michael J. Boehm, Tianyun Wu, Alex G. Stone, Bart Kraakman, Donna A. Iannotti, G. Edwin Wilson, Laurence V. Madden, Harry A.J. Hoitink

Department of Plant Pathology: Faculty Publications

We report the use of a model system that examines the dynamics of biological energy availability in organic matter in a sphagnum peat potting mix critical to sustenance of microorganism-mediated biological control of pythium root rot, a soilborne plant disease caused by Pythium ultimum. The concentration of readily degradable carbohydrate in the peat, mostly present as cellulose, was characterized by cross-polarized magic-angle spinning 13C nuclear magnetic resonance spectroscopy. A decrease in the carbohydrate concentration in the mix was observed during the initial 10 weeks after potting as the rate of hydrolysis of fluorescein diacetate declined below a critical threshold level …

Promoters From Chlorellavirus Genes Providing Expression Of Genes In Prokaryotic And Eukaryotic Hosts, Amitava Mitra, James L. Van Etten

Department of Plant Pathology: Faculty Publications

The invention is directed to novel promoters or mutants thereof from Chlorella virus DNA methyltransferase genes. A Chlorella virus gene promoter is operably linked to a first and/or second DNA sequence encoding a gene that is different from the Chlorella virus gene to form an expression cassette. An expression cassette can be introduced into prokaryotic and/or eukaryotic cells and can provide for a high level of expression of the gene encoded by the first and/or second DNA sequence. The invention also provides a method for screening other Chlorella virus genes for promoters that can function to express a heterologous gene …

Expression And Characterization Of An Rna Capping Enzyme Encoded By Chlorella Virus Pbcv-1, C. Kiong Ho, James L. Van Etten, Stewart Shuman

Department of Plant Pathology: Faculty Publications

We report that the A103R protein of Chlorella virus PBCV-1 is an mRNA capping enzyme that catalyzes the transfer of GMP from GTP to the 5’ diphosphate end of RNA. This is a two-step reaction in which the enzyme first condenses with GTP to form a covalent enzyme-GMP intermediate and then transfers the GMP to an RNA acceptor to form a GpppN cap. Purified recombinant A103R is a 38-kDa monomer that lacks RNA (guanine-7-) methyltransferase activity. With respect to its size, amino acid sequence, and biochemical properties, A103R is more closely related to the yeast RNA guanylyltransferases than it is …

Twig, Branch, And Stem Diseases Of Pine, John R. Hartman

Agriculture and Natural Resources Publications

Tip Blight

Tip blight, caused by the fungus Sphaeropsis sapinea (formerly Diplodia pinea), is a serious disease of mature Austrian, Scots (Scotch), and Mugo pines in Kentucky. In the landscape, tip blight is normally not observed until pines reach about 12 years old and begin to bear cones. Severe infections year after year can greatly weaken and eventually kill affected pines.

United States Patent 5,500,360: Rna Transformation Vector, Paul G. Ahlquist, Roy C. French

Department of Plant Pathology: Faculty Publications

A + strand RNA viral transformation of host organisms with foreign RNA, and expression of said foreign RNA. The foreign RNA is inserted into an infective RNA viral segment containing replication elements, and allowed to infect the host organism. The invention is exemplified utilizing brome mosaic RNA modified to contain a gene coding for chloramphenicol acetyl transferase (CAT) in the transformation of barley protoplasts.

The Complete Nucleotide Sequence And Genome Organization Of The M Rna Segment Of Peanut Bud Necrosis Tospovirus And Comparison With Other Tospoviruses, Satyanarayana Tatineni, S. E. Mitchell, D. V. R. Reddy, S. Kresovich, R. Jarret, R. A. Naidu, S. Gowda, J. W. Demski

Department of Plant Pathology: Faculty Publications

The M RNA of peanut bud necrosis virus (PBNV; synonym groundnut bud necrosis virus) is 4801 nucleotides in length. It comprised two ORFs in an ambisense organization and terminal inverted repeats. The 3' large ORF (3363 nucleotides in the virus-complementary strand) encoded a protein with a predicted size of 127.2 kDa which was identified as the glycoprotein precursor (GP) of the G1 and G2 glycoproteins. A comparison of the deduced amino acid sequence of GP revealed 37 % identity and 58-59% similarity with that of tomato spotted wilt virus (TSWV, serogroup I) and impatiens necrotic spot virus (INSV, serogroup III), …

Peanut Bud Necrosis Virus: Purification Of Nucleocapsids And Sequence Homology Of Nucleocapsid Protein And Glycoprotein Precursor With Other Tospoviruses, Satyanarayana Tatineni, S. E. Mitchell, D. V. R. Reddy, S. Brown, S. Kresovich, R. Jarret, S. Gowda, R. A. Naidu, J. W. Demski

Department of Plant Pathology: Faculty Publications

A procedure for the purification of peanut bud necrosis virus (PBNV) nucleocapsids was developed. Virus particles were treated with nonionic detergent to disrupt the envelope membrane and free nucleocapsids were separated. into three lightscattering zones after sucrose gradient centrifogation. Nucleocapsids from the top zone contained S RNA and traces ofM RNA; whereas, nucleoplasids from the middle zone contained M RNA with detectable levels of S RNA and those from the bottom zone contained L RNA with traces of M and S RNAs. Clones from a cDNA library made from the purified PBNV Sand M RNAs were characterized and sequenced. Comparison …

Diagnosis And Resistance Breeding Of Peanut Bud Necrosis Virus, D. V. R. Reddy, Satyanarayana Tatineni, S. L. Dwivedi, A. S. Ratna, A. A. M. Buiel, G. V. Ranga Rao, S. N. Nigam, R. A. Naidu, H. T. Hsu, J. W. Demski

Department of Plant Pathology: Faculty Publications

The occu!fence of peanut bud necrosis (PBN) disease in India was first reported in 1968. The high incidence ofPBN disease during the 1960s coincided with largescale imports of the peanut cultivars Asiria Mwitundae and Spanish Improved, both of which are highly susceptible to PBN. Since then, a number of reports have been published in India describing bud necrosis under at least seven different names (Reddy 1988). Crop losses due to PBN have been estimated at USD89 million per year in India during 1976-1986. The disease is also currently recognized as economically important in Nepal (Sharma 1996), in Sri Lanka, and …

Fumonisins And Alternaria Alternata Lycopersici Toxins: Sphinganine Analog Mycotoxins Induce Apoptosis In Monkey Kidney Cells, Hong Wang, Clinton Jones, Janice Caiacci-Zanella, Todd Holt, David G. Gilchrist, Martin B. Dickman

Department of Plant Pathology: Faculty Publications

Fusarium moniliforme toxins (fumonisins) and Alternaria alternata lycopersici (AAL) toxins are members of a new class of sphinganine analog mycotoxins that occur widely in the food chain. These mycotoxins represent a serious threat to human and animal health, inducing both cell death and neoplastic events in mammals. The mechanisms by which this family of chemical congeners induce changes in cell homeostasis were investigated in African green monkey kidney cells (CV-1) by assessing the appearance of apoptosis, cell cycle regulation, and putative components of signal transduction pathways involved in apoptosis. Structurally, these mycotoxins resemble the sphingoid bases, sphingosine and sphinganine, that …

A Mammalian 2-5a System Functions As An Antiviral Pathway In Transgenic Plants, Amitava Mitra, Dan W. Higgins, William G. Langenberg, Huiqin Nie, Dibyendu N. Sengupta, Robert H. Silverman

Department of Plant Pathology: Faculty Publications

Resistance to virus infections in higher vertebrates is mediated in part through catalysis of RNA decay by the interferon-regulated 2-5A system. A functional 2-5A system requires two enzymes, a 2-5A synthetase that produces 5"phosphorylated, 2',5'-linked oligoadenylates (2-5A) in response to double-stranded RNA, and the 2-5A-dependent RNase L. We have coexpressed these human enzymes in transgenic tobacco plants by using a single plasmid containing the cDNAs for both human RNase L and a low molecular weight form of human 2-5A synthetase under control of different, constitutive promoters. Expression of the human cDNAs in the transgenic plants was demonstrated from Northern blots, …

Molecular Diagnostics Of Three Diabrotica (Coleoptera: Chrysomelidae) Pest Species, Allen L. Szalanski, Thomas O. Powers

Department of Plant Pathology: Faculty Publications

A 257 bp region of the mitochondrial ND4 gene was analyzed for genetic variation in three species of corn rootworm, southern corn rootworm (Diabrotica undecim punctata howardi Barber, SCR), northern corn rootworm (D. barberi Smith and Lawrence, NCR), and western corn rootworm (D. virgifera virgifera LeConte, WCR). Nucleotide sequencing revealed 26 polymorphic sites. Genetic distances averaged 8% for all pair-wise comparisons among the three species. Restriction maps were constructed from sequence data and compared to potential species specific restriction sites. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) revealed three restriction enzymes (Alu I, Apo I …

United States Patent, Number: 5,466,788: Subgenomic Promoter, Paul G. Ahlquist, Roy C. French

Department of Plant Pathology: Faculty Publications

A subgenomic promoter of a positive strand RNA virus is disclosed which directs the amplified expression of a structural gene in plant tissue. The core region and an upstream activating domain of the subgenomic promoter are identified. This promoter can be utilized in a modified virus, or in an appropriate engineered recombinant DNA derivative, which may be chromosomally integrated or maintained as an episome in transformed cells.

Research On Plant Disease And Pest Management Is Essential To Sustainable Agriculture, R. James Cook, Clifford J. Gabriel, Arthur Kelman, Sue Tolin, Anne K. Vidaver

Department of Plant Pathology: Faculty Publications

In the United States, a country with food in great abundance, it is difficult to realize that, were it not for the current level of plant disease and pest management, most human resources would be needed to obtain enough food and other plant and animal products merely to survive. Instead, there are surpluses, markets for many agricultural products are depressed, and funds available for research on plant disease and pest management-and for agricultural research generally-have plateaued or are declining. Why does the United States need more research on plant disease and pest management? Because the health and productivity of the …

Research On Plant Disease And Pest Management Is Essential To Sustainable Agriculture, R. James Cook, Clifford J. Gabriel, Arthur Kelman, S. Tolin, Anne K. Vidaver

Department of Plant Pathology: Faculty Publications

In the United States, a country with food in great abundance, it is difficult to realize that, were it not for the current level of plant disease and pest management, most human resources would be needed to obtain enough food and other plant and animal products merely to survive. Instead, there are surpluses, markets for many agricultural products are depressed, and funds available for research on plant disease and pest management-and for agricultural research generally-have plateaud or are declining.

Why does the United States need more research on plant disease and pest management? Because the health and productivity of the …

Biosystematics And Diversification In The Genus Striga Lour. (Scrophulariaceae) In Africa, Kamal-Eldin Ibrahim Mohamed

Biological Sciences Theses & Dissertations

Of the 34 taxa of Striga (29 species) that occur in Africa, 25 are endemic. Species diversity differs from region to region. The subtropical zone has 74% of the taxa including 41% endemics. Within this region, the West African part (from Senegal to eastern Nigeria) has 62% of the total taxa including 24% endemics. South of the equator the number of taxa is 56% of the total with 21% endemics, a proportion slightly less than that for West Africa. I recognize 29 species based on extensive herbarium and field studies. A new species from Angola is described. Striga yemenica previously …

Fundamental Principles Of Plant Pathology For Agricultural Producers, Paul C. Vincelli

Agriculture and Natural Resources Publications

All crop plants produced in Kentucky have the potential to become diseased under certain conditions. Diseases of crops can affect yield and/or quality of the harvested commodity. This can impact profitability and increase the risks of farming.

A plant is diseased when it is affected by some agent that interferes with its normal development. Some disorders are caused by noninfectious factors, such as temperature extremes or nutrient deficiencies. However, this publication focuses on diseases caused by infectious microorganisms.

Diseased plants exhibit a variety of symptoms. These can include stunting, yellowing, wilting, twisting, reddening, browning, blighting, root rot, fruit rot, …

Meloidogyne Javanica Parasitic On Peanut, E. K. Tomaszewski, M. A. M. Khalil, A. A. El-Deeb, Thomas O. Powers, J. L. Starr

Department of Plant Pathology: Faculty Publications

Peanut fields in four governorates of Egypt were surveyed to identify species of Meloidogyne present. Fourteen populations obtained from peanut roots were all identified as M. javanica based on perineal patterns, stylet and body lengths of second-stage juveniles, esterase phenotypes, and restriction fragment length polymorphisms of mtDNA. Three of 14 populations, all from contiguous fields in the Behara governorate, had individuals with a unique two-isozyme esterase phenotype. All populations of M. javanica tested on peanut had levels of reproduction on the M. arenaria-susceptible peanut cultivar Florunner that were not different from M. arenaria (P = 0.05), and had lower …

Identification And Characterization Of Aspergillus Nidulans Mutants Defective In Cytokinesis, Steven D. Harris, Jennifer L. Morrell, John E. Hamer

Department of Plant Pathology: Faculty Publications

Filamentous fungi undergo cytokinesis by forming crosswalls termed septa. Here, we describe the genetic and physiological controls governing septation in Aspergillus nidulans. Germinating conidia do not form septa until the completion of their third nuclear division. The first septum is invariantly positioned at the basal end of the germ tube. Block-and-release experiments of nuclear division with benomyl or hydroxyurea, and analysis of various nuclear division mutants demonstrated that septum formation is dependent upon the third mitotic division. Block-and-releasee xperiments with cytochalasin A and the localization of actin in germlings by indirect immunofluorescence showed that actin participated in septum formation. In …

Biological Control Of Doublegee : Israeli Weevil Could Help Fight Doublegee, John Scott, Paul Yeoh

Journal of the Department of Agriculture, Western Australia, Series 4

Since its deliberate introduction from South Africa as a salad vegetable in 1830 the doublegee has spread to become a major weed throughout much of Australia.

It is one of the most serious weeds of crops and pastures in Western Australia, smothering other more useful plants while young, and troubling both humans and animals with its sharp spiny seeds when mature.

Using biological control techniques, scientists are now attacking it and related docks in three ways - with an aphid, a weevil and a fungus.

Within a few years it is hoped that while still present, the doublegee will be …

Biological Control Of Doublegee : Doublegee Decline And The Dock Aphid, John Scott, Francoise Berlandier, Kristy Hollis

Journal of the Department of Agriculture, Western Australia, Series 4

Since 1990 farmers in the Western Australian wheatbelt have been reporting doublegee plants that appear to be diseased, stunted and producing poorly formed fruit (the spiny casing around the single doublegee seed). Often no obvious cause of this decline in plant health is apparent. Experiments carried out in 1990 showed that an aphid, which feeds hidden in the growing tips of doublegee stems and in young distorted leaves, is the most likely cause. This North American aphid, the dock aphid (Brachycaudus rumexicolens), arrived in WA in 1987. It appears to only feed on docks, doublegees and related plants and is …

Characterization Of Heterorhabditis Isolates By Pcr Amplification Of Segments Of Mtdna And Rdna Genes, Susan A. Joyce, Ann M. Burnell, Thomas O. Powers

Department of Plant Pathology: Faculty Publications

Restriction digests of amplified DNA from the mitochondrial genome and the nuclear ribosomal internally transcribed spacer region have been evaluated as genetic markers for species groups in Heterorhabditis. Six RFLP profiles have been identified. These profiles supported groupings determined by cross-breeding studies and were in agreement with less definitive groupings based on other biochemical and molecular methods. Digestion patterns of both amplification products provided strong evidence for the recognition of species groups, which include Irish, NW European, tropical, and a H. bacteriophora complex. The H. bacteriophora complex could be further resolved into three genotypes represented by H. zealandica, …

Biological Control Of Doublegee : Fungi May Be Another Weapon, Roger Shivas, John Scott

Journal of the Department of Agriculture, Western Australia, Series 4

A fungus has been assessed both in Australia and South Africa since 1989 for its potential to control doublegee.

Under optimal environmental conditions it causes a severe stem blight which ultimately kills the plant. It also infects seeds, and caused up to 30 per cent mortality at a field site near Badgingarra.

Hopes to develop the fungus as a mycoherbicide (fungal killer of plants) have had to be dropped because it produces a potent toxin but it is still contributing to control in the field.

Kentucky Plant Disease Management Guide For Soybeans, Donald E. Hershman

Agriculture and Natural Resources Publications

This guide contains information on the biology and management of the most important diseases of soybeans in Kentucky. Fundamental information on symptoms, disease cycle, and management is provided. For some diseases, more extensive information on biology and management is also available in other Extension publications. Additional sources of information are listed under individual diseases.

Disease management in soybeans relies heavily on using disease-resistant varieties, when available, and employing sound agronomic practices. It is important to integrate both of these strategies into a comprehensive disease management program. Failure to consider one or the other will compromise the success of your efforts. …

Kentucky Plant Disease Management Guide For Small Grains, Donald E. Hershman, Paul C. Vincelli

Agriculture and Natural Resources Publications

This guide contains information on the biology and management of the most important diseases of small grains (wheat and barley) in Kentucky. Fundamental information on symptoms, disease cycle, and management is provided. For some diseases, more extensive information on biology and management is also available in other Extension publications. Additional sources of information are listed under individual diseases.

Disease management in small grains relies heavily on using disease-resistant varieties and employing sound agronomic practices. It is important to integrate both of these strategies into a comprehensive disease management program. Failure to consider one or the other will compromise the success …

Kentucky Plant Disease Management Guide For Forage Legumes, Paul C. Vincelli

Agriculture and Natural Resources Publications

This guide contains information on the biology and management of the most important diseases of forage legumes in Kentucky. Fundamental information on symptoms, disease cycle, and management is provided. For some diseases, more extensive information on biology and management is also available in other Extension publications. Additional sources of information are listed under individual diseases.

Disease management in forage legumes relies heavily on using disease-resistant varieties and employing sound agronomic practices. It is important to integrate both of these strategies into a comprehensive disease management program. Failure to consider one or the other will compromise the success of your efforts. …

Kentucky Plant Disease Management Guide For Corn And Sorghum, Paul C. Vincelli, Donald E. Hershman

Agriculture and Natural Resources Publications

This guide contains information on the biology and management of the most important diseases of corn and sorghum in Kentucky. Fundamental information on symptoms, disease cycle, and management is provided. For some diseases, more extensive information on biology and management is also available in other Extension publications. Additional sources of information are listed under individual diseases.

Disease management in corn and sorghum relies heavily on using disease-resistant hybrids and employing sound agronomic practices. It is important to integrate both of these strategies into a comprehensive disease management program. Failure to consider one or the other will compromise the success of …

Effect Of Organic Matter Decomposition Level On Bacterial Species Diversity And Composition In Relationship To Pythium Damping-Off Severity, Michael J. Boehm, L.V. Mdden, H.A.J. Hoitink

Department of Plant Pathology: Faculty Publications

Rhizosphere bacteria were isolated from root tip segments of cucumber seedlings grown in a suppressive, slightly decomposed light-colored peat mix, a conducive, more decomposed dark-colored peat mix, and a suppressive dark peat mix amended with composted hardwood bark. The bacteria were identified by a gas chromatographic fatty acid methyl ester analysis. The total number of taxa recovered from a single root tip segment ranged from 9 to 18. No single taxon predominated on all root tip segments harvested from any of the mixes. The highest relative population density reached by a given taxon on any root tip segment was 45%. …

The Polymerase Chain Reaction And Plant Disease Diagnosis, Joan M. Henson, Roy C. French

Department of Plant Pathology: Faculty Publications

The polymerase chain reaction (PCR) provides a simple, ingenious method to exponentially amplify specific DNA sequences by in vitro DNA synthesis. Three essential steps to PCR (Figure 1) include (a) melting of the target (b) annealing of two oligonucleotide primers to the denatured DNA strands, and (c) primer extension by a thermostable DNA polymerase (123). Newly synthesized DNA strands serve as targets for subsequent DNA synthesis as the three steps are repeated up to 50 times. The specificity of the method derives from the synthetic oligonucleotide primers, which base-pair to and define each end of the target sequence to be …

Leptospira Genomes Are Modified At 5'-Gtac, David Ralph, Quideng Que, James L. Van Etten, Michael Mcclelland

Department of Plant Pathology: Faculty Publications

Genomic DNAs of 14 strains from seven species of the spirochete Leptospira were resistant to cleavage by the restriction endonuclease RsaI 1 (5'-GTAC). A modified base comigrating with m⁴C was detected by chromatography. Genomic DNAs from other spirochetes, Borrelia group VS461, and Serpulina strains were not resistant to h a 1 digestion. Modification at 5'-GTAm⁴C may occur in most or all strains of all species of Leptospira but not in all genera of spirochetes. Genus-wide DNA modification has rarely been observed in bacteria.

Evidence For Virus-Encoded Glycosylation Specificity, Ing-Nang Wang, Yu Li, Quideng Que, Meenakshi Bhattacharya, Leslie C. Lane, William G. Chaney, James L. Van Etten

Department of Plant Pathology: Faculty Publications

Four spontaneously derived serologically distinct classes of mutants of the Paramecium bursaria chlorella virus (PBCV-1) were isolated using polydonal antiserum prepared against either intact PBCV-1 or PBCV-1-derived serotypes. The oligosaccharide(s) of the viral major capsid protein and two minor glycoproteins determined virus serological specificity. Normally, viral glycoproteins arise from host-specific glycosylation of viral proteins; the glycan portion can be altered only by growing the virus on another host or by mutations in glycosylation sites of the viral protein. Neither mechanism explains the changes in the glycan(s) of the PBCV-1 major capsid protein because all of the viruses were grown in …