Microbiology Commons^™

Metagenomic Analysis Of Root-Associated Microbiome Of Healthy And Taproot Decline-Affected Soybeans And Identification Of Healthy Soybean Root Endophytes With Protective Activity Against The Causal Agent, Xylaria Necrophora, Uyen Wesser

Theses and Dissertations

Plant roots are associated with a diverse microbial community of bacteria and fungi. The root microbiome communities associate with the root surface or penetrate the superficial layers of root tissues. It is of high agronomic interest to characterize root microbiomes and identify microbes with beneficial effects on plant defense against pathogens. Soybean taproot decline (TRD) is an emerging soil-borne disease caused by a fungus classified as Xylaria necrophora, challenging to control and with devastating effects on yield. Our group has initiated a study of the soybean root microbiome with three primary experiments: (I) perform a comparative study of root …

Genetic Characterization Of Antimicrobial Activities Of Endophytic Bacteria Burkholderia Strains Ms455 And Ms389, Jiayuan Jia

Theses and Dissertations

Strains MS455 and MS389, endophytic bacteria, were isolated from healthy soybean plant growing adjacent to a patch of plants affected by charcoal rot disease, caused by the fungal pathogen Macrophomina phaseolina. The complete genomes of both strains were sequenced and identified as Burkholderia species Strain MS455 exhibits broad-spectrum antifungal activities against economically important pathogens, including Aspergillus flavus. Random and site-specific mutations were employed in discovery of the genes that share high homology to the ocf gene cluster of Burkholderia contaminans strain MS14, which is responsible for production of the antifungal compound occidiofungin. RNA-seq analysis demonstrated ORF1, a …

Exploring Primitive Legume Symbiosis Using Chamaecrista Fasciculata As A Model, Zachary E. Zawada

Theses and Dissertations

Legumes form symbiotic associations with diazotrophs collectively termed “rhizobia” leading to the formation of nodules and N2-fixation and contribute significant amounts of fixed N to agricultural and natural environments. The mechanisms of nodulation and N2-fixation are extensively studied using model legumes that belong to the Papilionoideae, in which nodulation is widespread and advanced. In contrast, very little is known about the mechanisms of nodulation and N2-fixation in in basal Caesalpinioideae subfamily in which nodulation is rare. The nodulating caesalpiniod legume Chamaecrista fasciculata is widespread in North America and is suggested as a complementary model to study legume nodulation because of …

Bottom-Up Controls (Micronutrients And N And P Species) Better Predict Cyanobacterial Abundances In Harmful Algal Blooms Than Top-Down Controls (Grazers), Scott Andrew Collins

Theses and Dissertations

The initiation, bloom, and bust of harmful Cyanobacteria and algae blooms (HAB) in lakes are controlled by top-down and bottom-up ecological controls. Excess phosphorous and nitrogen inputs from anthropogenic sources are primary to blame, but eukaryotic grazers may also promote or curb Cyanobacteria dominance. We tracked shifts in bacterial composition, lake chemistry, and eukaryotic grazing community weekly or bi-weekly through spring and summer and modeled the causes of specific Cyanobacterial species blooms and busts across three lakes in Utah, USA, with differing lake trophic states. Regardless of trophic status, all three lakes experienced blooms of varying composition and duration. Aphanizomenon …

Evaluating Fungal Pathogen Inoculum Loads In Field Seed Banks, Taryn Lori Williamson

Theses and Dissertations

Quantification of soilborne pathogen inoculum loads is important in both agricultural and wildland settings. Quantitative Polymerase Chain Reaction (qPCR) methods using SYBR Green chemistry have been shown to be useful for quantifying fungal inoculum loads in environmental samples. The purpose of this study was to develop a method to quantify fungal pathogen inoculum loads in soil seed banks using a qPCR method with SYBR Green chemistry. The invasive annual grass Bromus tectorum was chosen for this seed bank study. There were three objectives: 1) to design target-specific primers for three fungal pathogens known to be important in Bromus tectorum seed …

Deciphering The Multi-Tiered Regulatory Network That Links Cyclic-Di-Gmp Signaling To Virulence And Bacterial Behaviors, Xiaochen Yuan

Theses and Dissertations

Bis-(3’-5’)-cyclic dimeric guanosine monophosphate (c-di-GMP) is a bacterial second messenger that regulates multiple cellular behaviors in most major bacterial phyla. C-di-GMP signaling in bacterial often includes enzymes that are responsible for the synthesis and degradation of c-di-GMP, effector proteins or molecules that bind c-di-GMP, and targets that interact with effectors. However, little is known about the specificity of c-di-GMP signaling in controlling virulence and bacterial behaviors. In this work, we have investigated the c-di-GMP signaling network using the model plant pathogen Dickeya dadantii 3937.

In Chapter 2, we characterized two PilZ domain proteins that regulate biofilm formation, swimming motility, Type …

Fixation Of Dormant Tilletia Teliospores For Thin Sectioning, John Scott Gardner

Theses and Dissertations

Dormant Tilletia caries teliospores in fixative solution or distilled water were frozen onto specimen chucks of an FTS Sorvall- Christensen frozen thin sectioner and cut or fractured at various temperatures (-20 to -75 C) and thickness settings (10, 15, 20, and 25 um). Cytoplasm of dormant spores was well preserved and organelles were found to differ from those of germinated spores in morphology. Irregular electron dense and electron opaque areas of lipid bodies were sometimes evident in dormant and germinating Tilletia caries teliospores. When dormant teliospores were sectioned in buffered fixative, lipids had an appearance similar to lipids in thin …

Light And Electron Microscopy Investigation Of Developing Wheat Caryopses Infected By Tilletia, Melvin Douglas Grove

Theses and Dissertations

Caryopses of wheat were studied during infection by Tilletia caries and T. controversa. Initially the pathogens penetrated embryos of the host. After the embryo tissue was consumed by the fungi, endosperm tissue was penetrated and consumed. Initial penetration of endosperm tissue was in localized areas. During infection the fungus mycelium spread intercellularly, but occasionally was seen intracellularly. As the host tissue was consumed teliospores were formed. At maturity a host cell layer 4-6 cells thick remained which retained the mature teliospores. Histochemical studies indicated that carbohydrates and lipids of the host disappeared soon after invasion by the pathogens. Nuclei and …

A Pectin Histochemical Study Of The Host Pathogen Relationship Between Pyrenochaeta Terrestris And Allium Cepa, Leroy Richard Cobia

Theses and Dissertations

The involvement of pectin and pectinases in the host pathogen interaction of P. terrestris and Allium cepa were investigated by use of pectin histochemical stains at the electron microscope level. Several different pectin histochemical stains were used, but only two (the hydroxylamine reaction, and the pectin stain developed in this study) gave reliable results. It was observed that by the time the fungus has reached the host cell wall pectinesterase and endoplygalacturonase have fully removed the pectin from the host cell wall. When this has occurred, cellulases are released which continue to degrade the host cell wall. Electron transparent areas …

Ultrastructural And Histochemical Investigations Of Ipomoea Batatus Lam. Infected By Rhizopus Stolonifer (Fr.) Lind, Kendall O. Smith

Theses and Dissertations

The ultrastructural aspects of Rhizopus stolonifer (Fr.) Lind. Infection in Ipomoea batatus Lam. Roots and the histochemistry of cell walls affected by enzymes secreted by the fungus were investigated. Specimens were prepared for viewing in the electron microscope by thin-sectioning techniques. Degradation of cellular membreanes and host tissues in advance of the fungus was evident. Breakdown of the middle lamella was detected by special histochemical stains for pectin. Breakdown occurred in the following was: (1) maceration of the middle lamella before maceration of the cell wall, (2) simultaneous degradation of both the middle lamella and the cell wall, (3) maceration …

Ultrastructural Investigations Of Tilletia Caries Teliospores, James Vincent Allen

Theses and Dissertations

The purpose of this study was to investigate the ultrastructure of Tilletia caries teliospores. Specimens were prepared for viewing in the electron microscope by freeze-etching and thin-sectioning techniques. Thin-sectioning techniques gave excellent results with the teliospore walls and the lipid bodies within the teliospore but failed to adequately fix the membranes and internal organelle systems. Micrographs of Tilletia caries teliospores prepared using thin-sectioning show three major wall layers and two partition wall layers and abundant lipid bodies. The freeze-etch method of spore preparation proved superior to the thin-sectioning used in this study to reveal the internal organelle systems of the …

Surface Characteristics Of Conidia From Monosporous Cultures Of Penicillium Digitatum And Aspergillus Nidulans Var. Echinulatus, Raymond Kunito Fuji

Theses and Dissertations

The purpose of this investigation was to evaluate the possible taxonomic significance of the "rodlet" patterns and spore wall configurations of conidia from monosporous cultures of Penicillium digitatum Saccardo and Aspergillus nidulans Eidam var. echinulatus Fennell & Raper. Freeze-etching the conidiospores from single spore isolates of these fungi revealed that spore wall patterns and configurations vary much too greatly to be of taxonomic importance on the strain and subspecies level. Environmental factors and genetic influences are discussed as possible mechanisms causing the variations of the spore wall configurations. A membrane-like structure that covers the "rodlet" patterns and which hinders spore …

The Identification Of A Germination Factor For Basidiospores Of Psilocybe Mutans, Neal K. Van Alfen

Theses and Dissertations

Basidiospores of the Basidiomycete Psilocybe mutans have been found to germinate only in the presence of water extracts of animal dung. The chemical nature of the factor present in the dung that induces germination is not known, nor has it ever been isolated· Experiments showed that extracts of bile salts cause the basidiospores to germinate, indicating that since bile salts are found in dung, they may be the factor which stimulates the spores to germinate. Investigations of the properties of the factor in dung show that the factor has solubility properties that are similar to those of the bile acids. …

A Comparative Survey Of Soil Microfungi From Three Vegetation Types In Cedar Valley, Utah, Brent T. Wahlquist

Theses and Dissertations

Microfungi were isolated from soil samples by the soil plate method. Soil samples were collected at depths of 0-1", 1-4", and 4-8" both between and beneath the canopy of the dominant vegetation in stands of greasewood, sagebrush, and pinyon-juniper. Salinity, pH, and percent organic matter were measured for each soil sample. A total of 148 strains of fungi representing 141 species and 46 genera were isolated and identified from these alkaline soils, Few strains, including some Aspergilli, occurred only in the more saline greasewood soils, while many strains, including several Penicillia, occurred in both sagebrush and piny-on-juniper soils but were …

A Study Of Aquatic Fungi In Powell's Slough, Chao-Chih Hsiao

Theses and Dissertations

Aquatic fungi in-Powell's Slough were.studied in 1967 & 1968. Collections were made and water temperature, oxygen content & pH values were measured at weekly intervals. For collections, wire baskets containing substrata were submerged in water for one month. After collecting, substrata were brought to the laboratory. Identification was based on the keys of Sparrow, 1960. Aquatic fungi identified included seven orders, nine families, fifteen genera, and thirty species, from thirty-three collections of fifteen types of substrata. The substrata used in this study were: (i) fruits: apples, rose hips, plums, pears, haws; (ii) twigs: poplar, weeping willow, river birch, weeping white …

Ultrastructural Investigations Of Powdery Mildew Of Rose Caused By Sphaerotheca Pannosa (Wallr.) Lev, Ani Clipper Watene

Theses and Dissertations

The purpose of this study was to evaluate the ultrastructural aspects of the host-pathogen relationship between the fungus Sphaerotheca pannosa (Wallr.) Lev. and a susceptible horticultural variety of floribunda rose "Eutin". Attention was given to the penetration of hyphal tubes, and their subsequent development into: haustorial elements in epidermal cells of rose. In addition, changes in the morphology of infected epidermal cells were described. Thin sections of rose leaves infected with S. pannosa were examined in a Hitachi electron microscope, model HS-7, after glutaraldehyde-acrolein fixation, OsO4-uranyl acetate staining, and embedding in Epon plastic. The components of S. pannosa haustoria consisted …

The Taxonomy And Ecology Of The Fleshy Fungus Flora Of The Snowbanks In The Mirror Lake Region Of The Uinta Mountains, Mary Virginia Charlton Dublin

Theses and Dissertations

The ecology and taxonomy of the snowbank fleshy fungi in the vicinity of Mirror Lake, Uinta Mountains, Utah were investigated during 1963, 1964, and 1965. A total of 59 speciaes, representing the Agaricales, Polyporales, Thelephorales, Gastromycestes, Myxomycetes, Dacrymycetales, and Ascomycetes, were found associated with the snowbanks. Four of these species (Geupiniopsis alpinus, Polyporus alboluteus, Polyporus leucospongia and Sterile myclium I) have presence percentages of 100% and three (Stereum Rugisporum, Dasyscypha arida and Herpotichia nigra) had presence percentages of 90%. The lignicolous fungi were found to be more frequent around the snowbanks than either the terrestrial or coprophilous fungi. No fleshy …

A Phytosociological Study Of Coprophilous Ascomycete And Basidiomycete Communities From Santaquin Canyon, Utah, A. Clyde Blauer

Theses and Dissertations

Numerous reports have been published on the taxonomy and distribution of the coprophilous Ascomycetes and Basidiomycetes. No known quantitative work has been done, however, on the succession and structure of the communities formed by these higher fungi. This research was undertaken to study those two phases of the ascomycete and basidiomycete communities which grow and fruit on cow dung collected from Santaquin Canyon, Utah.

A Study Of Albinism, And Some Mating Reactions In Psilocybe Mutans, Henry L. Curtis

Theses and Dissertations

In recent taxonomic works albinism is not generally recognized as being present in the Agaricales. This study was made to find how albinism was inherited in Psilocybe mutans McKnight. Cultures of P. mutans were incubated in a constant temperature room at 20-22°C. With artificial lighting at 150 foot candles for 16 hours per day and on a laboratory bench at a comparable temperature with diffuse natural light of a lesser intensity. Numerous fruit-bodies were obtained from cultures which grew on substrates containing hot water extracts of rabbit fecal pellets and from cultures grown on substates containing no fecal extracts. In …

A Study Of The Effects Of Different Substrates On Growth And Reproduction In Certain Coprophilic Agaricaceae, Raymond C. Brown

Theses and Dissertations

Psilocybe mutans sp. nov. had ceased fruiting consistently in artificial culture several years prior to the initiation of this study. In the couse of this study fruiting bodies were produced on a number of different substrates. All cultures were inoculated by mycelial transfer or by spraying with a suspension of pre-germinated spores. All cultrues were incubated for one to two weeks in a constant-temperature room at 70°F. on a shelf fourteen inches below a fluorescent lighting fixture. Lighting was continuous with an intensity at shelf level of approximately 3,000 foot-candles. Fruiting on any particular substrate was improved if the substrate …

A Study Of Physoderma On Three Species Of Portulacaceae, David L. Mumford

Theses and Dissertations

Three species of the Portulacaceae each infected by a Physoderma parasite were collected at several locations in Utah. The hosts have been identified as Claytonia lanceolata Pursh., Oreobroma pygmaeum (A. Gray) Howell, and Erocallis triphylla (S. Wats.) Rydb. Since our present knowledge of Physoderma on members of the Portulacaceae is meager, it seemed desirable to learn as much as possible about the parasite, its hosts, and the relationship between parasite and host. Plants of all three hosts activated from perennating organs were grown for extended periods of time under uniform conditions. Cold treatments were most successful in activating host perennating …