Life Sciences Commons^™

Investigating The Regulation Of Indole-3-Acetic Acid Production By The Plant Associated Microbe Pantoea Sp. Yr343, Kasey Noel Estenson

Doctoral Dissertations

The auxin indole-3-acetic acid (IAA) plays a central role in plant growth and development and many plant-associated microbes produce IAA. Several IAA biosynthetic pathways have been identified in microbes which use the precursor tryptophan. Pantoea sp. YR343, which was isolated from the Populus deltoides rhizosphere, is a robust plant root colonizer that produces IAA. Using genomic and metabolomics analyses, we predicted that the indole-3-pyruvate (IPA) pathway is the major pathway in Pantoea sp. YR343 for IAA production. To better understand IAA biosynthesis and the effects of IAA exposure on cell physiology, we performed proteomics on Pantoea sp. YR343 grown in …

Non-Canonical Signaling From The Etr1 And Etr2 Ethylene Receptors In Arabidopsis Thaliana, Arkadipta Bakshi

Doctoral Dissertations

The gaseous phytohormone ethylene regulates several physiological and developmental processes in higher plants. There are five ethylene receptor isoforms that mediate the responses to ethylene in the model plant Arabidopsis thaliana. Prior research has shown that these five ethylene receptor isoforms in Arabidopsis have both overlapping and non-overlapping roles in regulating diverse responses such as growth in air, growth recovery after removal of ethylene, and ethylene stimulated nutational bending. Functional divergence of ETR1 has been determined in controlling some of these traits and in some of these cases, ETR1 subfunctionalization requires the receiver domain. Using homology modeling and sequence …

Systematics And Biogeography Of The Cortinarius Violaceus Group And Sequestrate Evolution In Cortinarius (Agaricales), Emma Harrower

Doctoral Dissertations

Phylogenetics is a powerful tool used for illuminating the diversity of life on Earth, their evolution and their ecology. I created a multi-gene phylogenetic tree of Cortinarius section Cortinarius and uncovered five previously overlooked species, increasing the number of species in the section from seven to twelve. All members of the clade possess both cheilocystidia and pleurocystidia and possess a pigment known as (R)-39,49-dihydroxybphenylalanine. Ancestral state reconstruction estimated that the ancestral host was most likely an angiosperm, switching hosts when encountering novel host species in new lands, and only C. violaceus associating with the Pinaceae in North America. Biogeographic analysis …

Reproduction And Bioconfinement Of Mir156 Transgenic Switchgrass (Panicum Virgatum L.), Chelsea Renai Johnson

Masters Theses

Genetic engineering of switchgrass (Panicum virgatum L.), an emerging cellulosic bioenergy feedstock, has been performed to alter cell walls for improved biofuel conversion. However, gene flow from transgenic switchgrass presents regulatory issues that may prevent commercialization of the genetically engineered crop in the eastern United States. Depending on its expression level, microRNA156 (miR156) can reduce, delay or eliminate flowering, which may be useful to mitigate transgene flow. However, flowering transition is dependent upon both environmental and genetic cues. In this study of transgenic switchgrass, two low (T14 and T35) and two medium (T27 and T37) miR156 overexpressing ‘Alamo’ lines …

Genetic Analysis Of Field Populations Of The Plant Pathogens Cercospora Sojina, Corynespora Cassiicola And Phytophthora Colocasiae, Sandesh Kumar Shrestha

Doctoral Dissertations

Genetic markers and whole genome sequencing (WGS) were used to study the disease dynamics and population structure for three important plant pathogens; Cercospora sojina (frogeye leaf spot of soybean), Corynespora cassiicola (target spot of soybean, cotton and many other crops) and Phytophthora colocasiae (taro leaf blight). For each pathogen, genome sequencing was used to guide the development of single nucleotide polymorphism (SNP) markers and both were used to investigate diversity in field populations. Investigation of C. sojina in Tennessee included comparisons of extant populations and historical isolates, revealing a dominant, potentially long-lived, clonal lineage. Characterization of QoI fungicide resistance indicates …

Response Of Glyphosate Resistant Palmer Amaranth (Amaranthus Palmeri) To Protoporphyrinogen Oxidase Inhibiting Herbicides In Tennessee, Alinna Marie Umphres

Doctoral Dissertations

In many agronomic cropping systems across the United States, Palmer amaranth (Amaranthus palmeri) is the most economic and troublesome weed for producers. The introduction of glyphosate resistant (GR) crops gave producers the benefit of controlling Palmer amaranth as well as other weeds, a broad window of application, and reduced tillage practices. With the confirmation of GR Palmer amaranth, producers implemented protoporphyrinogen oxidase (PPO or Protox)-inhibiting herbicides to control these populations in crops such as soybean [Glycine max (L.) Merr.] and cotton [Gossypium hirsutum (L.)]. However the continuous use of PPO herbicides has caused a shift in …

The Impact Of Genetic And Environmental Factors On Phytonutrient Concentrations Within Leafy Specialty Crops In Controlled Environments, Rosalie M. Metallo

Masters Theses

Specialty leafy greens are excellent sources of antioxidants, vitamins, and minerals. Many of these metabolites are influenced by microclimate environmental conditions and genotype. The objective of this thesis was to measure the impacts of abiotic factors on plant growth and development along with nutritional content of specialty leafy greens in controlled environments. Chapter one looks at changes in biomass and nutritional content of different microgreen cultivars grown in a greenhouse over four growing seasons. Chapter two looks at the influence of light-emitting diode (LED) treatments on the growth and nutritional content of hydroponically grown kale. The morphology and nutritional content …

Volume 13, Number 1 (Spring/Summer 2017), Ut Institute Of Agriculture

Tennessee Land, Life and Science Magazine

Issue Highlights:

• The four pillars of the Institute of Agriculture
• Alumna forges partnership amid Waldo Canyon fire
• Fishery biologists revive a river

Effects Of Mycorrhizal Fungi On Vigna Radiata Growth In Soil Differing In Fertilizer Concentration, Ming Sum Jessica Cheng

Pursuit - The Journal of Undergraduate Research at The University of Tennessee

Mycorrhizal fungi form mutualistic relationships with the roots of some plants, allowing the plant access to nutrients and minerals while the fungi obtain food from the plant. Given that this relationship is beneficial to the plant, this paper investigates the nature of the impact of presence of mycorrhizal fungi on the growth of Vigna radiata (mung beans) in soil of differing chemical environments. Through comparing the stem lengths of plants seven days after germination, it is found that in soil with 0.0% fertilizer, the presence of locally collected, unclassified mycorrhizal fungi impacts the growth of Vigna radiata negatively; in intermediate …

Myosin Xi-I Works In Tandem With A Microtubule-Associated Mechanism To Position The Nucleus In Arabidopsis Root Hairs, Ian Andrew Windham

Chancellor’s Honors Program Projects

No abstract provided.

Pathogenesis, Virulence And Population Genetics Of Puccinia Emaculata, The Causal Agent Of Switchgrass Rust, Qunkang Cheng

Doctoral Dissertations

The infection process of Puccinia emaculata on Panicum virgatum leaves was studied histologically. Appressoria were formed approximately 10 hr after inoculation and penetrations were observed over stomatal openings. Substomatal vesicles developed 3 days after inoculation (DAI) and at 5 DAI, both haustorial mother cells and haustoria were observed. At 11 DAI, uredinia were developing, but urediniospores were immature. Until 14 DAI, matured uredinia ruptured host epidermis and urediniospores were released for secondary infection. This clearly studied infection process will help understand resistance mechanisms of a resistant cultivar in future research.

Twelve agronomic and ornamental switchgrass cultivars were inoculated with 40 …

Scope And Influence Of Enhanced Triazine Degradation In U.S. Soils, Ethan Trent Parker

Doctoral Dissertations

The triazines are one of the most widely used herbicide classes ever developed, and play a role in managing herbicide-resistant weed populations in sustainable agricultural production systems. The triazines are traditionally valued for their persistence and season-long weed control in over 50 crops including corn, soybeans, wheat, and vegetables. The literature suggests that atrazine, the most widely used triazine, may no longer remain persistent in soils due to enhanced microbial degradation. Experiments examined the rate of degradation of atrazine and two other triazine herbicides: simazine and metribuzin in both atrazine adapted and non-adapted soils from across the United States. Additional …

Evaluation Of Off-Type Grasses In Interspecific Hybrid Bermudagrass [Cynodon Dactylon (L.) Pers. X C. Transvaalensis Burtt-Davy] Putting Greens, Eric Hall Reasor

Doctoral Dissertations

The economic impact of the golf industry in the United States (U.S.) in 2011 was estimated to be $176.8 billion. Interspecific hybrid bermudagrasses [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy] are some of the most widely utilized grasses on golf courses throughout tropical, subtropical, and temperate climates. In 2007, bermudagrass was grown on 80% of putting green acreage in the southern U.S. ‘Tifgreen’ and ‘Tifdwarf’ were two of the first widely established cultivars on putting greens, but their genetic instability led to the occurrence of phenotypically different off-type (OT) grasses. Several OT grasses were selected and released as …

Evaluation Of Hall’S Panicgrass (Panicum Hallii Vasey) As A Model System For Genetic Modification Of Recalcitrance In Switchgrass (Panicum Virgatum (L.)), Joshua Nathaniel Grant

Masters Theses

While switchgrass (Panicum virgatum (L.)) has long been recognized as a viable bioenergy feedstock, it and other plants have cell walls with recalcitrance to processing. Recalcitrance is recognized as a major barrier to broad adoption of switchgrass and other feedstocks for cellulosic bioenergy. In an effort to reduce recalcitrance, transgenic plants have been generated with altered cell wall phenotypes such as reduced lignin. Unfortunately, stable transformation of switchgrass and other C4 grasses is time intensive, costly, and genetic analysis is further complicated by polyploid genomic structures. Unlike switchgrass, which can be tetraploid to octoploid, a closely related species, Hall’s …

Protein, Methionine, And Cysteine Upregulation In Phaseolus Vulgaris ‘Black Turtle Bean’ Seeds Through Sulfur Fertilization At V2 And R2 Stages Of Growth, Hannah Paige Barry

Masters Theses

The purpose of this research was to increase protein, methionine, and cysteine content in Phaseolus vulgaris L., common bean in relation to the inhibitory compound tannin. Previous research has shown that sulfur fertilization increases total protein, methionine and cysteine content in various crops, but always in tandem with inhibitory compound increases. If successful, the resulting bean seed will have a better nutrient profile for malnourished populations around the world.

Granular gypsum was applied at 0 kg S ha^-1 [kilograms of sulfur per hectare], 10 kg S ha^-1, 20 kg S ha^-1, 40 kg S ha …

Effect Of The Mutant Danbaekkong Or Stem Termination Alleles On Soybean Seed Protein Concentration, Amino Acid Composition, And Other Seed Quality And Agronomic Traits, Mia Justina Cunicelli

Masters Theses

Soybean [Glycine max (L.) Merr.] is the world’s leading source of vegetable oil and high quality protein meal. Increasing soybean protein concentration through selection while maintaining oil concentration and yield has been a constant goal for plant breeders, as there is a negative correlation between protein and oil and protein and yield. The objective of this study was to determine if marker assisted selection (MAS) for the Danbaekkong (Dan) protein allele influences agronomic and seed quality traits. A population of 24 F_8:10 [eighth filial generation advanced to the tenth filial generation] near isogenic lines (NILs) of soybean was …

Volume 13, Number 2 (Fall/Winter 2017), Ut Institute Of Agriculture

Tennessee Land, Life and Science Magazine

Issue Highlights:

• The four pillars of the Institute of Agriculture
• Alumna forges partnership amid Waldo Canyon fire
• Fishery biologists revive a river