Life Sciences Commons^™

Impacts Of Long-Term Precipitation Manipulation On Hydraulic Architecture, Xylem Function, And Canopy Status In A Piñon-Juniper Woodland, Patrick J. Hudson

Biology ETDs

The Southwestern US is predicted to become hotter and drier, as global climate change forces increasing temperatures and variability in timing and size of precipitation inputs. Drought stress has become more frequent in recent decades, and resulted in massive forest mortality in piñon-juniper woodlands. During recent severe droughts (2000-2003, 2009-2012), piñon pine (Pinus edulis Englem.) suffered disproportionately high mortality compared to co-occurring one-seed juniper (Juniperus monosperma [Engelm.] Sarg.). A large-scale precipitation manipulation experiment was established in a piñon-juniper woodland in central New Mexico to test hypotheses regarding tree survival and mortality with respect to altered water regimes. Our …

Salvinia Molesta: An Assessment Of The Effects And Methods Of Eradication, Arti Lal

Master's Projects and Capstones

Salvinia molesta is an invasive aquatic fern. It is now the second worse aquatic invader in the world. Since the 1930s, it has invaded most tropical and some temperate countries. S. molesta plants grow vegetatively and can increase in size rapidly. S. molesta can form thick mats of up to 1-meter-thick. There are a number of ways these thick mats negatively affect the environment: 1) reduce light to benthic organisms, 2) reduce oxygen in the water column for other organisms, 3) accumulate as organic matter at the bottom of the water column, 4) decrease nutrients for other organisms, and 5) …

Association Mapping Of Seed Weight, Protein, And Sucrose Content; And Kinetics Of Edamame Under Infrared Treatment, Laura Melissa Lara Santisteban

Graduate Theses and Dissertations

Edamame is a specialty large-seeded soybean (Glycine max L. Merr.) harvested at an immature stage (R6) that has become the second largest consumed soyfood. Although United States is the largest soybean producer, majority of edamame is imported from Asia, highlighting the importance of developing new edamame varieties. Association mapping (AM) provides an alternative to bi-parental linkage mapping method to detect quantitative trait loci (QTL) adding higher resolution and broader germplasm information. Seed weight, sucrose, and protein are quantitative traits of value when selecting edamame lines. However molecular mechanisms controlling each of these traits are still inconclusive and have not been …

Dissecting Salt Tolerance In Soybean By Profiling Differential Physiological Responses Under Salt Stress, Jade Amber Newsome

Graduate Theses and Dissertations

Saline soils are common worldwide and limit the yield potential of many crops. Plants respond in a variety of ways to the stress imposed by saline soils. Plants under salt stress must first sense their surroundings and transmit a signal alerting the rest of the plant to the saline conditions. Salt tolerance in soybeans is typically defined by exclusion of chloride ions from foliar tissues. Though differences in ion uptake among soybean genotypes is well documented, the key mechanisms employed by tolerant cultivars to cope with salt stress on the whole-plant level are still largely unknown. Objectives of the current …

The Biology And Management Of Palmer Amaranth (Amaranthus Palmeri S. Wats) In Indiana, Douglas J. Spaunhorst

Open Access Dissertations

Palmer amaranth is a pernicious summer annual weed that has evolved resistance to six herbicide sites of action in the U.S. and threatens agriculture production. In 2011, Palmer amaranth was identified in flood plains in two southern Indiana counties (Posey and Vanderburgh). Determining if Palmer amaranth can survive and reproduce in northern Indiana may provide insight if this weed will be problematic for northern row crop producers. The objectives of our research were to identify fields containing Palmer amaranth and determine the distribution of herbicide resistance traits in Indiana; determine the influence of tillage frequency and tillage intervals on Palmer …

Identification And Characterization Of Genes Involved In Metabolism Of N5 Monoene Precursors To N5 Anacardic Acids In The Trichomes Of Pelargonium X Hortorum., Richa A. Singhal

Electronic Theses and Dissertations

Unusual monoenoic fatty acids (UMFA’s) and specialized metabolites called anacardic acids (AnAc) are produced in glandular trichomes of Pelargonium ´ hortorum (geranium). The UMFA’s, 16:1^∆11 and 18:1^∆13 are precursors for the synthesis of unsaturated AnAc 22:1n5and 24:1n5 that contribute to pest resistance in geraniums. UMFAs and their derived AnAc metabolites not only provide a useful biological marker that differentiates the biosynthetic pathway for unusual mononenes from the common fatty acids (i.e. stearic, palmitic, oleic, linoleic and linolenic) but also have industrial, medical and agricultural applications. Fatty acid biosynthesis enzymes like acyl carrier proteins (ACPs); thioesterases (TEs) and β-ketoacyl-ACP …

Comparison Of Mesophyll Protoplast Isolation And Transformation Between Panicum Virgatum And Panicum Hallii, Andrea Grace Collins

Masters Theses

Protoplasts are appropriate targets for genome editing, DNA functional screens and transgenesis. This project focuses on the comparison of inexpensive mesophyll protoplast isolation via the use of food-grade enzymes and transformation between diploid Panicum hallii Vasey (PAH) and polyploid cellulosic feedstock Panicum virgatum L (switchgrass), a relative of PAH. PAH has great potential as a C4 model species for crop and bioenergy research. Here an inexpensive switchgrass and PAH mesophyll protoplast isolation and transformation system was developed; the first protoplast system for PAH. Using low-cost commercial food-grade enzymes, a cost reduction of ~1000-fold was achieved compared to traditional protoplast isolating …

Quantitative Trait Loci (Qtl) For Salt Tolerance In Soybean And Physiological Response To Salt Stress During Early Growth Stage, Cindy Massiel Lopez Ramirez

Graduate Theses and Dissertations

Soybean is a major cash crop used as a source of high–quality protein and oil. Salt stress is one of the main abiotic stresses causing significant yield losses in soybean, which is considered a moderately salt–sensitive crop. Breeding selection is a promising strategy to improve salt tolerance as soybean germplasm display wide variation in response to salinity stress. However, the physiological and genetic mechanisms for salt tolerance are not quite clear. The discovery of novel QTL/genes associated with salt tolerance facilitates the development of tolerant cultivars through marker-assisted selection (MAS). The objectives of this study were: 1) identify/confirm QTL associated …

Cover Crop Establishment And Potential Benefits To Arkansas Farmers, Ashley Elizabeth Humphreys

Graduate Theses and Dissertations

Soybean farmers in Arkansas need best management practices (BMPs) that maximize the benefits of using cover crops including planting date and fertilization recommendations. An evaluation of cover crop species, planting dates, seeding rates, fertilizer rates, and N accumulation aids in providing these BMPs. The first objective of this research is to assess the effect of planting date on biomass production, as well as looking at the interaction of seeding rate or fertilizer rate for legumes or non-legumes, respectively, using Austrian winter pea (Pisum sativum), cereal rye (Secale cereale), black oats (Avena strigosa), wheat (Triticum aestivum), and tillage radish (Raphanus sativus). …

Iron Signaling In Arabidopsis Thaliana, Celina Abundis

Masters Theses

Iron is among the essential micronutrients for all living organisms and is a cofactor for many cellular redox reactions. Although iron is a highly abundant metal element found in the earth’s crust, it is also a limiting factor in plant development when it is present as insoluble ferric oxides. Plants have evolved two strategies to acquire soluble iron referred to as Strategy I and Strategy II. Our lab has focused on the Arabidopsis thaliana double mutant ysl1ysl3. The mutants display a chlorotic phenotype and are unable to correctly respond to iron deficiency.

Grafting is a common method for joining …

The Archaeopalynology Of Crystal River Site (8ci1), Citrus County, Florida, Kendal Jackson

USF Tampa Graduate Theses and Dissertations

The Woodland-period (ca. 1000 B.C. to A.D. 1050) fisher-hunter-gatherers of the Crystal River drainage on Florida’s Big Bend Coast are well known among southeastern archaeologists for their elaborate shell mound architecture, maritime lifeway, and exotic exchange goods. Recent archaeological investigations at the Crystal River site have employed high-resolution topographic mapping, geophysical surveys, trench excavations, and coring to model the temporality of mound construction and occupation at the site; this work has set the stage for subsequent research focusing on community structure, resource extraction, and human-ecosystem dynamics. However, like many central and north peninsular Gulf Coast sites, our understanding of Crystal …

Identification And Characterization Of The Isoflavonoid-Specific Prenyltransferase Gene Family To Prevent Stem And Root Rot In Soybean, Arjun Sukumaran

Electronic Thesis and Dissertation Repository

Soybean is one of the most predominantly grown legumes worldwide, however, one deterrent to maximizing its yield is the pathogen, Phytophthora sojae, which causes stem and root rot disease. Many strategies have been implemented to combat this pathogen such as use of pesticides and certain agricultural practices. However, these have been largely ineffective in completely preventing P. sojae infection. An alternative strategy would be to improve the innate resistance of soybean by promoting increased glyceollin production. Glyceollins are soybean-specific antimicrobial agents which are derived from the isoflavonoid branch of the general phenylpropanoid pathway. Soybeans produce 3 forms of glyceollin: …

Evapotranspiration From Extensive Green Roofs: Influence Of Climatological Conditions, Vegetation Type, And Substrate Depth, Maria Eloisa Sia

Electronic Thesis and Dissertation Repository

Green roofs are gaining popularity worldwide as a low impact development tool to mitigate increasing stormwater runoff within dense urban areas. Evapotranspiration (ET) is the key hydrologic process governing the capacity of a green roof to retain rainfall as it regenerates available water storage space in the green roof substrate (soil) between rainfall events. To date, there are limited data on how the interaction between different climatological conditions and design parameters (e.g., vegetation type, substrate depth) affect ET rates. This currently limits the ability to optimize green roof design for stormwater management. In this field study, the impact of climatological …

An Investigation Of The Plant Growth Promoting Abilities Of Pseudomonas Fluorescens Uw4 Under Toxic Metal Stress, Joshua J. Frank

Electronic Thesis and Dissertation Repository

I investigated plant-microbe-metal interactions under metal stress. In theory, plant growth promoting rhizobacteria (PGPR) promote plant growth by reducing stress ethylene and synthesizing indole-3-acetic acid (IAA). The putative PGPR Pseudomonas fluorescens UW4 and a mutant strain that lacked an enzyme critical to the reduction of plant ethylene were studied to determine if they could promote Arabidopsis thaliana growth under cadmium and copper stress conditions. Both strains of P. fluorescens UW4 adhered to roots and synthesized IAA, and the wild-type lowered metal stress-induced ethylene in Arabidopsis, but neither strain enhanced plant growth. Wildtype P. fluorescens UW4 and its mutant had …

Propagation And Container Production Of The Amelanchier Spicata Complex, Gregory J. Melcher

Electronic Theses and Dissertations

Amelanchier is a genus in the Rosaceae containing shrubs and trees indigenous to North America that possess traits valued by the horticulture industry. Amelanchier spicata (dwarf serviceberry), a heterogeneous complex of hybrids indigenous to eastern North America, has agricultural and ornamental merit with notable characteristics. White blossoms emerge in early spring, edible pomes ripen in the summer, and vibrant, orange foliage occurs in the fall. I investigated phenological and physiological factors influencing adventitious rooting of stem cuttings, the effects of nitrogen source on the development of seedlings grown in container culture, and phenotypic variation among seedlings of A. spicata from …

Evaluation Of The Water Stress-Inducible Promoter Wsi18 In The Model Monocot Brachypodium Distachyon, Patrick D. Langille

Electronic Thesis and Dissertation Repository

Water deficit-inducible promoters that function in multiple species are valuable components for engineering stress-tolerant crops. Wsi18 is a water deficit-inducible promoter native to Oryza sativa. In this study, Brachypodium distachyon (B. distachyon) was used to determine if Wsi18 retained its water deficit-inducible characteristics in another monocot. Transgenic B. distachyon plants, in which the Wsi18 promoter drove the expression of the uidA reporter gene, were developed and exposed to osmotic stress generated by mannitol, salt stress conditions, and the water deficit-signaling phytohormone abscisic acid (ABA). GUS histochemical assays demonstrated increased uidA expression in the leaves and stem of …

Computational Analyses Of Mrna Ribosome Loading In Arabidopsis Thaliana, Joseph Benjamin Ernest

Doctoral Dissertations

Translation of mRNA into protein is a critical step in gene expression, but the principles guiding its regulation at the genome level are not completely understood. Translation can be quantified at a genome scale by measuring the ribosome loading of mRNA—the extent to which mRNA is associated with ribosomes. In this dissertation, I present investigations into how genome-wide ribosome loading is controlled in Arabidopsis thaliana. In chapter 1, I give an overview of regulation of ribosome loading and translation. In chapter 2, I present research demonstrating for the first time that genome-wide ribosome loading in plants is partially controlled by …

Modification Of Carbohydrate Active Enzymes In Switchgrass (Panicum Virgatum L.) To Improve Saccharification And Biomass Yields For Biofuels, Jonathan Duran Willis

Doctoral Dissertations

The natural recalcitrance of plant cell walls is a major commercial hurdle for plant biomass to be converted into a viable energy source as alternative to fossil fuels. To circumvent this hurdle manipulation of carbohydrate enzymes active in the cellulose and hemicellulose portions of the plant cell wall can be utilized to improve feedstocks. Production of cellulolytic enzymes by plants have been evaluated for reducing the cost associated with lignocellulosic biofuels. Plants have successfully served as bioreactors producing bacterial and fungal glycosyl hydrolases, which have altered plant growth to improve saccharification. A bioprospecting opportunity lies with the utilization of insect …

Decoding The Cellular Zipcode: Functional Analysis Of Transit Peptide Motifs And Mechanistic Implications In Plastid Targeting And Import, Kristen N. Holbrook

Doctoral Dissertations

Eukaryotic organisms are defined by their compartmentalization and various organelles. The membranes that define these organelles require complex nanomachines (known as translocons) to selectively mediate the import of proteins from the cytosol where they are synthesized into the organelle. The plastid, (specifically the chloroplast) which is characteristic of plant cells, possibly represents the most complex system of protein sorting, requiring many different translocons located in the three membranes found in this organelle. Despite having a small genome, the vast majority of plastid-localized proteins are nuclear-encoded and must be post-translationally imported from the cytosol. These proteins are encoded as a larger …

Do Novel Weapons That Degrade Mycorrhizal Mutualisms Explain Invasive Species Success?, Philip L. Pinzone Mr.

Biology Theses

Invasive plants often dominate novel habitats where they did not co-evolve with local species. Several hypotheses suggest mechanisms that explain increased exotic plant success, including 'novel weapons' and 'degraded mutualisms'. Japanese knotweed (Fallopia japonica) and European buckthorn (Rhamnus cathartica) are widespread plant invaders in North America that can dominate ecosystems. The goal of this study is to test whether these impacts are more consistent with novel weapons or degraded mutualism hypotheses. I examine tree seedling recruitment, (germination and initial survival) growth, (biomass) and mycorrhizal invasion (AMF content) as a function of F. japonica and R. cathartica …

The Biology And Management Of Waterhemp In Indiana, Joseph M. Heneghan

Open Access Theses

Waterhemp is a dioecious weed species indigenous to the Midwestern United states yet it has only recently become problematic in agronomic crop production in Indiana. Waterhemp is a small-seeded broadleaf which has increased in prevalence in conjunction with an increase in conservation tillage practices. Waterhemp germinates and emerges from the top 3 cm of soil and is known to exhibit extended periods of continual emergence, longer than most other summer annual weed species that are typically present in agronomic production settings. As a C4 species, waterhemp then grows rapidly and is capable of producing thousands of seeds, while effectively competing …

Testing The Temporal Stability Of The Climate Response Of Tree Species At Norris Dam State Park, Tennessee, U.S.A., Allison Elizabeth Ingram

Masters Theses

Temporal stability of the climate-tree growth relationship means that over time, tree species were responding to a specific climate variable and continue to respond to that variable into the present. The stability of this response is important to test prior to attempting to reconstruct past climate. In this study, I sampled oaks (white oak = Quercus alba L. and chestnut oak = Quercus montana Willd.) and pines (Virginia pine = Pinus virginiana Mill. and shortleaf pine = Pinus echinata Mill.) growing in Norris Dam State Park in eastern Tennessee and tested the temporal stability of these species and their potential …

Characterization Of Echinochloa Spp. In Arkansas, Hussain Tahir

Graduate Theses and Dissertations

Echinochloa species are the most problematic grass weeds in rice and soybean production throughout the southern United States. The species under this genus has high intra- and interspecific variability, with many ecotypes, observed within a species. This study was conducted to: i) characterize the morphology and phenology of Echinochloa accessions from Arkansas in a common garden; ii) verify the species identity of these accessions based on their morphological traits, and iii) evaluate the dormancy characteristics of Echinochloa accessions. Junglerice (E. colona) was identified as the most common species, comprising about 78% of the accessions collected, with barnyardgrass (E. crus-galli) and …

High Throughput Phenotypic Evaluation Of Drought-Related Traits In Soybean, Hua Bai

Graduate Theses and Dissertations

Drought limits crop growth and yield in soybean. Rapid and effective methods of screening large numbers of soybean lines for drought tolerance are urgently needed. Two experiments were conducted to evaluate the effects of drought in soybean during reproductive stages. In the first experiment five genotypes from maturity groups 2 through 5 were tested under well-irrigated and drought conditions. Beginning at R5, leaf samples were taken for nitrogen concentration analysis. Pictures were taken across the top of each plot to determine the intensity of greenness using the Dark Green Color Index (DGCI). Aerial photographs were also taken to determine aerial …

Genetic Basis Of Biosynthesis And Cytotoxic Activity Of Medicago Truncatula Triterpene Saponins, Brynn Kathleen Lawrence

Graduate Theses and Dissertations

Saponins are a large family of specialized metabolites produced in many plants. They can have negative effects on a number of plant pests and are thought to play a role in plant defense. With current and possible future uses in industry and agriculture, saponins have also been shown to be hypocholesterolemic, hypoglycemic, immunostimulatory, antioxidative, anti-inflammatory, and cytotoxic. In spite of their usefulness, our understanding of the genetic basis for saponin biosynthesis is still incomplete. We generated recombinant populations with parents from genetically distinct accessions of Medicago truncatula, with either high or low accumulation and varying profiles of saponins. Primers for …

Characterization Of Sip470, A Family 1 Lipid Transfer Protein And Its Role In Plant Stress Signaling, Timothy Ndagi Audam

Electronic Theses and Dissertations

SIP470, a putative tobacco lipid transfer protein, was identified in a yeast two-hybrid screen to interact with SABP2. SABP2 is a critical role in SA-mediated signaling in tobacco and other plants. In vitro studies using purified recombinant SIP470 confirmed that it is a lipid binding protein. In an attempt to determine its role in mediating stress responses, Arabidopsis T-DNA insertion knockout lines lacking SIP470 homolog were used for the analysis. These mutant plants were defective in basal resistance against microbial pathogens. Expression of defense gene PR-1 was also delayed in these mutant plants. Interestingly, these mutant plants were not defective …

Chemically Mediated Interactions Between Hosts, Parasitic Plants And Insect Herbivores, Muvari C. Tjiurutue

Doctoral Dissertations

Species interactions, by changing phenotypic traits, can alter the outcome of subsequent interactions. Plant-mediated responses to herbivores have been extensively studied, but little is known about plant-mediated responses involving parasitic plants within a broader community context that also includes herbivores. Because parasitic plants are important components of many ecosystems and can shape community structure, it is important to understand how host-mediated interactions influence parasite preference and success. The goal of this thesis is to examine interactions between hosts, parasitic plants and herbivores mediated by chemical traits. We first examined the effects of dodder (Cuscuta sp.) parasitism on induced defenses …

Organics: Exploring The Parallels Between Botany And Human Anatomy Through Sculpture And Watercolor Painting, Allison Borek

Honors Theses

Integrating my two passions of the visual arts and science for my senior thesis, I created a collection of paintings that represent human organs and the parallels between plant biology and animal biology. Genetically, plants are just as complex – if not more – than many animals. They have intricate sensory and regulatory systems highly comparable to humans, and on a cellular level, we share many analogous features. In addition, every single carbon atom that makes up the human body was at one time fixed in a plant during photosynthesis. We also rely on photosynthesis to give us the oxygen …

Role Of Fatty Acid Omega-Hydroxylase 1 And Abscisic Acid In Potato Tuber Suberin Formation, Meg Haggitt

Electronic Thesis and Dissertation Repository

Suberin is a complex biopolymer composed of two distinct but covalently-linked domains. The first domain is composed of polymerized phenolic monomers, whereas the second domain is predominately fatty acid derivatives esterified with glycerol. Deposited in specialized cells during development or in response to abiotic stress, suberin functions as a barrier to water loss and pathogen attack. In potato, more than 65% of suberin monomers undergo ω-hydroxylation, representing a major class of fatty acids in the final biopolymer. The ω-hydroxylation reaction is catalyzed by Cytochrome P450 (CYP) proteins, of which few have been characterized to date. In 2009, CYP86A33 from potato …

Searching For Potential Binding Partners Of Arabidopsis Β-Amylase2 Using Yeast 2-Hybridization, Megan E. Hines

Senior Honors Projects, 2010-2019

BAM2 is a chloroplast-targeted member of the β-amylase gene family that currently has an unknown function in starch hydrolysis. Previous research indicated that BAM2 did not have significant catalytic activity, but, because the gene is highly conserved and there is a starch-excess phenotype in older plants lacking BAM2, it was hypothesized that BAM2 may instead have a regulatory function. Many regulatory proteins function by interacting with other proteins, so we wanted to test for potential protein binding partners for BAM2 using the yeast two-hybrid system. A plasmid containing the BAM2 gene from Arabidopsis thaliana was co-transformed into Y190-strain yeast ( …