Life Sciences Commons^™

A Comparative Study Of Medicago Truncatula Transcriptomes As They Relate To Saponin Defenses Against Insect Pests, Audra Mae Rogers

Graduate Theses and Dissertations

Triterpene saponins are a class of defensive plant-derived compounds, which have a

variety of functions including antimicrobial, insecticidal, and nematicidal activities. This

research assessed the performance of the beet armyworm, Spodoptera exigua, following ad

libero feeding on Medicago truncatula accessions differing in specialized metabolite and

saponin profiles. Insect performance did not directly relate to the foliar saponin levels in the

accessions, which was measured using HPLC mass spectrometry. Accession ESP105 had the lowest foliar saponins overall, yet had similar levels of soyasaponins compared to the other accessions. Conversely, accessions A17, PRT178, and GRC43 had high foliar saponins with particularly high …

The Effects Of Meloidogyne Incognita And Heterodera Glycines On The Yield And Quality Of Edamame In Arkansas, Juliet Fultz

Graduate Theses and Dissertations

Edamame (Glycine max), also known as vegetable soybean, was introduced to the United States from Japan in 1890 and has been growing in popularity as a nutrient-rich, low-sugar snack in recent years. In 2012, the American Vegetable Soybean and Edamame, Inc. established the first domestic commercial processing plant in Mulberry, Arkansas and contracted local growers for production. Since the crop is harvested when seed are immature, management practices are different from those for traditional soybean. Plant-parasitic nematodes, particularly Meloidogyne incognita (southern root-knot) and Heterodera glycines (soybean cyst), are common in Arkansas and are pests of concern for edamame growers. Edamame …

Rice Blast Disease In The U.S. And Africa: Determination Of Pathogen Diversity And The Identification Of Resistance Genes For Disease Management, Felix Rotich

Graduate Theses and Dissertations

Rice blast caused by Magnaporthe oryzae (= Pyricularia oryzae) B. Couch, is a leading disease of rice. Magnaporthe oryzae exhibits a high degree of diversity. The diversity of isolates of M. oryzae from Africa and the U.S. were examined using vegetative compatibility and virulence phenotyping as well as determination of variation in the avirulence gene AVRPiz-t in isolates from Africa. Also, evaluation of blast resistance genes in the interspecific rice germplasm “New Rice for Africa” NERICA was done using F2 progeny of the cross of U.S. susceptible cultivar M204 and NERICA 12. The U.S. isolates were in three vegetative compatibility …

Investigation Of The Inherent Chemical, Structural, And Mechanical Attributes Of Bio-Engineered Composites Found In Nature: Alligator Gar’S Exoskeleton Fish Scales, Wayne Derald Hodo

Graduate Theses and Dissertations

The U.S. Army has determined a huge cost savings of up to 51% can be accomplished by reducing the gross vehicle weight, for their personnel carrier, by 33%. To cut cost, composite materials are needed. Man-made composites can have superior material properties (high-strength, high-fracture toughness, and lightweight), but they are prone to delamination at the glued-layered interface. In contrast, fish scale is a natural composite that has the same material properties and, additionally, tend not to delaminate.

The focus of this study was to learn how nature integrates hard and soft materials at each length scale to form a layered …

The Role Of G-Protein Signaling In Pathogenesis In Cercospora Zeae-Maydis, Brant Smith

Graduate Theses and Dissertations

Gray leaf spot, caused by Cercospora zeae-maydis, is one of the most destructive foliar diseases of maize worldwide. C. zeae-maydis orients hyphal growth towards stomata (stomatal tropism) and forms infectious structures (appressoria) that are necessary for successful infection. Although some genes involved in pathogenesis in C. zeae-maydis have been identified, the molecular mechanisms are not well understood. In fungi, heterotrimeric G-proteins consist of three subunits (α, β, and γ) and mediate responses to environmental stimuli. They regulate diverse functions, including nutrient detection, virulence, fungal development, conidiation, secondary metabolism, and pathogenesis in many plant pathogenic fungi. This research explored the role …

Storage Of Round And Square Switchgrass Bales: Effect Of Storage Time And Fungal Inoculation On Saccharification Efficiency, Noaa Frederick

Graduate Theses and Dissertations

To produce fermentable sugars from lignocellulosic biomass feedstock, severe pretreatment conditions are needed (either high acid concentration, temperature, or retention times). High severities can produce toxic byproducts which inhibit enzymatic hydrolysis or fermentation. In order to reduce pretreatment severities (and thus increase enzyme and fermentation efficiency), the white-rot fungus Pleurotus ostreastus was seeded into square and round bales of Kanlow switchgrass (Panicum virgastum L.) and left in the field over a period of 9 month. The laccase producing fungus is believed to selectively degrade lignin, a common plant structural polymer, which can function as an enzymatic inhibitor. Samples were taken …

Economic Feasibility Of Aquaponics In Arkansas, Leah Ashley English

Graduate Theses and Dissertations

Concerns regarding population growth and resource scarcity have led to a recent renaissance of food production research. Over the past few decades, scientists have discovered new and innovative methods for growing food that, cumulatively, may hold the key to efficiently and sustainably feeding an ever-increasing world population. One method, known as aquaponics, has shown promise as being a sustainable solution for producing food locally in all parts of the world. Although many studies have shown aquaponic food production to be technically feasible, there are relatively few studies concerning the economic feasibility of aquaponics in various regions. To determine whether aquaponics …

A Regional Approach To Analysis Of Food Security Framework And Policies Of The Economic Community Of West African States (Ecowas), Hannah Elizabeth Shear

Graduate Theses and Dissertations

Food security is always a concern for consumers, but especially for those in West Africa, where the population of food insecure people has continued to grow over the past decade despite attempts by initiatives such as the World Food Program and the establishment of Millennium Development Goals. The people of West Africa are subject to repetitive natural disasters and are often in political upheaval. Many economic policies have been established to mitigate the impact that production disasters have on the consumers; one of these policies is the utilization of regional food reserves.

In 2010, the Economic Community of West African …

Evaluating The Impacts Of Respondent Errors In Arms: A Case Of Farm Service Agency Loans, Louise Nicole Mcminn

Graduate Theses and Dissertations

Many studies have used the U.S. Department of Agriculture’s (USDA) Agricultural Resource Management Survey (ARMS) to research various aspects involving the agricultural sector in the United States. Since nonresponse and inaccurate reporting may cause significant bias in statistical analysis, research was conducted to determine the magnitude of response error on the farm debt section of the ARMS Phase III. A multinomial logit model identified demographic, structural, and financial characteristics of FSA Farm Loan Program (FLP) borrowers who refused to indicate if they had end of year farm debt, or who accurately or inaccurately classified their farm operations as having end …

Portion Size Communication By Means Of Package Design, Tami J. Strickland

Graduate Theses and Dissertations

This qualitative study assessed consumers’ current methods of determining portion sizing of chicken products and examined their perceptions of how effectively three package designs communicate portion size. Everett M. Rogers’ Diffusion of Innovations (DI) Theory analyzes the characteristics of the consumer of the innovation (adopter) and the impact these characteristics have on adopting new innovations. The innovation in this study will be the prototype packaging. Focusing on Rogers’ adopter characteristics and defined proprietary consumer segmentation characteristics, this study will be pivotal for future package design projects targeting nutrition education.

Focus group questions were scrutinized through a pilot study and revised …

Perceptions Of Agricultural Leadership Academic Programs At 1862 Land-Grant Universities, Jackson Cole Alexander

Graduate Theses and Dissertations

This study sought to characterize perceptions of agricultural leadership programs in colleges of agriculture, food, life, human, or environmental sciences at 1862 land-grant institutions. Twenty-six academic programs were identified with a major, minor, graduate degree, specialization, concentration, or certificate in agricultural leadership. Programs were identified through analyzing the APLU and USDA NIFA websites, searching academic college websites, and contacting deans and departments heads. Objectives included identifying programs, describing the need for programs, describing evolution that has taken place within the discipline, describing faculty recommendations for future development and growth in the field, and examining why faculty believe programs are relevant. …

Eicosapentaenoic Acid (Epa) From Porphyridium Cruentum: Increasing Growth And Productivity Of The Microalgae For Pharmaceutical Products, Maryam Asgharpour

Graduate Theses and Dissertations

One of the major nutritional requirements in our diet is an adequate intake of omega-3 specially eicosapentaenoic acid (EPA). In the present study, the effects of two temperatures (16°C & 20˚C) and light intensities (140 & 180µE/M2.S) and four nitrate levels (0.075, 0.3, 0.5 and 0.7g/L) on the cell growth and lipid productivity of Porphyridium cruentum, one of the most promising oil-rich species of microalgae, were investigated. A growth comparison was carried out using pure CO2 and 5% CO2/air. Additionally, the ratio of the fatty acids with omega-3 and omega-6 groups at various growth conditions were compared, since an appropriate …

Soybean Planting And Risk-Return Tradeoffs In The Mid-Southern United States, Weston Weeks

Graduate Theses and Dissertations

This thesis is comprised of two studies on the effects of soybean (Glycine max (L.) Merr.) planting date (PD) and maturity group (MG) selection on producer expected returns. Having to replant soybean after early-season planting because of poor stand establishment is costly for producers. Replanting costs have increased in the last ten years as seed and other input costs for soybean have increased. Using five years of field trial results from two locations in Arkansas, the yield response to early and late season plant population density has been estimated to determine yield and future revenue potential for the purpose of …

Composition Of Four Selected Arkansas-Grown Non-Gmo Soybean Cultivars And The Development Of High Protein Beverage Using A Selected Soybean Protein Hydrolysate, Quyen Tran Phuong Nguyen

Graduate Theses and Dissertations

Protein beverages made with non-genetically modified (non-GM) ingredients have been in demand due to the increasing consumers’ interest in healthy eating habit. Beverages formulated with non-GM soy protein are rare in the United States market since 93% soybeans planted in U.S (2013) are labeled as GM. This study aimed to develop protein hydrolysate beverages using one cultivar among the four Arkansas grown non-GM soybean cultivars including Osage, R95-1705, R08-4004 and R05-4969. R08-4004 was selected since it had the highest amounts of the three branched amino acids including Phenylalanine (51.4 mg/g), Leucine (74.9 mg/g), and Isoleucine (49.7 mg/g) with lowest amount …

Response Of Bacterial Cells To Fluctuating Environment, Sudip Nepal

Graduate Theses and Dissertations

We have studied morphological and genomic variations occurring in a mesophilic bacterium Escherichia coli (E. coli) in a wide range of continuous and fluctuating hydrostatic pressures. For all the studies here the temperature is maintained at 37◦C, the optimal growth tem- perature of E. coli at atmospheric pressure. Cell division is inhibited at high hydrostatic pressures resulting in an increase of cell length. The increase of cell-length depends on the extent and duration of the stress applied on bacterial cells. We have studied the effect of high pressure stress in three different conditions – (i) Wild-type cells (almost no genetic …

Optimizing A Luciferase-Based Tool For Studying The Effects Of Fatty Acid Desaturase 7 On Singlet Oxygen Accumulation In Arabidopsis Thaliana, Abeer Muhammedali Alnasrawi

Graduate Theses and Dissertations

In plants, reactive oxygen species (ROS) are generated as a byproduct of normal metabolism, as well as in response to adverse conditions such as light stress, extreme temperatures, and exposure to pests and pathogens. Singlet oxygen (1O2) is a ROS that is formed during photosynthesis in photosystem II (PSII) of the chloroplasts. Levels of 1O2 and other ROS are tightly controlled in healthy plants, but some studies suggest that levels of fatty acid desaturase (FAD) activity in Arabidopsis thaliana can influence constitutive and/or stress-responsive ROS accumulation. In this study, a luciferase-based reporter gene that is selectively stimulated by 1O2 (AAA-ATPase: …

Impacts Of Feedstock And Parboiling Conditions On Quality Characteristics Of Parboiled Rice, Kanokporn Leethanapanich

Graduate Theses and Dissertations

Parboiling involves soaking, steaming, and drying, and is known to improve head rice yield (HRY), remove chalkiness, and retain nutrients. Because of an increasing number of rice cultivars developed, commingling of rice may happen during harvesting, distributing, or storage. Using commingled rice with a wide range of gelatinization temperatures (To) as a feedstock may cause inconsistent parboiled rice products. Therefore, this study was aimed at investigating the effect of soaking temperature and steaming duration on the quality of parboiled, commingled rice. Rough rice samples of individual or commingled rice cultivars with different To ranges were soaked at different temperatures (25, …

Southeastern Monochamus And Their Interactions With Healthy Shortleaf Pine Trees And Associated Ips Grandicollis Bark Beetles, Matthew Walker Ethington

Graduate Theses and Dissertations

Insects in the genus Monochamus are medium to large-sized, wood-boring beetles whose primary hosts in the Northern Hemisphere are pine trees. These beetles interact with both conifer hosts and associated insects throughout their life history. Past research has demonstrated that Monochamus are saprophagic, but recent findings show that they may colonize healthy pine trees. To determine if southeastern Monochamus could colonize healthy pines, adult Monochamus were attracted to healthy shortleaf pine trees from May to September, 2014, using host volatiles, Ips bark beetle kairomones, and congeneric pheromones. Subsequent development of oviposited eggs from 18 host trees was monitored. The results …

An Inventory Of Endemic Leaf Litter Arthropods Of Arkansas With Emphasis On Certain Insect Groups And Diplopoda, Derek Alan Hennen

Graduate Theses and Dissertations

Endemic arthropods of Arkansas were sampled and their nomenclature and distributions were updated. The Arkansas endemic species list is updated to 121 species, including 16 species of millipedes. A study of the millipedes of Arkansas was undertaken, and resulted in the first checklist and key to all millipede species in the state. 68 species are known from Arkansas, including the genera Cylindroiulus and Polydesmus. The first state records for Ophyiulus pilosus, Cylindroiulus sp., and Ptyoiulus coveanus are reported, and new county records are reported for 16 species. This represents the first key to a state's species since 1980, and the …

Stink Bugs: Spatial Distribution, Pecan Phenological Susceptibility And Sampling Program, Brian Cowell

Graduate Theses and Dissertations

An effective management program for stink bugs (SBs) in pecan groves requires knowledge of: stages of the pecans susceptible to SB damage; strata of the tree with SB damaged nuts; a practical SB monitoring method; and, effects of landscapes contributing SBs into pecan groves.

Stink bugs produced feeding punctures in pecan shucks at all phenological stages. Pecans punctured before the dough stage drop from the tree. Kernel damage occurs in the pecans’ dough stage, whereas mature pecans are not damaged.

The pecans collected from the whole tree using the tree shaker had significantly less punctures than the pecans collected from …

Autophagy And Its Potential Role In Stress And Feed Efficiency Using Avian Lines, Alissa Laura Piekarski

Graduate Theses and Dissertations

Autophagy is a highly conserved cellular mechanism that is responsible for the degradation and recycling of damaged organelles. Recently, autophagy has been involved in critical roles during overall development of the organism and degradation of damaged cellular components. This pathway has witnessed dramatic growth in the last few years and has been extensively studied in yeast and mammals, however, there is a paucity of information in avian (non-mammalian) species. First, we characterized genes involved in the autophagy pathway in male and female Jungle Fowl to determine gender and tissue specific differences. Secondly, tissue and genotype differences in Japanese quail selected …

Field Screening Of Diverse Soybean Cultivars For Flood Tolerance, Jane Achando Khatenje Mokua

Graduate Theses and Dissertations

Flooding can significantly reduce soybean growth, development, and yield. Therefore, screening and identification of flood-tolerant soybeans will enhance development of cultivars that are well suited for flood-prone areas. Sets of screening tests were conducted in Stuttgart, Arkansas using three separate but related experiments, with the purpose of establishing effective flood tolerance screening protocol that can identify tolerant and sensitive cultivars. Each experiment was completely randomized with three replications. The first experiment involved screening of 256 maturity group (IV and V) cultivars. Flooding was imposed at the fifth-node (V5) or first-bloom (R1) stage for ten days. Post-flood visual ratings and stand …

Microbial Safety, Shelf Life Stability, Quality Preservation, And Consumer Acceptance Of Vacuum-Infused, Irradiated Chicken Breast Meat Treated With Natural Plant Extracts And Organic Acids, Kenneth Franklin Over

Graduate Theses and Dissertations

Contamination of poultry products with food borne pathogens is a consistently recurring problem in the United States and the world. Recalls associated with chicken contamination are responsible for considerable economic losses to the poultry industry. Many decontamination steps are currently in place to reduce the likelihood of contaminated products reaching the consumer, but despite these safeguards, contamination events are still uncomfortably frequent. Irradiation is a safe and effective means of ensuring the safety of both ready-to-cook and ready-to-eat poultry but is not utilized in the United States. This is due, in part, to certain irradiation dose-dependent quality characteristic defects associated …

Sampling Terrestrial Arthropod Biodiversity: A Case Study In Arkansas, Michael Joseph Skvarla

Graduate Theses and Dissertations

The Interior Highlands is a biodiversity hotspot, with at least 200 known endemic species, but is understudied compared to hotspots, such as the Southern Appalachians. In order to begin to rectify this issue, a nine month study was conducted from mid-March through early December at a 4 ha site at Steel Creek, Buffalo National River, in Newton County, Arkansas. Thirteen collecting methods were employed, including three colors of Lindgren funnel trap, five colors of pan trap, Malaise traps, canopy traps with upper and lower collectors, pitfall traps, and Berlese-Tullgren extraction of leaf litter, which resulted in the collection of 1311 …

The Abundance And Distribution Of Mallards In The Lower Mississippi Alluvial Valley Of Arkansas, John Andrew Herbert

Graduate Theses and Dissertations

The management of wintering waterfowl in North America requires flexibility because of constantly changing landscapes and conditions. Many mallards use the lower Mississippi Alluvial Valley (MAV) for wintering habitat, making this an area of emphasis for improving management strategies. In this study, I used mallard observation data from 2009-2014 aerial surveys collected in the Arkansas portion of the lower MAV to explain the abundance and distribution and of mallards. Using spatial hierarchical models and breaking covariate data to 2x2 km grid cells, I analyzed how covariates relate to the changes of abundance and distributions within and among surveys. Mallard abundance …

Understanding The Causal Agent Of Rose Rosette Disease, Patrick Louis Di Bello

Graduate Theses and Dissertations

A number viruses are known to infect roses, ranging from those in the genera Nepovirus, and Ilarvirus, which have been reported since the inception of rose virology, to recently discovered viruses in the genera Carmovirus, Closterovirus, Emaravirus, Luteovirus, Rosadnavirus, and Potyvirus. Of the viral diseases in rose, arguably the most damaging is Rose rosette (RRD), which is associated with the Emaravirus, Rose rosette virus (RRV). The objective of this thesis is to fill in the gaps in knowledge on the epidemiological aspects of RRD and RRV. There has been significant progress in the epidemiology of the RRD agent prior to …

Analysis Of Ac/Ds Activation Tagged Mutants In Tomato (Solanum Lycopersicum), Ipeleng Randome

Graduate Theses and Dissertations

Tomato (Solanum lycopersicum) is a crop of immense economic and nutritional importance worldwide and also a good model organism for genomic studies of other dicot species. The recent completion of the tomato genome sequence is a great milestone towards learning about the tomato genome. Elucidation of the function of the different genes using different functional genomic tools is therefore important in adding to this resource. To this end, we have developed an Ac-Ds transposon ‘activation tagging’ (ATag) system to be able to transpose transposon inserts, bearing a strong 35S-enhancer element, all around the genome. An Ac-Ds ATag construct was used …

Systematics Of Testudacarine Torrent Mites (Parasitengona: Torrenticolidae), Joseph Charles O'Neill

Graduate Theses and Dissertations

Thirteen new species of Testudacarus (Torrenticolidae: Testudacarinae) are described, four species are redescribed, and the status of previously problematic species are addressed. For Testudacarinae this represents the first published: 1) descriptions from multiple specimens (therefore providing ranges); 2) colored photographs; 3) explicit illustrations and discussion of sexual dimorphism within the subfamily; 4) genetic data. A comprehensive literature review is also included.

Hydrology-Biology Response Relationships In The Ozark Highlands, Dustin Thomas Lynch

Graduate Theses and Dissertations

I examined flow-ecology relationships among stream communities in the Ozark Highlands, USA. I sampled fish, crayfish, and benthic macroinvertebrates during two consecutive summers, including a drought year (2012) and a flood year (2013). Biological response variables related to community structure were assessed via two different statistical methods: an Information Theoretic approach relating response variables to a priori selected predictor variables incorporating hydrology, habitat, geomorphology, and water quality, and canonical ordination using forward selection to relate these same response variables to a large assortment of hydrologic metrics. In addition to assessing metrics related to predicted natural flow, flow alteration at gaged …

Utilization Of Weed Ecology, Tank Mixtures, And Application Technology To Improve Efficacy Of Herbicide Applications In Soybean, Christopher John Meyer

Graduate Theses and Dissertations

New herbicide-resistant soybean traits will increase the number of herbicides that can be applied in soybean and change the technology currently used to make herbicide applications in soybean. Palmer amaranth (Amaranthus palmeri) remains one of the most difficult weeds to manage in soybean and thus is the primary focus of this research. Therefore, experiments were conducted to investigate Palmer amaranth temporal emergence, control of common Arkansas weeds with new soybean herbicide programs, and the effect of application technology on dicamba-containing tank mixtures. Palmer amaranth emergence exceeded 400 plants m-2 for tillage treatments in 2013 and 2014, and tillage events typically …