Plant Breeding and Genetics Commons^™

Towards Improved Stress Resilience, Optimal Growth And Enhanced Biosafety In Transgenic Plants, Xiaotong Chen

All Dissertations

This dissertation investigates biotechnology strategies to improve plant stress resilience, growth, and biosafety in transgenic perennial grasses using creeping bentgrass as a model system. Functional analyses of non-coding RNAs such as miR164 and miR169 showed that regulatory non-coding RNAs influence plant architecture and abiotic stress responses through broad developmental and transcriptional networks, supporting them as valuable engineering targets for complex trait improvement. The dissertation also developed a dual recombinase platform for transgene containment and removal, linking trait engineering with biosafety control. Additionally, the recombinases themselves were examined for their potential impact on heterologous host and were found to reshape plant …

Sorghum Grain Secondary Metabolites And Underlying Genetics To Reduce Foodborne Pathogens In Poultry, Maria A. Conti

All Dissertations

The rise in antibiotic-resistant pathogens poses a threat to the poultry industry's ability to maintain animal health, prompting growing interest in alternatives to synthetic antibiotics. The use of non-tannin sorghum [Sorghum bicolor (L.) Moench] in poultry rations offers a valuable alternative, as this cereal grain has a high bioactive profile that can provide health benefits, including antimicrobial (AM) activity. The scope of this study was to examine the AM potential of non-tannin sorghum grain against Clostridium perfringens, a major foodborne pathogen that negatively impacts poultry health and production. To that end, the inhibitory effects of a non-tannin sorghum …

Citrullus Amarus Drought Tolerance: An Above And Below Ground Analysis, Ben A. Hyland

All Theses

Ever rising environmental temperatures threaten global food security by worsening severity and increasing the occurrence of drought. Commercially cultivated watermelon (Citrullus lanatus), have reduced drought tolerance due to a narrow genetic base caused by breeding for desirable traits such as sweetness, size, and flesh/rind color. Comparatively, the crop wild relative desert watermelon variety (Citrullus amarus), while more drought tolerant than their commercially cultivated relatives (C. lanatus), still require large amounts of water to grow and produce reliable fruit yields. Watermelon root morphology plays a key role in their ability to tolerate drought, with more …

Breeding For Disease Resistance In Melon And Watermelon, Venkata Rao Ganaparthi

All Dissertations

Watermelon and cantaloupe are two widely consumed cucurbits, but their acreage in the United States reduced by nearly 50% in last two decades. Fusarium wilt caused by a soil borne pathogen Fusarium oxysporum f. sp. niveum(Fon) race 2 is a major limiting factor in watermelon production as it reduces yields by 80%. Grafting watermelon plants onto the root stock of wild, disease-resistant varieties like ‘Carolina Strongback’ is the best strategy to manage Fon race 2. Though effective, this approach increases production costs.

Part of this dissertation focused on finding more sustainable, cost-effective solutions to control Fusarium wilt …

Purple Tomatoes Boost Nutrition Crop Value And Create New Opportunities For United States (U.S) Agriculture, Tariq Alam

Agronomic Crops

The agricultural landscape in the United States is continually evolving, with growers and the tomato industry seeking innovative ways to meet consumer demands while enhancing profitability. The introduction of both bioengineered and classically bred anthocyanins-enriched purple tomatoes presents a unique opportunity for U.S. growers to cultivate a high-value crop that appeals to niche markets and commands premium pricing. Bioengineered purple tomatoes achieve high anthocyanin levels through the introduction of snapdragon transcription factors, while classically bred 'Indigo Rose' purple tomatoes are developed via classical breeding methods, providing an alternative for consumers who prefer traditionally bred products. Specifically, the purple tomato holds …

Breeding Biofortified Protein Rich Organic Pulses For Better Human Health, Sonia Salaria

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Pulse crops are dry grains of legumes, the second most consumed plant crops in the world after cereals. These crops are one of the primary sources of plant-based protein and contain high concentrations of pre-biotic carbohydrates, minerals and vitamins. Recognizing the health benefits of pulses intake, their demands as sustainable food and changes in people’s diet preferences for plant-based protein have increased awareness for pulses consumption. With this scenario, improving the nutritional profile of pulse crops for rich nutrition has been an opportunity for breeders to explore and tailor the available germplasm to develop nutrient dense pulses. Furthermore, the genomic …

Identification And Characterization Of Intermediate Phenotypes To Decipher Genetic Architecture Of Stalk Lodging Resistance In Maize (Zea Mays L.), Bharath Kunduru

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Maize is a key contributor to global food security and incurs severe yield losses due to stalk lodging, the permanent displacement of plants from an upright growth habit due to mechanical damage to the stem (stalk). Stalk lodging resistance, an indicator of the stalk ability to resist lodging, is a complex trait and determined by several structural, geometric, and material properties of stalks, collectively referred to as intermediate phenotypes, whose identity and genetic framework are poorly understood. Therefore, progress in resolving the genetic architecture of stalk lodging resistance was impeded by a lack of standardized phenotyping methodologies and a poor …

Understanding The Genetic And Metabolic Underpinnings Of Complex Traits In C4 Grasses, Manwinder Singh Brar

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Maize (Zea mays L.) and sorghum (Sorghum bicolor (L.) Moench) are two important cereal crops cultivated worldwide for food, animal feed, and industrial products. Productivity of these crops is significantly impacted by various biotic and abiotic stresses, such as diseases, insect pests, drought, salinity, and heat. Among factors influencing crop performance under stress, the regulation of leaf longevity plays a critical role in determining yield. Leaf senescence is a highly regulated process essential for nutrient remobilization through the degradation of cellular components in aging leaves, but premature or accelerated senescence reduces photosynthetic efficiency and yield. Staygreen, a phenotype …

Investigate The Possibility Of Producing Healthier, Safer Peanuts Through Molecular Breeding And Novel Fungal Pathogen Management Strategies, Tariq Alam

All Dissertations

Peanut allergy, a critical health concern with high morbidity and mortality rates, is a leading cause of fatal anaphylactic reactions in the United States. Managing peanut allergy is challenging due to the prevalence of peanuts in processed foods and the risk of contamination. This dissertation evaluates the U.S. peanut mini-core collection for four major immunogenic proteins, Ara h1, Ara h2, Ara h3, and Ara h6, using gel electrophoresis, enzyme-linked immunosorbent assay, liquid chromatography, and mass spectrometry. The study identified 26 genotypes with reduced concentrations of allergenic proteins. Genome-wide association studies (GWAS) of protein traits revealed 10 significant SNPs and identified …

Enhancing Crop Resilience: Physiological And Omics Approaches For Drought And Heat Stress Tolerance In Soybean And Peanut, Jyoti Prasad Kakati

All Dissertations

Soybean and peanut are two major crops globally grown for oil and protein. Climate change-associated factors like drought and increased temperature (heat stress) challenge the global production of soybeans and peanuts. Though the United States is the second-largest producer of soybean and the fourth-largest producer of peanuts, it still faces production constraints associated with drought and heat stresses. In the present study, we have examined the responses of soybean and peanut plants to drought and heat stresses during germination and reproductive phases. We conducted field and controlled environmental studies to elucidate the impact of drought stress on germination and seedling …

Transcriptomic Profile Of Armillaria Root Rot Fungi Affecting The U.S. Stone Fruit Industry, Jared Weaver

All Theses

Armillaria Root Rot (ARR) is a significant replant disease threatening the future of the United States stone fruit industry. Economic loss in South Carolina peach orchards is estimated to be $8M annually due to approximately 3-4% of annual tree deaths caused by ARR on replant sites. Management solutions are insufficient and can at best extend the life of the orchards on replant sites. The only solution to solving the ARR problem, apart from abandoning the replant site for peach production, is planting orchards on ARR-resistant rootstock. Significant progress has been made towards providing growers with genetically resistant rootstock, however, for …

Enabling Breeding For Fruitlet Freeze Tolerance In Peach, Ufuk Caglar

All Theses

Climate change is affecting the production of temperate fruit crops, with cold temperatures emerging as a critical abiotic stressor that limits plant growth and performance. Freeze damage, particularly in spring, has resulted in significant economic losses in peach production in the southeastern United States. Research efforts in peach and other Prunus species have primarily focused on studying dormancy-related traits associated with bloom time, such as chill and heat requirement, with fruitlet freeze tolerance not equally represented. Breeding for climate resilience in peach requires a combination of these traits to allow for late bloom via targeted chill requirement and high heat …

A Genome Wide Association Study Of Heat Tolerance In Snap Bean (Phaseolus Vulgaris), Morgan Stone

All Theses

Bean production in the United States has decreased while the temperatures have been steadily increasing, reaching new highs each year. Heat stress is detrimental to common bean (also known as snap bean) production. Symptoms of heat stress include decrease in pollen viability, shriveling of pods, and pod abortion making them unmarketable. Pod production of 323 snap bean accessions from a large diversity panel was assessed in a randomized complete block design with field trials at two different times in the spring season. The results show a significant decrease in the number of pods produced per plant and weight of pods …

Integrated Techniques To Identify And Characterize Resistance To Fusarium Wilt Caused By Fusarium Oxysporum, F. Sp. Vasinfectum Race 4 In Two Domesticated Gossypium Species, Stephen Parris

All Dissertations

Fusarium wilt of cotton (Gossypium hirsutum and G. barbadense), caused by Fusarium oxysporum f. sp. vasinfectum race 4 (FOV4), is the most threatening disease faced by today’s cotton breeders. During the past 20 years, over $7 million have been dedicated to efforts in breeding upland cotton for resistance to FOV4 while yielding little to no results. To counteract this, we conducted a study in Clint, TX, that utilized control plots and geostatistical methods to adjust phenotypic data for the heterogeneous distribution of FOV4 in the field, improving the accuracy of genetic resistance assessments. Concurrently, early-generation genetic mapping in …

Breeding Cotton For Determinate Growth Habit: Increasing Cotton Fiber Yield By Remobilization Of End-Of-Season Perennial Reserves, Salman Naveed

All Dissertations

Cotton (Gossypium spp.) is a major export commodity for the U.S. Despite advances in plant breeding and management practices, the cotton yield gains in the U.S. have stagnated. Therefore, to increase cotton fiber yield, we undertook a novel approach by altering the growth habit of cotton from perennial to annual. In this effort, eight genotypes showing strong expression alleles for five floral induction and meristem identity genes were selected from 44 Upland cotton mini-core collection genotypes and genetically crossed in various combinations to stack the strong expression alleles in a genotype. These efforts have allowed us to develop high-yielding, …

Identifying Genetic Sources Of Anthracnose Resistance In Global Sorghum Lines, Mary-Frances Behnke

All Theses

Anthracnose of sorghum (causal agent: Colletotrichum sublineola) is the most detrimental disease of sorghum (Sorghum bicolor) worldwide, significantly reducing grain yield. This study includes a literature review of the disease and a meta-analysis of genome-wide association studies (GWAS) of anthracnose-resistance in sorghum as means to elucidate genetic sources of the trait. The meta-analysis includes genotypic and phenotypic data from 5 unique studies and 1,071 sorghum lines. Original genotyping-by-sequencing data from were obtained primarily from National Center for Biotechnology Information’s Sequence Read Archive (NCBI-SRA) and prepared and processed using the Tassel 5 GBS v2. pipeline. Phenotypic data were …

Lentil (Lens Culinaris Medik.) Prebiotic Carbohydrates And Protein Quality: Uncovering Genomic Associations And Developing Rapid Ftir Phenotyping Methods, Nathan Johnson

All Dissertations

Lentil (Lens culinaris Medik.) is a cool-season food legume cultivated around the globe. This pulse crop boasts a rich nutrient profile including high concentrations of prebiotic carbohydrates, protein, essential amino acids, and micronutrients, such as folate, iron, zinc, and selenium. Prebiotic carbohydrates promote a healthy gut microbiome, which, in turn, is associated with reduced risk of numerous pathologies including obesity/overweight, type II diabetes, irritable bowel disease, and colon cancer. Known as “poor man’s meat,” lentil also provides high quality plant-based protein at a low cost. As the world increasingly looks to crops to supplement and replace animal-based protein, lentil …

Crosscutting Understandings Of Fusarium Resistance In Sorghum And Wheat For Development Of Breeding Strategies And Novel Opportunities In Germplasm Improvement, Arlyn Ackerman

All Dissertations

Fusarium causes widespread disease in crops resulting in yield and quality loss across a range of host taxa that results in global incidence of carcinogenic mycotoxins contaminating the world’s food systems. This research sought to crosscut frameworks developed across the Fusarium host crop species of wheat (Triticum aesitivum) and sorghum (Sorghum bicolor [L] Moench) to further understand mycotoxin suppression and resistance. A deeper understanding of the biochemical resistances available in sorghum grain mold (SGM) was built by following research of wheat based upon deoxynivalenol resistance to Fusarium head blight (FHB). Through this research, phenotyping methods for Fusarium damaged kernels …

Pre-Breeding Of Kale (Brassica Oleracea Var. Acephala) – Organic Adaptation And Shelf Life, Craig Reda

All Theses

Kale (Brassica oleracea var. acephala) is a nutritionally rich leafy green that that contains vitamins, minerals, and prebiotic carbohydrates. As a popular organic crop, kale accounted for 1.3% of total US organic produce sales in 2020, a market valued at over 17 billion USD. However, organic production is limited by its inability to use synthetic pesticides and fertilizers and suffers from decreased yield when compared to conventional agriculture, partially due to the creation of a significantly different growing environment. Additionally, the absence of synthetic products can also negatively impact the shelf of leafy greens like kale. To determine …

An In Vitro Approach To Identify Sources Of Resistance To Fusarium Wilt Caused By Fusarium Oxysporum F. Sp. Vasinfectum Race 4 In Domesticated Cotton, Stephen Parris

All Theses

Cotton lint produced by the plants Gossypium barbadense L. (pima cotton) and Gossypium hirsutum L. (upland cotton) is the world’s leading source of renewable textiles. The fibers of the cotton plant have been woven so intricately into our society that it would be hard to imagine life without their products. Cotton breeders must then not only continue to work to improve the quality of cotton fibers (fineness, strength, dyability, etc.) but also to improve the resilience of the plant against biotic and abiotic factors. Fusarium oxysporum f. sp. vasinfectum race 4 (FOV4) is an aggressive fungal pathogen, which causes Fusarium …

Enabling Breeding For Targeted Heat Requirement In Peach, Omer Atagul

All Theses

Peach [Prunus persica (L.) Batsch] germplasm varies in heat requirement and bloom time. This variability can be utilized in breeding for targeted environment or overall climate resilience. Development of molecular tools to aid in targeted selection of dormancy related traits is needed to support breeding for these traits. This project furthers our understanding of heat requirement accumulation diversity and genetic control in peach.

Peach bloom date (BD) is determined by the dynamic relationship of temperature requirements, from the sequential fulfillment of chill requirement (CR) and heat requirement (HR). Knowledge of HR and its influence on BD would provide deeper …

Fine Mapping Of Chilling Requirement And Bloom Date To Enable Marker-Assisted Breeding Of Climate Resilient Peach, Gizem Demirel

All Theses

Peach (Prunus persica (L.) Batsch) fruit is a delicious summer treat appreciated for its sweet, juicy, and aromatic taste all over the globe. With only 44 calories and zero fat per fruit, peach has a great popularity among consumers and producers for its nutritional and economic value. Peach production is threatened by unpredictable climate changes, rising temperatures that reduce winter chill, especially in the warmer growing areas, resulting in fruit and yield loss. Therefore, it is necessary to develop cultivars that are resilient to environmental changes. Peach breeding takes a long time, and this process can benefit from the …