Master of Science in Environmental Science, Cleveland State University, 2025, College of Arts and Sciences

Isolated trees in urban green spaces face unique environmental conditions that influence their structural and functional traits, shaping canopy architecture differently than trees in natural forests. This study examined how functional traits, including those associated with Corner's rules and the plant economic spectrum, relate to total twig-scale leaf area (TLA) and leaf area index (LAI) in isolated trees. We aimed to determine whether commonly measured traits could serve as predictors of canopy structure, informing urban forest management. Between June and September 2022, we measured leaf and twig traits for 32 tree species growing in open conditions at Secrest Arboretum. Key traits, including specific leaf area, leaf dry matter content, leaf size, twig diameter, and twig density, were assessed to determine their influence on TLA. Whole-canopy traits, including wood area index, branch angle, and branching intensity (i.e., ‘branchiness') were estimated using terrestrial laser scanning between February and April 2022. Additional canopy traits, including LAI, leaf area density, and diffuse non-interceptance, were estimated using a gap fraction analyzer between September 2022 and August 2023. To further contextualize canopy structure, we also considered phyllotaxy, twig density, and shade tolerance. Our findings revealed partial support for Corner's rules in isolated trees in urban green spaces. While TLA was positively correlated with twig diameter, individual leaf area and twig diameter were not strongly linked, suggesting that certain aspects of Corner's rules may not fully apply to isolated trees. Leaf size and twig diameter emerged as key predictors of TLA, indicating that thicker twigs and larger leaves contribute to greater TLA. At the canopy scale, almost 50 to 60% of LAI variation was explained by phyllotaxy, twig density, and TLA downstream of the second-most-distal branch order, standardized by cross-sectional area. This suggests that simple trait m (open full item for complete abstract)

Bachelor of Science (BS), Ohio University, 2025, Environmental and Plant Biology

Production of offspring is essential for every species of organism on Earth and plants are no exception. Plants have evolved countless techniques for efficient reproduction in the habitats they exist in. Seeds are the reproductive structures of two major groups of plants: gymnosperms (the more ancient group, often keeping their seeds on “scales” in cones) and angiosperms (flowering plants that protect their seeds in fruit). Seeds carry a plant's genetic material and represent the one time in a plant's life cycle that it can spread to new locations. This latter process is called dispersal and is vital for the survival and expansion of plant species. Unlike the vegetation of a plant, which will wilt and die without water, seeds are often the only part of a plant that can survive complete desiccation (or drying out) over long periods of time. With this unique ability to withstand extreme conditions, they ensure the continuation of plant species through time and across different habitats. The capacity of plant species to produce persistent, viable seeds enables them to endure temporally unfavorable environmental conditions. Seeds that have dormancy or are persistent in soil make up the seed bank of a community. The dynamics of a seed bank are essential to the ability of a community to maintain itself and respond to changes. While seed research has existed for many years, vegetative traits have always gotten more attention in the world of plant biology. Only in recent years has interest grown in understanding the ecological and evolutionary significance of seed traits. Tropical and subtropical species have been especially underrepresented in seed trait research, and scientists are only just tapping into the understanding of seed dormancy in the tropics. Understanding the seed bank of a community and the dormancy dynamics and germination requirements that exist within it can help with its restoration efforts. The purpose of this study is to contribute to the sparse data o (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2025, Food, Agricultural and Biological Engineering

The global economy relies on natural rubber (NR) for transportation of goods and people via tires and automobile components. Rubber is also critical to a plethora of industrial and medical products including gloves, condoms, and catheters. New and emerging uses of NR include space exploration, innovative medical procedures and specialized electronics. Despite the fact that thousands of plants produce NR, the tropical rubber tree, Hevea brasiliensis, remains the sole commercial source of NR. H. brasiliensis is unable to keep up with projected increases in NR demand due to many factors but especially small growing regions that are unable to expand without illegal deforestation of rainforests and high susceptibility of rubber trees to diseases. Concerns for the NR supply have sparked interest in alternative NR-producing plants with potential to supplement or replace the Hevea supply chain. There are three species besides Hevea which have been commercialized and had rubber extracted in bulk quantities during World War II: 1) Parthenium argentatum Gray (guayule), 2) Scorzonera tau-saghyz Lipsch. & G.G.Bosse (STS, mountain gum), and 3) Taraxacum kok-saghyz Rodin (TK, rubber dandelion). The work of this dissertation focuses on the potential of TK as an alternative rubber-producing crop. Of the three alternative rubber plants which have been successfully commercialized in the past, it is the only one capable of hydroponic growth, opening the door to unique NR production systems such as indoor and vertical farms. TK is also well suited to outdoor field production in temperate regions such as northern United States, much of Europe and a similar temperate region south of the equator, meaning it has a much larger habitable zone than Hevea. Additionally, at 6 months old TK has rubber of commercial quality, whilst Hevea is not tappable until 7 years old, making it a much more adaptable species for scaling up production in the event of a rubber crisis. The focus of this work wa (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2025, Plant Pathology

Rice (Oryza sativa L.), a staple crop for nearly 50% of the global population, particularly in Asia, is highly susceptible to various pathogens, leading to significant yield losses. To understand the molecular mechanisms underlying rice defense, two projects were carried out in this dissertation. The first study (Chapter 2) utilized rice as a model to examine transcriptional and metabolomic changes associated with the resistance (R) gene, Piz-t. Transcriptomic analyses revealed 2,791 Piz-t-specific differentially expressed genes (DEGs) following inoculation with Magnaporthe oryzae strain RO1-1. These findings highlighted correlations between gene expression and metabolite alterations, including changes in terpenoids, phenylpropanoids, flavonoids, fatty acids, amino acids, glycolysis/TCA intermediates, and phenylalanine pathways, providing critical insights into how R gene-mediated resistance enhances disease resistance in rice. The focus of the second study (Chapter 3) is to understand the role of programmed cell death (PCD) in rice immunity. Rice SPL11 cell-death suppressor 2 (SDS2), a receptor-like protein kinase, regulates PCD by phosphorylating and interacting with the U-box E3 ligase SPL11, as negative regulator of cell death, OsRLCK118 and OsRLCK176. The phosphorylated OsRLCK118 interacts with OsRbohB to mediate reactive oxygen species (ROS) generation. Despite these insights, the downstream pathways of SDS2-mediated resistance remain unclear. RNA-seq analysis of SDS2-ACT indicated higher expression of OsBDG1, suggesting possible interactor of SDS2, localizing to both the non-nuclear and nuclear area. OsBDG1 is a small protein with an LRR N-terminal domain and three LRR domains at its C-terminus, regulating in leaf inclination and grain size but no study was reported in disease resistance. Reduced luciferase and GUS activity were found by the co-expression of 35s::SDS2-HA and 35s::OsBDG1-GFP in rice protoplasts relative to the co-expression of 3 (open full item for complete abstract)

Master of Science, Miami University, 2025, Microbiology

Chlamydomonas reinhardtii is a model alga used in the study of photosynthesis. One of the attractive attributes of C. reinhardtii is its ability to grow autotrophically, heterotrophically, or mixotrophically depending on the availability of light and acetate. Due to the advantages of mixotrophic growth, many studies of the photosynthetic stress response are conducted in acetate supplemented medium, while studies conducted under autotrophic growth conditions are limited. There is evidence that even under non- stressed conditions, mixotrophically grown cultures exhibit distinct photophysiology. To describe differences in the response to abiotic stress, C. reinhardtii growth and physiology during control and long-term stress (high light, high salt, combined high light/high salt) were compared under autotrophic versus mixotrophic conditions. Photochemistry, ATP:ADP ratios, and abundance of photosynthetic proteins were measured. Higher growth rates in mixotrophic vs. autotrophic-grown cultures were accompanied by retention of photosystem II activity and higher rates of photosystem I- driven cyclic electron flow. Under long-term stress, mixotrophic cultures exhibited reduced capacity for non-photochemical quenching and increased abundance of photosystem II. We conclude that mixotrophic growth conditions significantly impact the physiology and tolerance of C. reinhardtii to stress. Trophic mode should be considered when using C. reinhardtii to study the photosynthetic stress response.

Master of Science (MS), Wright State University, 2024, Biological Sciences

Emerald ash borer (EAB), Agrilus planipennis, is an invasive pest that significantly impacts olive trees (Olea europaea). This study aimed to assess the role of abiotic stress factors such as drought and salinity in influencing plant defenses and resistance to EAB, while also examining cultivar variation in resistance. The study specifically aimed to address: (1) What effects do varying degrees of abiotic stress (drought, salinity) have on olive trees' antioxidant and peroxidase activity in olive tree? (2) Do distinct olive cultivars exhibit varying levels of resistance to EAB under various stressors? We used a controlled experimental design with two stress treatments (drought and salinity) and 20 olive cultivars to conduct the bioassay. Growth metrics (height and stem diameter), peroxidase activity, and antioxidant activity were measured, while EAB survival and performance were assessed by monitoring larval feeding and growth. Results indicated no significant differences in antioxidant activity between treatments, although low salinity slightly enhanced antioxidant responses. Peroxidase activity was highest under high salinity, and growth responses varied by treatment and cultivar, with Leccino showing the highest antioxidant activity. EAB larvae performed best under drought conditions but exhibited poor survival on certain cultivars. These findings suggest that abiotic stress influences both plant defense mechanisms and pest resistance, with cultivar-specific responses to stress and pest pressure.

Doctor of Philosophy (PhD), Ohio University, 2024, Plant Biology (Arts and Sciences)

Plants encounter various biotic and abiotic stresses daily and have developed defense mechanisms to overcome these challenges. One key system involved in these defense mechanisms is the ubiquitin (Ub)-26S proteasome system (UPS), which targets malfunctioning proteins for degradation through Ub-tagged proteasomal pathways. The E3 ligases, specifically S-phase kinase-associated protein 1 (SKP1), Cullin 1 (CUL1), and F-box (SCF) complexes, play crucial roles in this process by recognizing and tagging specific protein substrates. Arabidopsis thaliana, with over 700 F-box proteins, has the largest group of E3 ligases, yet only 5% have been functionally characterized. Phylogenetic relationships among 111 plant species have identified four clusters of F-box genes, including a cluster with more conserved F-boxes, referred to as core Arabidopsis F-box (CAF) genes. Given that CAF genes have more known functions compared to other clusters, this dissertation hypothesizes significant potential for discovering new functions among the uncharacterized F-boxes within this group. Considering the evolutionary conservation of most CAFs, I adopted a genetic approach to investigate the roles of CAFs during seed germination and seed development. To address the challenges posed by functional redundancy of duplicated CAF genes and the lethality associated with constitutive F-box overexpression in transgenic plants, I created a library of inducible overexpression lines for 40 CAF genes, many of which lacked known biological functions. By systematically examining the effects of conditional overexpression of these 40 CAFs, I found that CAF overexpression during seed germination and seed development can positively or negatively regulate radicle rupture growth, thus controlling the germination process. Specifically, I identified 24 CAFs that enhance radicle rupture and two that inhibited it by interfering with abscisic acid (ABA)-mediated germination suppression. Induction of CAFs during seed (open full item for complete abstract)

Ph.D., Antioch University, 2024, Antioch New England: Environmental Studies

Climate change presents an unprecedented challenge to global agriculture and food security. Small farms are especially vulnerable to the local impacts of large-scale drivers of change. Effective adaptation in agriculture requires working across scales, and geographic, political, and disciplinary boundaries to address barriers. I use elements of case study, agent-based modeling and serious games, to design a model of farmer decision-making using the sociocognitive framework of climate change adaptation. I examine how adaptation functions as a process, how complex dynamics influence farmer behavior, and how individual decisions influence collective behavior in response to climate change. This novel approach to adaptation research in agriculture examines the relationships between the contextual, compositional, and cognitive elements of the sociocognitive theory. The tools developed for this research have broad practical and theoretical future applications in climate adaptation research and policymaking. This dissertation is available in open access at AURA (https://aura.antioch.edu) and OhioLINK ETD Center (https://etd.ohiolink.edu).

Doctor of Philosophy, The Ohio State University, 2024, Horticulture and Crop Science

Fusarium Head Blight (FHB, caused by Fusarium graminearum) causes economic losses in wheat by reducing grain yield due to Fusarium-damaged kernels (FDK) and by reducing food and feed quality through accumulation of the toxin deoxynivalenol (DON). Traditional breeding methods rely on visual symptom scoring of a Fusarium index (IND), but these have limitations in predicting DON levels in the grain. It is common to observe samples where DON levels are considerably lower or higher than what we would predict based on FDK or IND. This lack of correlation suggests that there may be resistance to toxin accumulation (RTA). The objectives of this study were to quantify the association between Fusarium biomass (FB), FDK, IND, and DON and determine the repeatability and prevalence of RTA among wheat genotypes. Through multi-year evaluations across different locations, significant genotype effects on FHB traits were identified. In almost all analyses FDK had the highest direct impact on DON indicating that FDK is a major factor influencing DON accumulation in wheat. FB had a large indirect effect on DON via FDK. Additionally, some genotypes consistently had low DON levels despite increasing FB levels, suggesting RTA. My second study investigated the use of genomic selection (GS) as a breeding tool for FHB resistance. GS utilizes genome-wide variants to predict phenotypes via statistical models, enabling breeding selection without direct phenotypic evaluation. A key iii consideration for GS implementation is the formation of the training population (TP). Wheat breeding programs collect phenotypic data over several years and trials, but the most effective way to use this data in the formation of a TP for GS is not yet clear. The objectives of this study were to evaluate the impact of the number of years of data in a TP and the impact of excluding data from stage-1 testing. We found that GS accuracy was not affected by omitting stage-1 data from the TPs. Additionally, including (open full item for complete abstract)

Master of Science, The Ohio State University, 2024, Horticulture and Crop Science

Sub-zero freezing temperatures cause 5-15% of annual crop losses to worldwide grapevine cultivation. Based on their cold hardiness, i.e., the ability to survive under low temperature conditions, grapevine genotypes can be classified as a) cold sensitive, such as Vitis vinifera (-18℃ to -22℃ critical range), and b) cold hardy, such as Vitis labrusca (-26℃ to -29℃). During spring, late-spring frost conditions can cause injury to young shoots emerging from dormant buds, affecting grapevine yield and wine quality. Enhancing cold hardiness and frost tolerance can improve grapevine's survivability under extreme low temperature conditions. Cold hardy wild grapevine species, such as native North American Vitis labrusca, are being utilized for the development of cold hardy hybrid cultivars, however, most of these species have low-chilling requirements, leading to early budburst in spring. Therefore, despite being cold hardy as dormant buds, it is unknown if the young shoots of Vitis labrusca have higher frost tolerance than those of Vitis vinifera cultivars. Our goal was to determine the difference in frost tolerance and transcriptomic response related to low temperatures between young shoots of cold hardy V. labrusca acc. ‘GREM4' and cold sensitive V. vinifera cv. ‘Cabernet Sauvignon'. Results showed that ‘GREM4' shoots had significantly higher frost tolerance than those of ‘Cabernet Sauvignon'. Transcriptomic analysis for chill (4℃) and freeze (-2℃) stress revealed that 'GREM4' shoots exhibited upregulation of genes encoding cell-wall-associated receptor kinases and extensin proteins under both chill and freeze stress. Moreover, genes encoding 3-ketoacyl-coenzymeA synthase (KCS), a key enzyme involved in wax biosynthesis, and genes related to sugar transport and metabolism were differentially expressed between ‘GREM4' and ‘Cabernet Sauvignon'. Interaction analysis between species and temperature treatments revealed that the gene encoding abscisic acid (ABA) degrading enzym (open full item for complete abstract)

BS, Kent State University, 2024, College of Arts and Sciences / Department of Biological Sciences

Wetlands act as a filter between the terrestrial land and a body of water, regulating the flux of nutrients between these. An overabundance of nutrients, such as phosphate, can lead to a harmful algal bloom (HAB), which is known to deplete oxygen from aquatic ecosystems and produce harmful toxins. The goal of this study was to determine the effect of different vegetation patches on the amount of bioavailable phosphorus, measured as soluble reactive phosphate (SRP), in both the surface water and sediment. We sampled surface water and sediment from Turtle Creek Bay located in Magee Marsh Wildlife Area, Ohio, where we identified four distinct vegetation patches: grasses, hardwoods, Typha spp. (cattail), and submerged aquatic vegetation (SAV). Results of this study showed that the SAV patch exhibited significantly less SRP than the other patches (p<0.05). However, there was no significant difference in SRP concentrations for the rest of the patches. Additionally, we experimentally incubated intact sediment cores sampled from a diagonal transect across Magee Marsh. The cores were incubated with four different SRP concentration treatments based on in situ SRP measurements. We found that at ambient SRP concentrations (4 ug/L), sediments released 455.2 ± 518.3 ug SRP/m2/d into surface waters, but when SRP concentrations in the surface water increased (to 18, 39, and 60 ug SRP/L), sediments removed SRP at increasing rates (-919.9 ± 278.7, -2062.3 ± 1001.61, -7378.5 ± 4267.1 ug SRP/m2/d, respectively).The increasingly negative mean flux rates suggest that these coastal wetland sediments can sequester increasing amounts of SRP as surface water concentrations increase.

PHD, Kent State University, 2024, College of Arts and Sciences / Department of Biological Sciences

White-tailed deer are one of the most widespread mammalian herbivores throughout both North and South America. Throughout much of this broad geographic range, deer populations occur at densities that greatly exceed historic estimates. At high densities, deer can negatively suppress juvenile tree growth, inhibit plant regeneration, and alter plant communities which can have long-term cascading effects on small mammals, birds, and plants. Anthropogenic development can help support overabundant deer populations by creating novel foraging opportunities via disturbance regimes and supplementary foraging opportunities. Moreover, apex predators that can help regulate deer populations have been extirpated from many areas, which enables deer populations to reach high densities. The objectives of this dissertation are to identify how white-tailed deer use anthropogenic landscapes at multiple spatial scales, determine the plant chemical properties that influence deer forage selection, and discern how unique predator communities influence the spatiotemporal activity of deer in multiple ecosystems. My first study developed a novel method to measure activity densities of white-tailed deer in multiple habitats that also excluded non-target species from interfering with data collection. In my second study, I measured the activity densities of deer in forest ecosystems that are fragmented by anthropogenically developed meadows. I found that during times of the year when resources are abundant across the landscape, deer preferred meadow patches that contained an abundance of plants that provided deer with a better foraging opportunity than the adjacent forest patches. The third study in this dissertation examined how plant chemistry and volatile scent-cues influence the forage selection of white-tailed deer. During summer I found that deer preferred plants with higher carbohydrate content, likely due to these plants providing fat reserves before winter. Whereas during winter, deer we (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2024, Translational Plant Sciences

Grapevine (Vitis) is the world's most valuable fruit crop, therefore, reducing yield losses to stressors is paramount. Vitis labrusca, a wild North American grapevine, is well adapted to its local environment, exhibiting stout pathogen resistance. Meanwhile, Vitis vinifera grapevine, grown worldwide for winemaking, is native to Europe and is highly susceptible to biotic stressors, particularly fungal and insect pests. V. labrusca has been long utilized in Vitis breeding programs to imbue resistance. Therefore, in this dissertation, we determined if V. labrusca acc. ‘GREM4' was more insect herbivory resistant than V. vinifera cv. ‘PN40024' and investigated the morphological, genetic, and metabolomic factors which may contribute to resistance. In an herbivory choice assay, Japanese beetles (Popillia japonica), a major pest of grapevine, preferred to feed upon ‘PN40024' compared to ‘GREM4'. Further, increased leaf area was consumed on ‘PN40024' compared to ‘GREM4' in a time course (30min, 1h, and 4h) feeding assay. These results reported ‘GREM4' is resistant to Japanese beetle herbivory compared to ‘PN40024'. To determine morphological adaptations that may impact defense, trichomes were next investigated. Trichome densities were greater on ‘GREM4' compared to ‘PN40024' leaves. In trichome-focused herbivory studies, beetles exhibited a preference for lower trichome density sides of leaves and, when provided tissues with equal trichome densities for both ‘GREM4' and ‘PN40024', more leaf tissue was still lost from ‘PN40024' compared to ‘GREM4'. These results report that trichomes play a role in resistance but are not the sole factor. Therefore, we conducted a comparative transcriptomic analysis to identify differences in gene expression upon insect herbivory between the two species. When comparing constitutive expression differences prior to insect herbivory, genes with greater expression in ‘GREM4' were enriched in secondary metabolite biosynthesis while enr (open full item for complete abstract)

Master of Science, The Ohio State University, 2024, Horticulture and Crop Science

Biostimulant products are substances made of microbial and non-microbial ingredients that benefit plant growth and health. They can be used to mitigate soil and water pollution caused by fertilizer use in plant production. Most biostimulant research has focused on agronomic crops grown in soil and little is known about the efficacy of different biostimulants in floriculture crops grown in soilless substrates. Floriculture crops are commonly grown in peat-based substrates, and their market value is dictated by their visual quality. Wilted plants are commonly seen in retail shops, where they may receive infrequent or inadequate irrigation. Water limitation affects visual quality and marketability, therefore causing economic losses for growers. Microbial biostimulants are proven to enhance plant growth and improve crop yield in some cases. These biostimulants, which include plant growth-promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF), have been shown to stimulate physiological processes in plants, leading to increased nutrient availability, and enhanced tolerance to abiotic and biotic stresses such as drought. Humic substances, a non-microbial biostimulant, are extracted from organic matter and have been demonstrated to enhance plant growth by increasing plant height and weight, improving nutrient uptake, and influencing various plant processes such as enzyme activity, protein metabolism, photosynthesis, increasing water and nutrient uptake, as well as improving soil structure. However, the lack of consistent results has limited the adoption of biostimulants by growers. The goal of this study was to identify biostimulants with high efficacy in floriculture crops grown in peat-based soilless substrate. This was accomplished with two objectives: (1) analyze the efficacy of humic substances at enhancing plant growth and health in floricultural crops produced in soilless substrate and (2) determine how pH and fertility levels influence the efficacy of micr (open full item for complete abstract)

Doctor of Philosophy (PhD), Ohio University, 2024, Plant Biology (Arts and Sciences)

Transcription factors involved in regulating plant cell wall biosynthesis are diverse and come from various families, including but not limited to AP2/ERF, MYB, NAC, bZIP, and WRKY. These TFs play crucial roles in modulating the expression of genes responsible for cell wall synthesis, composition, and structure, thereby influencing plant development and responses to environmental stimuli. Using gene association networks (GAN) analysis, four transcription factors co-expressed with cellulose synthases and glycosyltransferases for xylan biosynthesis were identified, namely, Os06g0194000 (OsERF071), Os02g0782700 (OsERF070), Os09g0434500 (OsERF072) from the AP2-ERF family, and Os08g0549000 (OsMYB102) from the MYB family. Loss-of-function allelic mutants were created using CRISPR/Cas9 technology. Allelic mutants that are homozygous and Cas9-free were evaluated morphologically, physiologically, and biochemically in the T2 generation. Mutants in Os06g0194000 (OsERF071) exhibited the most significant alterations compared to the CRISPR control plants, prompting the generation of overexpression lines for this gene to enable a more comprehensive functional analysis of this gene. Mutants lacking OSERF071 were taller plants with larger seed sizes, panicle lengths, thousand grain weights, biological yields, and grain yields compared to the CRISPR control plants, while the opposite phenotypes were observed in overexpression lines. Additionally, the allelic mutants exhibited higher content of lignin in their tissues compared to the control and showed higher expression levels of the OsCesA genes related to secondary cell wall biosynthesis compared to those linked to primary cell wall biosynthesis, suggesting OsERF071 may function as a repressor of lignin biosynthesis during primary cell wall deposition. Taken together, my results suggest that OsERF071 may function as a repressor of secondary cell wall formation in tissues that are dividing and growing. Another gene of interest wa (open full item for complete abstract)

Doctor of Philosophy (PhD), Ohio University, 2024, Plant Biology (Arts and Sciences)

Protein degradation through the Ubiquitin (Ub)-26S Proteasome System (UPS) is a major gene expression regulatory pathway in plants. In this pathway, the 76-amino acid Ub proteins are covalently linked onto a large array of UPS substrates with the help of three enzymes (E1 activating, E2 conjugating and E3 ligating enzymes) and direct them for turnover in the 26S proteasome complex or through autophagy-mediated degradation. The S-Phase Kinase-Associated Protein 1 (Skp1), cullin (CUL)1, and F-box (FBX) protein (SCF) complexes have been identified as the largest E3 ligase group in plants. Since the FBX proteins recognize and determine the specificity of SCF substrates, much effort has made to characterize their genomic, physiological, and biochemical roles in the past two decades of functional genomic studies. The co-immunoprecipitation failed to capture transient interaction while the yeast two-hybrid only test protein interaction in yeast cell instead of plant tissue. Therefore, the sheer number and high sequence diversity of the FBX gene family demands new approaches to uncover unknown functions. In this research, first, from the proteomic level, I developed and tested a proximity labeling and co-immunoprecipitation approach for determining the proteome of active FBX proteins and their associated complexes in Arabidopsis. We demonstrate that ASK1-TurboID is not fully functioning, which led us to discover a novel antagonism between biotinylation and ubiquitylation in regulating protein stability in vivo. This discovery lowers the effectiveness of proximity labeling in ubiquitylation studies. Second, from the FBX level, I characterized a new FBX protein that is involved in reproductive development. The mutant was created using CRISPR/Cas9. And it was confirmed that mutation of this FBX gene impacted seed development. The potential substrates were identified and confirmed using yeast two-hybrid and split-luciferase assay. Third, from the substrate (open full item for complete abstract)

Doctor of Philosophy (PhD), Ohio University, 2024, Molecular and Cellular Biology (Arts and Sciences)

Functional studies of the ubiquitin (Ub)-26S proteasome system (UPS) have demonstrated that virtually all aspects of the plant's life involve UPS-mediated turnover of abnormal or short-lived proteins. However, developmental characterization of the UPS, including in seeds and fruits, remains scarce. Unfortunately, early termination of embryogenesis limits the scope for characterizing the UPS activities in reproductive organs. In this dissertation, I utilized a biochemical approach to tackle the developmental role of UPS in plants, using Arabidopsis thaliana (Arabidopsis hereafter) as a model. The overarching goal of my research is to unravel the molecular mechanisms of UPS underpinning seed development so that new molecular breeding technologies could be developed to promote seed production. First, I systematically compared expression changes of multiple 26S proteasome subunits along with the dynamics of proteasome activity and total protein ubiquitylation in seedlings and developing siliques of Arabidopsis. Because autophagy plays the second largest role in maintaining proteome stability, I parallelly studied three late-limiting enzymes that are involved in autophagy influx. My experiments unexpectedly discovered that, in opposite to the activities in seedlings, both protein and transcript levels of six selected 26S proteasome subunits gradually decline in immature siliques toward maturation while the autophagy influx rises, albeit in a nutrient-rich condition. I also discovered a reciprocal turnover pathway between the proteasome and autophagy. While the autophagy influx is suppressed in seedlings by UPS-mediated degradation of its three key enzymes, transcriptional reprogramming dampens this process in siliques that in turn stimulates a bulk autophagy degradation of proteasomes. Collectively, my discovery about the developmental changes of the UPS and autophagy activities suggests that they relay the proteome homeostasis regulation in early seed development, w (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2024, Horticulture and Crop Science

Soybean, a vital oilseed crop and protein meal source, plays an important role in the global economy and food supply. It serves as a major source of vegetable oil and primary protein for swine and poultry feed due to its unique seed compositions. However, challenges arise from the negative correlation between oil and protein contents, and between yield and protein content, posing challenges to developing cultivars with high yield, high oil, and high protein contents. Despite extensive studies on the biochemistries of these traits, the complexities persist, driving the need for advancements in breeding and biotechnology. Efforts and progress in using genetics and biotechnology to understand and modulate soybean traits were reviewed in Chapter 1. To contribute to such collective efforts, in my study, I utilized breeding and biotechnology techniques to develop genetic resources and tools for characterizing and improving the traits of seed oil and protein contents. In Chapter 2, I examined singleand multiple-trait methods for quantitative trait locus (QTL) analyses using recombinant inbred populations with elite backgrounds. The project revealed that single-trait QTL analysis was sufficient for high-heritability traits like seed oil and protein contents and provided QTLs for marker-assisted selection and possibilities to determine their allelic effects on yield, thanks to the elite pedigree. Candidate genes were identified from the QTLs for functional analysis. The lack of tools for efficient gene characterization in soybean seed traits was addressed in Chapter 3 through a proposed CRISPR/Cas9-mediated gene silencing method via particle bombardment of embryogenic tissues. The approach holds the potential for rapid gene functional characterization by bypassing the need for full plant regeneration. Though the project yielded negative results, most likely due to low transformation frequency in soybean, more optimizations could be tested to improve the too (open full item for complete abstract)

Master of Science (MS), Bowling Green State University, 2024, Geology

Yearly, millions of tons of sediments are dredged from USA lakes and federal navigation channels to maintain the economic activity of ports and harbors. About 1.5 million cubic yards of dredged sediment are excavated yearly from the Western Lake Erie Basin, Ohio. Following the prohibition on dumping dredged material into open water, the State of Ohio recommends finding several beneficial uses for this material, including using the sediment as farm soil amendment. My research examined the health risk assessment of potential heavy metal contamination in specialty crops grown in soils amended with dredged material. The research objectives were to (1) determine the potential bioaccumulation of organic (PAHs) and inorganic (heavy metals) contaminants in specialty crops, (2) determine the expected daily intake of metals, ecological risk coefficient, health risk index, transfer factor, and their implications in soil and human health, and (3) provide insights on ecological and agricultural implications when dredged sediments are used as farm soil amendment. Our soil blends consisted of 100% farm soil, 90% farm soil/10% dredged sediment, and 100% dredged sediment. The ecological risk assessment index (taking into consideration the metal toxicity) indicated that Pb, As, Zn, Cr, Ni, Co, and Cu were below the threshold value of 40 (unitless). Values below 40 represent lower sensitive toxicity to organisms when exposed to the specific metal. Our results indicated a small translocation of Al, Co, Cr, Fe, Mn, Pb, Ni, and Zn into the edible biomass from the mixture soil as reported by the translocation factor. Only arsenic showed enrichment in the edible biomass across all treatments and crops; however, the enrichment decreased as the dredged sediment ratio increased, except for lettuce in the mixture treatment. We also calculated the health risk index that takes into consideration the reference oral dose (maximum exposure with likely no detrimental effects on human health). The a (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2023, Plant Pathology

Phytophthora root and stem rot is one of the top ten most yield-limiting soybean [Glycine max (L.) Merr] diseases in the U.S. and Canada. The causal agent of this disease, Phytophthora sojae (Kaufmann & Gerdemann), is an oomycete (water mold) organism that is often managed by using disease-resistant soybean cultivars containing a single Rps gene to a specific pathotype of the pathogen combined with quantitative disease resistance (QDR). Due to the limitation of the number of effective Rps genes available, as the populations of this pathogen have adapted to these genes, it is a necessity to find new Rps genes and identify perfect markers for QDR genes, which have a smaller effect but can resist all pathotypes of P. sojae, that can be used in the development of modern soybean cultivars. In this dissertation, the main approach for all three chapters is to examine the mechanisms of disease resistance in soybeans towards P. sojae using different forward and reverse genetic approaches. A previous study found more than 100 candidate genes by mapping the expression quantitative disease-resistance loci (eQDRL) from the Conrad × Sloan population. To explore and validate the functions of these genes, a fast neutron (FN) population from the University of Minnesota, derived from soybean cultivar M92-220, with these genes deleted was employed. Thus, the first chapter's first objective was to compare cultivars M92-220 and Conrad at phenotypic and transcriptomic levels for their QDR resistance to determine if the molecular mechanisms associated with the eQDRLs were similar to those previously found in Conrad. Then, the next objective was to explore how the loss of the candidate genes using mutants that were highly susceptible would affect the soybean resistance response following inoculation with P. sojae by examining the three most susceptible FN mutants. Conrad and M92-220 were found to share high levels of QDR in the phenotypic assay as well as having several similar defense-r (open full item for complete abstract)