Master of Science, The Ohio State University, 1961, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2020, Horticulture and Crop Science

In recent years, the North American region has seen increased usage of grafted vegetable transplants to reduce soil-borne disease incidence, increase tolerance to abiotic stress, enhance fruit quality, and increase yields over conventional nongrafted transplants. Grafting itself is a unique agrotechnology that merges a vegetable crop (scion) with the root system of another plant (rootstock) to form one transplant that benefits from both traits. In North America, a recent survey showed nearly 60 million grafted transplants are produced annually for fruiting vegetable crops, including tomato, watermelon, cucumber, pepper, eggplant, and muskmelon. Due to the limited number of nurseries in North America, transplants are commonly shipped 3-5 d to distant producers and have reportedly experienced chilling stress during transportation that reduces transplant quality and may affect post-transplanting performance. However, few studies have explored the specific effects of transport-related chilling stress on seedling quality and post-transplanting development. Using watermelon (Citrullus lanatus), a highly chilling sensitive member of the Cucurbitacea family, we examined effects of acute chilling stress on seedlings quality and post-transplanting development. When grafted and nongrafted seedlings were exposed to 0 - 48 h of 3 °C chilling, we found that seedling quality and post-transplanting development were unaffected by chilling. However, when the chilling temperature was reduced to 1 °C, seedlings exhibited increased visual damage of seedlings with longer durations, decreased chlorophyll fluorescence (Fv/Fm), and increased delays in the number of days it took for plants to reach male and female flower anthesis after transplanting. Nongrafted plants had longer delays in days to flower anthesis than grafted plants, indicating that grafted plants may have been more resistant to chilling or had enhanced flower primordia development that reduced the effects of acute chilling. (open full item for complete abstract)

Committee: Chieri Kubota (Advisor); Joseph Scheerens (Committee Member); Matthew Kleinhenz (Committee Member) Subjects: Agriculture; Horticulture; Physiology; Plant Biology; Plant Sciences

Master of Science (MS), Bowling Green State University, 2020, Biological Sciences

Introduced to the Great Lakes Region from Europe before 1900, invasive Butomus umbellatus (Flowering rush) forms monotypic stands that crowd native species and cover open water systems across Great Lakes shorelines and reservoirs in the northern US. Factors contributing to invasion persistence and impacts on ecosystem function by this species are poorly understood. This study characterizes vegetation and environmental factors at the Ottawa National Wildlife Refuge, which borders Lake Erie, to understand how sediment nutrient levels in watersheds affect B. umbellatus invasion. We hypothesized that increased sediment nutrient levels are important drivers of B. umbellatus invasion success. Sediment nutrient levels, matter, water depth, and vegetation were sampled within 1m2 plots throughout the management units of the marsh complex. Vegetation of B. umbellatus and 18 other species present were harvested or canopy characteristics measured to estimate biomass. B. umbellatus was the most abundant of all identified emergent invasive species found, occurring at 55 % of the surveyed plots. B. umbellatus rhizome bud count averaged 509 per plot, with a range of 0 – 2760 buds. While sediment nutrient analysis of nitrogen and phosphorus showed heterogeneity within and across management units, nutrient levels did not predict B. umbellatus abundance. However, B. umbellatus biomass decreased with increasing community biomass. Vegetative propagule production via rhizome buds decreased with increased nutrients and increased community biomass. B. umbellatus was found to have a wide range of nitrogen and phosphorus in leaf tissue, and 2 – 4 times more average phosphorus than all analyzed native species. This data will assist managers in identifying timing and approaches for controlling this invasive species and restoring wetland biodiversity.

Committee: Helen Michaels PhD (Advisor); Andrew Gregory PhD (Committee Member); Kevin McCluney PhD (Committee Member); Angélica Vázquez-Ortega PhD (Committee Member) Subjects: Biology

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2017, Biological Sciences

Transport is an essential component of the regulation of polyamines, but to date only one family of Polyamine Uptake Transporters (PUTs) have been characterized in plants, and their impact on polyamine regulation has not been defined. Here we show that knockout mutants of put5 in A. thaliana, promote early flowering and result in plants with smaller leaves, thinner stems, and fewer flowers. In contrast, heterologous expression of the rice gene OsPUT1 in A. thaliana using the Put5 promoter at 22°C produced plants with larger leaves, a two-week delay of flowering and more flowers and siliques. Similar effect on leaf size, flowering time and number of siliques also were observed in transgenic plants with constitutive expression of OsPUT1 or OsPUT3. The delay of flowering was associated with significantly higher levels of spermidine and spermidine conjugates in the leaves prior to flowering. These experiments outline the first genetic evidence for the control of flowering by polyamines. How polyamine levels control the timing of flowering at a molecular level is not yet known, but this delay of flowering has been demonstrated to be upstream of the stimulation of flowering by the gibberellin and temperature sensitive response pathways. It has been assumed that there exists a single cytosolic pathway for the synthesis of putrescine in A. thaliana. Here we show that A. thaliana and Glycine max, have a chloroplastlocalized putrescine biosynthetic pathway. This pathway comprises of arginine decarboxylase and an agmatinase to synthesize putrescine from arginine. Analysis of expression data suggests that it is the major route of putrescine synthesis in response to stress signals. Since compartmentation of polyamines has been demonstrated to play an essential role in polyamine homeostasis, the identification of other types of polyamine transporters is a critical knowledge gap. We show here that PDR11 is an important long-distance transporter of polyami (open full item for complete abstract)

Committee: Paul Morris (Advisor); Andrew Torelli (Committee Member); Vipa Phuntumart (Committee Member); Scott Rogers (Committee Member); George Bullerjahn (Committee Member) Subjects: Biology; Molecular Biology; Plant Biology

Doctor of Philosophy, The Ohio State University, 2012, Evolution, Ecology and Organismal Biology

Extensive gene flow between cultivated plants and wild relatives can be of concern because crop alleles may persist in wild populations and dilute the native gene pool or confer traits that enhance lifetime fitness, perhaps increasing the wild populations' tendency toward weediness. Switchgrass (Panicum virgatum L.) is a warm-season North American perennial that is widely planted for forage and soil conservation. Certain switchgrass cultivars have undergone a limited degree of breeding for use as a biofuel crop and could be planted on a large scale in the near future. However, very little research has examined the potential impact that mass plantings will have on wild populations. The goals of my research were to examine the potential for crop-to-wild gene flow and associated fitness effects by studying ploidy levels, flowering phenology, fitness components, and volunteer establishment. First, I determined ploidy levels of eight wild populations in Ohio and three in Illinois. Eight populations were tetraploid (4x), one was octaploid (8x), and two had mixed ploidy. In 2008 and 2009, I planted two common garden experiments at Ohio State University in Columbus, Ohio, with plants from three wild Ohio populations and seven cultivars: Kanlow (4x), Advanced Kanlow (4x), Summer (4x), Shawnee (8x), Trailblazer (8x), and two Advanced Octaploid strains (8x). I then compared the height and numbers of florets, filled seeds, and shoots of two- and three-year-old plants. Ohio native biotypes were similar to each other in all measured characteristics. Flowering times of native biotypes and the cultivars overlapped, but the degree of overlap varied, with Kanlow-type plants flowering much later than the rest. Kanlow-type plants were taller and produced four times as many florets as native biotypes, while Kanlow and Summer produced twice the number of filled seeds as the native biotypes. All other cultivars were similar to the native plants, except one Advanced Octaploid strain, which (open full item for complete abstract)

Committee: Allison Snow PhD (Advisor); Karen Goodell PhD (Committee Member); Kristin Mercer PhD (Committee Member); Maria Miriti PhD (Committee Member) Subjects: Ecology; Plant Sciences

Doctor of Philosophy, The Ohio State University, 2011, Plant Cellular and Molecular Biology

For successful reproduction, angiosperms must form fertile flowers in the appropriate positions and at the appropriate time. The timing of flower formation is especially important for annual plants, such as the model Arabidopsis thaliana used in this study. Floral fate is controlled by a set of genes termed floral meristem identity genes, the most important of which is the plant-specific transcription factor LEAFY (LFY). LFY's function can be divided into two phases, which are both temporally and genetically separable. In the first phase, LFY controls the expression of genes, such as other floral meristem identity factors, that control phyllotaxy and organ number. In the second phase, LFY is necessary for activation of the floral organ identity genes, which are responsible for differentiating the organs of the flower from each other. LFY is a transcription factor that does not have transcriptional activation or repression activities on its own and therefore must act in multiprotein complexes. Region- and stage-specific control of LFY target genes is provided by co-factors. However, until very recently little information was available about other factors that are present in such LFY-containing complexes. This work aims to identify components of LFY transcriptional complexes and characterize their function(s) in flower development. We demonstrate that LFY acts as a homodimer, which is mediated by a domain that is conserved across land plant LFY orthologs, suggesting that dimerization is important for the function of the entire LFY family. We report the isolation of putative LFY-interacting proteins and their preliminary characterization. Finally, we present an in depth analysis of one such LFY-interacting protein, FRIEND OF LEAFY1 (FOL1), which is a novel C2H2 zinc finger transcription factor. FOL1 is expressed in inflorescence meristems, floral meristems, male and female gametophytes and in embryos. Based on gain of function and loss of function analyses, FOL1 ap (open full item for complete abstract)

Committee: Rebecca Lamb PhD (Advisor); David Somers PhD (Committee Member); Iris Meier PhD (Committee Member); Patrice Hamel PhD (Committee Member) Subjects: Molecular Biology; Plant Biology

Doctor of Philosophy, The Ohio State University, 2008, Plant Pathology

The rice E3 ubiquitin ligase SPL11 was previously characterized as a negative regulator of both programmed cell death (PCD) and broad-spectrum disease resistance, suggesting its putative role in the ubiquitination/protein degradation machinery, or other ubiquitin-mediated pathway. A novel role for SPL11 in flowering time control was identified via its interaction with SPIN1 (SPL11-interacting protein 1), a nuclear, RNA/DNA binding protein and STAR (signal transduction and activation of RNA) family member. In addition to ubiquitinating SPIN1 in vitro, SPL11 downregulated the expression of Spin1 during the light phase to promote flowering. Overexpression of Spin1 inhibited flowering in both short and long days and affected Spl11 expression as well. These results link ubiquitination and RNA metabolism in flowering time control. Isolation of spl11-mediated cell death suppressor mutants (sds) provided additional evidence that PCD is under genetic control in the spl11 mutant. The sds mutants showed various levels of cell death suppression, had wild-type levels of resistance to bacterial blight, and repressed the elevated defense gene expression of spl11. The delayed flowering phenotype of spl11 in long days was partially repressed in sds plants independently of cell death suppression levels, suggesting that the PCD and flowering pathways may partially overlap. Another RNA binding protein was identified in a yeast two-hybrid screen designed to isolate SPIN1-interacting partners. Rbs1 (RNA binding and SPIN1-interacting 1) was shown to promote cell death when overexpressed in both Nicotiana benthamiana and rice. Rbs1 was upregulated in lesion mimic-expressing leaves of spl11, suggesting that it may contribute to the cell death phenotype. RBS1 may constitute a link between the flowering and PCD pathways controlled by SPL11. The data presented here provides the first evidence of a link between cell death control and the switch to reproductive development in plants.

Committee: Guo-Liang Wang PhD (Advisor); David Mackey PhD (Committee Member); Biao Ding PhD (Committee Member); Terrence Graham PhD (Committee Member) Subjects: Botany; Molecular Biology; Plant Pathology

Doctor of Philosophy, The Ohio State University, 2007, Plant Biology

Recent studies have indicated that the plant nuclear pore complex (NPC) plays important roles in several processes, including plant-microbe interactions, hormone signaling, and stress tolerance. However, both the protein components of and the various activities associated with the plant NPC are poorly understood. Here, I focused on analyzing two plant NPC-associated proteins located at opposite sides of the NPC. First, I identified an Arabidopsis protein called NUCLEAR PORE ANCHORE (NUA) as the homolog of mammalian Tpr, yeast Mlp1/Mlp2, and Drosophila Megator, long coiled-coil proteins associated with the inner basket of the NPC and involved in mRNA export, telomere organization, spindle pole assembly, and unspliced RNA retention. Four T-DNA insertion mutants of nua were identified, which comprise an allelic series with increasing severity for several correlating phenotypes, such as early flowering, increased abundance of SUMO conjugates, and altered expression of flowering regulators. Together with the genetic interaction between NUA and ESD4 (a SUMO protease), these data suggest that NUA is a conserved component of NPC-associated steps of sumoylation in plants. Defects in SUMO homeostasis affect signaling events of flowering time regulation and additional developmental processes. Secondly, I identified a plant-specific family of NPC-associated membrane proteins, WPP domain-interacting proteins (WIPs), which bind to the WPP domain of Arabidopsis Ran GTPase-activating protein RanGAP and are responsible for the NPC-association of RanGAP. Mammalian RanGAP targeting to NPC during interphase and to kinetochores during mitosis requires interaction of its sumoylated C-terminal domain with nucleoporin Nup358/RanBP2. In contrast, I demonstrated that binding to the coiled-coil domain of WIP is a plant-unique mechanism for targeting RanGAP to the NPC. Moreover, I presented data to suggest that the targeting of plant RanGAP appears to involve different mechanisms during differ (open full item for complete abstract)

Committee: Iris Meier (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2006, Horticulture and Crop Science

In plants, the cryptochrome gene family is responsible for mediating photomorphogenic processes in response to blue light. Here, RT-PCR and RACE techniques were used to clone CRY1 and CRY2 from Nicotiana sylvestris. In a reverse genetics approach, antisense and overexpression constructs for each gene were then used to transform N. sylvestris and N. tabacum cv. Maryland Mammoth plants by inoculating sterile leaf explants via Agrobacterium tumafaciens. RT-PCR results indicate that for N. sylvestris, one CRY1 overexpression line (S1-6) and one CRY2 overexpression line (NsS2-2) were produced. Two CRY1 overexpression lines (S1-3 & S1-4) and two CRY2 overexpression lines (NtS2-2 & S25) were generated in N. tabacum cv. Maryland Mammoth. Western analysis confirmed overexpression of CRY1 in S1-3, S1-4 and S1-6 plants. To characterize the transgenic plants at a functional level, hypocotyl length and leaf chlorophyll content was measured. Major reductions in hypocotyl elongation and increased in chlorophyll were observed in all of the CRY1 and CRY2 overexpression plants in both species. Also in both species, the effect of CRY1 and CRY2 overexpression on flowering time was examined. In marginally inductive and in naturally changing photoperiods, the appearance of visible flower buds occurred sooner than in wild type plants. Unexpectedly, flowering occurred in non-inductive conditions, indicating that the photoperiodic timing mechanism of these obligate species is influenced in part by CRY1 and CRY2. Additional effects on vegetative growth and leaf development were explored. Aspects specific to sun leaf morphology, including increased thickness of palisade parenchyma and higher stomatal density were seen in CRY1 overexpression plants that were grown in low light conditions. Finally, the N. sylvestris CRY1 and CRY2 overexpression constructs were used to generate transgenic petunia plants. Compared to wild type the growth rate of CRY1 overexpression plants was dramatically reduced (open full item for complete abstract)

Committee: James Metzger (Advisor) Subjects:

Master of Science (MS), Bowling Green State University, 2012, Geology

Predicting and mapping invasive wetland plant species is an important process for future management decisions and strategies. Controlling and mapping such plant species requires robust methods that are applicable at different ecological scales to map and monitor their spread. In particular, this study tested the feasibility of classification tree analysis (CTA) by using a high resolution Applanix 439 Digital Sensor System (DSS) aerial imagery (< 20 cm) and linear spectral unmixing (LSU) analysis by using Landsat Thematic Mapper (TM) data to produce different distribution maps of invasive flowering rush (Butomus umbellatus L.) potential in the Ottawa National Wildlife Refuge (ONWR) wetlands, in Northwest Ohio. The classification accuracy from CTA maps derived from different splitting rules was evaluated by kappa statistics. The overall accuracy within the different runs varied between 35 to 56 % while the “Gini” splitting rule had the best performance. The endmembers from the best CTA performing map were utilized by the LSU method for estimating sub-pixel endmember fractions at a broader geographical scale. The results derived from the aerial imagery were slightly better than those from the Landsat imagery, as the goodness of fit between the flowering rush fraction map and the data measured in the field was lower. This study was intended to demonstrate the potential for flowering rush mapping over larger area using knowledge developed from smaller geographical scale using high resolution imagery. Results indicate that both methods show promising results for the prediction of flowering rush, but additional research that encompass different field data collection techniques, datasets of imagery and modeling methods need to be explored.

Committee: Peter Gorsevski (Advisor); Helen Michaels (Committee Member); Enrique Gomezdelcampo (Committee Member) Subjects: Remote Sensing