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Over the last year the Faculty of Biological Sciences at East Tennessee State University have been evaluating core coursework for biology majors and working towards transforming teaching approaches to enhance the undergraduate learning experience and improve overall learning outcomes among our graduates. Our institution serves a large population of low-income and first generation college students living and working in Southern Appalachian region. The most important motivation behind transformation is to provide highly-qualified graduates who can contribute to the economic development and growth of the area. In focusing on traineeship and skills development of graduates, we adopted an action plan focused on students, faculty, and curriculum development. Under the leadership of the chair, productive and positive discourse on curricular goals among faculty has shaped well-defined core concepts and competencies we envision for our graduates. Several faculty are using research-based methods to improve the core curriculum and to infuse best teaching practices in the classroom. The strengths of our program lie in having demonstrated success in providing students with authentic research experiences in upper-level courses. We are working towards infusing these ideas and skills-development into the introductory core curriculum in hopes of increasing the number of undergraduates who pursue professional graduate degrees. Our hopes are that investing in transformative changes in the classrooms and providing high-quality educational opportunities will increase the time our students devote to STEM career development and ultimately result in large-scale economic development on the Southern Appalachian community.

Taxonomic recognition of Solidago lancifolia (Torrey & A. Gray) Chapman and diagnostic characters used for identification have vacillated among floras and treatments. Fieldwork greatly expanded the specimen base in US herbaria, extended the known range in Tennessee, and identified new occurrences in North Carolina and Virginia. A morphometric analysis of herbarium specimens identified qualitative and quantitative characters unambiguously diagnostic for S. lancifolia. These included the presence of glands on the phyllaries; long, wide-diameter rhizomes; thick stems; and a long pappus on disk florets. Using these characters, an analysis of herbarium specimens corrected widespread misidentifications and showed that S. lancifolia is strictly endemic to a 12-county region encompassing the high elevations (> 1,400 m) in the mountains of southwestern Virginia, northwestern North Carolina, and northeastern Tennessee. Based on the narrow geographic range and small population sizes, prior uncertainty of the taxonomic validity and geographic range of S. lancifolia has been resolved. Consequently, for North Carolina and Virginia, the recommendation is for an upgrade in the conservation status to “Endangered” with a state rank of “S1.” Moreover, the narrow geographic range and small number of populations are consistent with a global rank of “G2” and consideration as a federal Species of Concern.

Unequal sex ratios are widespread in dioecious plants and understanding their cause is important to understanding fundamental aspects of their population dynamics, and yet what causes biased sex ratios in plants is still poorly understood. Competition experiments have been used in plants to predict the outcome of species interactions, but they have rarely been used to help explain sex ratio bias. This study used a response surface competition design to measure the relative competitive abilities of the sexes of the bryophyte Marchantia inflexa (a thallus liverwort of Marchantiaceae) to predict the outcome of competition before the onset of sexual reproductive structures. In bryophytes, dioecy and sex ratio bias is especially common, making them effective organisms for studying sex ratio bias. Given the frequency of female bias in bryophytes, the hypothesis was that females will show a higher competitive ability relative to males. The experiment was conducted in greenhouse conditions at several densities and proportions over the course of seven months. As individuals grew and formed clumps, identities were tracked, and growth measurements were made using photographs and computer imaging software. Both sexes grew on average 41% more with the opposite sex relative to their single-sex cultures. A model predicting future sex ratios showed coexistence between the sexes and predicted a male biased sex ratio of 3.2 males to 1 female. A trade-off was observed for males where single-sex cultures contained more asexual structures than mixed-sex cultures and the reverse for growth rate. Higher levels of asexual reproduction in males in single-sex cultures might be selected for to increase male dispersal for a higher probability of encountering females. This pattern was not found for females. The overyielding results suggest an interaction effect may exist due to niche differentiation between the sexes. In addition, the results suggest that in some dioecious plants a change in sex ratio can occur before differences in their allocation to sexual reproduction.

Unleached root-zones represent an environmental ideal by eliminating wasteful leaching of nutrients and water. NASA grows plants in space in unleached root-zones, incorporating polymer-coated fertilizer (PCF) into a ceramic media (Turface or Profile). However, lack of growth productivity in space has led to the need for research to improve the nutritional and physical environment of the root-zone, which is the objective of this research. PCF types are diverse in release characteristics and the effects of temperature and substrate water content have not been well characterized. In spite of widespread use, studies on chemical properties and applied studies to verify soil physical models of ceramic media have been limited. We quantified the release rate of three widely-used types of PCF (Polyon, Nutricote, and Osmocote) in water and in sand over a wide range of temperature (5, 15, 20, 30, and 40ºC). Results indicated that substrate water content had a minimal effect on release rates. Nutricote fertilizers were the most consistent in releasing individual nutrients with temperature and over time. Polyon fertilizers had the slowest release rates relative to the manufacturer's specifications, but a relatively linear response to temperature. Osmocote fertilizers rapidly released nutrients at all temperatures. For more efficient PCF use, we present a comprehensive model that couples models to predict plant growth and PCF nutrient release rates. This model is based on phosphorus release, the nutrient found to be limiting to PCF-fertilized plants. The efficacy of the model to accurately predict PCF application rates was verified with a growth trial. In ceramic media, relative media-sorbed nutrient concentrations were highly variable from bag to bag. Excesses of manganese, boron, magnesium, and sulfur in the media induced nutrient imbalances in plant tissues. Rinsing and soaking procedures on the media helped mitigate these nutrient imbalances. Ceramic media also interacted with added fertilizer ions. Copper, phosphorus, and zinc ions were largely removed from solution by these interactions. We also used plants to extract water from root-zones of ceramic media to characterize plant-available water and water supply dynamics. The results suggest that soil physical models may be used to predict plant-available water in ceramic media.

Arceuthobium americanum is a vascular plant which is parasitic upon Pinus contorta var murrayana. Its documented effects include reductions in host growth, vigor and wood quality. The specific physiological changes that occur in the host are, for the most part, unknown.

Morella cerifera is a rapidly expanding native shrub on the Virginia barrier islands which displaces other native coastal species and may interrupt normal sediment dynamics. Barrier islands are considered stressful environments with low nutrients, high solar load, and frequent drought and salt exposure; facilitation often dominates in stressful environments according to the Stress Gradient Hypothesis. The objective of this project was to understand the importance of species interactions with grasses on the growth and physiology of M. cerifera at the seedling life stage through both field and lab experiments. Grasses provided ~1.3°C insulation to shrubs during winter freeze events and a freezing threshold for M. cerifera seedlings was experimentally found between -6°C and -11°C. Seedlings competed for light with grasses during warm months and grew more where grasses were clipped, revealing a tradeoff between winter insulation and summer light competition. M. cerifera shows evidence of ecosystem engineering at the seedling stage by significantly reducing summer maximum temperatures. This enables rapid expansion of M. cerifera across the landscape. As M. cerifera expands, island migration is altered, leading to decreased island stability and increased erosion. Although seedlings are small and relatively vulnerable, this life stage appears to have significant implications for the ecosystem trajectory and stability of the Virginia barrier islands.

Fusarium graminearum is one of the most problematic phytopathogens in US agriculture. This fungus causes head blight, foot rot, and damping off on wheat and barley. The infection lowers the grain yield and causes contamination of the grain product with mycotoxins. Effective control measures are lacking, and new fungicides that kill F. graminearum but remain safe and economical to use are needed. Newly synthesized aminoglycosides (JL22, JL38, JL39, JL40, NEOF004, NEOF005), classic aminoglycosides (amikacin, gentamicin, kanamycin A, kanamycin B, neomycin, and ribostamycin), and a lipopeptide, syringomycin E (SRE), were studied to determine their antifungal potential to control F. graminearum. Aminoglycosides are protein synthesis inhibitors that mainly target bacteria, but a few were recently observed to kill fungi. They consist of an aminocyclitol ring bound with two or more amino sugars. Novel aminoglycosides were recently synthesized using novel glycodiversification synthetic schemes involving the replacement of the original amino sugars with unusual amino sugars. SRE is an antifungal lipodepsinonapeptide produced by Pseudomonas syringae pv. syringae. This bacterium is an opportunistic pathogen in a wide range of plant species and produces several fungicidal lipopeptides. SRE forms pores on fungal plasma membrane and causes ion fluxes. An enhancement of its antifungal activity is reported in the presence of rhamnolipid surfactants. The antifungal activities of various aminoglycosides, SRE, and a SRE-rhamnolipids mixture were determined against F. graminearum by measuring in vitro minimum inhibition concentrations (MICs) and in planta lesion area and chlorosis development using a leaf infection assay protocol. It was determined that using Tween® 20 at 0.2 % (v/v) concentration in the leaf infection assay promotes lesion development by F. graminearum with minimum phytotoxicity. In vitro, SRE, SYRA, and synthetic aminoglycoside JL38 showed the best antifungal activities. With the in planta assay, all three antifungal agents prevented infection by F. graminearum. However, inconsistent phytotoxicities were observed with SRE and SYRA that were influenced by the Tween® 20 surfactant included in the leaf infection assay. How Tween® 20 induces these phytotoxic inconsistencies is not known.

The period between pollination and fertilization, or the progamic phase, is a critical life history stage in seed plants and innovations in this life history stage are hypothesized to have played an important role in the diversification of flowering plants. Over the course of this dissertation research, I investigated programic phase development in Nymphaeales (water lilies), an ancient angiosperm lineage that diverged from the basalmost or next most basal node of the angiosperm phylogenetic tree and that is represented in the oldest angiosperm fossil record. I used field experiments and microscopy to document pollination biology, breeding system, and reproductive developmental traits in two families of Nymphaeales: Cabombaceae (Brasenia, Cabomba) and Hydatellaceae (Trithuria). Nymphaeales exhibits considerable variation in reproductive traits and true carpel closure, wind-pollination, and a primarily selfing breeding system have arisen independently in the lineage. Pollen tube pathway length, timing of stigma receptivity, and pollen tube growth rates are conspicuous traits that have undergone considerable modification in concert with shifts in pollination biology and breeding system. Post-pollination developmental processes in Nymphaeales appear to experience selective pressures similar to those experienced by more derived angiosperms and to evolve in similar ways. Nymphaeales also exhibits traits, such as accelerated pollen tube growth, callosic pollen tube walls, and the formation of callose plugs, that are almost certainly plesiomorphic in angiosperms and may have facilitated modification of carpel structure and progamic phase ontogenies. The finding that pollen tube traits that underlie developmental flexibility were already in place before the divergence of Nymphaeales supports the hypothesis that innovations in male gametophyte development were instrumental in facilitating early angiosperm diversification.

Genetic engineering is important to enhance crop characteristics and certain traits. Genetically engineered crop cultivation brings environmental and ecological concerns with the potential of unwanted transgene escape and introgression. Transgene escape has been considered as a major environmental and regulatory concern. This concern could be alleviated by appropriate biocontainment strategies. Therefore, it is important to develop efficient and reliable biocontainment strategies. Removing transgenes from pollen has been known to be the most environmentally friendly biocontainment strategy. A transgene excision vector containing a codon optimized serine resolvase CinH recombinase (CinH) and its recognition sites RS2 were constructed and transformed into tobacco (Nicotiana tabacum cv. Xanthi). In this system, the pollen-specific LAT52 promoter from tomato was employed to control the expression of CinH recombinase. Loss of expression of a green fluorescent protein (GFP) gene under the control of the LAT59 promoter from tomato was used as an indicator of transgene excision. Efficiency of transgene excision from pollen was determined by flow cytometry (FCM)-based pollen screening. While a transgenic event in the absence of CinH recombinase contained about 70% of GFP-synthesizing pollen, three single-copy transgene events contained less than 1% of GFP-synthesizing pollen based on 30,000 pollen grains analyzed per event. This suggests that CinH-RS2 recombination system could be effectively utilized for transgene biocontainment. A novel approach for selective male sterility in pollen was developed and evaluated as a biocontainment strategy. Overexpression of the EcoRI restriction endonuclease caused pollen ablation and/or infertility in tobacco, but exhibited normal phenotypes when compared to non-transgenic tobacco. Three EcoRI contained 0% GFP positive pollen, while GFP control plants contained 64% GFP positive pollen based on 9,000 pollen grains analyzed by flow cytometry-based transgenic pollen screening method. However, seven EcoRI events appeared to have 100% efficiency on selective male sterility based on the test-crosses. The results suggested that this selective male sterility could be used as a highly efficient and reliable biocontainment strategy for genetically engineered crop cultivation.