Department: Botany ![[clear]](close-x.png "Remove this limiter")
81 matches in the database.
These are records: 1 - 30.
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1.
Ahlquist, Tia Kay.
A Morphological Analysis of the Trifolium amabile Kunth Species Complex in North America.
Degree: MS, Botany, 2012, Miami University
► The Trifolium amabile Kunth species complex (Fabaceae) is a group of New…
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▼ The Trifolium amabile Kunth species complex (Fabaceae) is a group of New World of clovers ranging from the mountains of southern Arizona of the United Sates, throughout the mountainous regions of Central America, and continuing southward to northern-central Argentina. As currently circumscribed in Zohary and Heller’s monograph (1984), this group is comprised of a singular species, T. amabile, and five varieties. Specimens from herbaria worldwide have been utilized for a morphometric examination to determine specific boundaries for the North American members of this complex. In this paper nine species, including four new species, are recognized as distinct and described. These species include: Trifolium amabile, T. blanquitum sp. nov., T. cognatum, T. goniocarpum, T. hickeyi sp. nov., T. laciae sp. nov., T. lozani, T. mexicanum, and T. sonoranensis sp. nov.
Advisors/Committee Members: Vincent, Michael A.
Subjects: Botany
Keywords: Trifolium amabile; Trifolium; taxonomy
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2.
Ash, Jeremy D.
Assessment of sustainable leaf harvest from the understory palm, Chamaedorea radicalis.
Degree: MS, Botany, 2007, Miami University
► Long-term demographic studies of plant species subjected to harvest for non-timber forest…
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▼ Long-term demographic studies of plant species subjected to harvest for non-timber forest products can potentially be used to derive methods to rapidly assess harvest sustainability. Here I develop a rapid assessment protocol for Chamaedorea radicalis, a palm in northeastern Mexico, the leaves of which are harvested for use in the international cut-greens industry. I developed a multiple regression model relating the finite rate of population growth (lambda) to vegetative, reproductive and population-level variables from a five-year demographic study across leaf harvest treatments in the El Cielo Biosphere Reserve, Mexico. The strongest predictors of lambda were the proportion of seedlings in a population and the total adult fecundity. However, the application of the model to 21 sampled populations throughout El Cielo generated estimates of lambda with prediction intervals bracketing the net replacement rate of lambda=1. Practical implementation of this protocol is thus limited by the imprecision of the estimates of lambda.
Advisors/Committee Members: Gorchov, David L.
Keywords: El Cielo Biosphere Reserve; Tamaulipas, Mexico; matrix model; Life Table Response Experiment; Non-timber forest product
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3.
ATHY, ERIN R.
EFFECTS OF MULCH ON TREE SEEDLING SURVIVAL AND EDAPHIC CONDITIONS ON A CLOSED OHIO LANDFILL.
Degree: MS, Botany, 2003, Miami University
► Landfills are ideal locations for short-rotation forestry, tree-based bioremediation, and wildlife habitat…
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▼ Landfills are ideal locations for short-rotation forestry, tree-based bioremediation, and wildlife habitat reconstruction. However, tree survival is reduced by harsh growing conditions and poor soil quality. This study was designed to determine survival of various tree seedlings and effects of different mulch types and depths on edaphic properties, germination, and herb emergence on a closed landfill. In spring of 2002, five species of hardwood tree seedlings were planted in clustered plots, which received a mulch treatment. The status of each seedling and soil properties were recorded for two growing seasons. Survival and growth were species dependant. Fraxinus had the highest survival rate (70%) while Prunus performed the worst (7%). Leaf mulch (15 cm deep) increased organic matter and modified various edaphic properties after the second growing season. Mulch treatments did not significantly affect seed germination rates or aboveground herbaceous biomass when compared to non-mulched controls. Practical applications of these results are discussed.
Advisors/Committee Members: KEIFFER, CAROLYN H.
Keywords: RESTORATION ECOLOGY; LANDFILL; MULCH
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4.
Barker, Michael Shane.
A Revision of Caribbean Adiantopsis.
Degree: MS, Botany, 2003, Miami University
► Adiantopsis is a tropical cheilanthoid fern genus that unlike other cheilanthoid genera,…
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▼ Adiantopsis is a tropical cheilanthoid fern genus that unlike other cheilanthoid genera, is unstudied. The present work evaluated the taxonomy and relationships among Caribbean Adiantopsis . A total of 136 characters were examined on approximately 500 herbarium specimens. This study identified nine Caribbean Adiantopsis species, of which three are newly discovered. Additionally, an intriguing pattern of morphological and reticulate evolution was revealed by the analyses. Adiantopsis consists of three different lamina morphologies; palmate, pedate, and pinnate. The two pedate taxa are hypothesized to be fertile allotetraploid derivatives of the single palmate A. radiata and two different pinnate taxa. In this regard they parallel the origin of the South American A. × austropedata . Thus, it appears that the pedate lamina morphologies in Adiantopsis are convergent, having originated multiple times via hybridization. This study provides testable hypotheses of morphological and reticulate evolution in the genus and presents a novel view of Caribbean Adiantopsis .
Advisors/Committee Members: Hickey, R. James.
Subjects: Biology, Botany
Keywords: Pteridophytes, Adiantopsis , Cheilanthoids, Taxonomy, Reticulate Evolution
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5.
Bartuszevige, Anne M.
THE INFLUENCE OF HABITAT SUITABILITY, LANDSCAPE STRUCTURE, AND SEED DISPERSERS ON INVASION OF AN EXOTIC PLANT SPECIES, LONICERA MAACKII (RUPR) HERDER, AMUR HONEYSUCKLE.
Degree: PhD, Botany, 2004, Miami University
► Although invasive plants are recognized as a major ecological problem, little is…
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▼ Although invasive plants are recognized as a major ecological problem, little is known of the relative importance of plant community characteristics versus landscape context in determining invasibility of communities. For animal-dispersed plants, invasion patterns may be influenced by landscape features that influence movement of seed dispersers. In this study, I investigated the relative importance of community and landscape features in the invasion of Lonicera maackii in woodlots in southwest Ohio. I also determined the bird species responsible for seed dispersal of this plant and the timing of fruit loss. I regressed Lonicera maackii presence and density separately against community and landscape characteristics quantified from 30 woodlots. Presence of L. maackii was significantly negatively associated with distance from the nearest town. Density of L. maackii was significantly positively related to amount of edge in the landscape and significantly negatively related to total tree basal area, number of native woody species, and sapling shade tolerance index. Analysis of seeds recovered from feces of birds mist-netted near fruiting L. maackii shrubs revealed four native and one exotic bird species dispersed viable L. maackii seeds. I performed feeding trials to determine the effect of gut passage on L. maackii seeds. Germination was inhibited by passage through Cedar Waxwings, but not through American Robins. Radio-tracked American Robins moved mostly along woodlot edges and fencerows, leading me to project that most viable seeds would be defecated in such habitats. I used fruit traps to determine the timing of fruit loss (abscission + removal). Fruit loss from L. maackii shrubs was significantly related to winter temperature and precipitation. Fruit removal by frugivores was greater in cold temperatures and low precipitation. In general there was no effect of temperature and precipitation on fruit abscission. This study shows that L. maackii invades through expansion of multiple foci and is facilitated by bird dispersal. Through bird dispersal, L. maackii is able to navigate the landscape and invade new suitable habitats. The interaction of L. maackii and American Robins involves a positive feedback loop, in which seeds are defecated in highly suitable habitat where the birds also forage on L. maackii fruits.
Advisors/Committee Members: Gorchov, David L.
Subjects: Biology, Ecology
Keywords: Lonicera maackii; Landscape features; Connectivity; Seed dispersal; Fruit abscission; Frugivory; Invasive species
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6.
Bauman, Jenise M.
ECTOMYCORRHIZAL COMMUNITIES ASSOCIATED WITH RESTORATION PLANTINGS OF AMERICAN CHESTNUT (CASTANEA DENTATA) SEEDLINGS ON OHIO MINE LANDS: PLANTING METHODOLOGIES TO PROMOTE ROOT COLONIZATION.
Degree: PhD, Botany, 2010, Miami University
► Ectomycorrhizal (ECM) fungi form mutualistic symbioses with woody trees and shrubs allowing…
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▼ Ectomycorrhizal (ECM) fungi form mutualistic symbioses with woody trees and shrubs allowing for an increase in water and nutrient uptake. The absence of these microbes may contribute to seedling mortality and the arrested succession observed in barren landscapes and grasslands in Ohio. The central objective of this dissertation was to develop planting methodologies to accelerate succession by woody tree establishment; specifically by maximizing the effectiveness of ECM root colonization. American chestnut and chestnut hybrids were used to describe host response to root colonization in both abandoned and reclaimed mine sites in central Ohio. A set of experiments was designed to test the influence existing vegetation, site selection, soil modification, and the addition of ECM inoculum may have on seedling establishment in former mine sites. I investigated the influence existing vegetation had on germination and survival of chestnut in an abandoned mine site. Three areas were assessed: center, areas that had monoculture plantings of Pinus virginiana, and forest edges. Small monoculture plantings of pines had a greater facultative effect on the germination and survival of deciduous hardwood seedlings than did the forest edge; presumably by alleviating negative density-dependent factors. Importantly, pine and chestnut shared ECM symbionts. This provided an ECM propagule source to chestnut and resulted in an increase in seedling biomass, which may have contributed to the increase in survival after two years. In reclaimed mines, heavy equipment and the use of exotic species as cover crops have resulted in severely compacted soils with aggressive herbaceous canopies. I evaluated surface soil treatments, which included deep ripping and traditional plow and disking, as ways to remediate these mine lands in arrested succession. These methods were very successful in alleviating compaction and disturbing the aggressive herbaceous canopy, thereby promoting chestnut seedling establishment. In addition, mechanical soil treatments resulted in seedlings with significantly more ECM root tips with greater species richness. Further, there was a significant interaction between soil treatment and ECM colonization. Chestnut seedlings naturally colonized by ECM fungi in treatment plots had the greatest shoot production when compared to their non-ECM counterparts. I assessed the field performance of five different ECM fungi inoculated on hybrid chestnut. These ECM species did not persist on chestnut after one year in the field or impede natural root colonization of native fungi. However, the presence of ECM inoculum greatly contributed to the survival of hybrid chestnut seedlings. Therefore, introduced inoculum that was present in the very early stages of outplanting had persisting effects with regard to seedling development in the field, even if the original inoculum did not persist. Important to chestnut restoration was that native ECM fungi colonized chestnuts and resulted in an increase in seedling growth. Soil variables and ECM community data were used to determine the influence the soil environment has on ECM community composition and root colonization of American chestnut. Differences in ECM communities were associated with differences in nutrient availability; this may have catalyzed a shift in fungal communities to species better able to persist in acidic soils under nutrient-limited conditions. In addition, certain species appeared not to exist as mycelium on existing vegetation, but have the ability to rapidly recruit after mechanical soil treatments. Results of this study help us better understand whether abiotic soil variables can be used to predict ECM composition and root colonization potential in mine restoration using blight-resistant chestnut hybrids. Proper site selection and soil surface treatment methods significantly contributed to ECM root colonization on chestnut in abandoned and reclaimed mine sites in central Ohio. Employing methodologies that encourage the formation of native ectomycorrhizas may aid in promoting the long-term survival of woody tree species in mine reclamation and accelerate succession to closed canopy forests.
Advisors/Committee Members: Keiffer, Carolyn.
Subjects: Botany
Keywords: Amercian chestnut (Castanea dentata), ecological restoration, ectomycorrhizal fungi, mine reclamation, community assemblage
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7.
Berry, Eric J.
Population ecology of the harvested understory palm Chamaedorea radicalis: pollination biology, female fecundity, and source-sink population dynamics.
Degree: PhD, Botany, 2006, Miami University
► The harvest of non-timber forest products (NTFP) is an important source of…
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▼ The harvest of non-timber forest products (NTFP) is an important source of income for rural communities worldwide, and as such there is concern over the sustainability of NTFP extraction. One example is concern over reduced yields from harvested populations of Chamaedorea, a large genus of dioecious understory palms whose leaves are sold commercially for use in floral displays. To accurately assess the sustainability of harvest, however, requires an understanding of the population biology of harvested species. In this study, I investigated factors that influence female fecundity and population growth in harvested populations of C. radicalis within the El Cielo Biosphere Reserve (Mexico). Pollinator exclusion and scanning electron microscopy of pollen grains revealed that C. radicalis is primarily wind-pollinated. Fruit number and fruit set of females were not dependent on sex ratio or density of males at either the neighborhood or population scale. Female fecundity was most dependent on palm size, as larger individuals produced the most flowers and fruits. These large palms were more abundant on rock outcrops than the forest floor, suggesting that rock outcrops are better microsites for C. radicalis. However, field experiments revealed that differences between the substrates were not from natural variation in microsite conditions, but rather due to differences in browsing by free-range livestock, which negatively affects palm survival, growth, and fecundity. I modeled populations exposed to livestock by incorporating field data into a source-sink transition matrix model that linked the demography of non-browsed palms on rock outcrops (source) and browsed palms on the forest floor (sink) via seed migration. Models projected that seed dispersal from rock outcrops was both necessary and sufficient to sustain the subpopulation on the forest floor. Adding leaf harvest reduced the survival and fecundity of all non-browsed adults, including important ‘source’ palms, with the result that rock outcrops were no longer a sufficient source of recruitment for the entire population. This finding indicates that the combination of harvest and browse is not sustainable. Based on these results, I recommend conservation efforts that improve reproduction and seedling recruitment in harvested populations, such as fencing livestock and protecting fruiting females from harvest.
Advisors/Committee Members: Gorchov, David L.
Keywords: Chamaedorea radicalis; dioecy; fruit set; Mexico; plant demography; population dynamics; seed dispersal; source-sink dynamics; wind pollination
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8.
Castellano, Steven Michael.
Effect of Alliaria petiolata invasion on ectomycorrhizal colonization of Quercus rubra.
Degree: MS, Botany, 2008, Miami University
► Exotic plant invasion may result in the disruption of symbioses between plants…
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▼ Exotic plant invasion may result in the disruption of symbioses between plants and soil biota, potentially affecting plant fitness and community composition. I tested whether the invasive biennial Alliaria petiolata (garlic mustard) affects abundance and community composition of ectomycorrhizal fungi (EMF) associated with experimentally planted Quercus rubra (northern red oak) seedlings. Proportional EMF colonization, EMF species richness and diversity, and Q. rubra survival were lower for seedlings in a stand with high density A. petiolata than in a stand without A. petiolata. Community composition of EMF also differed between stands. A comparison of naturally occurring Q. rubra seedlings in a moderate vs. a low density site showed a trend toward less EMF with more A. petiolata, while richness and diversity did not differ. Though confounded by uncontrolled environmental variables, these results are consistent with A. petiolata negatively impacting ectomycorrhizal fungi, warranting more research on this indirect effect on native plants.
Advisors/Committee Members: Gorchov, David.
Subjects: Botany; Ecology
Keywords: Alliaria petiolata, Garlic mustard, ectomycorrhizae, invasive species, novel weapons
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9.
Chen, Jie.
Alternative polyadenylation regulates the expression of the light harvesting gene LHCB4.1 in Arabidopsis mutant oxt6.
Degree: MS, Botany, 2011, Miami University
► Recent studies revealed differential usage of Alternative Polyadenylation (APA) in Arabidopsis thaliana…
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▼ Recent studies revealed differential usage of Alternative Polyadenylation (APA) in Arabidopsis thaliana wild-type and the oxt6 mutant in which the Oxidative Stress Tolerance 6 gene (OXT6) encoding cleavage and polyadenylation specificity factor 30 (CPSF30) is interrupted. In this thesis I confirmed the differential patterns of APA for the gene LHCB4.1, encoding light harvesting complex II subunit, in wild-type versus the oxt6 mutant under either normal conditions or light/temperature stresses by using reverse transcription followed by real time PCR. It suggests the regulatory roles of AtCPSF30 and environmental stresses in the expression level and APA selection of other genes. In addition, leaves of oxt6 plants subjected to dark treatment etiolated faster than that of wild-type under dark treatment. Under dark treatment, LHCB4 protein abundance and its associated complexes were significantly lower in the oxt6 plants than in wild-type as determined by using blue native polyacrylamide gel electrophoresis and western blots. These results suggest that oxt6 mutant affects photosystem productivity and may explain why oxt6 plants have reduced stature.
Advisors/Committee Members: Li, Qingshun Quinn.
Subjects: Botany
Keywords: oxt6; alternative polyadenylation; LHCB4.1
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10.
Cui, Yunluan.
Adaptation of the Ballistospore Discharge Mechanism among Poroid Agaricomycetes.
Degree: MS, Botany, 2009, Miami University
► Most poroid basidiomycetes produce spores in vertically aligned fertilized hymenia in the…
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▼ Most poroid basidiomycetes produce spores in vertically aligned fertilized hymenia in the form of tubes. The violently discharged spores must be propelled over limited distance to avoid impaction on the opposing surface of the tubes. Based on the widely accepted spore discharge model, we aim to find the keys that control the spore discharge distance, in order to reveal how ballistospores are adapted to the wide range of tube sizes. The study involved the use of a high-speed video camera to record the spore discharge process, and morphological studies of the basidiospores using scanning electron microscopy. Our models suggest that the size of Buller’s drop, irrespective of spore size and mass, is the primary determinant of discharge distance. Meanwhile, the diverse morphology of ballistospores plays an important role in determining the final size of Buller’s drop.
Advisors/Committee Members: Money, Nicholas P.
Subjects: Biology
Keywords: poroid basidiomycetes; basidiospore; Buller's drop; surface tension catapult mechanism; spore morpholgoy
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11.
Eric, Tepe J.
Phylogeny, morphology, and the evolution of ant-plant associations in Piper section Macrostachys (Pipereceae).
Degree: PhD, Botany, 2005, Miami University
► Several Central American species of the Neotropical Piper sect. Macrostachys have developed…
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▼ Several Central American species of the Neotropical Piper sect. Macrostachys have developed associations with ants, in which the ant partner nests in, and derives food from modified plant structures. In turn, the ants protect the plant against fungal infection and some herbivores. In addition to these ant-plants that are nearly always occupied by ants, other species have resident ants only sometimes, and still other Piper species are never found to be inhabited by them. The aim of this dissertation is to utilize a molecular phylogenetic approach to understand the evolution of ant-plant mutualisms in sect. Macrostachys, including a detailed study of comparative morphology of stems and petioles that serve as ant domatia. Myrmecophytic species have petioles with appressed margins that form closed, protective chambers and serve as domatia for ants. In some Piper species, resident ants excavate the stem pith increasing the size of the domatia. Stems that are regularly excavated by ant colonists have markedly heterogeneous piths, and the excavated cavity is restricted to the central area of larger cells. Furthermore, the crystals that are abundant throughout the ground tissue of Piper stems are lacking in the area excavated by ants. This represents the first report of the absence of crystals in plant tissues excavated by ants, but this may be a widespread determinant in myrmecophytes around the world of which tissues ants will or will not excavate. The phylogeny supports a probable origin of sect. Macrostachys in northwestern South America 7-10 million years ago, with more recent radiation in Central America where all known myrmecophytes occur. The data suggest that most species of sect. Macrostachys are recently derived. Our results suggest that specialized myrmecophytism has evolved independently between two and four times with several reversals. Generalized associations, while only observed in two species, are likely to be much more widespread given the morphological plant traits that support them. Our current findings are similar to those in other ant-plant systems in which multiple independent origins of myrmecophytism with frequent reversals appear to be the rule rather than the exception.
Advisors/Committee Members: Watson, Linda E.
Subjects: Biology, Botany
Keywords: Piper section Macrostachys; Piperaceae; ant-plant mutualisms; evolution; domatia; plant morphology; phylogeny; biogeogrpahy
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12.
Fang, Feng.
EXPRESSION OF HEAT SHOCK GENES HSP16.6 AND HTPG IN THE CYANOBACTERIUM, SYNECHOCYSTIS SP. PCC 6803.
Degree: PhD, Botany, 2003, Miami University
► Heat shock proteins (HSP) are found in all living organisms in response…
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▼ Heat shock proteins (HSP) are found in all living organisms in response to elevated temperatures, and protect cells from heat damage. In this dissertation, hsp16.6 and htpG were studied in the cyanobacterium, Synechocystis sp. PCC 6803. The hsp16.6 transcriptional start point was positioned 44 base pairs (bp) upstream of ATG translation start codon. A reporter vector was constructed by ligating the 265 bp upstream fragment onto the upstream region of the lacZ coding sequence. Galactosidase analysis indicated the 265 bp region did not induce lacZ gene expression in E. coli; although lacZ expression was induced when the Synechocystis groESL promoter was used. In Synechocystis cells, lacZ was expressed when the 265 bp fragment was used as a promoter. Cold stress and ethanol did not induce lacZ expression, while heat shock, salt stress, sorbitol, hydrogen peroxide and high light induced lacZ. Deletions of the 265 bp region demonstrated that the induction of galactosidase activity was lost when a region upstream of the transcriptional start point was deleted. The htpG null mutant was obtained by inserting a chloramphenicol resistance cassette (Cmr) in the htpG coding sequence. The htpG null mutant, hsp16.6 null mutant, and the double mutant cells grew well at 30°C and 37°C, but not at 40°C. This suggests that HtpG and HSP16.6 proteins do not have an essential role at normal and mildly elevated temperatures. Cell growth, cell survival rate, and oxygen electrode measurements demonstrated that htpG mutant, hsp16.6 mutant, and double mutant cells were sensitive to heat stress. Decreased basal and acquired thermotolerance were observed when mutants were heat shocked, with double mutant cells being the most sensitive. A comparison of mutants showed that hsp16.6 mutant was more sensitive to heat shock than htpG mutant. In summary, a 265 bp region upstream of hsp16.6 was demonstrated to response to heat shock, salt stress, sorbitol, hydrogen peroxide and high light, and the deletion of a region upstream of the transcriptional start point resulted in the loss of heat induction. HtpG was demonstrated to be essential during heat stress, and the deletion of htpG caused decreased basal and acquired thermotolerance.
Advisors/Committee Members: Barnum, Susan R.
Subjects: Biology, Molecular
Keywords: Heat shock; cyanobacteria; Synechocystis; htpG; hsp16.6; regulation; reporter; promoter; basal thermotolerance; acquired thermotolerance
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13.
Farruggia, Frank Thomas.
A FLORISTIC DESCRIPTION OF A NEOTROPICAL COASTAL SAVANNA IN BELIZE.
Degree: MS, Botany, 2004, Miami University
► The diverse graminoid-dominated savannas of Central America remain poorly described. I used…
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▼ The diverse graminoid-dominated savannas of Central America remain poorly described. I used percent cover and frequency along line transects and in quadrats to assess the flora, community structure, and environment of a hyperseasonal coastal savanna near Sapodilla Lagoon in Stann Creek District, Belize. The flora consisted of 193 angiosperms, 2 gymnosperms, and 6 pteridophytes, and was dominated by graminoids. Species with the highest importance values were Mesosetum filifolium, Paspalum pulchellum, Rhynchospora plumosa, and Rhynchospora barbata. Woody species were scattered in dense clusters throughout the savanna, and were divided into a tall tree layer, dominated by Pinus caribaea, and a tree-palm-shrub layer, dominated by Acoelorraphe wrightii and Byrsonima crassifolia. Several large A. wrightii-dominated vernal pools were scattered about the landscape marking locations where water breaks through the impenetrable sub-surface. Variation in species composition within the savanna, explored with Non-Metric Multidimensional Scaling (NMDS), correlated strongly with particular species (A. wrightii and P. pulchellum), topography, cation exchange capacity, and copper concentration. Quantitative comparisons with two other savannas studied in Belize show distinct differences in flora, structure, and dominance in spite of previously being classified as similar.
Advisors/Committee Members: Vincent, Michael.
Keywords: Floristics; Belize; Savanna; Non-Metric Multidimensional Scaling
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14.
Fondom, Nicolas Yebit.
PHYSIOLOGICAL AND BIOCHEMICAL ADAPTATIONS IN SOME CAM SPECIES UNDER NATURAL CONDITIONS: THE IMPORTANCE OF LEAF ANATOMY.
Degree: PhD, Botany, 2009, Miami University
► This dissertation consists of an introduction and three independent research chapters. Chapter…
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▼ This dissertation consists of an introduction and three independent research chapters. Chapter one (introduction) presents a review of CAM (Crassulacean Acid Metabolism) biology, chlorophyll fluorescence, and leaf optical properties. Chapter two addresses the physiology, anatomy, and biochemistry of two tropical Peperomia species in the field in the El Cielo Biosphere Reserve in Tamaulipas, Mexico. Chapters three and four address similar studies in two morphs of Agave striata (red vs. green leaves) under natural condition in the high plateau desert region of Miquihuana, Tamaulipas, Mexico. The summary for each of the research chapters is discussed. In chapter two, I tested, under field conditions, the hypotheses that relative thickness of the spongy mesophyll layer is an indication of CAM and that water distribution within the leaf tissues of the two Peperomia species studied changes differently in response to drought. The results showed that when well-watered, P. obtusifolia has typical C3-activity and P. macrostachya has typical CAM-activity, with spongy mesophyll layer thickness of 26% and 76% respectively. In addition, the results also showed that the distribution of water in the leaf tissue in P. obtusifolia changes in response to drought, from the hydrenchyma to the chlorenchyma, but this is not the case in P. macrostachya. In chapter three, I tested the hypothesis that leaf epidermal pigments screen light of particular wavelengths from reaching the photosynthetic machinery, reducing dependence on the xanthophyll cycle as an energy dissipation process in two morphs of Agave striata (red vs. green leaves). The results showed that Fo (dark level fluorescence), Fv/Fm (maximum PSII efficiency), and ΦPSII (quantum yield of PSII) were higher under sun in leaves of the red morph compared to the green morph. Leaf surface temperature, xanthophyll conversion, and qN (non-photochemical quenching) were significantly higher during the day for leaves of the green morph compared to the red morph. From these results, it is clear that the sub-epidermal anthocyanins serve as a photoprotective barrier in the leaves of the red morph. Finally, in chapter four, the first goal of this project was to test the hypothesis that leaf wax development is a delayed response to sunlight exposure following cutin development. The second goal of this project tested the hypothesis that during leaf ontogeny in the two morphs of A. striata, energy dissipation shifts from non-photochemical to photochemical quenching. The results showed that on both the adaxial and abaxial leaf surfaces of young and mature leaves of both morphs, leaf wax thickness increased from the basal end of the leaf whereas cutin thickness decreased from the basal end of the leaf. Thus, as leaf age in both morphs of A. striata, cutin deposition exceeds wax deposition at the early stages of development. Furthermore, chlorophyll fluorescence data supported the photoprotective function of anthocyanin, indicating that the deposition of anthocyanins may help to reduce dependence of the leaf on energy dissipation via the xanthophyll cycle and non-photochemical quenching during leaf ontogeny.
Advisors/Committee Members: Huerta, Alfredo.
Subjects: Agriculture; Agronomy; Anatomy and physiology; Biology; Botany
Keywords: Crassulacean acid metabolism (CAM), Peperomia obtusifolia, Peperomia macrostachya, Agave striata, Leaf anatomy, Anthocyanins, Xanthophyll-cycle, Chlorophyll a fluorescence, Gas exchange, Carbon balance
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15.
Gilmore, Michael Patrick.
An Ethnoecological and Ethnobotanical Study of the Maijuna Indians of the Peruvian Amazon.
Degree: PhD, Botany, 2005, Miami University
► The Amazon basin is one of, if not the most, botanically diverse…
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▼ The Amazon basin is one of, if not the most, botanically diverse regions of the world. Unfortunately, Amazonian floristic and habitat diversity is relatively poorly known and understood. Indigenous peoples have highly detailed and extensive biological and ecological knowledge of the rain forest and studying these knowledge systems can provide insights into the heterogeneity and diversity of Amazonian forests. The research reported here investigates several aspects of the traditional culturally-based biological and ecological knowledge of the Maijuna Indians of the Peruvian Amazon. An ethnoecological framework is utilized to examine the classification, significance, and use of habitat types recognized by the Maijuna. The objectives of this portion of the dissertation are to: (1) document the habitat classification system of the Maijuna; (2) understand how they use the culturally-based habitat types, and their associated resources, seasonally and temporally; and (3) document the ecological knowledge and management strategies associated with each habitat type. The Maijuna have a complex and extensive habitat classification system identifying more than 70 forest and non-forest habitat types within the Sucusari River basin. The results of this portion of the research provide valuable insights into how indigenous peoples perceive, use, and manage resources and habitat types in Amazonia. An in-depth analysis of the significance of a habitat that the Maijuna call mañaco taco is also made. Mañaco taco are dominated by the small myrmecophytic tree or shrub Durioa hirsuta (Rubiaceae) and have a very open understory. The Maijuna have well-defined and constructed supernatural beliefs associated with these forests, believing that they are the home of malevolent supernatural beings. Understanding the significance and importance of habitat types to indigenous peoples is critical in discerning how they perceive and interact with these areas. A case study of resource use of a culturally important and necessary activity, canoe construction, was also undertaken and is discussed in detail. Canoes are amongst the most important and integral parts of the life and subsistence strategies of the Maijuna and other residents of the Peruvian Amazon. An ethnobotanical framework is utilized to: 1) examine the use and importance of canoes to the Maijuna; 2) understand the cultural and historical context of canoe construction; and 3) document the steps and plants used in constructing canoes.
Advisors/Committee Members: Eshbaugh, W. Hardy.
Keywords: Maijuna Indians; Ethnoecology; Ethnobotany; Ethnobiology; Peru; Amazon
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16.
Gonella, Michael Paul.
Myaamia Ethnobotany.
Degree: PhD, Botany, 2007, Miami University
► The Miami people have a rich and long-standing relationship with the…
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▼ The Miami people have a rich and long-standing relationship with the plants of their homelands. Much traditional Myaamia ethnobotanical knowledge has endured loss of homelands from governmental cessions, removal to Kansas and Oklahoma and societal and governmental pressures of assimilation. The purpose of this dissertation was to investigate the extent of existing Miami ethnobotanical knowledge and use that data to reconstruct the traditional Miami corn cultivation cycle and effects of harvesting and burning of two culturally important plants. Initiation of this ethnobotanical study was by the Miami people themselves, in their current efforts to revitalize traditional Miami culture, including educational programs and management of culturally significant plants on tribal lands. Myaamia ethnobotanical knowledge: This dissertation gathered and organized extant Miami ethnobotanical data and assembled it into a database for analysis. Survival of Miami ethnobotanical knowledge was evident in the abundant ethnobotanical data gathered in this study, from published and unpublished sources from historic and contemporary times, and from interviews with living Miami elders. Data on over 160 plant species were gathered, including data regarding traditional uses and stewardship. Comparisons of historic and contemporary data revealed changes in types of plant used, from pre- to post-removal times, and a non-traditional ranking of importance of habitat types was conducted. Myaamia miincipi: One of the most significant plants was myaamia miincipi, Miami corn. Gathered data were used to reconstruct the Miami year as based on the corn cultivation cycle, and this cycle provided indirect information regarding the hunting cycle and Miami (lunar) calendar. Lenin$i (Aslcepias syriaca L.) harvesting and burning: This study examined the effects of simulated traditional Miami harvesting and burning on growth and reproduction of A. syriaca. Harvesting and burning were generally found to sustain growth and reproduction although traditional harvest timing was critical to sustainability. Ahsapa (Apocynum cannabinum L.) harvesting and burning: This study examined the effects of simulated, traditional Miami harvesting and burning on growth and reproduction of A. cannabinum. Harvesting was found to sustain growth and reproduction but mowing had a negative effect on growth. Burning was not found to increase growth or reproduction.
Advisors/Committee Members: Greenberg, Adolph M.
Keywords: ethnobotany, Miami, Myaamia, Asclepias syriaca, Apocynum cannabinum, corn, indigenous harvesting
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17.
Harney, Dennis James.
The Physiological and Developmental Effects of Sulfur Nutrition and Light Intensity on Sulfur Deficiency Symptoms in Phaseolus Vulgaris.
Degree: PhD, Botany, 2003, Miami University
► The four objectives of this study were to: 1) Determine the usefulness…
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▼ The four objectives of this study were to: 1) Determine the usefulness of the plastochron index (PI) in S-deficiency studies in bean (Phaseolus vulgaris var. Bush); 2) Characterize the early onset of sulfur (S) deficiency; 3) Determine if higher light exacerbates S deficiency symptoms; and 4) Determine if glutathione (GSH) limitation is associated with onset of S deficiency symptoms. The PI can decrease variability in data, yet few physiological studies have employed it because stress often disrupts underlying PI assumptions of: early exponential growth, similar leaf relative growth rates (RGR), and similar plastochrons. In this study, while S-stressed plants showed exponential growth, RGR declined and plastochron increased. Calculation of the RGR-induced error suggested that the deviations had little negative impact on results. To address unequal plastrochrons, the curvilinear PI-time relationship was used to calculate Plastochron Index Derived Days (PID), i.e., chronological age predicted from PI. Using PID greatly decreased variability of physiological data (e.g., increased r2 for CO2 assimilation (A) vs. time from 0.2 to 0.7) and minimized subjective plant selection. Sulfur limitation caused stunted morphological development by 15 days after planting (DAP); decreased total leaf S and A by 16 DAP; and decreased %GSH in reduced form, maximal A (A max), Rubsico carboxylation efficiency (CE), Fv/Fm, dry weight, and chlorophyll concentration, but increased the CO2 compensation point (Γ), by 21 DAP. Higher light intensity (200 μmol m-2s-1) sped the onset and amplified the magnitude of S deficiency symptoms in bean. Higher light slowed morphological development, decreased A max, CE, %GSH, chlorophyll, dry weight, Fv/Fm, and increased Γ, but 60 μmol m-2s-1 effected these symptoms less or not at all. This project hypothesized a linkage between GSH-dependent photoprotection and onset of S deficiency symptoms. Surprisingly, neither supplied S nor light level had any effect upon total GSH in older leaves. In younger leaves, a lower S supply and 60 μmol m-2s-1 appeared to increase levels of total leaf GSH! These data suggest that GSH is probably not involved with the onset of S deficiency symptoms. It remains unclear why leaf GSH increased when total leaf S content decreased.
Advisors/Committee Members: Huerta, Alfredo J.
Subjects: Biology, Plant Physiology
Keywords: bean; Phaseolus vulgaris; developmental index; developmental age; plant age; plastochron index; plastochron index derived days; sulfur; sulfur nutrition; sulfur deficiency; light; light level; light sensitivity; photosensitivity
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18.
Hassett, Maribeth O.
SPLASH AND GRAB: BIOMECHANICS OF PERIDIOLE EJECTION AND FUNCTION OF THE FUNICULAR CORD IN BIRD’S NEST FUNGI.
Degree: MS, Botany, 2012, Miami University
► The bird’s nest fungi (Agaricales, Nidulariaceae) package a millions spores into sporangia…
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▼ The bird’s nest fungi (Agaricales, Nidulariaceae) package a millions spores into sporangia (referred to as peridioles) that are splashed from their basidiomata by the impact of raindrops. Peridioles are splashed from flute-shaped basidiomata at speeds of 1 to 5 meters per second (11 mph). This study examines the mechanism of peridiole ejection and funicular cord function in Cyathus and Crucibulum using high-speed video. The funicular cord is a highly-extensible bundle of hyphae whose tensile strength is maximized by the modification of clamp connections. The funicular cord remains in a condensed form during flight with an adhesive pad exposed on the projectile surface. The cord unravels when the pad sticks to surrounding vegetation and acts as a brake that quickly reduces the velocity of the projectile. This elaborate mechanism tethers peridioles in a perfect location for browsing by an herbivore and is viewed as a beautiful adaptation for a coprophilous fungus.
Advisors/Committee Members: Money, Nicholas.
Subjects: Botany
Keywords: Agaricales; Bird’s nest fungi; Clamp connections; Crucibulum; Cyathus; Fungal spore dispersal; Mycocalia; Nidula; Nidularia; Nidulariaceae; Splash cup
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19.
Henson, Brian Junior.
Evolution, Variation, and Excision of Developmentally Regulated DNA Elements in the Heterocystous Cyanobacteria.
Degree: PhD, Botany, 2005, Miami University
► In some cyanobacteria, heterocyst differentiation is accompanied by developmentally regulated DNA rearrangements…
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▼ In some cyanobacteria, heterocyst differentiation is accompanied by developmentally regulated DNA rearrangements that occur within the nifD, fdxN, and hupL genes, referred to as the nifD, fdxN, and hupL elements. These elements are excised from the genome by site-specific recombination during the latter stages of heterocyst differentiation. In this dissertation, two major questions are addressed: 1) what is the evolutionary history of the nifD and hupL elements and 2) how is the nifD element excised? To answer the first question, full length nifD and hupL element sequences were characterized and compared; and xisA and xisC sequences (which encode the recombinases that excise the nifD and hupL elements, respectively) were phylogenetically analyzed. Results indicated extensive structural and compositional variation within the nifD and hupL elements. The data suggests that the nifD and hupL elements are of viral origin and that they have variable patterns of evolution in the cyanobacteria. To answer the second question, a recombination system was devised where the ability of XisA to excise or recombine variants of the nifD element (substrate plasmids) was tested. Using PCR directed mutagenesis, specific nucleotides within the flanking regions of the nifD element were altered and the effects on recombination determined. Results indicate that nucleotides within and outside of the direct repeats are involved in excision, and that not all nucleotides within the direct repeats are required. In certain nucleotide positions, the presence of a purine versus a pyrimidine greatly affected recombination. Although excision was inhibited when certain nucleotides were mutated, PCR analyses revealed that excision occurred at a low level. The data also indicate that the site of excision occurs within the direct repeats. The results presented here suggest that the elements may be variable in size, composition, and excision.
Advisors/Committee Members: Barnum, Susan R.
Keywords: Cyanobacteria; nifD element; hupL element; heterocyst differentiation; developmentally regulated DNA rearrangement
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20.
Hesch, Lindsey Elizabeth.
Community dynamics in an experimental southwestern Ohio prairie.
Degree: MS, Botany, 2007, Miami University
► The factors determining community composition are of great interest and consequence. The…
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▼ The factors determining community composition are of great interest and consequence. The degree to which communities are governed by deterministic or chance processes has become more ambiguous than what was previously thought. Composition may also be unpredictable if chance plays a large role or communities can remain stable with various compositions. I partition variation in plant community composition from the seed mix to second growning season percent cover to variables in order to examine three community dynamics paradigms: niche (deterministic predictability), neutral (non-deterministic unpredictability), and multiple attractor (deterministic unpredictability) theories. I also examine relationships between the plant and insect communities as according to niche theory communities are structured by abiotic and biotic components of the environment. I found communities to be mostly governed by deterministic processes but chance still plays an important role. Communities may be unpredictable. The plant and insect communities are linked in abundance and composition.
Advisors/Committee Members: Stevens, Martin H.
Keywords: forbs; herbivores; plant; dat; str; aov.tab; insect
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21.
Hochstedler, Wendy Wenger.
Alliaria petiolata (garlic mustard) response to herbicide and June precipitation, and subsequent effects on the forest floor community.
Degree: MS, Botany, 2006, Miami University
► The impact of invasive plant species on native plants is largely assumed…
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▼ The impact of invasive plant species on native plants is largely assumed to be negative, but supporting evidence is sparse. We examined the long-term effects of herbicide on Alliaria petiolata and the subsequent effects on the plant community in southwestern Ohio. November herbicide application effectively killed A. petiolata, but did not reduce recruitment; spring densities of A. petiolata rosettes were not lower in sprayed plots. Only modest differences were noted in forest floor vegetation, suggesting A. petiolata rosettes competed with other plant species. We tested the hypothesis that higher June precipitation promotes rosette growth and survival with a rain shelter experiment. The three different water treatments affected soil moisture, but not A. petiolata growth or survival. Dry treatments may not have replicated drought years based on water availability measurements. June precipitation is probably not a reliable predictor of A. petiolata rosette survival in years with above average precipitation.
Advisors/Committee Members: Gorchov, David L.
Keywords: Alliaria petiolata; garlic mustard; invasive species; forest floor plant community
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22.
Hopkins, Jane A.
Phototropism and Gravitropism in Transgenic Lines of Arabidopsis Altered in the Phytochrome Pathway.
Degree: MS, Botany, 2011, Miami University
► Roots of Arabidopsis thaliana grow toward gravity, positive gravitropism. In addition, these…
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▼ Roots of Arabidopsis thaliana grow toward gravity, positive gravitropism. In addition, these roots exhibit negative phototropism relative to blue light and positive phototropism relative to red light. Our studies investigated the importance of phytochromes, the red-light photoreceptors, for root and shoot gravitropism and phototropism. We used two transgenic lines, one which was deficient in phytochrome in the roots (M0062/UASBVR) and the other was deficient in phytochrome in the cotyledons (CAB3::pBVR). The transgenic lines were grown in either light or dark conditions to determine whether roots directly perceive light signals or if the signal is perceived in the shoot and then transmitted to the root. Kinetics of tropistic curvature and growth were assayed by standard methods or with a computer-based feedback system. We found that the perception of red light occurs directly in the root and that signaling also may occur from root to shoot in gravitropism.
Advisors/Committee Members: Kiss, John.
Subjects: Biology; Botany; Molecular Biology; Plant Biology
Keywords: phytochrome, phototropism, gravitropism, M0062/UASBVR, CAB3::pBVR, root-shoot signaling
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23.
Kennedy, Aaron H.
Phylogeny and Evolution of Mycorrhizal Associations in the Myco-heterotrophic Hexalectris Raf. (Orchidaceae : Epidendroideae).
Degree: PhD, Botany, 2009, Miami University
► Some plant species have abandoned an autotrophic life style and obtain their…
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▼ Some plant species have abandoned an autotrophic life style and obtain their carbon and mineral nutrition exclusively from mycorrhizal fungi. Although myco-heterotrophic species have evolved in many plant families, they are most common in the Orchidaceae. Several myco-heterotrophic orchid species have been shown to associate with a very narrow range of ectomycorrhizal forming fungi, revealing a high degree of mycorrhizal specificity. However, these studies have often investigated single or few, often unrelated, species without support for their monophyly or knowledge of their phylogenetic relationships. Using primarily molecular methods and phylogenetic analyses, this dissertation investigates i) the monophyly and circumscription of Hexalectris species, ii) interspecific phylogenetic relationships within Hexalectris, iii) the identities of the mycorrhizal fungi that associate with each Hexalectris species, iv) the breadth of mycorrhizal associations within Hexalectris and within each of its species, and v) uses a Hexalectris phylogeny as a framework for investigating mycorrhizal specificity and patterns of associations. The monophyly of H. warnockii, H. grandiflora, H. brevicaulis, and H. nitida, plus the H. spicata species complex, are well supported. The remaining species are not monophyletic, prompting the recircumscription of H. spicata s.l. as H. spicata and H. arizonica, H. revoluta s.l. as H. revoluta and H. colemanii, and H. fallax as a synonym of H. parviflora. Extreme specificity with ectomycorrhizal agaricomycete fungi was identified in each Hexalectris species. Hexalectris warnockii associates exclusively with members of the Thelephoraceae; H. brevicaulis and H. grandiflora associate exclusively with members of Russulaceae and Sebacinaceae subgroup A; the remaining species, all members of the H. spicata complex, associate strictly with members of Sebacinaceae subgroup A. Optimizing these associations onto a Hexalectris phylogeny reveals that, with one exception, each Hexalectris species associates with a different clade or group of fungal clades, and that shifts in association from one group of fungi to another occurred during each speciation event in the evolutionary history of this genus.
Advisors/Committee Members: Watson, Dr. Linda E.
Subjects: Biology; Botany
Keywords: Orchidaceae; orchid; Hexalectris; phylogenetics; molecular systematics; mycorrhizae; myco-heterotrophy; mycoheterotrophy; ITS; plastid; specificity; tripartite; ectomycorrhizae
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24.
Kenyon, Kyle Christopher.
Phylogenetic Analysis of the Heterocystous Cyanobacteria as Assessed by 16S and 23S Ribosomal RNA.
Degree: MS, Botany, 2003, Miami University
► This study used 16S and 23S rRNA sequence data for phylogenetic analysis…
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▼ This study used 16S and 23S rRNA sequence data for phylogenetic analysis of the heterocystous cyanobacteria. Twenty-eight strains of cyanobacteria were cultured in the laboratory; DNA was extracted; the 16S and 23S ribosomal RNA genes amplified by PCR, cloned, and sequenced. Parsimony, distance and maximum likelihood analysis of the 16S and 23S data supports the monophyly of the heterocystous cyanobacteria. Subsection V cyanobacteria are also supported as a monophyletic clade, embedded within Subsection IV. Members of the genera Calothrix, Tolypothrix and Rivularia are paraphyletic and their relationship is not clearly defined. The Nostoc and Anabaena are not monophyletic or sister to one another. Based on these analyses Anabaena PCC7120 should be reassigned as a Nostoc and PCC73102 Nostoc is not well supported as a type strain for the genus. Nodularia and Cylindrospermum strains are well-supported clades. Two distinct copies of the 23S rRNA were detected in several strains.
Advisors/Committee Members: Barnum, Susan R.
Keywords: Phylogeny; Heterocyst; Heterocystous; Cyanobacteria; 16S ribosomal RNA; 23S ribosomal RNA; Subsection IV; Subsection V; Blue-green algae; systematics
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25.
Keppler, Mary Lee.
Promoting Botanical Education through Children's Gardens and Program Assessment.
Degree: MA, Botany, 2010, Miami University
► This internship report describes how the author integrated three internship experiences into…
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▼ This internship report describes how the author integrated three internship experiences into a cohesive model of botanical education practices. The three experiences each contribute to the cycle of effective educational programming which includes design, implementation, evaluation, and revision. Teaching experience in informal curriculum development and implementation culminated in the Oxford Children’s Garden. Formal program design took place at Peaslee Garden in Cincinnati, and extensive assessment and revision occurred during The Conservatory Program Evaluation. This report details each internship experience, the proposed and achieved goals, and the impact they had on the author’s outlook on the profession of botanical education. This narrative satisfies the requirements for the Master of Arts degree in Botany from Miami University.
Advisors/Committee Members: Schussler, Elisabeth.
Subjects: Botany; Education
Keywords: botanical education; informal program assessment; children's gardens; field trip; student surveys; curriculum design
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26.
Klein, Laura L.
Morphology and Introgressive Hybridization in North American Diphasiastrum.
Degree: MS, Botany, 2012, Miami University
► Although interspecific hybridization in plants often results in sterility, occasionally hybrids show…
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▼ Although interspecific hybridization in plants often results in sterility, occasionally hybrids show evidence of fertility. Because of their reproductive competence, such F1’s have the ability to interbreed with each other and with their parents, forming introgressive offspring that are morphologically intermediate between the original parental forms. North American Diphasiastrum complanatum, D. digitatum, and D. tristachyum exhibit evidence of such introgressive hybridization. To test for introgression, morphological measurements for parental and putative hybrid taxa were collected and analyzed using principle components analyses and hybrid indices. Spore fertility was also analyzed within the study set. Results support the presence of introgression among all three pair combinations. Although not infrequent, the numbers of hybrid forms are far exceeded by parental forms and so there are no compelling reasons not to recognize these three taxa at the species level.
Advisors/Committee Members: Hickey, R. James.
Subjects: Biology; Botany
Keywords: Lycopodiaceae; Lycopodium; Diphasiastrum; Morphology; Introgression; Hybridization; Hybrid Index
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27.
Kokulapalan, Wimalanathan.
Genome-wide Computational Analysis of Chlamydomonas reinhardtii Promoters.
Degree: MS, Botany, 2011, Miami University
► As a model organism, use of Chlamydomonas reinhardtii is not only limited…
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▼ As a model organism, use of Chlamydomonas reinhardtii is not only limited with biological experiments to understand chloroplast and flagella, but is also extended to biodiesel production. Chlamydomonas promoter regions were extracted based on available RNA-Seq data and community genome annotation, and promoters were used to analyze and detect core and proximal promoter elements. While the evidence suggests only the TATA box (canonical and non-canonical TATA boxes) as the only core promoter element, it also indicates that the TATA box in Chlamydomonas is different than Arabidopsis and human TATA boxes. While some proximal promoter elements discovered show weak similarities to known promoter elements from other species, most are novel elements only present in Chlamydomonas. Most of the proximal promoter elements detected show significant similarities to each other. It is evident from this study that the promoter architecture in Chlamydomonas seems to be simpler compared to animals and plants.
Advisors/Committee Members: Liang, Chun.
Subjects: Bioinformatics
Keywords: Chlamydomonas reinhardtii; promoters; RNA-seq; core promoter; proximal promoter; TATA box
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28.
Kumar, Neela Shiva.
Cellular Mechanisms of Gravitropism in ARG1 (Altered Response to Gravity) Mutants of Arabidopsis Thaliana.
Degree: PhD, Botany, 2008, Miami University
► Many studies have been conducted in an effort to understand the mechanisms…
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▼ Many studies have been conducted in an effort to understand the mechanisms involved in gravitropism. Gravity perception in plants occurs by the sedimentation of starch-filled plastids termed statoliths. These statoliths are located in the endodermal cells of stem-like organs and columella cells of the root cap. Plastids play an important role during the graviperception mechanism in plants in that they act as gravity sensors in the roots, hypocotyls and inflorescence stems of flowering plants. Gravity perception leads to signal transduction that eventually results in tropic curvature in plants. ARG1 (altered response to gravity) is a gene involved in gravitropism and encodes a DnaJ-like protein, suggesting its possible interaction with the cytoskeleton. We investigated whether the arg1 mutation affects gravitropism by modulating plastid sedimentation in gravity perceiving cells in Arabidopsis thaliana. By using cryofixation procedures and light microscopic studies, we have determined that ARG1 affects gravitropism in hypocotyls by reducing the plastid sedimentation process. The arg1-2 mutant exhibited reduced and delayed gravitropism in roots, shoots, and inflorescence stems in both light- and dark-grown conditions. We performed light microscopic studies of plastid movement in the gravity-perceiving statocytes (endodermal cells) of hypocotyls of arg1-2 and WT seedlings to better characterize the role of ARG1 in gravitropism. Cryofixation and freeze substitution procedures were used since these methods provide a reliable indication of rapid cellular events within the statocytes. We found that sedimentation of plastids in response to gravity in statocytes of the arg1-2 mutant was reduced and ARG1 affects gravitropism by reducing plastid movement/sedimentation, a process known to be essential for early phases of signaling cascades in the statocytes. The precise location of ARG1 protein within the columella cells has been further investigated by high resolution electron microscopy and indirect immunogold labeling suitable for Arabidopsis roots. These studies confirm that ARG1 is found specifically localized to the components of the endomembrane system such as Golgi apparatus, endoplasmic reticulum, secretory vesicles, and that this protein plays a key role in gravitropism. The significance of our study is that we have elucidated multiple roles of ARG1 both in gravity perception and signal transduction phase in statocytes.
Advisors/Committee Members: Kiss, Dr. John Z.
Subjects: Botany
Keywords: ARG (altered response to gravity) protein; actin cytoskeleton; Arabidopsis; columella cells; electron microscopy; endodermis; endomembrane system; gravitropism; gravity perception; immunocytochemical; plastid movement; signal transduction; statocytes
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29.
Larkin, Claire Cecilia.
Effects of Common Disturbances on Composition and Succession in Coppice Plant Communities on Eleuthera, the Bahamas: Conservation Implications.
Degree: MS, Botany, 2010, Miami University
► Different disturbances in similar habitats should produce unique successional assemblages of plants.…
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▼ Different disturbances in similar habitats should produce unique successional assemblages of plants. Plant species cover data was collected to investigate the effects of three common disturbances–fire, bulldozing, and bulldozing followed by goat grazing–on early-successional coppice communities on Eleuthera, The Bahamas. For each disturbance type, both the ground layer (< 0.5 m) and shrub layer (> 0.5 m) were sampled in eight patches (> 1 ha) of varying age (1-28 yr) since disturbance. Results suggest that goats accelerate succession by quickly removing non-woody ground cover, and increase the representation of woody ground cover; these results also suggest that managed goat grazing delays plant succession by inhibiting growth of tree species and maintaining early-successional shrubs. These effects may lead to different coppice successional trajectories, and may have important conservation implications for the threatened Kirtland’s warbler (Dendroica kirtlandii), who’s wintering habitat consists of early-successional coppice rich in Lantana fruits.
Advisors/Committee Members: Kwit, Dr. Charles.
Subjects: Botany; Ecology
Keywords: succession; coppice; Bahamas; Kirtland's warbler; fire; goat grazing; dry tropical forest
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30.
Levings, Carolyn K.
A Monograph of the Genus Maackia.
Degree: MS, Botany, 2006, Miami University
► The genus Maackia (Papilionoideae, Fabaceae) comprises trees and shrubs native to China,…
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▼ The genus Maackia (Papilionoideae, Fabaceae) comprises trees and shrubs native to China, Japan, Korea, Russia, and Taiwan. Morphologically, Maackia appears most closely related to Cladrastis. However, molecular data indicate that Maackia is distantly related to that genus, being more closely allied to some Sophora species, Salweenia, and Euchresta, whereas Cladrastis is basal to the subfamily. Individual floras have mentioned the genus, but none have included all the species in Maackia, and no previous monograph exists. Over 600 specimens were obtained on loan from herbaria around the world. Separate analyses of fruiting and flowering specimens were conducted, because flowers and fruit do not occur simultaneously on one plant. From 130 specimens, 77 vegetative characters, 16 pod and seed characters, and 56 floral characters were measured. Data were analyzed using NTSYS – pc and MINITAB. Eleven species are recognized, one of which is new, another newly named, and a new subspecies combination made.
Advisors/Committee Members: Vincent, Michael A.
Subjects: Biology, Botany
Keywords: Maackia; taxonomy; legume; East Asia
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