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Title: Regulation of the interaction between the white clover lectin, trifoliin A, and Rhizobium trifolii
Creator: Sherwood, John Edward
Date: 1984
Collection: Electronic Theses & Dissertations

Title: Part I. Detection and sequencing of oligosaccharides and peptides. Part II. Chromatography and detection of sulphoquinavose and suspected metabolites from Rhizobium meliloti bv. 1021
Creator: Bradford, James J.
Date: 2000
Collection: Electronic Theses & Dissertations

Title: Aspects of heme biosynthesis in free-living and symbiotic rhizobium japonicum
Creator: Avissar, Yael
Date: 1978
Collection: Electronic Theses & Dissertations

Title: Characterization of biochemical elements important for host-pathogen interaction in the Rhizobium-legume system : a paradigm of infection
Creator: Wang, Jianjun
Date: 1997
Collection: Electronic Theses & Dissertations

Title: Isolation and characterization of symbiotically defective mutant strains of Rhizobium trifolii and Rhizobium meliloti
Creator: Gardiol, Alicia E.
Date: 1985
Collection: Electronic Theses & Dissertations

Title: Dissection of endotoxin biological activities using variant lipid A and synthetic antagonists
Creator: Lill-Elghanian, Deborah Ann
Date: 1992
Collection: Electronic Theses & Dissertations

Title: Exploring the nodule microbiome community structure of Trifolium species
Creator: Shetty, Prateek
Date: 2016
Collection: Electronic Theses & Dissertations
Description: "Plant associated microbes have been shown to increase plant growth and production drastically, yet we are just beginning to understand the parameters that impact these interactions. Rhizobia are primary bacterial symbionts of legumes and infect root hairs to form nodules, within which, the symbiotic rhizobia fix atmospheric nitrogen into biologically available forms in exchange for carbon from the host. The aim of this project is to understand the community structure and diversity of the...
Show more"Plant associated microbes have been shown to increase plant growth and production drastically, yet we are just beginning to understand the parameters that impact these interactions. Rhizobia are primary bacterial symbionts of legumes and infect root hairs to form nodules, within which, the symbiotic rhizobia fix atmospheric nitrogen into biologically available forms in exchange for carbon from the host. The aim of this project is to understand the community structure and diversity of the nodule microbiome, with emphasis on the less abundant members, among coexisting clover species. North American clover Trifolium-Rhizobium communities are a good system to study host interactions with microbiomes given the high local species diversity. We analyzed the nodule microbiome of six congeneric clover plants when they were grown in soils conditioned by members of their own species and in soils conditioned by congener species by sequencing the 16s rRNA gene. The visualized microbiomes are similar, with 96% of all reads belonging to the order Rhizobiales. The rest of the OTUs belong to rarer groups of microbes. Further, the structure of the microbiome is impacted by both the host plant species and the soil in which the host is grown in, with soil explaining a larger degree of variation. There also is a strong interaction between soil and host in structuring the microbiome. The results are similar when the microbiome is analyzed with and without its most dominant order (Rhizobiales)."--Page ii.
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Title: The role of resource mutualism in plant response and adaptation to abiotic environments
Creator: Suwa, Tomomi
Date: 2016
Collection: Electronic Theses & Dissertations
Description: Symbiotic interactions between microbes and plants are ubiquitous in nature. These symbioses can facilitate a plant’s ability to tolerate biotic and abiotic stress. For example, resource mutualists, such as arbuscular mycorrhizal fungi and nitrogen-fixing bacteria can not only aid nutrient acquisition but also confer tolerance to drought and pH stress. Using an annual legume, Amphicarpaea bracteata, and nitrogen-fixing bacteria, Bradyrhizobium sp., as a model system, I investigated whether...
Show moreSymbiotic interactions between microbes and plants are ubiquitous in nature. These symbioses can facilitate a plant’s ability to tolerate biotic and abiotic stress. For example, resource mutualists, such as arbuscular mycorrhizal fungi and nitrogen-fixing bacteria can not only aid nutrient acquisition but also confer tolerance to drought and pH stress. Using an annual legume, Amphicarpaea bracteata, and nitrogen-fixing bacteria, Bradyrhizobium sp., as a model system, I investigated whether symbiotic microbes mediate plant fitness responses and adaptation to abiotic stressors, including soil moisture, limited light availability, and nitrogen limitations.First, using a large reciprocal transplant experiment, I demonstrated that soil moisture is likely an important selective agent driving plant adaptation. Additionally, I found that symbiotic rhizobia influence patterns of plant adaption to soil moisture. Given the intimate relationship between plants and symbiotic microbes, such as mycorrhizae, endophytes and rhizobia, such patterns may be prevalent in nature. My results also highlight the importance of examining both biotic and abiotic factors in adaptation studies.Second, because rhizobia are notoriously difficult to manipulate in the field, and to further identify soil moisture as the selective agent driving plant local adaptation, I conducted a multi-factorial greenhouse experiment manipulating soil moisture, plant genotype and rhizobia genotype (both collected from the same wet or dry sites). While I found weak evidence of plant adaptation to soil moisture, I found that rhizobia performance was strongly affected by the match between rhizobium origin and plant origin (wet or dry sites), suggesting that plant divergence across wet and dry sites results in traits that differentially benefit rhizobium genotypes isolated from wet versus dry sites.Finally I tested for plant population variation in plant response to other key selective agents on the legume-rhizobium mutualism (light and nitrogen availability). I found that plants and rhizobia responded differently to changes in resource availability. Symbiosis was most beneficial for rhizobia under high light and low nitrogen conditions, as predicted by resource mutualisms theory. For plants, however, symbiosis was beneficial in low nitrogen treatments regardless of light conditions. These asymmetric effects of both traded resources are, in part, driven by plants’ ability to control nodulation under unfavorable conditions.
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Title: Investigations of the molecular mechanisms for host specificity and infection in the Rhizobium/legume symbiosis
Creator: Cedergren, Robert A. (Robert Alexander)
Date: 1996
Collection: Electronic Theses & Dissertations

Title: Characterization and functional analysis of SB-1 lectin from cultured soybean root cells
Creator: Malek-Hedayat, Shahnaz
Date: 1988
Collection: Electronic Theses & Dissertations

Title: Frequency dependent selection and fluorescent nodule phenotyping in the legume/rhizobia symbiosis
Creator: Siler, Eleanor A.
Date: 2018
Collection: Electronic Theses & Dissertations
Description: "The relationship between legumes and rhizobia is an important model mutualism for several reasons. It is essential to agriculture, it provides a crucial ecosystem service by fixing atmospheric nitrogen, and it provides a tractable system for examining questions about mutualism, evolution, and ecology [1, 2]. This symbiosis remains generally mutualistic despite the fact that models predict that mutualistic rhizobia will eventually be out-competed and overwhelmed by parasitic rhizobial...
Show more"The relationship between legumes and rhizobia is an important model mutualism for several reasons. It is essential to agriculture, it provides a crucial ecosystem service by fixing atmospheric nitrogen, and it provides a tractable system for examining questions about mutualism, evolution, and ecology [1, 2]. This symbiosis remains generally mutualistic despite the fact that models predict that mutualistic rhizobia will eventually be out-competed and overwhelmed by parasitic rhizobial symbionts known as cheaters. Here I investigate one possible mechanism that could maintain the diversity of rhizobia strains: frequency-dependent selection. I also introduce a novel method of conducting rhizobia competition experiments that uses non-destructive macroscopic fluorescent imaging to identify rhizobial symbionts in root nodules."--Page ii.
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