Electronic Theses and Dissertations

Date of Award


Document Type


Degree Name

M.S. in Biological Science



First Advisor

Marjorie M. Holland

Second Advisor

Sarah J. Liljegren

Third Advisor

Colin R. Jackson

Relational Format



Plant-associated microbes influence plant functions, including development and growth and abiotic stress tolerance. Rhizosphere microbial communities have been shown to vary according to differences in wetland vegetation. Owing to the complexity of factors influencing soil microbial community structure, a greater knowledge of the relationship between rhizosphere microbial communities and different types of plant species will lead to a deeper understanding of plant-microbe interactions in wetlands. Thus, the purpose of my research was to determine the influence of plant species on rhizosphere microbial communities from different freshwater wetlands. The spatial variability, associated with different wetland sites, of rhizosphere microbial communities was also assessed by determining vegetation and environmental effects on bacterial community structure. Next generation sequencing of bacterial 16S rRNA genes was used to seasonally assess rhizosphere bacterial community structure associated with different plant species at different sites. Each plant species (Andropogon virginicus, Carex lurida, and Juncus effusus) had a distinct bacterial community structure in rhizosphere soils. Rhizosphere bacterial communities are affected by different plants and sites. Although the community diversity is not different for seasonal change, I found some impacts of season on the most dominant bacterial phyla. Bacterial communities are correlated with site-specific environments and plant type associated with root length, while soil chemistry has no impact on change in rhizosphere bacterial community diversity. In the most dominant eight phyla and ten OTUs, Verrucomicrobia phylum (OTU07, OTU09, and OTU10) is associated with A. virginicus, while Planctomycete (OTU06) and Chloroflexi (OTU08) phyla are associated with C. lurida. However, the top 10 OTUs are not associated with J. effusus. Rhizosphere bacterial communities of A. virginicus were significantly different from those of C. lurida and J. effusus across all sampling sites, while those of C. lurida shohigh similarity to those of J. effusus. This finding is likely caused by the upland niche of A. virginicus, as opposed to the wetland niche of C. lurida and J. effusus. Therefore, plant species from two different niches had impacts on diversity and composition of rhizosphere bacterial communities.

Included in

Biology Commons



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