Theses and Dissertations

Issuing Body

Mississippi State University


Wallace, Lisa

Committee Member

Ervin, Gary

Committee Member

Brown, Matthew

Date of Degree


Document Type

Graduate Thesis - Open Access


Biological Sciences

Degree Name

Master of Science (M.S.)


College of Arts and Sciences


Department of Biological Sciences


The legume-rhizobia relationship is an important symbiosis. Studies have found variation in specificity and the functionality of symbiotic specificity can vary among plants of the same species and among rhizobia, as well as in concert with geographical variation. Here, we examined the diversity and geographic structure of rhizobia nodulating Chamaecrista fasciculata, which grows throughout the east-central U.S. and is symbiotic with Bradyrhizobium species. We investigated the association of geography and soil variables on rhizobial diversity by sampling plant nodules and soil across Mississippi and evaluated variation in rhizobia housed in different nodules of individual plants. Using nifH and truA, we conducted phylogenetic analyses and mantel tests but did not find that geography correlates with genetic diversity. However, soil variables and genetic distance were significantly correlated. Lastly, we found that rhizobia across nodules of the same plant varied substantially. These results contribute to the knowledge of rhizobial assemblages in natural populations.