Student Scholar Symposium Abstracts and Posters

Document Type


Publication Date

Fall 12-1-2021

Faculty Advisor(s)

Dr. Hagop Atamian, Dr. Kenjiro Quides


The microbiome of a host can change within a single generation, and repeated exposure to the same species of host can eventually shape a microbiome to be beneficial. In our study, we used the Lotus japonicus-Mesorhizobium loti symbiosis to explore the dynamics of simple artificial rhizobial populations using qPCR. To explore these population dynamics, we conducted a rhizobial passaging experiment wherein rhizobial populations were serially transferred to rhizobia–free plants. According to the sanctions hypothesis, we expect M. loti genotypes that fix more nitrogen to attain greater population sizes over time. We tested the sanctions hypothesis in populations that started with two different combinations of M. loti genotypes. The first combination consisted of a mediocre strain and a non–beneficial strain. The second combination of M. loti genotypes included the wildtype, a mediocre, and a non–beneficial strain. For our mediocre and non–beneficial combination of M. loti genotypes, we did not find support for the sanctions hypothesis. However, we did find support for the sanctions hypothesis in our wildtype, mediocre, and non–beneficial strain combination. The experimental approach used here could only be accomplished using molecular methods, such as qPCR, because the mediocre and non-beneficial strains are indistinguishable through culture-based methods. By utilizing a rapid, relatively cheap, and powerful technique, such as qPCR, future studies will be able to investigate the ecological dynamics of dozens of other M. loti mutants.


Presented at the virtual Fall 2021 Student Scholar Symposium at Chapman University.

Available for download on Thursday, January 01, 2099