Student Scholar Symposium Abstracts and Posters

Document Type


Publication Date

Fall 12-1-2021

Faculty Advisor(s)

Hagop Atamian, Kenjiro Quides


Legumes and rhizobia engage in a symbiotic relationship that is a model for studying microbial mutualisms. This interaction revolves around the nutrient exchange of rhizobia derived nitrogen for legume synthesized carbon that increases the growth of both partners. Therefore, measuring rhizobial population size can indicate the amount of beneficial nitrogen legumes receive. However, legumes interact with genotypes of rhizobia that provide varying levels of nitrogen, and it is unclear how rhizobial populations shift over time. Here, we use quantitative polymerase chain reaction (qPCR) to rapidly track simple, two-genotype, populations of rhizobia, and compare our results to a traditional colony forming unit (CFU) method for analyzing rhizobial abundance in more complex populations. First, we confirmed that qPCR yielded similar results to CFU estimation for rhizobial populations within individual nodules. Next, we passaged and tracked our rhizobial population proportions across multiple plant generations and found that genotypes that fix more nitrogen increased in population proportion over time. Taken together, data collected for individual nodules and the passaging experiment validated the qPCR method. These experiments demonstrate the utility of qPCR for future experiments interested in analyzing rhizobia genotype proportions and how they relate to the level of benefits legumes receive.


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

Available for download on Thursday, January 01, 2099