Assessing the diversity of natural rhizobia communities using a novel multi-locus sequencing approach

Our project involves the symbiotic relationship of leguminous plants with bacteria that reside within nodules located on the plant’s roots (henceforth referred to as rhizobia). Within nodules, plants provide rhizobia with a source of carbon while rhizobia fix atmospheric nitrogen for the plant. Depending on the availability of other nitrogen sources in the soil (e.g., nitrate, ammonia), the effectiveness of nitrogen fixation exhibited by rhizobia can have a huge impact on the growth and persistence of legume host populations. Recent field surveys attempting to quantify rhizobia diversity have revealed a tremendous amount of variation, both in terms of genetic identity and nitrogen fixation effectiveness when paired with host plants. However, these studies often involve a limited diversity of hosts and use sequencing techniques that likely underestimate rhizobial diversity. By using a novel multi-locus sequencing approach, we hope to compare the natural diversity of rhizobia associated with several legume species (native and introduced) that occur around KSR. In doing so, we hope to address several questions, including whether different legume species exhibit varying degrees of selectivity (i.e., only associate with specific strains), or whether hosts tend to pick up the most dominate strain at a given site. Overall, we hope to add significantly to the growing database on rhizobial biodiversity, and generate hypotheses that we can later test in field studies.

Principal Investigator: Megan Frederickson

Researcher: Rebecca Batstone

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