Bower, Justin


Undergraduate Senior 

University of Minnesota - Twin Cities

Research interests: biological trade-offs, conflict of interests, and plant sanctions in the legume-rhizobia mutualism; determination of how rhizobia strain quality should be quantified as it relates to plant health. 

Background: Rhizobia are soil bacteria that can grow and reproduce in nodular swellings on legume plant roots. Non-reproductive rhizobia may divert resources from nitrogen fixation to rhizopine, which can be used as an additional carbon source for reproductive rhizobia in the same nodule. Consequentially, rhizopine producing rhizobia would benefit at the host’s expense and could harm agriculture. 

Past work: From June 2010 to March 2011, I measured the nitrogen-fixation efficiency of two Sinorhizobium meliloti strains that synthesized rhizopines and two Sinorhizobium meliloti strains that did not synthesize rhizopines to determine if rhizopine production reduces the quantity of nitrogen fixation. My results show that one rhizopine producing strain had lower nitrogen fixation efficiency than the other three strains. However, the other three strains were statistically identical. Therefore, rhizopine production genes may not necessarily impact nitrogen fixation efficiency at a detectable level. Future researchers should repeat this work with isogenic rhizopine synthesis mutants to determine how detectable this trade-off actually is.

Current work: In plants inoculated with one of two rhizobia strains (single inoculations) or both strains together (mixed inoculations), I am comparing the plant dry mass to the rhizobia strain or nodule occupancy ratio respectively. If the results for single and mixed inoculations conflict with each other, we can conclude that mixed inoculation experiments better quantify each strain’s actual benefit to legumes than single inoculation experiments because the poor nodulator is actually an effective nitrogen fixer. Scientists generally used single strain inoculations to quantify a strain’s benefit to legumes. Therefore, this work could change the way future experiments are conducted.  

Career goals: I will be graduating this coming May and leaving the lab to pursue other career goals. I am going to take this opportunity to shift my focus towards more industrial careers rather than discovery or hypothesis-driven research science. For instance, my ideal careers would be in industrial bacteriology or food safety. However, I may still work in a more research-oriented lab as an associate microbiologist in the field of microbial diversity.   

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