[ESAC Seminar] Rachel Shen

“Iron as a Biogeochemical Constraint: From Microbial Metabolic Partitioning to Plant–Microbe Interactions”

Iron availability can regulate biogeochemical processes by constraining both microbial metabolism and plant nutrient acquisition. In this seminar, I will discuss the role of iron across two distinct biological systems: denitrifying microbial communities and plants. The first half of the talk focuses on denitrification, a major pathway of nitrogen loss that is frequently partitioned among metabolic specialists in natural communities. We ask whether iron limitation can help explain why these partitioned metabolisms are so prevalent in the environment. Because the enzymes catalyzing individual steps of denitrification have highly uneven iron requirements, we compare the growth of generalist and specialist communities across iron availability and examine how these communities accumulate intermediates such as nitrite. The second half examines iron acquisition by the model plant Arabidopsis thaliana through redox-active coumarins, compounds that mobilize poorly accessible mineral iron. Intriguingly, pathways regulating coumarin production respond to both iron limitation and microbial signals, raising the possibility that microbes can influence plant iron acquisition and, in turn, the biogeochemical cycling of iron. Using LC-MS, we develop an approach to quantify coumarin production, including responses associated with immune induction, providing a framework for investigating how plant–microbe interactions alter iron mobilization and nutrient cycling in soils. Together, these studies highlight iron as a biogeochemical constraint that links metabolic organization, nitrogen transformations, and plant-mediated mineral nutrient acquisition.

ESAC Early-Career Seminar Series —

A forum for students and postdocs to share recent research, hone presentation skills, and build community among peers, sponsored by the EAPS Student Advisory Committee. Open to current EAPS graduate and undergraduate students and postdocs. Typically hosted on Thursdays during the semester, including pizza lunch.

Contact: esac.officers@gmail.com