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Seminar Series

IBIO Seminars, Tuesdays once a month, 3:00 – 4:00 pm EST

Contact Elizabeth Tinsley-Johnson at etinsley@msu.edu for Zoom information.

Please join us for a hybrid MSU Integrative Biology Seminar:

Tuesday, November 15 at 3:00 pm EST, Entomology Seminar Room, NatSci Room 244

Dr. Jim Moran, Associate Professor, Departments of Integrative Biology and Plant, Soil, and Microbial Sciences, Michigan State University

Improving understanding of rhizosphere nutrient exchange processes

While the rhizosphere occupies a modest physical space, it exerts disproportionately large impacts on associated plants and landscapes while housing a true hotspot of biogeochemical activity. Yet, despite its importance, the small stature, subsurface location, and complex interactions inherent in rhizosphere complicate achieving a mechanistic understanding of this crucial environment. Here, we describe recent efforts to better interrogate various aspects of rhizosphere structure and activity, paying particular attention to spatially resolved approaches designed to capture the heterogenous distribution of nutrients and activities. These methods were developed using laboratory grown switchgrass microcosms constructed with soil harvested from the Kellogg Biological Station, Hickory Corners, Michigan, USA. We adapted laser ablation-isotope ratio mass spectrometry for analysis of rhizosphere samples and used the approach coupled with a 13C tracer to track variable rates of photosynthate flow into different roots and the rhizosphere. We are also exploring the use of spectroscopy-based 13C quantification to improve measurement sensitivity and spatial resolution. We employed a laser-induced breakdown spectroscopy technique to enable mapping of macro- and micro-nutrients in the soil surrounding roots and demonstrated its ability to identify specific elemental foci that may support hotspots of microbial activity. Finally, we are developing two methods to evaluate the microbial components and activity within the system: 1) spatially resolved proteomics assays and 2) selective activity-based staining of specific enzymatic functions (e.g., phosphatase activity). Our technique involves transferring mobile phase proteins onto a membrane while maintaining their spatial distribution in the soil. This technique is non-destructive to the host plant and enables timeseries analysis of the microbial community. Our ultimate goals are to combine these unique approaches to track and evaluate the spatial controls on rhizosphere physiological plasticity with implications for on nutrient exchanges, plant productivity, and overall biogeochemical cycling.

IBIO Seminars, Tuesdays once a month, 3:00 – 4:00 pm EST