Alicia McElwee
Faculty Advisor: Maria Harrison
Year: 2021
Mentor: Shiqi Zhang

“Environmental Impacts on Cytosolic Phosphate Levels in B. distachyon Root Cells During Arbuscular Mycorrhizal (AM) Symbiosis”

Project Summary:

Arbuscular mycorrhizal (AM) fungi form symbiotic associations with the roots of a majority of vascular plants. Their ability to provide phosphate otherwise not accessible to plants through arbuscules has become of great interest in work to optimize the use of non-renewable phosphorus fertilizers. Little is known about how environmental factors impact host plant acquisition of phosphate during AM symbiosis. To assess some environmental factors’ impacts on host root cytosolic phosphate levels, we measured cytosolic phosphate levels across different fungal species and nitrogen conditions using a set of FRET-based phosphate sensors in live roots.

Transgenetic Brachypodium distachyon plants expressing the sensors were 1) colonized with either Rhizophagus irregularis of Diversispora epigaea fungi for testing fungal impact, or 2) colonized with D. epigaea or no fungi and given high nitrogen treatment for testing nitrogen’s impact in AM symbiosis and non-AM symbiosis conditions. The sensor’s signal was measured by imaging the roots’ fluorescence using a confocal microscope. The results showed a difference in root relative cytosolic phosphate levels between the two fungi conditions as well as an increase in root relative cytosolic phosphate levels in the high nitrogen treatment for the non-AM symbiosis condition. No data was collected for the nitrogen AM symbiosis condition due to lack of fungal colonization.

Overall, the results indicate for the first time that relative cytosolic phosphate levels in host roots differ between different fungal species associations and increases with nitrogen application. This emphasizes the additional considerations of environmental conditions if AM symbiosis is to be utilized to optimize crop phosphorus acquisition.

My Experience:

My experience at BTI this summer has allowed me to grow as a researcher, not only introducing me to the field of plant biology through conducting my own experiments but also engaging me with the wider research community of others in this field. Under the guidance of my mentor and others in the lab, I gained confidence in my ability to grasp new experimental techniques and utilize them to develop and test novel questions which build upon our current understandings. Further, the mentoring atmosphere and overall setup of the program showed me first-hand the expanse of resources available for networking and collaboration as I pursue my graduate degree and research career beyond that. The community I was immersed in at BTI and Cornell, including the faculty, students, and my fellow interns, has reinforced my desire to pursue plant research as a field where I can flourish.