NSF Postdoctoral Fellowship in Biology FY 2021: Spatially Resolving the Cellular Landscape of Arbuscular Mycorrhizal Symbiosis with M. truncatula and D. epigaea

Tivey Trevor R, Corvallis OR

Investigators

Abstract

This action funds an NSF Plant Genome Postdoctoral Research Fellowship in Biology for FY 2021. The fellowship supports a research and training plan in a host laboratory for the Fellow who also presents a plan to broaden participation in biology. The title of the research and training plan for this fellowship to Trevor Tivey is "Using Spatial RNA-Seq and endocycle analyses to spatially resolve the cellular landscape of arbuscular mycorrhizal symbiosis with Medicago truncatula and Diversispora epigaea". The host institution for the fellowship is the Boyce Thompson Institute and the sponsoring scientist is Dr. Maria Harrison. A broad diversity of plants and a limited group of soil fungi interact together in a type of association known as arbuscular mycorrhizal symbiosis. This underground relationship between plants and fungi takes place within plant root cells, and helps both plants and fungi acquire critical nutrients. Key plant genes governing this symbiosis have been identified, however the timing and regulation of plant and fungal gene expression during colonization is complex and requires further understanding. To characterize this interaction, this project will measure plant and fungal transcripts during symbiosis at a fine spatial resolution and identify gene expression differences between cells along a gradient of fungal colonization. Results from this project will help to develop resources for the study of root-microbe interactions and enable the application of these methods to address similar questions in major crops. In the process, this project will promote research participation of undergraduates who are underrepresented in biology and support students from the local community through outreach and teaching. This project will use spatial mRNA-Seq to map the plant and fungal transcriptomes and compare gene expression in all plant cell types along a spatiotemporal gradient of colonization, enable the creation of plant-fungal gene co-expression networks, and correlate transcriptomic and microscopical evidence of endoploidy to identify candidate gene pathways. To address the controls on endoploidy, plant mutants, cell cycle markers, and image analysis will be used to disrupt symbiosis signaling and to examine the effects on endoreduplication. An increased understanding of the significance of endoploidy in AM symbiosis has the potential to inform mechanisms of symbiotic and parasitic biotroph colonization in plants. Spatial transcriptome datasets will be made publicly available in the NCBI Gene Expression Omnibus. M. truncatula cell cycle marker lines and endocycle regulation mutants will be shared for future experimental studies of the plant cell cycle and biotrophic interactions. Keywords: host-microbe, mycorrhiza, spatial transcriptomics, endoreduplication, colonization This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.