NSF Postdoctoral Fellowship in Biology FY 2020: Quantifying nutrient sharing across mutualisms and identifying involved genetic factors

Conti-Jerpe, Inga Elizabeth, San Francisco CA

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 Dr. Inga Conti-Jerpe is "Quantifying nutrient sharing across mutualisms and identifying involved genetic factors". The host institution for the fellowship is the University of California, Berkeley and the sponsoring scientists are Dr. Rebecca Tarvin and Dr. Todd Dawson. Symbiotic relationships in which two species exchange nutrients afford both partners access to auxiliary nutritional resources, allowing them to survive under nutrient limited conditions. Many plants, for example, live in symbiosis with soil fungi that provide nutrients the plant cannot assimilate on its own. In exchange, the fungus receives sugars produced by the plant through photosynthesis. These types of relationships exist in other lifeforms including marine invertebrates (corals, jellyfish, clams, sea slugs, and flat worms) that associate with single-celled algae, and lichens, which are comprised of algae and fungi living together. By coupling their nutrition, these partners thrive in nutritional deserts and provide the foundation for critical ecosystems such as forests and coral reefs. This research will investigate patters in the evolution of symbioses by measuring nutrient sharing in plants, marine invertebrates, and lichens, and identifying traits associated with tightly and loosely coupled partners. This will create a predictive framework where traits can be used to assess the nature of nutritional exchange within a symbiotic relationship. Additionally, this research will manipulate a model symbiosis between trees and fungi to identify genes that underpin nutrient sharing between partners. The broad scope of this project lends itself to the mentorship of undergraduates who will conduct independent research on one of the many symbiotic partnerships investigated. Additional broader impacts are a regular, bimonthly workshop focused on supporting and transferring skills to women in science, as well as the development and deployment of a high school lesson plan on data visualization and interpretation. The same set of disparate traits have evolved in symbioses across multiple taxa: 1) obligate vs facultative relationships, 2) intracellular vs extracellular associations, and 3) vertical vs horizontal transmission of symbionts. These traits are thought to influence coevolution between symbiotic partners, however there is little understanding of how they affect nutrient sharing within the holobiont. Further, the genes that regulate these symbiotic adaptations are unknown. This project uses stable isotope analysis to quantify nutrient sharing across symbioses exhibiting disparate traits to test the hypothesis that nutrient sharing is greater between obligate, intracellular partners that maintain vertical transmission compared to facultative, extracellular partners that rely on horizontal transmission. Further, this work will use transcriptomics to compare gene expression in Alnus incana (grey alder) when associated with arbuscular mycorrhizae or ectomycorrhizae and test whether genes involved in nutrient transfer are upregulated in symbiosis with intracellularly associated partners compared to extracellularly associated partners. Stable isotope data will be available on the Dryad Digital Repository (https://datadryad.org/stash) and/or IsoBank (http://isobank.tacc.utexas.edu/en/). Raw sequence reads will be digitally archived with the NCBI Sequence Read Archive (https://www.ncbi.nlm.nih.gov/sra) and comparative transcriptomics data will also be archived on Dryad. 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.