Symbiotic Impacts on Plant Stress Response
Collaborative Research: Metabolic Bet-Hedging as a mechanism for the maintenance of functional diversity in tree-ectomycorrhizal mutualisms
Forest trees can host dozens of mycorrhizal fungal species at the same time. But what controls this diversity? In this project, we ask if trees manage their fungal partners the way investors manage a portfolio. Do trees use fungi to balance risk so they can stay resilient in an unpredictable world? In this collaborative project, our UC Davis team is testing this idea by running greenhouse experiments that pair Douglas-fir trees with different mixes of root-associated fungi. Using stable isotopes, we will track how trees allocate carbon to their fungal partners and examine how fungal diversity helps trees withstand variable soil and environmental conditions. Together with field studies across the Douglas-fir’s native range and mathematical modeling led by our partners at UCSB, we are uncovering how these hidden networks shape tree health, forest biodiversity, and resilience in complex ecosystems.
Symbiotic impacts on tree drought response
We have several ongoing projects focusing specifically on how ectomycorrhizal fungi shift the response of Douglas-fir seedlings to drought stress. Using gene expression data from both the seedlings and the mycorrhizal fungi, and pairing this with physiological measurements of Douglas-fir water use (lysimetry) and drought stress (Fv/Fm), we are identifying the mechanisms by which symbiosis with fungi change plant response to drought stress. Our first project in this direction, led by undergraduate researcher Demorie Galarza and PhD student Brittany Long, examines how the yellow truffle Truncocolumella citrina alters Douglas-fir drought response. Since then, undergraduate researcher Emma Kacharmina has expanded on this work by adding diversity on the plant side of the symbiosis, comparing drought response and gene expression in coastal vs interior Douglas-fir associated with Suillus lakei fungi. We are working to improve transcriptomic references for Douglas-fir and common fungal partners to support many future experiments shedding light on the interactions between symbiotic roots, fungi, and drought stress.
Understanding fungal response to osmotic stress
How does Suillus lakei navigate osmotic stress as it traverses hypervariable environments in the soil? Understanding this process could help us understand how these fungi improve plant response to drought and challenging soil conditions. Undergraduate researcher Kotomi Sato is leading this project, using gene expression analysis to explore how a diverse collection of Suillus lakei cultures respond to osmotic stress. By identifying the genes that allow this species to withstand this stress, we will be able to better understand both how it conveys symbiotic benefit to host plants, and how variable these properties might be from fungal individual to fungal individual.
