COS 219-3 - Aspen fungal microbiomes respond to historic seasonal drought via modifications to total activity, community composition, and gene expression

Thursday, August 18, 2022

8:30 AM – 8:45 AM EDT

Location: 518A

Presenting Author(s)

JN

Jake Nash

PhD Candidate
Duke University, United States

Coauthor(s)

KT

Keaton Tremble

University of Utah, United States
MC

Melissa A. Cregger

Biosciences Division, Oak Ridge National Laboratory
Oak Ridge, TN, United States
CS

Christopher W. Schadt

Biosciences Division, Oak Ridge National Laboratory
Oak Ridge, TN, United States
ND

Nicholas C. Dove

Oak Ridge National Laboratory, United States
CB

Corbin Bryan

Duke University, United States
BL

Brian Looney

Duke University, United States
YK

Yi-Hong Ke

Duke University, United States
RV

Rytas Vilgalys

Duke University
Durham, United States

Background/Question/Methods

Quaking aspens (Populus tremuloides) associate with diverse communities of root endophytic and mycorrhizal fungi that contribute to plant health and nutrition. The aspen fungal microbiome may facilitate host acclimation to environmental stress by rapid changes in community composition and gene expression. We used a historic seasonal drought that afflicted the American west in the summer of 2021 as a natural experiment to understand how aspen fungal communities respond at multiple levels to stressful environmental conditions. We performed metatranscriptomics and RNA/DNA-based ITS metabarcoding of aspen fine root samples that were sampled in the spring, summer, and fall from nine independent sites in the Uinta Mountains of Utah that constituted a soil moisture gradient. We developed a novel synthetic RNA spike-in protocol that allowed for the calculation of absolute gene expression and total fungal transcriptomic activity. Soil moisture and temperature were tracked with sensors that collected data at 15 minute intervals and seasonal fluxes in available nutrients were measured with ion-exchange resins.

Results/Conclusions

We found drastic seasonal shifts in total fungal activity at riparian sites, but not at upland sites, suggesting that premature stream drying was a strong limit on fungal activity. Many assembled transcripts could be assigned to known aspen fungal associates. The genus Cortinarius in particular demonstrated high seasonal turnover in activity. Comparison of DNA and RNA based metabarcoding profiles will allow for comparison between the total and active fungal communities and may reveal dormancy to be mechanism of fungal drought acclimation. Our results show that turnover in total activity, community composition, and gene expression are all mechanisms that can structure the emergent function of plant microbiomes in response to environmental change. Further work will investigate the relevance of these response mechanisms for plant fitness under drought stress.