Thu, Aug 18, 2022: 8:30 AM-8:45 AM
518A
Background/Question/MethodsQuaking 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/ConclusionsWe 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.
Results/ConclusionsWe 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.