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Contributed Poster

Session: Biogeochemistry

PS 40-115 - Investigating the relationship between sagebrush leaf chemistry and microbiome

Wednesday, August 9, 2023
5:00 PM – 6:30 PM PDT
Location: ESA Exhibit Hall
Abstract: Sagebrush (Artemisia tridentata) is the foundation species of the sagebrush steppe, the largest rangeland ecosystem in the United States. Sagebrush has a complex chemical profile, with a variety of secondary metabolites that differ from other plant species found in this ecosystem. The plant’s chemical phenotype mediates herbivory and community interactions, and is likely mediating the leaf microbiome. Studies on other plant species have shown that microbes living in and on plant leaves can sometimes alter plants’ secondary metabolites: they are part of a plant’s ‘extended phenotype’. The species Artemisia tridentata has ecologically distinct subspecies (tridentata, vaseyana and wyomingensis) that also vary in ploidy. The goal of this study is to investigate the relationship between plant chemistry and leaf microbiome in a common garden setting with co-occurring subspecies. We hypothesize that differences in host chemistry related to subspecies designation and ploidy will be correlated with differences in microbial communities. Our approach to addressing this hypothesis is to use subspecies and ploidy designation assigned from a set of individual plants grown together in a common garden in Idaho. This allows separation of plant traits from environmental effects. We sampled sagebrush leaves from over 70 plants in both 2012 and 2021. For leaf chemical analyses, we measured nitrogen and carbon stable isotopes, as well as LC-MS to characterize phenolic compounds. We did fungal and limited bacterial metabarcoding to examine microbial community composition across host subspecies, ploidy, and chemistry. Our metabarcoding results showed no differences in alpha diversity across subspecies, but significant differences in beta diversity, or community composition among samples, for subspecies and year. Stable isotope results showed significant differences between all three subspecies for delta 15N stable isotope data in 2012, but in 2021 the difference was significant only between tridentata and vaseyana. Stable isotope delta 13C was significantly different in 2012 between vaseyana and tridentata, but not in 2021. LC-MS data showed significant differences among subspecies and ploidy levels, but no differences between years, suggesting that phenolic compounds are stable over time within individual plants. Ongoing analyses will connect distinct chemical peaks with differences in microbial taxa. We aim to further understand the relationship between plant chemistry across subspecies of this foundational plant and its microbiome. Potentially, this information can be used to inform future restoration and management within a threatened ecosystem.