Data from: Plant host traits mediated by foliar fungal symbionts and secondary metabolites

Fungal symbionts living inside plant leaves ("endophytes") can vary from beneficial to parasitic, but the mechanisms by which the fungi affect the plant host phenotype remain poorly understood. Chemical interactions are likely the proximal mechanism of interaction between foliar endophytes and the plant, as individual fungal strains are often exploited for their diverse secondary metabolite production. Here, we go beyond single strains to examine commonalities in how 16 fungal endophytes shift plant phenotypic traits such as growth and physiology, and how those relate to plant metabolomics profiles. We inoculated individual fungi on switchgrass, Panicum virgatum L. This created a limited range of plant growth and physiology (2–370% of fungus-free controls on average), but effects of most fungi overlapped, indicating functional similarities in unstressed conditions. Overall plant metabolomics profiles included almost 2000 metabolites, which were broadly correlated with plant traits across all the fungal treatments. Terpenoid-rich samples were associated with larger, more physiologically active plants and phenolic-rich samples were associated with smaller, less active plants. Only 47 metabolites were enriched in plants inoculated with fungi relative to fungus-free controls, and of these, LASSO regression identified 12 metabolites that explained from 14–43% of plant trait variation. Fungal long-chain fatty acids and sterol precursors were positively associated with plant photosynthesis, conductance, and shoot biomass, but negatively associated with survival. The phytohormone gibberellin, in contrast, was negatively associated with plant physiology and biomass. These results can inform ongoing efforts to develop metabolites as crop management tools, either by direct application or via breeding, by identifying how associations with more beneficial components of the microbiome may be affected.All data files are .csv and analysis files are in .Rmd, which can be opened in any text editor, R, and many other programs. Funding provided by: National Institute of Food and AgricultureCrossref Funder Registry ID: http://dx.doi.org/10.13039/100005825Award Number: 2017-67013-29207Funding provided by: National Institute of Food and AgricultureCrossref Funder Registry ID: http://dx.doi.org/10.13039/100005825Award Number: HATCH accesssion no 1018688Switchgrass (Panicum virgatum) seedlings were inoculated individually with 16 foliar fungal endophytes at 4 weeks old and at least 4 cm tall and grown for an additional 6 weeks under well-watered conditions. Controls were fungus-free plants inoculated with water. Each treatment and control included 6 replicates, although mortality resulted in fewer at the harvest. All fungi were Ascomycetes isolated from plants in central Texas. Plants were monitored weekly for height, wilt, water loss, and survival. At the harvest, leaf-level physiology (photosynthesis and conductance) was measured, along with fresh shoot biomass and oven-dried root biomass. A subset of leaf replicates was further characterized by untargeted metabolomics profiling