EukFunc: A Holistic Eukaryotic Functional Reference for Automated Profiling of Soil Eukaryotes

The soil eukaryome constitutes a significant portion of Earth's biodiversity that drives major ecosystem functions, such as controlling carbon fluxes and plant performance. Currently, however, we miss a standardised approach to functionally classify the soil eukaryome in a holistic way. Here we compiled EukFunc, the first functional reference database that characterises the most abundant and functionally important soil eukaryotic groups: fungi, nematodes and protists. We classified the 14,060 species in the database based on their mode of nutrient acquisition into the main functional classes of symbiotroph (40%), saprotroph (26%), phototroph (17%), predator (16%) and unknown (2%). EukFunc provides further detailed information about nutrition mode, including a secondary functional class (i.e., for organisms with multiple nutrition modes), and preyed or associated organisms for predatory or symbiotic taxa, respectively. EukFunc is available in multiple formats for user-friendly functional analyses of specific taxa or annotations of metabarcoding datasets, both embedded in the R package EukFunc. Using a soil dataset from alpine and subalpine meadows, we highlighted the extended ecological insights obtained from combining functional information across the entire soil eukaryome as compared to focusing on fungi, protists or nematodes individually. EukFunc streamlines the annotation process, enhances efficiency and accuracy, and facilitates the investigation of the functional roles of soil eukaryotes-a prerequisite to better understanding soil systems.