Rapid and chemically diverse C transfer from trees to mycorrhizal fruit bodies in the forest

Ectomycorrhizal fungi (EMF) are common belowground tree symbionts, supplying trees with water and nutrients. In return, large amounts of C assimilated by trees can be allocated into EMF. However, the chemical forms in which the C is transferred from trees to fungi under field conditions are mostly unknown. In this study, we aimed to unravel the fate of tree-derived C in EMF. We conducted 13CO2 pulse labeling of Pinus halepensis trees in two forest sites with adjacent EMF sporocarps, combined with a non-targeted metabolomics profiling of root and sporocarp tissues. 13C was measured in sporocarps of Tricholoma terreum and Suillus collinitus up to 3 m from pine stems. C was assimilated in the labeled trees’ needles and transferred to their roots. Starting from day 2 after labeling, the C was transferred to adjacent sporocarps, peaking on day 5. We identified more than 100 different labeled metabolites of different chemical groups present in roots and sporocarps. Of them, 17 were common to ..., , , # Rapid and chemically diverse C transfer from trees to mycorrhizal fruit bodies in the forest

[https://doi.org/10.5061/dryad.34tmpg4s5](https://doi.org/10.5061/dryad.34tmpg4s5)

## Description of the data and file structure

Ectomycorrhizal fungi (EMF) are common belowground tree symbionts, supplying trees with water and nutrients. In return, large amounts of C assimilated by trees can be allocated into EMF. However, the chemical forms in which the C is transferred from trees to fungi under field conditions are mostly unknown.

In this study, we aimed to unravel the fate of tree-derived C in EMF. We conducted 13CO2 pulse labeling of *Pinus halepensis* trees in two forest sites with adjacent EMF sporocarps, combined with a non-targeted metabolomics profiling of root and sporocarp tissues. 13C was measured in sporocarps of *Tricholoma terreum* and *Suillus collinitus* up to 3 m from pine stems.

Here we provide a table with soil properties (pH, salinity, and mineral composition) under t...