DOI: 10.5061/dryad.k98sf7m6x
title: Data for mycorrhizal C/N ratio determines plant-derived carbon and nitrogen allocation to symbiosis

description: Nutrient cycling in temperate forests is driven by carbon allocation of
 trees to soil via ectomycorrhizas (EM). The sink activities of different
 fungal taxa for host resources are unknown. Aboveground
 dual labeling of young beech with 15N and 13C was used to trace
 resource transport to ectomycorrhizal root tips. Isotope enrichment in EM
 correlated with that in the corresponding EM-attached lateral root,
 supporting that EM drive taxon-specific N- and C-fluxes. The
 enrichments with 13C and 15N in EM increased with decreasing C/N
 ratio of the symbiotic association.  Abundances of EM species
 were positively correlated with 13C enrichment, demonstrating higher
 fitness of stronger than of less C-demanding symbioses. Overall, our
 results imply that differences among the resource traits of EM species
 regulate the supply of the symbioses with host-derived C and N. Here we
 provide the data sets containing information on the identities of fungal
 species colonizing roots tips of European beech and for N, C, 15N and 13C
 contents in bark, coarse roots, fine roots, very fine lateral roots,
 ectomycorrhizal species and rhizosphere soil and for biomass of the
 different compartments. The data were collected 5 and 20 days after
 labelling.
description: Young, healthy beech
 (<em>Fagus sylvatica</em>) trees (n = 40) with fully open
 leaves were excavated in May in a beech forest. The trees were carefully
 removed and placed with intact soil layers individually in pots (diameter:
 183 mm, height 255 mm, corresponding to about 6.5 L soil volume) and were
 kept under common garden conditions in Göttingen until labelling. Three
 adjacent top, three middle and three bottom leaves were slightly abraded
 and exposed for 3 days to
 <sup>15</sup>NH<sub>4</sub>Cl (99%
 NH<sub>4</sub>Cl, Campro Scientific GmbH, Berlin, Germany).
 The labelled leaves were removed and the plants were exposed in gas-tight
 chambers for two days to
 <sup>12</sup>CO<sub>2</sub>, then for three days
 to <sup>13</sup>CO<sub>2</sub> and then for two
 days to <sup>12</sup>CO<sub>2. </sub> The
 experimental exposures were conducted in two independent runs, each with
 ten trees. Ten non-labelled trees were used as controls. Harvests took place immediately
 after removal and 15 days after removal of the trees from the chambers,
 corresponding to 5 and 20 days since the start of the
 <sup>13</sup>CO<sub>2</sub> treatment. Rhizosphere
 soil, bark, roots and ectomycorrhizas were harvested, used for stable
 isotope analyses and mycorrhizal species identification by internal
 transcribed spacer (ITS) sequencing. The mycorrhizal sequences were
 blasted in NCBI GenBank (www.ncbi.nlm.nih.gov) and UNITE (unite.ut.ee)
 databases and deposited in NCBI Genbank under the accession numbers
 MK430999 to MK431014. The morphotypes, species assignments and abundances
 are listed in Table 1. The labelled and non-labelled
 soil, plant and fungal samples were analyzed in an isotope ratio mass
 spectrometer (IRMS; Delta C, Finnigan MAT, Bremen, Germany) in the Center
 for Stable Isotopes (KOSI, University of Goettingen, Göttingen, Germany)
 to obtain C, N, 13C and 15N contents. The data are shown in Table 2.
  
description: # Data for mycorrhizal C/N ratio determines plant-derived carbon and
 nitrogen allocation to symbiosis
 **Table 1
 (Table_1_repository): Ectomycorrhizas detected on root tips of Fagus
 sylvatica.** Columns indicate species hypothesis (based on &gt;97%
 sequence identities), accession numbers under which the sequences were
 deposited in NCBI, abbreviations and species numbers used in Table 2.
 Blast information obtained from NCBI and UNITE is also shown. Abundance
 (%) per fungal species on day 5 and day 20 after the start of the
 experiment. The table is useful for diversity studies. It is not required
 for quantitative analyses. The ectomycorrhizal fungal sequences were
 searched in two open databases (National Center for Biotechnology
 Information (NCBI) using nucleotide BLAST
 () and UNITE using “run
 analysis” (), which is also based on the BLAST
 algorithm. Further explanations regarding the column heading for the
 molecular identification can be found under:
 
 **Table 2 (Table_2_repository) : 13C, C, 15N, and N contents in
 rhizosphere soil, bark, fine, coarse, lateral roots and in ectomycorrhizal
 species** in control samples (non-labelled) and labelled samples, 5 and 20
 after the start of the 13C pulse-labeling. Table 2 is useful for
 quantitative analyses.  **Table 3 (Table_3repository)** : Height,
 diameter, and plant biomass. Table 3 provides the amount of plant biomass
 and rhizosphere per sample and the estimated number of root tips per
 plant. The table is useful for quantitative analyses. **Table 4 (readme):
 Readme: explains all abbreviations, column headings and units**.