PMC

Heat map showing clustering of fungal families in (A) soil and (B) root samples. The color code of the heat map indicates presence (red) or absence (black) of fungal families (in rows) in the individual samples (in columns).

Species richness (H_max), Shannon index (H′), and Evenness (E) of fungi in soil, roots, and of root-associated ECM communities. Diversity indices are means (n = 27 ± SE). Significant differences between bar heights (P ≤ 0.05) are indicated by different letters above bars. H_max = ln (species number).

Distribution of fungal families in soil and root samples according to their relative abundance. Significant differences (P < 0.05) between soil and roots are indicated by black circles; open circles indicate fungal families with similar abundance in soil and roots. Families with abundances above 1% were labeled with a star. Red line indicates equal abundances in both roots and soil; 100% is the total abundance of all fungal families.

Soil cores (B) were taken on a 2-year-old poplar plantation (A) and cut into two longitudinal sections. 454 Pyrosequencing was applied on one half to study fungal soil and root communities. Out of the second half, poplar roots were isolated. Ectomycorrhizal fungi colonizing poplar roots were described by morphotyping (C) and ITS-sequencing (left picture: Hebeloma sacchariolens; right: Laccaria tortilis).

NMDS plot of the fungal community structure using the Bray–Curtis dissimilarity measure. Each point represents the fungal community of a given sample. Permutation tests revealed a highly significant classification (P = 0.001). Samples were classified according to the plant genotype (wildtype; L18 and L21, transgenic), sampling point, and sample type (black circles, soil; open circles, root). Stress value = 13.63, R² = 0.98. Ellipses separate samples into two categories: left ellipse, soil samples; right one, root samples. Confidence area of ellipses = 0.95.

Distribution of fungal species with different ecological lifestyle in soil and root samples. OTUs with >97% sequence identity to known species were classified based on their taxonomic affiliation to six different ecological lifestyles. Only OTUs accounting for 90% of overall relative abundance were included in the analysis. All ecological lifestyle groups were significantly different (P < 0.05) from the dashed line, which indicates the same abundance in roots and soil. AM, arbuscular mycorrhizal; ECM, ectomycorrhizal fungal species; OTU, operational taxonomic unit.