Partner specificity and association networks in ectomycorrhizal symbiosis

Partner specificity is a well-known phenomenon in biotic interactions including ectomycorrhizal symbiosis, but little is known about biotic and abiotic factors that determine partner specificity. Using PacBio long-read sequencing of soil samples from monospecific and mixed forest stands, we inferred the factors that determine partner specificity in both ectomycorrhizal plants and fungi. All studied tree genera host a large number of specialists, and specificity is driven by both plant species effects, their phylogenetic relatedness, vegetation age and dominance. Generalist fungi mainly contribute to the high diversity in mixed forests. Our results suggest that besides conserving mixed forests, protection of old pure stands may be particularly important for conserving specialised EcM fungi.