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.

共生伙伴专一性是包括外生菌根（ectomycorrhizal）共生在内的生物交互作用中广为熟知的现象，但目前针对调控该专一性的生物与非生物因子仍知之甚少。本研究针对单优林分与混交林分的土壤样本开展PacBio长读长测序（PacBio long-read sequencing），以此推断同时调控外生菌根植物与真菌共生伙伴专一性的相关因子。所有被纳入研究的树木属均宿主有大量专性共生类群，共生专一性同时受植物物种效应、其系统发育亲缘关系、林龄以及物种优势度共同驱动。广适性真菌是混交林高物种多样性的主要贡献者。本研究结果表明，除保护混交林外，对老龄纯林的保育或许对于专性外生菌根真菌（Ectomycorrhizal fungi, EcM）的保护尤为关键。