Ectomycorrhizal fungi significantly shape endorhizal bacteria associated with <i>Pinus taiwanensis</i> in heavy metal soils

Abstract The understanding of ectomycorrhizal (ECM) fungi's role in shaping bacterial groups and regulating heavy metals in soils was limited in the past. A mesocosm experiment with inoculation treatments ( Pezicula ericae K2 and Pisolithus tinctorius ) was applied to Pinus taiwanensis . The study aimed to explore the impact of ECM fungi, specifically, P. ericae K2 and P. tinctorius , on bacterial communities within the rhizosphere and endorhiza (root tips) of P. taiwanensis seedlings. Additionally, it sought to evaluate the interaction between environmental factors, including heavy metals and bacteria associated with ECM fungi. Furthermore, the study aimed to elucidate the influence of ECM fungi on host plant biomass, environmental conditions, and heavy metal concentrations. Next‐generation sequencing analyzed rhizosphere soils and root tip bacterial communities. Results confirmed P. ericae K2 as an ECM fungi; dominant phyla in rhizosphere soils were Acidobacteria and Proteobacteria , while in mycorrhizal root tips were Actinobacteria and Proteobacteria ; rhizosphere soils had a more robust influence of environmental factors and heavy metals; the most dominant Actinomycetales and Burkholderiales were associated with rhizosphere soils and root tips, respectively; diversity indices escalated for seedlings with ECM fungi; most negative correlations of bacterial rhizosphere soils signified their resistance to heavy metals; nitrogen fixers displayed intricate positive correlations in the root tips; ECM fungi increased plant biomass, soil cations, pH, and cation exchange capacity while reducing soil nitrogen and heavy metal concentrations. The study highlighted that ECM fungi's ecological contributions were crucial for regulating metal‐laden soils, benefiting plant health and tolerance, and sustaining ecosystems.