Root-associated fungi in acid mine drainage-impacted environments

Acid mine drainage (AMD) poses persistent environmental challenges despite ongoing restoration efforts, particularly through the generation of acidic and metal-rich substrates. Fungi-assisted phytoremediation has emerged as a complementary strategy to support plant establishment in these environments. This study examines culturable root-associated fungi from four plant species, Populus balsamifera (PBA), Salix discolor (SDI), Scirpus atrocinctus (SAT), and Typha latifolia (TLA), growing at an AMD-impacted site and a nearby non-impacted reference site. Culture-dependent estimates of culturable fungi were obtained from bulk soil, rhizosphere soil, and root samples using two culture media. The taxonomic composition of culturable root-associated fungi was characterized, and relationships among taxa, soil physicochemical properties, and plant mineral parameters were examined. Estimates of culturable fungi on Modified Melin-Norkrans medium increased from bulk soil to roots, indicating stronger associations with root compartments under AMD-related stress. Most of the isolates belonged to Ascomycota, with a substantial proportion identified as dark septate endophytes (DSE). Phialocephala spp. were strongly associated with SAT and TLA growing in acidic, metal-rich, and water-saturated soils typical of AMD-impacted sites, whereas Cadophora spp. were more frequently associated with plants growing under less stressful environmental conditions. Overall, these results highlight the influence of site-specific edaphic conditions on the composition of culturable root-associated fungi and their associations with plant hosts. Together, these patterns suggest that specific fungal-plant associations may contribute to fungi-assisted phytoremediation in AMD-impacted environments.