Arbuscular mycorrhizal fungal ( <scp>AMF</scp> ) communities in sand bars associated with <i>Ipomoea pes‐caprae</i> : a promising strategy for petroleum spill bioremediation in coastal dunes

Abstract Introduction Polycyclic aromatic hydrocarbons (PAHs), a class of petroleum‐derived compounds known for causing cellular damage and for their recalcitrant behavior, severely limit effective biodegradation. Arbuscular mycorrhizal fungi (AMF) from oil‐contaminated environments can mitigate PAH‐related stress on host plants, highlighting the bioremediation potential of associations between native AMF and local plant species. Objectives This study aimed to evaluate the role of native AMF–plant associations in the bioremediation of petroleum‐contaminated dune sand, using Ipomoea pes‐caprae as a model pioneer species. To this end, a native AMF inoculum derived from sandbars of the Restinga de Jurubatiba National Park, southeastern Brazil, was applied in a controlled experiment simulating an oil spill. Methods The inoculum, propagated in trap pots, consisted of three dominant sporocarpic Glomus species native to the study area. Ipomoea pes‐caprae cuttings were rooted in vitro and transplanted into sterilized sandbar sediment. To simulate an oil spill, 8 g of petroleum were applied to each pot, with or without bioaugmentation (sediment + plant + AMF + oil [SPFO] and sediment + plant + oil treatments), over 48 days. Residual hydrocarbons were compared with a natural attenuation control (sediment + oil). Results The bioaugmented treatment (SPFO) showed reductions in hydrocarbon concentrations, with 34.8% terpane degradation and 45.4% PAH degradation. PAH accumulation within intraroot fungal structures was confirmed through fluorescence microscopy and image analysis. Conclusion This study demonstrates that AMF enhance the performance of I. pes‐caprae under petroleum contamination, strengthening plant–fungus interactions in coastal dunes. Native AMF improved early stabilization and supported the plant's capacity to cope with hydrocarbon stress, confirming their ecological relevance for restoring oil‐affected coastal systems.