Arbuscular mycorrhizal fungi helped lettuce cope with PET microplastic pollution by cutting uptake by 20% and boosting biomass by 11% through improved nucleotide metabolism and zeatin biosynthesis. But the same fungi increased the uptake of PP and PS microplastics, worsening toxicity by disrupting antioxidant and stress-response pathways. Their benefit appears specific to PET, pointing to a targeted bioremediation role rather than a universal solution.