Arbuscular mycorrhizal fungi promote arsenic accumulation in Pteris vittata L. through arsenic solubilization in rhizosphere soil and arsenic uptake by hyphae

The introduction of arbuscular mycorrhizal fungi (AMF) is considered an effective strategy for improving the arsenic phytoremediation efficiency of Pteris vittata L. (P. vittata). However, how hyphae take up arsenic and translocate it to the root cells of P. vittata in the symbiotic mycorrhizal structure is currently unclear. In this study, the role of hyphae in arsenic enrichment in P. vittata and the mechanism of arsenic species transformation in the rhizosphere were studied via a compartmented cultivation setup. After Claroidoglomus etunicatum (C. etunicatum) colonization, the arsenic content of P. vittata increased by 234%. Hyphae contributed 32% to the accumulation of arsenic in symbionts. C. etunicatum promoted the conversion of iron and aluminum oxides to crystalline states in rhizosphere soil, promoted the desorption of arsenic bound to iron and aluminum oxides, and increased the content of available arsenic in rhizosphere soil by 116%. The transfer of arsenic from arbuscular structures to root cells was confirmed by transmission electron microscopy (TEM)/scanning electron microscopy– energy dispersive X-ray spectroscopy (SEMEDS) analysis. This study demonstrated that C. etunicatum inoculation enhances the phytoremediation efficiency of P. vittata in arsenic-contaminated soils through hyphal uptake, plant growth promotion, and alteration of the rhizosphere environment. [Display omitted] •C. etunicatum promotes the activation of arsenic in the rhizosphere soil of P. vittata.•The hyphal pathway contributes nearly one-third of the arsenic in AMF-P. vittata symbionts.•Arsenic in hyphae can be transferred to the root cells of P. vittata.•Colonization of C. etunicatum increased the biomass and arsenic concentrations in P. vittata.