Mycorrhiza-Inducible Phosphate Transporter PvPht1;6 Enhances Phosphorus Acquisition with Host-Dependent Plant Arsenic Accumulation

: Arbuscular mycorrhizal fungi (AMF) promote arsenic (As) accumulation in As-hyperaccumulator Pteris vittata , in contrast to reduced As accumulation in non-hyperaccumulator plants. The AMF-inducible P-transporter PvPht1;6 has been proposed to mediate P and arsenate (AsV) uptake at P. vittata root-AMF interface based on its subcellular localization and P/AsV transport activity in yeast. However, its in planta evidence remains lacking. Here, for the first time, we identified two additional AMF-enhanced P-transporter genes PvPht1;7/1;8 in P. vittata. All three genes contained typical AMF-responsive elements in their promoter regions and were induced by AMF symbiosis, with PvPht1;6 showing the strongest induction (15-fold). To test its in planta function, we expressed PvPht1;6 in rice and tobacco using promoters from AMF-inducible genes OsPT11 and LePT4 , respectively. AMF symbiosis activated PvPht1;6 expression by 7.2–73 fold in rice and 7.0–26 fold in tobacco, whereas its expression was nearly undetectable without AMF. Under AMF symbiosis, PvPht1;6 increased shoot P concentrations by 16–41% in rice and 11–26% in tobacco, showing a consistent effect on P acquisition. Its effect on As accumulation differed between the two hosts. PvPht1;6 increased shoot As concentrations by 13–38% in rice but had little effect in tobacco. However, total root As accumulation increased by 1.1–1.8 fold in tobacco, supporting the function of PvPht1;6 in As acquisition. This difference may be explained by efficient OsLsi1/2-mediated As translocation in rice, which tobacco lacks. These results suggest potential contribution of PvPht1;6 to P and As uptake at the root-AMF interface in P. vittata , whereas shoot As accumulation further depends on the plant’s endogenous As translocation capacity. These findings provide a potential strategy for improving AMF-assisted P acquisition and As phytoremediation in As-contaminated soils.