Low-affinity transporter for external inorganic phosphate (Pi) probably involved in the acquisition of phosphate released by arbuscular mycorrhizal (AM) fungi during AM symbiosis. NH4(+)(in) = NH4(+)(out) Present on the periarbuscular membrane in cells containing arbuscules during arbuscular mycorrhizal (AM) symbiosis with AM fungi. Expressed at low levels in non-mycorrhized roots. Accumulates during arbuscular mycorrhiza (AM) formation after inoculation with AM fungi (e.g. Glomus intraradices). Although related to the sugar transporter family, it does not transport sugars. Belongs to the major facilitator superfamily. phosphate:H(+) symporter (TC 2.A.1.9) family.