Symbiosis-specific regulated inorganic phosphate (Pi) transporter. Probably involved in symbiosis-mediated Pi uptake in roots colonized by myccorhizal fungi. Specifically induced by the mycorrhizal fungus G. intraradices colonization in roots. 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.