Proton-coupled high-affinity phosphate transport revealed from heterologous characterization in Xenopus of barley-root plasma membrane transporter, HvPHT1;1

High‐affinity phosphate transporters mediate uptake of inorganic phosphate (P_i) from soil solution under low P_i conditions. The electrophysiological properties of any plant high‐affinity P_i transporter have not been described yet. Here, we report the detailed characterization of electrophysiological properties of the barley P_i transporter, HvPHT1;1 in Xenopus laevis oocytes. A very low K_m value (1.9 µm ) for phosphate transport was observed in HvPHT1;1, which falls within the concentration range observed for barley roots. Inward currents at negative membrane potentials were identified as nH⁺:P_i^‐ (n > 1) co‐transport based on simultaneous P_i radiotracer uptake, oocyte voltage clamping and pH dependence. HvPHT1;1 showed preferential selectivity for P_i and arsenate, but no transport of the other oxyanions SO₄^2? and NO₃^‐. In addition, HvPHT1;1 locates to the plasma membrane when expressed in onion (Allium cepa L.) epidermal cells, and is highly expressed in root segments with dense hairs. The electrophysiological properties, plasma membrane localization and cell‐specific expression pattern of HvPHT1;1 support its role in the uptake of P_i under low P_i conditions.