PHT1familien

The PHT1 family, also written as the PHT1 family of phosphate transporters, comprises a group of high-affinity inorganic phosphate (Pi) transporters that are predominantly expressed in the roots of land plants. Members of the family mediate uptake of Pi from the soil into root cells and, in some species, facilitate Pi transfer in arbuscular mycorrhizal associations. The family is one subdivision of the larger PHT transporter superfamily.

Structural features include multiple predicted transmembrane segments (typically 8–12) and cytosolic loops containing regulatory motifs. PHT1 transporters function as H+-coupled Pi symporters at the plasma membrane, enabling uptake particularly under low Pi availability. Transport capacity and affinity vary among family members and across species.

Gene expression is highly responsive to Pi status. Pi deficiency commonly upregulates PHT1 genes in roots, while sufficient Pi represses expression. Regulation involves transcription factors such as PHR1/PHR2 and complex post-translational mechanisms, including endocytosis and phosphorylation, that adjust transporter abundance at the plasma membrane. Some PHT1 members are specifically induced during mycorrhizal symbiosis and contribute to Pi delivery through the fungal partner.

Across plant species, the PHT1 family is expanded, with multiple paralogs providing tissue-specific and environmental-condition-specific Pi uptake strategies. Functional redundancy and specialization support plant phosphate-use efficiency and adaptation to Pi-poor soils, with implications for crop improvement and sustainable agriculture.