PHT1

PHT1, or phosphate transporter 1, is a plant gene family encoding high-affinity inorganic phosphate (Pi) transporters belonging to the major facilitator superfamily. Members are primarily localized to the plasma membrane of root cells and other Pi-absorbing tissues, where they mediate uptake of Pi from soil and its subsequent loading for transport to shoots.

In Arabidopsis thaliana, the PHT1 family comprises multiple transporters (for example AtPHT1;1 and AtPHT1;4) that are upregulated under Pi deficiency and contribute to Pi uptake when soil Pi is scarce. Similar families exist in crop species such as rice (OsPHT1 family).

Functionally, PHT1 transporters show high affinity for Pi and operate in the first step of Pi acquisition from the rhizosphere. Their activity and expression respond to the plant Pi status through regulatory networks that involve transcription factors such as PHR1 and SPX-domain proteins, as well as microRNA pathways. In some plant species, certain PHT1 members participate in arbuscular mycorrhizal (AM) pathways, delivering Pi acquired via fungal partners.

Diversity among PHT1 genes supports tissue- and condition-specific Pi uptake, remobilization, and distribution. The family represents a major component of the plant Pi homeostasis system and is a target for improving phosphate-use efficiency in agriculture.