Transcriptional regulation of plant phosphate transporters

Phosphorus is acquired by plant roots primarily via the high-affinity inorganic phosphate (P-i) transporters. The transcripts for P-i transporters are highly inducible upon P-i starvation, which also results in enhanced P-i uptake when P-i is resupplied. Using antibodies specific to one of the tomato P-i transporters (encoded by LePT1), we show that an increase in the LePT1 transcript under P-i starvation leads to a concurrent increase in the transporter protein, suggesting a transcriptional regulation for P-i acquisition, LePT1 protein accumulates rapidly in tomato roots in response to P-i starvation. The level of transporter protein accumulation depends on the P-i concentration in the medium, and it is reversible upon resupply of P-i. LePT1 protein accumulates all along the roots under P-i starvation and is localized primarily in the plasma membranes. These results clearly demonstrate that plants increase their capacity for P-i uptake during P-i starvation by synthesis of additional transporter molecules.