Transcriptional regulation of plant phosphate transporters

Abstract

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.