Phosphorus is acquired by plant roots primarily via the high-affinity inorg
anic phosphate (P-i) transporters. The transcripts for P-i transporters are
highly inducible upon P-i starvation, which also results in enhanced P-i u
ptake when P-i is resupplied. Using antibodies specific to one of the tomat
o P-i transporters (encoded by LePT1), we show that an increase in the LePT
1 transcript under P-i starvation leads to a concurrent increase in the tra
nsporter protein, suggesting a transcriptional regulation for P-i acquisiti
on, LePT1 protein accumulates rapidly in tomato roots in response to P-i st
arvation. The level of transporter protein accumulation depends on the P-i
concentration in the medium, and it is reversible upon resupply of P-i. LeP
T1 protein accumulates all along the roots under P-i starvation and is loca
lized 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.