Phosphorus is a major nutrient acquired by roots via high-affinity inorganic phosphate (Pi) transporters. In this paper, we describe the tissue-specific regulation of tomato (Lycopersicon esculentum L.) Pi-transporter genes by Pi. The encoded peptides of the LePT1 and LePT2 genes belong to a family of 12 membrane-spanning domain proteins and show a high degree of sequence identity to known high-affinity Pi transporters. Both genes are highly expressed in roots, although there is some expression of LePT1 in leaves. Their expression is markedly induced by Pi starvation but not by starvation of nitrogen, potassium, or iron. The transcripts are primarily localized in root epidermis under Pi starvation. Accumulation of LePT1 message was also observed in palisade parenchyma cells of Pi-starved leaves. Our data suggest that the epidermally localized Pi transporters may play a significant role in acquiring the nutrient under natural conditions. Divided root-system studies support the hypothesis that signal(s) for the Pi-starvation response may arise internally because of the changes in cellular concentration of phosphorus.

peptide indicates a probable association of the protein with the Glycine-rich proteins (GRPs) are members of a family of proteins with unique repeats of glycine-containing motifs. This cell wall. Southern analysis shows that several LeGRP1 homologues are present in the genome. The LeGRP1 transcript feature facilitates their association with plant structural comaccumulates predominantly in the roots, stem and petioles of ponents such as cell wall and vascular tissues. A transcript encoding a new member (LeGRP1) of the GRP family was tomato. A relatively lower level of LeGRP1 message was observed in the leaf mid-rib, while the message is undetectable identified from roots of tomato by the method of differential display of mRNA species. The cDNA is 1.15 kb in size and has in the leaf lamina. Abiotic stresses like cold, heat, salt, an open reading frame encoding a peptide of 284 amino acids.desiccation and phosphate starvation did not significantly affect the expression of LeGRP1, whereas wounding resulted Glycine residues make up 55% of the deduced peptide and the sequence is characterized by repeating (Gly-X) n domains. The in a significant repression of the gene expression.