LeGRP1: A new member of glycine-rich proteins from tomato (Lycopersicon esculentum)

Glycine-rich proteins (GRPs) are members of a family of proteins with uniqu e repeats of glycine-containing motifs. This feature facilitates their asso ciation with plant structural components such as cell wall and vascular tis sues. A transcript encoding a new member (LeGRP1) of the GRP family was ide ntified from roots of tomato by the method of differential display of mRNA species. The cDNA is 1.15 kb in size and has an open reading frame encoding a peptide of 284 amino acids. Glycine residues make up 55% of the deduced peptide and the sequence is characterized by repeating (Gly-X), domains. Th e presence of a hydrophobic N-terminus with a putative signal peptide indic ates a probable association of the protein with the cell wall. Southern ana lysis shows that several LeGRP1 homologues are present in the genome. The L eGRP1 transcript accumulates predominantly in the roots, stem and petioles of tomato. A relatively lower level of LeGRP1 message was observed in the l eaf mid-rib, while the message is undetectable in the leaf lamina. Abiotic stresses like cold, heat, salt, desiccation and phosphate starvation did no t significantly affect the expression of LeGRP1, whereas wounding resulted in a significant repression of the gene expression. Temporal regulation of LeGRP1 was observed during fruit development.