Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/17/2000
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: Under phosphorus deficient (-P) conditions white lupin produces proteoid roots that secrete citrate as well as acid phosphatase to aid in the release of insoluble soil phosphate. Fragments for two different phosphate transporters were obtained by amplification of -P proteoid root or nodule cDNA of white lupin with degenerate primers. The phosphate transporter PCR fragments were used to screen a -P proteoid root cDNA library and two phosphate transporter genes, Lapt1 and Lapt2, were recovered. Lapt1 is 1965 bp long and encodes a protein containing 539 amino acids. Expression of Lapt1 is specifically enhanced in -P proteoid roots by 12 days after emergence and becomes very abundant 14 days after emergence. Lapt1 is induced not only by -P, but slight induction occurs with Fe and Al stress. In comparison, Lapt2 is 2167 bp long and encodes a protein containing 540 amino acids. It is constitutively expressed in both -P proteoid roots and leaves and phosphorus sufficient normal roots and leaves, but appears not to be expressed in flowers or pods. Lapt1 and Lapt2 share high homology with the phosphate transporters Apt1 (81.0% and 79.0%) and Apt2 (81.0% and 79.2%) from Arabidopsis thaliana, and Mtpt1 (82.9% and 81.0%) and Mtpt2 (83.2% and 80.6%) from Medicago truncatula. The Southern hybridization results suggest that both Lapt1 and Lapt2 are single copy genes.