Expression analysis suggests novel roles for members of the Pht1 family of phosphate transporters in Arabidopsis.
The completion of the Arabidopsis thaliana genome has revealed that there are nine members of the Pht1 family of phosphate transporters in this species. As a step towards identifying the role of this gene family in phosphorus nutrition, we have isolated the promoter regions from each of these genes, and fused them to the reporter genes beta-glucuronidase and/or green fluorescent protein. These chimeric genes have been introduced into A. thaliana, and reporter gene expression has been assayed in plants grown in soil containing high and low concentrations of inorganic phosphate (Pi). Four of these promoters were found to direct reporter gene expression in the root epidermis, and were induced under conditions of phosphate deprivation in a manner similar to previously characterised Pht1 genes. Other members of this family, however, showed expression in a range of shoot tissues and in pollen grains, which was confirmed by RT-PCR. We also provide evidence that the root epidermally expressed genes are expressed most strongly in trichoblasts, the primary sites for uptake of Pi. These results suggest that this gene family plays a wider role in phosphate uptake and remobilisation throughout the plant than was previously believed.
Mudge
Stephen R
SR
CSIRO Division of Plant Industry, 120 Meiers Road, Indooroopilly, Queensland 4068, Australia. Stephen.Mudge@csiro.au
Rae
Anne L
AL
Diatloff
Eugene
E
Smith
Frank W
FW
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D028061:Phosphate Transport Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism; D011058:Pollen / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D016415:Sequence Alignment
D029681:Arabidopsis Proteins; D028061:Phosphate Transport Proteins; D010758:Phosphorus