Phosphate is essential for plant growth and development. It is needed to make nucleic acids and phospholipids, and also functions in energy transfer reactions and a host of cell-signaling events. To fulfill these fundamental roles, plants not only must acquire phosphate from the soil, but also must tightly control its subsequent distribution to all cells and subcellular compartments of the plant. The transport of phosphate across membranes is a pivotal step in regulating its distribution, yet only a few phosphate transport systems have been described at the molecular level. The objectives of this project are to determine the tissue and subcellular distribution, and the biochemical properties and biological roles of each member of a phosphate transporter gene family in Arabidopsis designated PHT4. The PHT4 family is composed of six genes that encode proteins with similarity to phosphate transporters of animal origin, but not to any previously identified phosphate transporters in plants. Protein-sorting predictions suggest that the transporters may be located within organellar membranes. Consequently, these transporters are likely to have unique physiological roles, which may provide new insights into the mechanisms governing the subcellular distribution of phosphate in plants. Because phosphate is often the limiting factor for plant growth, an understanding of how plants utilize phosphate has broad agricultural and ecological implications. Graduate and undergraduate students supported by this grant will receive multidisciplinary training and will participate in conferences and teaching opportunities.
