Regulation of phosphate transport and homeostasis in plant cells

The inorganic phosphate (Pi) status of plants was reviewed based on the current knowledge of membrane transport systems and ion homeostasis. The Pi content and Pi distribution in plant cells were first considered in relation to experimental procedures used in their measurement. In order to understand the mechanisms which contribute to the Pi status, transport systems for Pi across the plasma membrane and the tonoplast were examined in detail. Recent progress in molecular biological approaches is discussed, especially for Pi transport across the plasma membrane. The molecular basis for Pi efflux across the plasma membrane and for Pi movements across the tonoplast still remains to be resolved. The involvement of Pi transport in Pi homeostasis is discussed from both the cellular and the whole plant perspectives.