Phosphate reserves in plants

The turnover of Phosphate (Pi) is essential for the metabolic balance in plants.  Typically plants store P in the vacuole as free Pi, and this storage is remobilized when Pi becomes insufficient. We have overexpresses a specific transcription factor in transgenic Arabidopsis plants, and as a consequence plants the plants overaccumulate Pi in the leaves (Nilsson et al.  2007 Plant Cell Environ 30: 1499-1512). Such overaccumulation may also lead to imbalance in metabolism. We presently work on creating a new storage for P in plants by engineering to express polyphosphate kinases in the tissue, which should allow for accumulation of polyphosphate as a P-storage in higher plants.