Metabolic Aspects of the Phosphate Starvation Response in Plants

Phosphorus is an element essential for normal plant growth and metabolism. It plays a central role in virtually all major metabolic processes in plants, including photosynthesis and respiration. Despite its ubiquitous importance to plant metabolism, orthophosphate (Pi) is one of the least available nutrients in many aquatic and terrestrial ecosystems. Most of the Pi absorbed by the roots of Pi-sufficient plants is transported in the xylem to the younger leaves. Apoplastic Pi concentration appears to be maintained at the expense of vacuolar and, occasionally, cytoplasmic Pi pools. During Pi stress, some plants reduce the permeability of the plasmalemma to Pi, thereby decreasing the amount of Pi leaked to the environment. The induction of acid phosphatase activity is a universal biochemical symptom of Pi stress in higher plants. Phosphate nutrition is intimately related to nitrate uptake and symbiotic nitrogen fixation in plants. The development of Pi stress-tolerant crops would reduce the amount of Pi fertilizers required to attain optimal crop productivity.