Regulation of phosphate starvation responses in higher plants

Background Phosphorus (P) is often a limiting mineral nutrient for plant growth. Many soils worldwide are deficient in soluble inorganic phosphate (P-i), the form of P most readily absorbed and utilized by plants. A network of elaborate developmental and biochemical adaptations has evolved in plants to enhance P-i acquisition and avoid starvation. Scope Controlling the deployment of adaptations used by plants to avoid P-i starvation requires a sophisticated sensing and regulatory system that can integrate external and internal information regarding P-i availability. In this review, the current knowledge of the regulatory mechanisms that control P-i starvation responses and the local and long-distance signals that may trigger P-i starvation responses are discussed. Uncharacterized mutants that have P-i-related phenotypes and their potential to give us additional insights into regulatory pathways and P-i starvation-induced signalling are also highlighted and assessed. Conclusions An impressive list of factors that regulate P-i starvation responses is now available, as is a good deal of knowledge regarding the local and long-distance signals that allow a plant to sense and respond to P-i availability. However, we are only beginning to understand how these factors and signals are integrated with one another in a regulatory web able to control the range of responses demonstrated by plants grown in low P-i environments. Much more knowledge is needed in this agronomically important area before real gains can be made in improving P-i acquisition in crop plants.