Sensing and Signaling of PO 4 3−

Abstract

Phosphorus (P) is one of the most limiting factors for plant growth, development, and productivity in many natural and agricultural ecosystems. P is acquired by plants from the soil in the form of inorganic phosphate (Pi). Due to the high reactivity of Pi with cations present in the soil and its rapid conversion to organic forms by microbial activity, in most soils, Pi is not readily available for plant uptake. However, during millions of years of evolution, plants acquired complex physiological, biochemical, and molecular strategies to survive and reproduce in soils with low Pi availability. Thus, plants display a low Pi rescue system that includes a wide range of adaptive responses, which integrate external and internal signals to maintain Pi homeostasis at the cellular, organ, and whole plant levels. These adaptive responses allow plants to enhance Pi availability in the soil, increase its uptake, and improve the efficiency with which plants use Pi to support its metabolic activities to grow and reproduce. The development of a comprehensive understanding of how plants sense phosphate status and coordinate the local and systemic responses via network pathways has become a major area of research in plant biology. This review is aimed to succinctly present the current state of research covering most of process related with Pi uptake, transport, and in particular the plant responses to Pi-deprivation, making special emphasis on recent developments in the molecular mechanisms and the signaling pathways that regulate these responses.