Molecular Mechanisms Underlying Phosphate Sensing and Signalling in Plants

Plants need nutrients for survival. Of the macronutrients, phosphorus (P), the second most important after nitrogen, is obtained by plants as phosphate (Pi) from the soil for sustained plant growth and development. Low Pi levels, therefore, could limit crop production, and it is imperative that adaptive mechanisms of plants to such conditions are deciphered to harness these mechanisms to engineer crops with traits enhanced for Pi acquisition and utilisation. There have been grand advances in the recent past, particularly in how plants sense Pi and maintain Pi homeostasis. In this chapter, we assess the recent findings on local and systemic Pi sensing with a focus on the molecular mechanisms behind root system architectural changes, Pi uptake and redistribution, and plant-microbiome interactions. We also focus on the recent advances in the discovery of the inositol pyrophosphate InsP8 as a signalling molecule in a plant's response to Pi fluctuation and the mechanism of its interaction with SPX domain proteins, which play significant roles in regulating PHR proteins, master regulators of the Pi starvation response.