This review provides an overview of the molecular mechanisms that regulate or coordinate phosphorus (P) starvation responses in plants, emphasizing P transport, sensing, and signaling. The authors highlight the major players and regulators responsible for Pi uptake and translocation, the perception of P at the root tip, systemic P signaling, and intracellular P sensing. They also discuss recent findings on the influence of P on plant-microbe interactions and the challenges and prospects for enhancing P utilization efficiency. The review covers historical milestones in understanding P transport, sensing, and signaling, including the discovery of key genes and proteins such as PHT1, PHO1, and SPX proteins. It details the roles of different Pi transporters, such as PHT1, PHT2/3/4, PHT5, VPE, PHO1, and SPDT, in Pi uptake and translocation. The review also explores the regulation of these transporters at the transcriptional and post-translational levels, the involvement of miRNAs like miR399 in systemic P signaling, and the role of SPX proteins as intracellular P sensors. Additionally, it discusses the importance of InsP8 as a metabolic messenger for intracellular P signaling and the crosstalk between P and other nutrients. The review concludes by highlighting the versatility of SPX-PHR modules in response to P status and plant-microbe interactions, including arbuscular mycorrhizal symbiosis and responses to pathogen infection.This review provides an overview of the molecular mechanisms that regulate or coordinate phosphorus (P) starvation responses in plants, emphasizing P transport, sensing, and signaling. The authors highlight the major players and regulators responsible for Pi uptake and translocation, the perception of P at the root tip, systemic P signaling, and intracellular P sensing. They also discuss recent findings on the influence of P on plant-microbe interactions and the challenges and prospects for enhancing P utilization efficiency. The review covers historical milestones in understanding P transport, sensing, and signaling, including the discovery of key genes and proteins such as PHT1, PHO1, and SPX proteins. It details the roles of different Pi transporters, such as PHT1, PHT2/3/4, PHT5, VPE, PHO1, and SPDT, in Pi uptake and translocation. The review also explores the regulation of these transporters at the transcriptional and post-translational levels, the involvement of miRNAs like miR399 in systemic P signaling, and the role of SPX proteins as intracellular P sensors. Additionally, it discusses the importance of InsP8 as a metabolic messenger for intracellular P signaling and the crosstalk between P and other nutrients. The review concludes by highlighting the versatility of SPX-PHR modules in response to P status and plant-microbe interactions, including arbuscular mycorrhizal symbiosis and responses to pathogen infection.