Insights into plant phosphate sensing and signaling

•Pi stress restricts primary root growth through dual regulatory pathways.•Vacuolar transporters regulate cytosolic Pi homeostasis.•InsP interacts with SPX domain to regulate Pi transport and/or signal transduction.•Phloem delivers Pi signaling RNAs to specific sinks for downstream regulation.•Phosphate starvation-response (PSR) attenuates plant defenses to allow symbiosis with beneficial microbes.