About 30 elements are required for optimal plant growth, and P is the second most limiting macro-element that restricts crop production on nearly 70% of the world’s agricultural soils. The esters and anhydrides of inorganic phosphate (Pi), the only form of P directly accessible to plants, constitute major structural building blocks and regulatory nodes in bioenergetics and metabolism. Thus, Pi nutrition directly impacts biosynthetic capacity and plant performance. To cope with inadequate Pi availability, which is a common situation in many ecosystems and a result of intricate soil chemistries, such as complex interactions with transition metals like Fe, plants activate a set of acclimatory responses that reprioritize internal Pi allocation and maximize external Pi acquisition. Such countermeasures include reprogramming of metabolism to maintain systemic Pi homeostasis and restructuring of root system architecture to accelerate soil exploration.
While the physiological and biochemical responses to Pi shortage are well understood, the sensory mechanisms monitoring external Pi availability and interpreting the environmental signal in Pi rescue efforts are largely unknown. We are particularly interested in the signaling networks that govern metabolic adjustments and root developmental responses to Pi availability as well as in the cross-talk between Pi, Fe and N sensing. A better understanding of how plants monitor and respond to external Pi status will be necessary for developing strategies to improve P use-efficiency in crops because rock phosphate reserves are a finite and non-renewable mineral resource essential for global food security.