Phosphate Resupply Differentially Impacts the Shoot and Root Proteomes of Arabidopsis thaliana Seedlings.

Phosphate (Pi) is an essential macronutrient for plant development that is often limited in soil. Plants have evolved dynamic biochemical, physiological and morphological adaptations to cope with Pi deficiency, known as the Pi starvation response (PSR). While many components of the PSR have been well-characterised, less is known about how metabolic homoeostasis is re-established upon Pi resupply, particularly tissue- and time-specific adaptations. Here, we applied label-free quantitative proteomics to quantify protein-level changes in Arabidopsis thaliana shoots and roots following Pi resupply after prolonged Pi deprivation. Sampling at 1 h and 48 h time-points, we captured immediate signalling and metabolic responses, along with longer-term recovery processes. Early responses prioritised metabolic adjustments restoring Pi pools via enhanced glycolysis and energy production, followed by later shifts toward anabolism. Several key enzymes, including ALTERNATIVE OXIDASE 1 A, FRUCTOSE-BISPHOSPHATE ALDOLASE 5 and subunits of PHOTOSYSTEM I exhibited tissue-specific and time-dependent regulation. Our findings reveal dynamic phases of metabolic reprogramming during recovery from Pi starvation, and identify candidate proteins as potential targets for enhancing Pi uptake- and use-efficiency in crops. While hydroponic liquid culture enabled precise control of Pi availability, soil responses may be further influenced by heterogeneity and other root interactions.