Abstract: Root phosphorus (P) acquisition capacity, a critical determinant of plant fitness in P- limited environments, stems from an evolutionarily refined hierarchy of molecular signaling, physiological modulation, and ecological collaborations. However, our understanding of this multiscale response, which spans intracellular signaling, plant phenotypic plasticity, and rhizosphere dynamics, remains fragmented. Few syntheses specify the causal interfaces and bidirectional feedbacks that connect these levels. A unified, cross-disciplinary framework that integrates the processes governing the phosphate starvation response (PSR) across levels is needed. Such integration would consolidate current knowledge and bridge fundamental theory to field practice, guiding ecological agriculture through molecular breeding. Here, we synthesize disparate findings into an integrated framework linking gene regulation to ecosystem processes, encompassing: (i) root molecular-scale P sensing and PSR activation mechanisms; (ii) signal-mediated phenotypic responses involving root morphological and functional modifications; and (iii) rhizosphere microbial partnerships that enhance root P acquisition. By explicitly mapping core PSR modules to rhizosphere functions, this framework clarifies how roots coordinate molecular signals, physiological modulation, and ecological interactions to overcome P limitation. It provides actionable insights for molecular breeding, microbiome-based inoculants, and more efficient stewardship of agricultural P, thereby aligning crop productivity with long-term soil health.

Key words: Low-P stress, Signal sensing and cascading, Root morphology, Root physiology, Root-microbe interactions