ZmPHR1 coordinates root–rhizosphere processes and phosphorus allocation to enhance phosphorus efficiency and yield in maize

BACKGROUND AND AIMS: Phosphorus (P) deficiency severely restricts crop productivity, making the improvement of P efficiency a major goal for sustainable agriculture. ZmPHR1, a central transcription factor in P signalling, has remained functionally unresolved in whole-plant coordination. METHODS: Here, CRISPR/Cas9 knockout (zmphr1) and overexpression (ZmPHR1-OE) lines were used to dissect its regulatory mechanisms from root to grain. KEY RESULTS: ZmPHR1 loss-of-function markedly reduced root biomass, total root length and rhizosphere acid phosphatase activity, leading to lower P accumulation and grain yield. In contrast, ZmPHR1 overexpression optimized root system architecture by narrowing root angle, increasing deep-root biomass and enhancing rhizosphere APase activity in low-P conditions. These changes improved soil P acquisition, leaf P concentration and photosynthetic rate, resulting in ≤48 % higher grain yield relative to wild type. ZmPHR1 further promoted P remobilization from vegetative organs to grains, coordinating biomass and P partitioning during reproductive growth. CONCLUSIONS: Collectively, ZmPHR1 integrates root morphological remodelling, rhizosphere activation and internal P redistribution to enhance P efficiency and yield in maize. This gene represents a promising molecular target for breeding P-efficient cultivars and optimizing fertilizer management.