OsPLT1 negatively regulates phosphorus deficiency tolerance by modulating nitric oxide-mediated cell wall phosphorus reutilization in rice.

BACKGROUND AND AIMS: Phosphorus (P) deficiency severely limits rice productivity, yet the role of root developmental regulators in P homeostasis remains unclear. Here, we show that the rice PLETHORA transcription factor OsPLT1 suppresses rice tolerance to P-deficient conditions. Under P-starved conditions, osplt1 mutants accumulated more biomass and exhibited higher soluble and total P concentrations, whereas OsPLT1-overexpressing lines were hypersensitive to P deficiency.

KEY

RESULTS

Mechanistically, osplt1 mutants displayed reduced P retention in root cell walls, particularly in the water-soluble pectin fraction, accompanied by increased water-soluble pectin uronic acid content and elevated pectin methylesterase activity. Enzymatic digestion assays confirmed enhanced release of wall-bound P in the mutants. Moreover, osplt1 mutants showed higher nitric oxide (NO) accumulation under P deficiency, whereas sodium nitroprusside treatment largely reduced the differences in cell wall P and soluble P between Nip and osplt1 mutants, suggesting that NO is associated with OsPLT1-dependent P reutilization. The phosphate uptake-related gene, OsPT6, was also more strongly induced in the mutants, which may contribute to improved P acquisition. Notably, OsPHR1/2 and representative PHR-responsive genes showed comparable expression among genotypes under the same P condition, suggesting that OsPLT1-mediated regulation may not primarily depend on major changes in canonical PHR signalling activity.

CONCLUSIONS

Together, these results reveal a link between root developmental control and P homeostasis and suggest that OsPLT1 may provide a useful genetic target for enhancing P-use efficiency in rice.