Strigolactone regulates phosphorus recycling in rice ( <i>Oryza sativa</i> ) through a nitric oxide-dependent pathway

Strigolactone (GR24) has been implicated in the plant response to phosphorus (P) stress; nonetheless, the precise molecular mechanisms involved remain obscure. The present study examined the role of GR24 in regulating the internal distribution of P and the mobilization of P from root cell walls in rice. The research involved subjecting rice plants to differential treatments of GR24 and P, followed by a comprehensive analysis employing biochemical and molecular methodologies to elucidate the mechanisms underlying P utilization. The findings indicated that diminished P levels result in a swift escalation of endogenous GR24 accumulation within the roots of rice plants. Moreover, the application of exogenous GR24 notably augmented the tolerance of rice to P deficiency, as evidenced by the enhancement of biomass and a reduction in the root/shoot ratio under P deficient conditions. The application of GR24 also alleviated the decline in P content observed in both roots and shoots. At a mechanistic level, GR24 facilitated the reutilization of P, particularly within the root pectin fraction, thereby increasing the liberation of soluble P. Additionally, GR24 promoted the expression of OsPHT1;2 (OsPT2), a gene implicated in the translocation of P from roots to shoots. Furthermore, it was observed that GR24 stimulated the production of nitric oxide (NO) in P-deficient rice roots. The application of sodium nitroprusside (SNP) further augmented the alleviating effect of GR24 on P deficiency. In summary, these findings underscore the potential of GR24 as a viable strategy to enhance the tolerance of rice to P deficiency and to improve P use efficiency in agricultural applications.