Overexpression of OsPHR3 improves growth traits and facilitates nitrogen use efficiency under low phosphate condition

Phosphorus (P) and nitrogen (N) are both essential macronutrients for maintaining plant growth and development. In rice (Oryza sativa L.), OsPHR3 is one of the four paralogs of PHR1, which acts as a central regulator of phosphate (Pi) homeostasis, as well being involved in N homeostasis. However, the functions of OsPHR3 in N utilization under different Pi conditions have yet to be fully studied. In this study, we aimed to dissect the effect of OsPHR3-overexpression on N utilization under Pi deficient regimes. Biochemical, molecular and physiological assays were performed to determine the N-influx, translocation, and accumulation in OsPHR3-overexpressing rice lines, grown under Pi-sufficient and -deficient conditions, in both hydroponic and soil systems. Furthermore, important agronomic traits of these plants were also evaluated. The overexpression of OsPHR3 increased N uptake under Pi stress regimes. Increased N uptake also elevated total N concentrations in these plants by inducing N transporter genes expression. Furthermore, overexpression of OsPHR3 increased N use efficiency, 1000-grain weight and grain yield under different Pi conditions. We established new findings that OsPHR3-overexpression facilitates N utilization under Pi deficient conditions. This will help achieving higher yields by coordinating the utilization of N and P.

Automated summary

Overexpression of OsPHR3 increases nitrogen uptake and utilization efficiency in rice plants under Pi stress conditions, leading to higher total nitrogen concentrations, upregulation of nitrogen transporter genes, and improved nitrogen use efficiency, 1000-grain weight, and grain yield under different Pi conditions. This study establishes that OsPHR3 overexpression facilitates nitrogen utilization under Pi deficient conditions, potentially enhancing crop yields by coordinating nitrogen and phosphorus utilization.