Overexpression of rice phosphate transporter gene OsPT6 enhances phosphate uptake and accumulation in transgenic rice plants

Whereas the expression patterns and kinetic properties of the rice (Oryza sativa) phosphate transporter gene OsPht1; 6 (OsPT6) are well documented, little is known about the biological functions of this gene. The aim of this study was to investigate the roles of OsPT6 in inorganic phosphate (Pi) acquisition and mobilization, and examine its potential to enhance agricultural production. Here, we generated OsPT6 overexpression transgenic plants using Wuyujing 7, a widely cultivated variety of japonica rice, and then treated transgenic lines and wild type with different Pi supply in hydroponic and soil experiments to explore the functions of OsPT6 in rice. The OsPT6-overexpressing rice lines grew better and accumulated more biomass than wild-type plants, and exhibited significant increases in P accumulation in various tissues, including reproductive tissues under both hydroponic and soil culture conditions. Phosphate-uptake experiment using radiolabeled Pi (P-33) showed that the rate of Pi uptake was 75 % and 73 % greater in transgenic plants grown under Pi-sufficient and -deficient conditions, respectively, than the wild-type controls, and that the shoot/root ratio of P-33 was 104 % and 42 % greater, respectively. In addition, the grain yield per transgenic plant was much higher than that of the wild-type plants under field conditions. Taken together, our results demonstrate that OsPT6 plays a vital role in Pi acquisition and mobilization in rice and suggest that this gene may be used for genetic engineering rice plants that require less Pi fertilizer.