Breeding Of Transgenic Rice With High Hosphorus Use Efficiency Through OsPHR3

Phosphate (Pi) is an important nutrient for plant growth and production. Heavy application of P-fertilizer not only increases cost but also results in sets of serious environmentalproblems. Thus, development of Pi-efficient crops is required for sustainable agriculture. The transcrption factor OsPHR3(LOC_Os02g04640) is a homo log of OsPHR2, the central regulator of Pi-signaling in rice. In this study, we cloned OsPHR2based on the sequence predicted by Rice Genome Annotation Project and developed transgenic plants with overexpression of OsPHR3driven by35S promoter (35S::OsPHR3) for its function analysis. The alignment analysis showed45.21%identical amino acids of OsPHR3with OsPHR2. The highly conserved MYB-CC domains were found in both OsPHR3and OsPHR2. The overexpression of OsPHR3in the transgenic plants were determined by quantitative real time PCR (QRT-PCR). Two independent lines (Ti) indicated by Southernblotting (designated as OsPHR3-Ov-1and OsPHR3-Ov-8) were used for the physiological analysis. The Pi concentration in the OsPHR3overexpressed plants in shoots increased1-2times compared with the wild type plants (Nipponbare cv. japonica) in a Pi-supplied solution culture (200μM). In the solution culture with tower Pi level (10μM), the Pi concentration in shoots of OsPHR3overexpressed plants was still significantly higher than that of the wild type plants (p<0.05). To further evaluate the function of OsPHR3on Pi uptake ability in plants, we also performed soil experiments with different phosphorus levels. Three Pi levels were designed as high Pi (HP:450kg/hm2P2O5), middle (MP:225kg/hm2P205) and lower (LP:0kg/hm2P205) for the experiments using the two independent lines. The plant height, number of panicles, yield per100plants and total P concentration in shoots and seeds were measured. The results showed that all of the measured parameters of the transgenic plants were significantly higher than these of the wild type plants. The yield of the transgenic plants increased by about32%,29%and40%in HP, MP and LP conditions compared with the wild type plants. Taken together, our results suggest that OsPHR3is a potential transcription factor for molecular breeding crops with enhanced Pi-uptake ability.