Expression of recombinant phytase in transgenic rice

For improving inorganic phosphorus use efficiency by expression of phytase in transgenic rice, a plant expression vector, containing the recombinant phytase gene driven by the maize ubiquitin (Ubi) promoter, was constructed, and was introduced into rice via Agrobacterium-mediated transformation, by using the rice immature embryo-derived callus as the explants. A total of 15 independent transgenic lines were regenerated, and the results of PCR and Southern blot analyses showed that the target gene had been integrated into the genome of transgenic rice. RT-PCR analysis of the total RNAs extracted from the immature seeds of several transgenic lines showed that the introduced phytase gene could be normally expressed. The result of measurement of the inorganic phosphorus level implied that the inorganic phosphorus content was significantly higher in the mature seeds of several primary transformants and the leaves of their progeny than that of the untransformed control.