AtPHR1 plays a central role in Pi-starvation signaling in Arabidopsis (Arabidopsis thaliana). Two PHR genes were isolated from rice and designated as OsPHR1 and OsPHR2 based on amino acid sequence homology to AtPHR1. Transgenic plants with overexpression and repression of OsPHR1 and OsPHR2, respectively, were used for investigation of roles of the genes in Pi-signaling pathway and Pi homeostasis under Pi-sufficient and deficient conditions. The results showed that both of the genes are involved in the Pi-signaling pathway, while overexpression of OsPHR2 mimics Pi-starvation stress with enhanced root elongation and proliferated root hairs, and results in the excessive accumulation of Pi in shoots under Pi-sufficient conditions. OsPHR2 regulated proliferation of root hair growth and root elongation suggests that OsPHR2 is involved in both systematic and local Pi-signaling pathways.