Protein phosphatase 5 mediates plant growth and phosphate homeostasis in rice

Protein phosphorylation is a reversible post-translational modification, and protein phosphatase is the most important regulator for protein dephosphorylation. Protein phosphatase 5 (PP5), which functions in many cellular processes essential for cell survival and growth in animals, has not been functionally reported in rice. In this study, we functionally identified OsPP5 in rice. OsPP5 is localized in both the nucleus and the cytoplasm which functions as a manganese (Mn2+)-dependent phosphatase. OsPP5 is expressed in most tissues of rice and is positively regulated by Pi supply at transcript and protein levels. Compared with the wild-type plants, OsPP5 overexpression lines showed increased Pi concentration under both Pi sufficient and Pi deficient conditions, while OsPP5 RNA interfering plants showed the opposite phenotype. Expression of phosphate transporters OsPT2, OsPT9, and OsPT10 were increased in OsPP5 overexpression plants. Our findings show that OsPP5 plays an important role in rice Pi homeostasis which could be a potential target for improving Pi absorption under low Pi environment in rice.