Analysis of phosphate deficiency sensing mechanism in rice

Abstract

It was believed that adaptation responses to phosphate-deficiency were controlled by two mechanisms; systemic long-distance signal transduction and local sensing mechanism for phosphate status. This study was aimed to clarify how these mechanisms regulated expression of OsPI1, a phosphate-deficiency responsible gene of rice. Rice plants were grown hydroponically under phosphate deficient (-P) and sufficient (+P) conditions. Their roots were split and transferred into -P (-P roots) and +P solutions (+P roots). Plants were continuously harvested until 5 d after root splitting. OsPI1 expression in -P roots transferred from +P were significantly higher than in +P roots. OsPI1 expression in -P roots remained high until 2 d after transfer from -P and strongly repressed thereafter. However, ANOVA showed that repressed expression level was still higher than in +P roots. Therefore, it was indicated that OsPI1 was controlled by not only long-distance signal transduction but also local sensing mechanism under -P conditions.