An R2R3 MYB transcription factor,
OsMYB2P-1, was identified from microarray data by monitoring the expression profile of rice (
Oryza sativa ssp. japonica) seedlings exposed to phosphate (
Pi)-deficient medium. Expression of
OsMYB2P-1 was induced by
Pi starvation.
OsMYB2P-1 was localized in the nuclei and exhibited transcriptional activation activity. Overexpression of
OsMYB2P-1 in Arabidopsis (
Arabidopsis thaliana) and rice enhanced tolerance to
Pi starvation, while suppression of
OsMYB2P-1 by RNA interference in rice rendered the transgenic rice more sensitive to
Pi deficiency. Furthermore, primary roots of
OsMYB2P-1-overexpressing plants were shorter than those in wild-type plants under
Pi-sufficient conditions, while primary roots and adventitious roots of
OsMYB2P-1-overexpressing plants were longer than those of wild-type plants under
Pi-deficient conditions. These results suggest that
OsMYB2P-1 may also be associated with the regulation of root system architecture. Overexpression of
OsMYB2P-1 led to greater expression of
Pi-responsive genes such as
Oryza sativa UDP-sulfoquinovose synthase,
OsIPS1,
OsPAP10,
OsmiR399a, and
OsmiR399j. In contrast, overexpression of
OsMYB2P-1 suppressed the expression of OsPHO2 under both
Pi-sufficient and
Pi-deficient conditions. Moreover, expression of
OsPT2, which encodes a low-affinity
Pi transporter, was up-regulated in
OsMYB2P-1-overexpressing plants under
Pi-sufficient conditions, whereas expression of the high-affinity
Pi transporters
OsPT6,
OsPT8, and
OsPT10 was up-regulated by overexpression of
OsMYB2P-1 under
Pi-deficient conditions, suggesting that
OsMYB2P-1 may act as a
Pi-dependent regulator in controlling the expression of
Pi transporters. These findings demonstrate that OsMYB2P-1 is a novel R2R3 MYB transcriptional factor associated with
Pi starvation signaling in rice.
