Abstract

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.

Highlights

  • 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

  • We identified a novel gene, OsMYB2P-1, belonging to a MYB family transcription factor (TF), and characterized its role in response and adaptation to Pi deficiency by overexpressing/interfering with OsMYB2P-1 in rice and Arabidopsis

  • Our results demonstrate that OsMYB2P-1 was rapidly induced by Pi deprivation and that overexpression of OsMYB2P-1 in rice allowed the transgenic rice plants to have a greater root system and to maintain a relatively higher Pi concentration in roots under Pi-deficient conditions due to enhanced up-regulation of Pi transporter genes and Pi-responsive genes of OsSQD, OsIPS1, OsMiR399, rendering rice plants more tolerant to Pi deficiency

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Summary

Introduction

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 OsPT2, which encodes a low-affinity Pi transporter, was up-regulated in OsMYB2P-1overexpressing 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 OsMYB2P1 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. We further show that overexpression OsMYB2P-1 activated the expression of OsPT6, OsPT8, and OsPT10 under low-Pi stress, whereas it induced the expression of OsPT2 under Pi-sufficient conditions, leading to excess accumulation of Pi in shoots These findings shed important light on the mechanism by which rice plants regulate Pi uptake and translocation under Pi-deficient conditions

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