A Rice OsAP23, Functioning as an AP2/ERF Transcription Factor, Reduces Salt Tolerance in Transgenic Arabidopsis

The AP2/ERF transcription factors of higher plants regulate transcriptional networks that control development and responses to biotic and abiotic stresses. In this study, the rice OsAP23 gene, which encodes an AP2/ERF transcription factor, was isolated from rice using a yeast-one-hybrid system. The OsAP23 transcription factor belongs to the B3 group of the ERF subfamily. Germination results for transgenic Arabidopsis plants hosting the OsAP23 gene revealed greater inhibition at the germination and seedling stages with increasing concentration of NaCl compared to the wild-type plants. Exogenous ABA also reduced the rate of germination of transgenic Arabidopsis seeds that over-express OsAP23 compared with wild-type Arabidopsis seeds. In addition, following exposure to high salt concentrations, several stress-responsive regulatory genes were induced to a significantly greater extent in the wild-type lines compared with lines that over-express OsAP23. These results suggested that OsAP23 might be a negative regulator of the salt stress response in higher plants.