Identification and Characterization of EDT1 Conferring Drought Tolerance in Rice

Basic Leucine Zipper (bZIP) transcription factors (TFs) play important roles in many processes, especially in abiotic stress response in plants. In this study, we characterized a new gene EHANCED DROUGHT TOLERANCE 1 (EDT1), member of group E of bZIP transcription factor family in rice. The EDT1 protein contains one bZIP domain, one putative nuclear localization signal (NLS) and six conserved phosphorylation sites. The expression of EDT1 is suppressed by several abiotic stresses, such as cold, droutht, and salt. Corresponding with expression patterns, several stress-associated cis-acting elements were found in the EDT1 promoter. The results of subcellular localization and transactivation ability analyses indicated that EDT1 was localized in the nucleus and functioned as a nuclear protein, with its transactivation activity primarily located in N-terminal. Transgenic rice overexpressing EDT1 showed drought tolerance that has been significantly improved. Real-time PCR analysis revealed that some stress-related genes, such as OsbZIP12, SNAC1, OsLEA3, OsbZIP16, OsbZIP10 and OsABI2 were up-regulated in EDT1 overexpression lines. These results indicate that EDT1 plays a positive role in drought tolerance and provides valuable targets for breeding drought-tolerant rice cultivars.