OsWRKY24/70-OsUGT85E1 Regulatory Module Improves Rice Seedling Salt Tolerance

Soil salinity seriously impedes rice growth and development and greatly reduces its production and quality. Rice responses to salt stress are precisely controlled by intricate transcriptional regulatory networks mediated by various transcription factors. Here, we identified rice WRKY DNA-binding protein 24 (OsWRKY24) and OsWRKY70 as positive regulators of rice seedling salt tolerance. Loss of both OsWRKY24 and OsWRKY70 functions resulted in reduced rice seedling salt tolerance, whereas overexpression of OsWRKY24 or OsWRKY70 improved rice seedling salt tolerance. Consistently, expression of several stress-related genes was reduced in oswrky24/70 double mutants but enhanced in transgenic plants overexpressing OsWRKY24 or OsWRKY70 . Further analysis revealed that OsWRKY24 can directly bind the promoter of OsUGT85E1 to activate its expression and OsWRKY70 also participates in the transcriptional regulation of OsUGT85E1 . Similarly, loss of OsUGT85E1 function rendered the rice seedling more sensitive to salt stress, whereas overexpression of OsUGT85E1 improved rice seedling salt tolerance. Interestingly, OsWRKY24 physically interacts with OsWRKY70 to form a functional complex and synergistically activate OsUGT85E1 expression. Genetically, OsWRKY24/70 positively regulates rice seedling salt tolerance in a partially OsUGT85E1- dependent manner. Taken together, our study provides insights into the OsWRKY24/70-OsUGT85E1 module in rice seedling salt tolerance and contributes to the construction of the salt stress-associated transcriptional regulatory networks in rice.