OsERF2 Acts as a Direct Downstream Target of OsEIL1 to Negatively Regulate Salt Tolerance in Rice

Salinity is a significant limiting factor that adversely affects plant growth, distribution and crop yield. Ethylene responsive factors play crucial roles in plant responses to and tolerance of various abiotic stresses. Recently, we revealed that OsERF2 is involved in root growth by transcriptionally regulating hormone and sugar signaling in rice. Here, we report that OsERF2 is a direct target gene of OsEIL1 and negatively regulates salt tolerance in rice. Compared to the wild type, the gain-of-function mutant of OsERF2 (nsf2857) and the knockdown of OsERF2 via an artificial microRNA (Ami-ERF2) exhibited decreased and increased salt tolerance, respectively. The enhanced salt tolerance observed in Ami-OsERF2 lines was associated with lower accumulations of malondialdehyde and reactive oxygen species (ROS) under salt stress, while the opposite was true for nsf2857 plants, which exhibited decreased salt tolerance. At the transcriptional level, several stress-related genes encoding ROS and NAD(P)H-related oxidoreductases were downregulated in nsf2857 plants but upregulated in Ami-ERF2 plants. Furthermore, yeast one-hybrid and ChIP assays revealed that OsEIL1 can bind to the of EBS cis element present in the promoter of OsERF2 (-bp), suggesting that OsEIL1 may directly regulate the expression of OsERF2. Collectively, our findings indicate that OsERF2 is a direct downstream factor involved in the regulation of salt tolerance in rice, highlighting its potential application in the genetic improvement of tolerance to abiotic stresses in this crop.