BdASR5 Positively Regulates Drought Tolerance by Mediating ABA Signaling Pathway in Brachypodium distachyon

Abscisic acid-, stress-, and ripening-induced (ASR) proteins are involved in response to abiotic stresses. However, the precise role of Brachypodium ASR genes in enhancing tolerance under drought stress conditions remains to be determined. In this study, we characterized the BdASR5 gene and determined that it has a function in drought stress tolerance. Overexpression of BdASR5 confers tolerance to drought stress in Brachypodium. Overexpression of BdASR5 resulted in higher relative water content and chlorophyll content, and lower ion leakage than WT plants under drought stress conditions. Moreover, overexpression of BdASR5 displayed increased antioxidant enzyme activity and upregulated expression of ROS-related, stress-related, and ABA-dependent pathway genes under drought stress condition. In addition, overexpression of BdASR5 showed hypersensitive to exogenous ABA at the germination stage. Moreover, overexpression of BdASR5 showed increased stomatal closure and decreased stomata conductance under ABA conditions. Collectively, these results suggest that BdASR5 functions as a positive regulator in response to drought stress.