Overexpression of OsUGT3 enhances drought and salt tolerance through modulating ABA synthesis and scavenging ROS in rice

Abscisic acid (ABA) is an important plant hormone that plays a crucial role in response to abiotic stresses. It is well-known that the level of ABA will be dynamically regulated under stress conditions, however, the regulatory mechanism of ABA homeostasis remains largely unknown. In this study, we isolated and characterized a putative UDP-glycosyltransferase (UGT3) in rice, which is proven to be stress-induced and involved in ABA dynamic change. Our data demonstrated that overexpression of the glycosyltransferase gene UGT3 enhanced drought and salt stress tolerance of the transgenic rice. However, ugt3 mutant exhibited sensitive phenotypes under stresses. The ectopic expression of UGT3 in Arabidopsis also enhanced the plant tolerance to drought and salt stresses. Overexpression of UGT3 in rice increased endogenous ABA level and showed hypersensitive phenotype to exogenous ABA treatment at both germination and post-germination stages. Further studies demonstrated that UGT3 elevated activities of the antioxidant enzymes and reduced the production of reactive oxygen species to control the oxidative burst under stress conditions. Taken together, this work reveals that glycosyltransferase UGT3 can cope with the environmental challenges through a possible interactive network of ABA, ROS and antioxidants under abiotic stresses.