Genome-wide Identification of the SWEET Gene Family in Elymus dahuricus and Functional Characterization of EdSWEET15 in Salt Tolerance

The SWEET (Sugars Will Eventually be Exported Transporter) family, a class of sugar transporters identified in recent years, is extensively involved in regulating plant growth and development. Beyond their basic physiological functions, existing studies have suggested that SWEET family members participate in plant stress responses, such as salt tolerance. However, the specific function of SWEET genes from Elymus dahuricus Turcz. in salt stress adaptation remains unclear. In this study, A total of 12 EdSWEET genes were identified from the whole-genome database of E. dahuricus Turcz., which were distributed across 8 chromosomes. The EdSWEET proteins exhibited substantial variations in molecular weight. Phylogenetic analysis classified these genes into four major subfamilies. Abundant regulatory elements were found to be associated with plant hormone signaling and stress responses, indicating that EdSWEET genes play crucial roles in coping with abiotic stresses. Expression profiling of E. dahuricus Turcz. roots and leaves under salt stress revealed that EdSWEET15 was significantly up-regulated in both tissues after salt stress treatment, suggesting its involvement in the salt stress response. The EdSWEET15 gene was cloned from E. dahuricus Turcz. Its open reading frame (ORF) is 930 bp in length, Further verification via heterologous overexpression in Arabidopsis thaliana demonstrated that, compared with the wild type (WT), EdSWEET15 overexpressing Arabidopsis lines displayed significantly enhanced salt stress resistance. Specifically, the accumulation of reactive oxygen species (ROS) was remarkably reduced under salt stress, while the scavenging activities of antioxidant enzyme systems, including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), were significantly elevated. This study clarifies the novel function of EdSWEET15 in plant salt stress responses and provides a theoretical basis and candidate gene resource for the genetic improvement of salt tolerance in E. dahuricus Turcz.