Characterization of the soybean ABF gene family and the key regulatory function of GmABF1 in salt stress response

The abscisic acid (ABA) response signal pathway depends heavily on ABRE binding factors (ABF), a distinctive subfamily of basic leucine zipper (bZIP) transcription factors in plants. The objective of this study was to conduct a comprehensive analysis of the soybean (Glycine max (L.) Merr.) ABF gene family across the entire genome and to understand the function and regulatory mechanisms of the GmABF1 gene in response to salt stress. A total of 20 ABF genes were identified in the soybean genome. Different soybean tissues, including roots, stems, leaves, flowers, pods, and seeds, all exhibited significant differences in the expression of GmABFs genes, indicating distinct tissue-specific patterns. The GmABFs family is located within the nucleus of the cell. According to the replication events in soybeans, the GmABF gene underwent tandem replication and fragment duplication. The promoter analysis revealed that the GmABF genes play a role in soybean growth, development, and stress response. Moreover, the GmABF genes were observed to be controlled by several stressors, such as salinity, alkaline, drought, and osmotic stress. GmABF1 was identified as an important regulator of soybean salt stress tolerance. GmABF1 overexpression effectively protected against ROS accumulation, thereby enhancing salt stress tolerance. Three polymorphic sites associated with salt tolerance were found in the promoter region of the GmABF1 gene. It was determined that the variation in the promoter region of the GmABF1 gene was closely associated with the salt tolerance of soybeans. These findings provide new insight into the biological functions ABF family members perform in plant stress responses, serving as a significant basis for developing soybean varieties with enhanced stress tolerance.