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

The abscisic acid (ABA) signaling pathway depends largely on ABRE-binding factors (ABFs), a distinct subfamily of plant bZIP transcription factors. Here, we carried out a genome-wide analysis of the ABF gene family in soybean (Glycine max (L.) Merr.) and investigated the function and regulatory mechanisms of GmABF1 in the plant's response to salt stress. A total of 20 GmABF genes were identified in the soybean genome, distributed across various chromosomes. The gene expression profiles of GmABF genes across diverse tissues and developmental stages in soybean indicate in regulating abiotic stress responses and plant hormone signaling. Among these genes, GmABF1 emerged as a key regulator of salt-stress tolerance. Functional assays showed that GmABF1 overexpression limited Na accumulation, reduced membrane damage, lowered reactive oxygen species (ROS) levels, and up-regulated ROS-scavenging enzymes, collectively alleviating oxidative stress and enhancing the plant's resilience to salinity. Additionally, three polymorphic sites in the promoter region of GmABF1 were identified, and their variation was closely associated with salt tolerance in soybean. These findings highlight the regulatory role of GmABF1 in salt stress responses and its potential for improving soybean stress tolerance.