Genome-Wide Identification of the BXL Gene Family in Soybean and Expression Analysis Under Salt Stress

β-D-xylosidases (BXLs) are pivotal enzymes in xylan degradation, playing essential roles in plant development and stress responses. In this study, we identified 29 <i>GmBXL</i> genes in soybean through homolog alignment. Phylogenetic analysis classified these genes into three groups, with Group III being legume-specific. The <i>GmBXLs</i> are unevenly distributed across 15 chromosomes, with their expansion driven by both tandem and segmental duplications. Conserved motif and domain analyses revealed functional conservation, particularly in family 3 of glycoside hydrolase domains. Promoter regions of <i>GmBXLs</i> are enriched with hormone-responsive and stress-related <i>cis</i>-elements, indicating their involvement in diverse biological processes. Tissue-specific expression analysis revealed differential <i>GmBXLs</i> expression across leaves, roots, flowers, and seeds, with <i>GmBXL13</i> and <i>GmBXL26</i> exhibiting notably high transcript levels in pods and seeds. Under salt stress, 26 <i>GmBXLs</i> exhibited significant expression changes, with 20 genes up-regulated in both leaves and roots, highlighting their roles in salt tolerance. These findings enhance our understanding of the evolutionary and functional characteristics of <i>GmBXLs</i>, providing valuable insights for molecular breeding of salt-tolerant soybean varieties.