De Novo Transcriptome Profiling of Salt Stress Responses in the Crop Wild Legume Vicia hirsuta (L.) Gray

Salt stress is a major environmental constraint affecting plant growth and productivity. Crop wild relatives provide valuable genetic resources for stress tolerance, yet transcriptomic information for forest-derived wild species remains limited. In this study, we analyzed transcriptional responses of V. hirsuta, a crop wild relative (CWR) of legumes, after seven days of salt stress using de novo transcriptome sequencing. Seedlings were exposed to salt stress, and differentially expressed genes (DEGs) were identified between control (Vh_S0) and salt-treated (Vh_S7) plants using an FDR-adjusted threshold (q < 0.05). Gene Ontology and KEGG enrichment analyses revealed that salt-responsive DEGs were mainly involved in regulatory signaling, metabolic adjustment, redox-related processes, and macromolecular organization. Up- and down-regulated DEGs showed distinct yet overlapping enrichment patterns, indicating complex transcriptional reprogramming under salt stress. Transcription factor analysis identified bHLH, MYB, bZIP, NAC, and WRKY families as major regulators, with many families containing both up- and down-regulated members. Notably, genes associated with Na⁺/K⁺ homeostasis were consistently up-regulated and validated by qRT-PCR. These results suggest that continuous seven days salt stress adaptation in V. hirsuta involves coordinated regulation of signaling pathways, transcriptional networks, and transporter-mediated ion homeostasis, providing a valuable transcriptomic resource for crop wild relatives.