Physiological and transcriptome analyses reveal key responses of <i>Festuca rubra</i> to salt stress

Soil salinization seriously damages plant growth and productivity. <italic>Festuca rubra</italic> (<italic>F. rubra</italic>) is a perennial grass with ecological and economic value, showing significant salt tolerance. However, its potential physiological and molecular mechanisms remain not fully elucidated. To explore <italic>F. rubra</italic>'s response to salt stress, this study treated plants with salt stress (1% NaCl solution, w/v). Physiological parameters (relative electrical conductivity, photosynthetic traits, antioxidant systems) and transcriptomic profiles were analyzed at the terminal stress stage. Salt-stressed plants accumulated significantly higher levels of osmolytes (soluble sugars and proline). Antioxidant defenses were activated, as evidenced by increased activities of key antioxidant enzymes and elevated malondialdehyde (MDA) content. Net photosynthetic rate markedly declined under salt stress. Transcriptomic analysis revealed that salt stress activated genes associated with antioxidant enzymes and phytohormone signaling (predominantly ABA). It also induced upregulation of genes involved in carbon metabolism and amino acid biosynthesis pathways. These results demonstrate that <italic>F. rubra</italic> coordinates osmotic adjustment, activates antioxidants, and regulates transcription (specifically through ABA signaling and metabolic reprogramming) to mitigate salt-induced damage. These insights offer potential strategies for enhancing salt stress tolerance in graminaceous crops.