Integrative Physiological and Transcriptomic Analyses of Oat (Avena sativa L.) Seedlings Under Severe Salt Stress

Crop productivity around the world is largely constrained by salt-induced stress, a key abiotic factor. Although oat (Avena sativa L.) can withstand challenging environmental conditions, the physiological and molecular responses underlying salt tolerance during germination and early seedling development remain insufficiently understood. To investigate these responses, 28 oat varieties were evaluated at the germination stage, and two contrasting varieties, the salt-tolerant Mengshi No. 1 (MS) and salt-sensitive Morgan (MG), were selected for detailed analysis under a severe NaCl treatment (300 mM) during early seedling stages. Under severe salt stress, the two oat varieties exhibited distinct growth and physiological responses, including changes in growth traits, chlorophyll content, membrane stability, osmotic adjustment, and antioxidant responses. Transcriptomic analysis revealed 14,109 differentially expressed genes (DEGs) between salt-treated MG and its respective control (CK), 19,405 between salt-treated MS and its CK, and 6161 between salt-treated MG and salt-treated MS, suggesting different transcriptional response patterns between the salt-tolerant and salt-sensitive varieties under severe salt stress. Weighted gene co-expression network analysis (WGCNA) revealed a salt-responsive module associated with MS, from which five hub genes, AVESA.00010b.r2.1CG0087930 (MGL), AVESA.00010b.r2.19DG0180280 (MGL), AVESA.00010b.r2.4CG1272260 (BCH1), AVESA.00010b.r2.5DG0989800 (GPAT7), and AVESA.00010b.r2.6CG1124100 (TPR10), were identified as candidate genes potentially associated with salt tolerance and stress responses.