Introgression of wild barley alleles improves seedlings salinity tolerance in the nested association mapping HEB-400...

Climate change is intensifying the frequency and severity of abiotic stresses that threaten global food security by reducing crop productivity. Among these, saline stress poses a serious threat to barley (Hordeum vulgare L.) production. These conditions are increasingly prevalent in arid and semiarid regions, as well as in regions with limited access to freshwater resources, making the identification of salt tolerance genes essential for breeding resilient varieties. In this study, we evaluated 400 genotypes from the barley nested association mapping population HEB-25 under control conditions and 40% seawater irrigation to simulate moderate-to-high salinity stress. A genome-wide association study (GWAS) was conducted to identify alleles from wild barley [H. vulgare L. subsp. spontaneum (C. Koch) Thell.] associated with enhanced salt tolerance. Phenotypic evaluation included germination percentage (Ger%), shoot length (SL), root length (RL), root-shoot length ratio, seedling fresh weight, seedling dry weight, and salt tolerance index of the different traits. The HEB-25 families exhibited significant variation in seedling responses to seawater-induced salinity, with contrasting effects on SL, RL, and dry weight. Compared to the elite parental Barke, several genotypes demonstrated high tolerance under seawater stress, maintaining stable Ger% and exhibiting the highest tolerance indices. Moreover, GWAS results identified 60 highly significant single nucleotide polymorphisms associated with seedling growth parameters under both conditions. These findings underscore the value of the HEB-400 panel as a genetic resource for dissecting salinity tolerance mechanisms, identifying stress-adaptive alleles lost during domestication and a source of pre-breeding material for developing genotypes with enhanced salinity tolerance.