Molecular and physiological insights of salt tolerance in hulled barley (Hordeum vulgare L. var. nudum)

Background The nutritional value of hulled barley makes it a promising resource for creating new healthy foods globally. However, improving the salt tolerance of certain barley cultivars remains a challenge, despite their inherent salt tolerance. Objective This study aims to investigate the physiological and molecular mechanisms associated with salt tolerance in barley, focusing on the expression of genes involved in regulating cellular ion homeostasis, detoxification, and water transport. Materials and methods Three barley cultivars were subjected to different levels of NaCl concentrations. Data on several growth parameters and gene expression were measured and recorded. Results and conclusion Increasing salinity affected shoot and root length, fresh and dry weight, depending on genotype. Giza-130 showed higher dry weight, followed by Giza-135, while Giza-136 showed the lowest value. Giza-130 exhibits the ability to regulate intracellular ion concentration through a higher expression level of the NHX1- gene, demonstrating its ability to effectively absorb water under salinity stress, due to its high expression level of the hvpip −aquaporin gene and effectively remove reactive oxygen species and reduces oxidative stress through the accumulation of higher concentrations of catalase, ascorbate peroxidase, glutathione S-transferase, and superoxide dismutase. In contrast, Giza-136 showed down-regulated gene expression and higher sensitivity to salt stress. Giza-130 was salt tolerant, followed by Giza-135 while Giza-136 was very sensitive. The genotype-specific regulation of gene expression not only highlights the important role of these genes in protecting plants against salt-induced oxidative stress but also improves our understanding of the salt stress tolerance of barley and plays an important role in improving salt tolerance in other crops.