Genetic Mapping Determining the Key Genomic Loci/QTNs for Stress Resilience via Controlling Antioxidant Defenses in Barley Under Salt Stress

Salinity stress is a major environmental factor impeding barley productivity on a global scale. Enhancing salt tolerance in barley is crucial for maintaining crop yield and agricultural sustainability. This study aimed to elucidate the genetic underpinnings of salt tolerance in barley, focusing on the identification of key genomic loci and quantitative trait nucleotides (QTNs) associated with stress resilience, particularly through the modulation of antioxidant defense mechanisms. A diverse set of barley lines was subjected to salinity stress conditions, and a genome-wide association study (GWAS) was conducted. Ten morphophysiological parameters related to salt stress tolerance, such as antioxidant enzyme activities, were evaluated. This study revealed distinct genomic loci and QTNs intricately linked with salt tolerance in barley. These genetic markers were found to influence the plant's antioxidant defenses, including enzymes like superoxide dismutase, catalase, and ascorbate peroxidase, which play pivotal roles in mitigating oxidative damage under salinity stress after the application of Se NPs. For instance, significant SNP (G:A) on chromosome 7H at position (521,369,195- 521,370,360 bp). Within this region, a gene mapped as peroxidase, HORVU.MOREX.r3.7HG0718950, was detected for SS_Se, SL_C, and SL_Se, suggesting the essential role of this gene in regulating the resilience of plant responses to salinity stress after application of selenium nanoparticles. Our findings provide a deeper understanding of the complex genetic architecture of salt tolerance in barley, highlighting the critical role of specific genomic regions in controlling antioxidant responses under salinity stress. The identified loci and QTNs serve as valuable genetic resources for the development of salt-tolerant barley cultivars, contributing to global food security and agricultural resilience in saline-prone environments.