Decoding Stress Responses in Barley Lines: Insights Using Next-Generation Sequencing from BOMI and RISO-1508

Objective: This study investigated how stress factors (abscisic acid:ABA and heat shock) impact barley genotypes BOMI and its isogenic mutant, RISO-1508, by analyzing gene expression and transcriptomics. Materials and Methods: The impact of ABA on stress during barley germination was studied, followed by heat shock stress application. After treatment, total RNA was extracted, and cDNA libraries were created for transcriptomic analysis using Oxford Nanopore Technology. Genes with altered expression levels in heat-stressed barley varieties were identified. The most highly expressed DEGs were further examined through GO and KEGG enrichment analyses. Results: High concentrations of ABA almost completely inhibited barley germination and negatively impacted leaf growth, whereas root growth was less affected. This study is the first to assess the effects of heat stress on BOMI/RISO-1508 cells, revealing significant genetic changes under heat stress. Both genotypes showed similar protective mechanisms by significantly increasing heat shock proteins (HSPs) under heat stress, with BOMI uniquely upregulating five HSPs. A notable difference was observed in fatty acid and energy metabolism, indicating a more robust stress response in the BOMI group. Compared with BOMI, RISO-1508 showed greater downregulation of key photosynthetic genes, such as ATP synthase subunit beta and ribulose biphosphate carboxylase. Under HS, ABA receptor PYL4-like (LOC123424614) was significantly increased in BOMI, unlike in RISO-1508, indicating that BOMI has a distinct ABA stress response under HS. Conclusion: The findings indicate that environmental changes disrupt metabolic pathways in heat stress adaptation due to genotype variations, emphasizing the need to improve heat tolerance in barley