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