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Genome-wide association mapping reveals pleiotropic loci coupling antioxidant defense with redox homeostasis in barley under combined drought and salinity
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DOI：10.1016/j.jplph.2026.154784.png)
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Abstract
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Combined drought × salinity poses a major constraint to barley productivity because osmotic limitation coincides with ionic toxicity and oxidative injury. Here, we quantified multi-trait performance across three successive generations (G1–G3) under control and combined drought × salinity and tested whether repeated ancestral exposure was associated with progressive buffering of stress impacts. Across generations, stress caused coherent penalties in yield formation and physiology, but these penalties weakened by G3: grain yield declined by 34.7% (G1), 24.2% (G2), and 17.7% (G3), with parallel reductions in harvest index, thousand kernel weight, spikes per plant, and grains per spike. Water relations and canopy stress signatures showed progressive moderation (RWC and stomatal conductance decreased less, while canopy temperature increases were dampened), and stress-induced heading delay decreased from 6.48% (G1) to 2.49% (G3). The salinity component remained strong but moderated across generations, with reduced Na+ accumulation, improved K+ retention, and partial recovery of K+/Na+, accompanied by progressively lower amplification of injury markers (electrolyte leakage, MDA, and H2O2) and reduced reliance on extreme proline accumulation; G3 increasingly preserved total soluble sugars and maximum root depth. Stress resilience indices (SR = stress/control) confirmed coordinated, module-wide improvement from G1 to G3, consistent with memory-linked buffering. Multi-trait GWAS of SR traits identified reproducible genomic hotspots, with the strongest effects for Na+ homeostasis and redox/membrane-stability traits, and haplotype contrasts validated significant allelic effects at lead loci. Candidate-gene mining and time-course expression profiling further supported regulatory, transport, and redox-protection mechanisms differentiating tolerant and susceptible genotypes. Collectively, these results indicate progressive stress memory stabilization of yield, water status, ion balance, and redox integrity under combined drought × salinity and prioritize genomic regions for validation and breeding deployment.
Keywords:
drought × salinity stress
barley productivity
stress memory
redox homeostasis
genome-wide association mapping
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