Integrative multi-omics for decoding and breeding wheat resilience to combined drought and salinity stress

Abstract Wheat ( Triticum aestivum L.) productivity is increasingly threatened by the co-occurrence of drought and salinity in water-limited and salt-affected agroecosystems. Their combination creates a distinct stress environment in which restricted water uptake interacts with ion toxicity, nutrient imbalance, oxidative injury, and developmental disruption, often producing responses and genotype rankings that cannot be predicted from either stress alone. This review examines how multi-omics and systems-level approaches can elucidate the biological basis of wheat adaptation to simultaneous osmotic and ionic constraints and translate this knowledge into crop improvement. Evidence across genomic, regulatory, biochemical, physiological, and phenotypic scales indicates that tolerance is not governed by a single pathway but by the coordinated maintenance of root hydraulic function, plant water status, ion and nutrient homeostasis, osmotic and redox balance, membrane integrity, carbon assimilation, and reproductive performance. Pan-genomic resources, network biology, cell-resolved profiling, high-throughput phenotyping, and environment-aware prediction are beginning to link molecular variation to whole-plant performance and distinguish causal or breeding-ready targets from discovery-stage associations. However, direct integrated studies under simultaneous drought and salinity remain scarce, and much of the current understanding is still inferred from individual-stress experiments or controlled seedling assays. Progress will therefore require common populations evaluated across controlled and field-relevant combined-stress environments, standardized environmental metadata, functional validation, and integration with genomic prediction, genome editing, accelerated breeding, and multi-environment testing. Treating combined drought and salinity as a distinct breeding target will be essential for developing wheat cultivars that sustain physiological function and yield under concurrent water and ionic limitations.