Molecular and Eco-Physiological Responses of Wheat (Triticum aestivum L.) to Drought Stress: Implications for Climate-Resilient Crop Improvement

Abstract

Drought stress is the most severe and widespread abiotic constraint limiting global wheat (Triticum aestivum L.) production, already causing ~10% yield losses worldwide and projected to intensify under climate change, with every additional 1°C of warming potentially reducing staple calorie production by 4.4%. This review provides a comprehensive synthesis of the molecular and eco-physiological responses of bread wheat to water deficit across multiple scales and developmental stages. It covers morphological adaptations (deeper root system architecture, leaf rolling, reduced leaf area, stay-green phenotype), physiological mechanisms (stomatal regulation via ABA, osmotic adjustment through proline, soluble sugars and K⁺, maintenance of relative water content and membrane stability), and biochemical defenses (antioxidant enzyme systems including SOD, CAT, APX, and non-enzymatic scavengers to mitigate ROS damage).
At the molecular level, the review details ABA signaling pathways (PYL-PP2C-SnRK2 core module), key transcription factor families (DREB/ERF, MYB, NAC, WRKY), protective proteins (LEA/dehydrins), and emerging roles of autophagy. Technological advances in field-based high-throughput phenotyping (RGB, thermal, hyperspectral, LiDAR), genomic selection, marker-assisted selection, speed breeding, and CRISPR-Cas9 genome editing are highlighted as powerful tools for dissecting and stacking drought-resilience traits. International efforts by CIMMYT and ICARDA, together with national releases in South Asia (e.g., DBW 187, HD 3271, HI 1634), demonstrate successful translation into farmer-adapted, climate-resilient varieties. The paper concludes with strategic directions toward a “drought-resilient ideotype” integrating deep roots, efficient water-use, robust antioxidant capacity, and multi-omics-assisted breeding for sustainable wheat production under future climate scenarios.