Raw Ct values for TaDHN genes in wheat cultivars

Drought stress is a primary constraint to global wheat production, particularly in arid regions like Central Asia. While dehydrin (TaDHN) genes are known to be critical for abiotic stress tolerance, the genotype-specific molecular strategies employed by regional cultivars remain poorly understood. This study evaluated the morpho-physiological and molecular responses of seven bread wheat (Triticum aestivum L.) cultivars from Uzbekistan, Tajikistan, and Russia under controlled terminal drought stress. We assessed key traits, including plant height, root architecture (number and length), and biomass accumulation. Furthermore, the relative expression profiles of five key dehydrin genes (TaDHN7, 9, 10, 12, and 13) were quantified using qRT-PCR. Our results identified a clear divergence in drought-response strategies: the cultivars Bardosh and Ezoz exhibited high morpho-physiological stability and were classified as tolerant, whereas Krasnodar99 and Baxmal97 showed significant growth inhibition and were sensitive. Molecular analysis revealed that Bardosh employs a broad-spectrum defense strategy, characterized by the robust upregulation of TaDHN7, 9, 10, and 12. In contrast, Ezoz demonstrated a specialized strategy, showing a pronounced and specific induction of TaDHN13. Sensitive cultivars failed to mount an effective transcriptional response, showing minimal or no TaDHN induction. These findings demonstrate that drought resilience in Central Asian wheat is linked to distinct, genotype-specific molecular signatures. The identified tolerant cultivars and their unique expression patterns provide elite genetic resources and potential molecular markers for the targeted breeding of climate-resilient wheat varieties.