Abstract
Abioticstress such as drought is a potential threat posing a severe challenge to wheat production across the globe. The current study comparatively delineated the performance of elite Pakistani bread wheat genotypes at physiological (chlorophyll, canopy temperature, cell membrane percentage stability and leaf relative water content), agronomic (plant height, tillers plant(-1), flag leaf area, spike length, spikelets spike(-1), grains spike(-1), grain yield spike(-1), thousand grain weight and plant biomass) and genetic (TaDREB1A, TaGROS A, TaLEA3, TaHSFA1a, TaWRKY44 and TaEXPA2) levels. Atri-replicate experiment was conducted in a two factorial arrangement using RCBD, and data were analyzed statistically using the computer-based programsStatistix8.1 and R-studio. In general, all wheat genotypes illustrated significant (p < 0.05) alterations in physiological and agronomic traits under drought stress as compared to the control; however, this alteration was significantly (p <= 0.05) different among all genotypes owing to their varying genetic potential. Furthermore, these genotypes were evaluated for the extent of the association of physiological and agronomic traits using PCA, correlation and heatmap analysis, which proved statistically significant variation in the paired association of traits among all genotypes during drought stress as compared to the control. In addition, based on statistical evaluations, the genotypes Pakistan-13, Shahkar-13, AAS-11, Chakwal86, Chakwal-50 and AUR-09 were found to be tolerant, while genotypes Anmol-97, Chakwal-97, Bhakkar-02 and BWP-97 were comparatively susceptible. Furthermore, these screened genotypes showed differential expression of drought-related genes, with relatively high expression in tolerant genotypes compared to susceptible genotypes. The current study concluded that physiological, agronomic and molecular characteristics are significantly interconnected, and these associations determine the end productivity of wheat genotypes during abiotic stress. Therefore, their integrated study can enhance the pace of wheat breeding for drought tolerance in the near future.