Integrating gene expression and morphological traits for drought stress adaptation in maize hybrids

Maize, the third major crop in Pakistan, faces yield challenges due to climate changes agronomic environment, and genetic factors. There is an urgent need for high-yielding hybrid varieties to adapt to different agro-climactic conditions to meet the day-by-day increasing demand of maize. This study utilized 7 commercially available genotypes to focus on the Line × Tester mating design to analyze the effects of drought stress on maize genotypes by using a Randomized Complete Design Block (RCBD) under normal irrigation conditions and 50% drought conditions to collect data of different agronomic traits such Root Length (RL), Shoot Length (SL), Root-to-Shoot Length Ratio (RSLR), Seedling Biomass (SB), Leaf Length (LL), Leaf Width (LW), and Leaf Area (LA) at the seedling stage, and for the evaluation of the effects of stress, Lipid Peroxidation, Malondialdehyde (MDA), H₂O₂ Concentration, and Enzymatic Activity analysis were performed. The results show highly significant genotypic differences of all traits with substantial genetic variability. Additive gene action was remarkable in root-to-shoot length ratio (RSLR) and seedling biomass. Dominant gene action under drought was particularly significant in root length and leaf area. Gene expression analysis of antioxidants under control and drought conditions showed great competition among oxidants and antioxidants to minimize the effects of stress. To the best of our knowledge, this is among few studies that present connecting gene expression signatures with seedling morphological responses, this work presents a breeding-relevant framework that makes it possible to select drought-tolerant maize hybrids more precisely.