Abstract

The development and productivity of plants are profoundly influenced by adverse environmental conditions, particularly drought stress. This study investigates the physiological, transcriptomic, and metabolomic responses of Nicotiana tabacum to varying levels of drought stress (well-watered, light drought, moderate drought, and severe drought). Comprehensive analyses were conducted to evaluate phenotypic changes, physiological parameters, gene expression, and metabolite profiles. Drought stress significantly inhibited plant growth, reduced relative water content, and altered transpiration rates. Protective enzyme activities also declined under increased drought intensity. Transcriptome analysis identified 7,483, 15,558, and 16,876 differentially expressed genes in light, moderate, and severe drought conditions compared to the control, respectively. Similarly, metabolome analysis revealed 410, 485, and 523 differentially accumulated metabolites under these conditions. Integrative analysis of transcriptomic and metabolomic data highlighted the phenylpropanoid biosynthesis pathway as a critical mechanism mediating drought tolerance in N. tabacum. Key metabolites, including chlorogenic acid, rutin, and taxifolin, exhibited significant changes, correlating with drought stress severity. These findings provide valuable insights into the molecular and biochemical strategies employed by N. tabacum to adapt to water scarcity. This study highlights the crucial role of phenylpropanoid biosynthesis in drought stress tolerance and identifies potential targets for molecular breeding to develop drought-resilient crops. The results contribute to a deeper understanding of plant responses to drought stress, aligning with the urgent need to mitigate the impact of climate change on agriculture.