Integrated morpho-physiological, metabolomic and transcriptomic profiling uncovers ethylene-mediated metabolic...

Drought represents a major constraint on global wheat production, and climate projections indicate an increased frequency of drought events with irregular rainfall. While physiological and metabolic adjustments contribute to stress adaptation, the regulatory networks integrating these responses remain poorly understood. Ethylene is a stress hormone, yet its role in coordinating drought resilience across contrasting wheat cultivars has not been systematically investigated. Three wheat cultivars differing in drought resilience were evaluated under water deficit by integrating morphological traits, phytochemical composition, metabolite profiling, and transcriptional regulation of ethylene biosynthesis and signaling genes.

Drought stress reduced biomass, chlorophyll content, and growth, while MH-97 maintained stable growth, suggesting better stress resilience and maintained photosynthetic capacity. Metabolite profiling revealed enrichment of organic acids, amino acid derivatives, and phenolics, supporting osmotic regulation and antioxidant defense. Elevated sugar-phosphates and TCA intermediates indicated enhanced energy metabolism, while lipid remodeling, terpenoids, and phenylpropanoid derivatives reinforced membrane stability and redox buffering. Expression profiling showed strong induction of TaACO, TaERS, TaETR, and TaEIN2 genes in both roots and shoots of FSD-08, while MH-97 exhibited restrained ethylene signaling with limited induction of TaEBF1-7B and TaRTE3-5 A.

Contrasting drought adaptation is linked to differential regulation of ethylene biosynthesis and signaling genes, integrated with physiological and metabolic adjustments to maintain water balance and redox homeostasis. By integrating genetic and metabolic insights with a pathway model, this study not only advances the understanding of ethylene-mediated drought tolerance but also lays the foundation for translating these molecular insights into strategies to enhance crop performance and yield stability in wheat under increasingly variable environmental conditions. Further functional validation and quantitative ethylene measurements will be necessary to confirm mechanistic relationships.