V.Anjana, K.Mondal Trehalose, metabolic, hub, carbon, nitrogen 118-122 2 (5) September, 2026 Trehalose is a non-reducing disaccharide that functions as a multifunctional component of plant metabolic regulation and environmental adaptation. Although present at relatively low concentrations in most vascular plants, trehalose metabolism is associated with carbohydrate homeostasis, cellular protection, photosynthetic performance, nitrogen utilization and abiotic stress responses. Its relevance to carbon–nitrogen (C-N) coordination arises from the dependence of nitrogen assimilation on carbon-derived skeletons, cellular energy and reducing power. Exogenous trehalose has been reported to enhance nitrate and ammonium assimilation, activities of key nitrogen-assimilatory enzymes, chlorophyll content, photosynthesis and growth under nitrogen limitation.