Beyond Energy: How Small-Molecule Sugars Fuel Seed Life and Shape Next-Generation Crop Technologies

Small-molecule sugars, such as glucose, sucrose, trehalose and raffinose, are essential for seed germination, seedling establishment and stress resilience. These sugars act as both energy sources and signalling molecules, regulating osmotic balance, gene expression and critical metabolic pathways involved in early growth. Key enzymes, including α-amylase (AMY1 and AMY2), hexokinase (HXK1) and sucrose-phosphate synthase (SPS), facilitate carbohydrate mobilisation during germination, fueling glycolysis, the tricarboxylic acid (TCA) cycle and the pentose phosphate pathway (PPP). Hormonal interactions, particularly with gibberellins (GA) and abscisic acid (ABA), integrate sugar metabolism with developmental and environmental cues. Sugar transport proteins, such as Sugars Will Eventually be Exported Transporters (SWEET), Sucrose Transporters (SUT) and Tonoplast Sugar Transporters (TST), ensure efficient distribution to growing tissues, whereas SNF1-related kinase 1 (SnRK1) modulates growth and stress responses, maintaining cellular energy homeostasis. Innovative seed treatments, such as sugar priming, biopriming and encapsulation, have proven effective in improving germination rates, stress tolerance and seedling vigour by optimising osmotic regulation, metabolic activation and microbial interactions. Sugar-based treatments offer substantial potential for enhancing crop productivity and resilience. Future research should focus on refining these strategies, exploring sugar–hormone interactions and using genomic tools to advance crop improvement. Thus, small-molecule sugars hold transformative potential for sustainable agriculture, providing a route to enhance seed technology and adaptability to global environmental challenges.