Multifunctional Roles of Green Seed Nanopriming, from Germination and Stress Tolerance to Metabolic Reprogramming for Sustainable Crops

Seed nanopriming has emerged as an innovative nanotechnology-based approach to improve seed vigor, germination, and stress tolerance, offering an efficient alternative to conventional priming techniques. By integrating nanoparticles (NPs) as nanoscale activators, this strategy enhances early metabolic activation, nutrient uptake, and antioxidant responses during seed imbibition. Among nanopriming modalities, green nanopriming, which uses biogenic NPs synthesized through plant, fungal, or microbial extracts, has gained particular relevance due its eco-friendly and biocompatible nature. The organic molecules serving as reducing and capping agents impart additional bioactivity, leading to synergistic physiological and biochemical effects. In this review, we compile and discuss the recent advances in green nanopriming mechanisms and outcomes, including improved germination, seedling vigor, and tolerance to abiotic stresses such as salinity, drought, temperature extremes, and heavy metal toxicity. The effects of various nanomaterials (Ag, Au, ZnO, CuO, FeO, TiO₂, Se, carbon-based nanostructures, among others) are examined in the context of dose-dependent responses, redox modulation, and stress memory formation. Collectively, the evidence positions green nanopriming as a promising and sustainable strategy that bridges nanotechnology and seed physiology to promote crop resilience while reducing environmental risks associated with chemically synthesized NPs. Graphical Abstract