Nano-enabled delivery of plant polyphenols: a climate-resilient strategy for enhancing crop stress tolerance and productivity

Abstract Climate change is posing resilience challenge in crops worldwide with stressors ranging from drought, salinity, heat waves to heavy metal toxicity. These stressors signal the plants to synthesize bioprotective polyphenols. While plants synthesize many polyphenolic compounds such as flavonoids, phenolic acids, and tannins which function as potent antioxidants and signalling molecules, their natural adaptive capacity is often modulated by rapid environmental changes. The exogenous application of these bioprotectants in conventional agriculture is limited by their low aqueous solubility, physico-chemical instability, and rapid degradation. This review explores Nano-Enabled Delivery as a transformative strategy to overcome these limitations and bioengineer climate-resilient crops. The diverse nanocarrier systems ranging from lipid-based liposomes and biodegradable polymers (e.g., chitosan) to metallic (ZnO, TiO 2 ) and mesoporous silica nanoparticles designed to encapsulate and shield bioactive polyphenols have been discussed. Mechanistically, these formulations function not only as transport vehicles but also as eustress elicitors that activate MYB transcription factors. This signalling cascade upregulates the Shikimate and Phenylpropanoid pathways, effectively boosting the endogenous supply and assembly lines for defense metabolites like flavonoids and lignin. In practical applications, this dual action sustained exogenous delivery coupled with metabolic activation significantly enhances crop resilience by optimizing ROS scavenging, maintaining osmotic balance, and protecting photosynthetic machinery under severe stress conditions. The review concludes by mapping the translational pathway from mechanistic hydroponic studies to open field validation, presenting nano-polyphenols as a sustainable, high efficiency alternative to synthetic agrochemicals for precision agriculture and climate resilience.