Abiotic Stress-Triggered Nanocarriers for Seed Nanopriming and Early-Stage Plant Development

Climate change and increasing soil salinity threaten global food security, particularly in arid and semiarid regions where crop productivity is already compromised. Addressing these challenges requires sustainable agricultural innovations that enhance the plant resilience to abiotic stress. Kinetin (Kn), a phytohormone that regulates plant growth and development, shows strong potential to enhance stress tolerance but suffers from poor solubility and instability under environmental conditions, limiting its agricultural use. To overcome these limitations, we developed zinc-caffeic acid-based metal-phenolic nanocarriers (CAFZin) to encapsulate kinetin. The resulting system, CAFZin-K, was synthesized through coordination-driven self-assembly and thoroughly characterized for its morphology, loading efficiency, and release behavior. CAFZin-K enabled sustained kinetin release and improved its stability, achieving a 3.7-fold increase in uptake compared to that of free Kn. When used for seed nanopriming, CAFZin-K significantly enhanced germination rate, shoot and root growth, and overall biomass compared to nonencapsulated Kn and untreated controls under both normal and saline conditions. These findings demonstrate the potential of metal-phenolic nanocarriers as cost-effective, green, and eco-designed systems for the protection and controlled release of bioactive molecules, supporting crop performance under challenging environmental conditions.