Effect of Copper Oxide Nanoparticles on In Vitro Plant Regeneration and Growth Improvement

Copper oxide nanoparticles (CuO-NPs) have emerged as promising tools in in vitro plant improvement because of their dual role as essential micronutrient providers and growth regulators. Copper is a vital element for several plant physiological and biochemical processes, including photosynthesis, respiration, and lignin biosynthesis. When supplied in nanoparticulate form, copper exhibits unique bioavailability and reactivity compared with conventional salts, enabling CuO-NPs to influence morphogenesis in tissue culture systems more effectively. Studies have demonstrated that CuO-NPs can significantly enhance callus induction, promote shoot organogenesis, stimulate root formation, and improve the overall vigor and survival of regenerated plantlets. These effects are linked to the controlled release of copper ions, modulation of reactive oxygen species (ROS) signaling, activation of antioxidant defense enzymes, and interactions with plant hormone signaling networks. The effectiveness of CuO-NPs is strongly concentration-dependent. At lower concentrations, they act as growth enhancers, while excessive application often leads to phytotoxic effects such as oxidative stress, cellular membrane disruption, and growth inhibition. Plant species and genotype further influence the response, and considerable variability exists among experimental outcomes. In addition, different application strategies including direct incorporation into Murashige and Skoog (MS) medium, pre-explant soaking treatments, and foliar application complicate direct comparisons and highlight the urgent need for methodological standardization. Despite the encouraging results, several challenges remain. Mechanistic insights into nanoparticle uptake, translocation, and subcellular localization are limited, and the long-term implications of nanoparticle use for plant health and environmental safety are not fully understood. Addressing these gaps, alongside the development of optimized and standardized protocols, will be critical for advancing the practical application of CuO-NPs in plant tissue culture. Future innovations such as the use of smart nanocarrier systems for controlled and targeted nutrient delivery may further enhance their efficiency while minimizing risks.