The First Review on Nano-Agricultural Applications of MXene and MBene-Based Materials for Plant-Immunoengineering,...

Producing quality food crops with a focus on climate and environmental improvement policies has become central to modern farming and sustainability strategies. However, the rising world population and food demand have region-dependently pushed these boundaries to the overuse of agrochemical inputs. These include plant antimicrobials, pesticides, and soil fertilizers, applied to boost crop yields, reaching a critical juncture. The reliance on agrochemicals has been proven effective in priming, plant growth, and enhancing defense/resistance to biotic stressors, such as phytopathogens and invasive organisms, as well as abiotic pressures, including heat, drought, salinity, and light stress, by increasing nutrient absorption and innate immunity or adaptive stress resistance. However, increasing concerns about the safety, cost, and environmental impact of agrochemicals have intensified the necessity for applying sustainable precision technologies. Nano-agriculture has introduced emerging possibilities for utilizing low-dimensional biomaterials for plant protection/stimulation applications, once these technologies are proven safe. Among them, carbon-based MXenes and derivatives (MBenes) show potential due to their high surface-to-volume area, biocompatibility at controlled doses, and tunable physicochemical/biological properties. These unique specifications support targeted delivery and sustained release, while also enhancing plant growth and stress tolerance. This comprehensive review covers their effect on seed germination, seedling maturation, plant-immunoengineering, priming, eliciting, stomatal closure, antimicrobial actions, and gene or phytohormone regulation. It also discusses their role as sustainable carriers for the delivery and release of agrochemicals and plant protection by nano-design, aiming to reduce agrochemical consumption. Lastly, we discuss the current environmental regulations for nanomaterials and recommend rational outlooks for future work.