High-permeability cellulose nanocrystals mediate systemic zinc redistribution through nsLTP2-dependent immune potentiation in plants.

Zinc (Zn) is an essential micronutrient that regulates plant growth, immunity and antiviral defence mechanisms. However, its limited bioavailability often necessitates excessive application, resulting in inefficiencies in production and environmental stress. In response, we propose an environmentally friendly and sustainable approach to enhance the utilization of Zn. We developed CNC@PDA@Zn by embedding Zn into the polydopamine (PDA) coating of cellulose nanocrystals (CNCs). Leveraging the high cell permeability of CNCs, this material increased the transport capacity of Zn in plants and demonstrated the ability to inactivate viral particles in vitro. Moreover, CNC@PDA@Zn showed a superior induction of resistance while reducing Zn content, specifically by reprogramming the expression and localization of the resistance-related non-specific lipid transfer protein 2 (nsLTP2), which enhanced the salicylic acid (SA) signalling pathway in plants. Furthermore, the high conservation of nsLTP2 in flowering plants increases the potential application range of CNC@PDA@Zn. Importantly, CNC@PDA@Zn represents the most effective Zn-based antiviral nanomaterial to date, achieving its effects at the lowest reported Zn concentration. Overall, our results highlight that CNC@PDA@Zn can more effectively upregulate the conserved nsLTP2, thereby inducing viral defence responses via the SA pathway. This strategy not only improves the operation and utilization rate of Zn but also reduces its environmental residues, laying a theoretical foundation for the development of antivirus defence.