Porphyrin‐Linked Antifungal Nanocarrier Promotes Plant Growth via <scp>UV RESISTANCE LOCUS</scp> 8‐Mediated Light Signalling Activation

Nanocarriers can improve pesticide delivery efficiency and reduce phytotoxicity, thereby supporting sustainable strategies for crop protection. Given this potential, it is essential to investigate their effects on crop physiology and development. The effects of porphyrin-containing covalent organic framework (COF) carriers on the delivery and biological performance of the fungicide Fludioxonil (FLU) were evaluated in Nicotiana tabacum. The COF exhibited a highly ordered crystalline architecture with an encapsulation efficiency of 60.9%. Treatments included FLU@COF, free FLU, untreated controls and additional reference groups, applied at concentrations of 5 and 50 mg L^-1. Compared with free FLU, the FLU@COF formulation enhanced antifungal activity against Fusarium oxysporum by 35.3%. Furthermore, it exhibited high soil mobility, facilitating effective dissemination. The COF penetrated root tissues and was systemically distributed throughout the plant. As a result, treated plants exhibited a 37.4% increase in leaf area, a 25.2% increase in plant height and more than 25.2% increases in chlorophyll a and b contents. Phytohormone profiling revealed that levels of indole-3-acetic acid (IAA), cytokinin (CK) and gibberellin (GA) each increased by more than 20.0%, accompanied by higher accumulation of carbon, nitrogen and soluble sugars. Multi-omics analyses, supported by virus-induced gene silencing (VIGS), demonstrated that the UV RESISTANCE LOCUS 8 (UVR8)-mediated CONSTITUTIVELY PHOTOMORPHOGENIC 1-ELONGATED HYPOCOTYL 5 (COP1-HY5) signalling pathway regulates COF-induced growth promotion. Moreover, the COF delivery system exhibited high biocompatibility and reduced the ecological toxicity of FLU. Collectively, these findings establish a robust, low-toxicity nanocarrier platform with strong potential for safe and effective application in sustainable agriculture.