Chlorine dioxide fumigation induces transcriptomic and metabolomic reprogramming enhancing resistance to soft rot in kiwifruit

Soft rot is a major cause of postharvest decay in kiwifruit. Chlorine dioxide (ClO 2 ) has been widely applied as a preservative in many fruit and vegetables, but its efficacy and underlying mechanisms against soft rot in kiwifruit are largely unknown. In this study, ClO 2 fumigant was applied to suppress two primary soft rot fungal pathogens, Botryosphaeria dothidea and Diaporthe eres in ‘Yunhai No. 1’ and ‘Hongyang’ kiwifruit ( Actinidia chinensis ). Treatment with 400 mg ClO₂ reduced disease incidence by up to 93 % and lesion diameter by 22.5 mm. Integrated transcriptome-metabolome analyses were performed to investigate its effect on the induction of plant defense responses. Transcriptomic analysis revealed 2828 differentially expressed genes, highlighting enrichment in defense-related pathways and upregulation of ERF, MYB, and WRKY transcription factors. Metabolomic profiling identified 1172 metabolites, with strong accumulation of antifungal compounds like jasmonic acid and luteolin-7-O-glucuronide under ClO₂ treatment. Correlation analysis confirmed strong associations between ERF transcription factors and key antimicrobial metabolites. Collectively, these findings demonstrate that ClO₂ fumigation controls soft rot not only through direct antifungal action but also by inducing host defense mechanisms, thereby providing new insights and practical references for eco-friendly preservation of kiwifruit.