Fungal Gene Mutation Analysis Elucidating Photoselective Enhancement of UV-C Disinfection Efficiency Toward Spoilage Agents on Fruit Surface.

Short-wave ultraviolet (UV-C) treatment represents a potent, clean and safe substitute to chemical sanitizers for fresh fruit preservation. However, the dosage requirement for microbial disinfection may have negative effects on fruit quality. In this study, UV-C was found to be more efficient in killing spores of in dark and red light conditions when compared to white and blue light. Loss of the blue light receptor gene , a homolog of in , led to hypersensitivity to UV-C in all light conditions tested. The expression of and , which encode UV-damage endonuclease and photolyase, respectively, were strongly induced by white and blue light in a -dependent manner. Gene mutation analyses of and indicated that they synergistically contribute to survival after UV-C treatment. assays showed that UV-C (1.0 kJ/m) abolished decay in drop-inoculated fruit only if the UV-C treatment was followed by a dark period or red light, while in contrast, typical decay appeared on UV-C irradiated fruits exposed to white or blue light. In summary, blue light enhances UV-C resistance in by inducing expression of the UV damage repair-related enzymes, while the efficiency of UV-C application for fruit surface disinfection can be enhanced in dark or red light conditions; these principles seem to be well conserved among postharvest fungal pathogens.