Pinocembrin-7-glucoside provides a novel strategy for preventing citrus postharvest blue mold caused by Penicillium italicum

The present study investigated the antifungal activity of pinocembrin-7-glucoside (P7G), a natural flavanone compound against citrus blue mold caused by Penicillium italicum. The in vitro inhibitory effects of P7G on mycelial biomass, energy status, morphology, and ultrastructure of P. italicum were determined. Moreover, the inhibitory effect of P7G against blue mold development on 'Newhall' navel orange fruits was determined in situ. The results showed that P7G significantly inhibited mycelial growth by causing cell membrane damage, as evidenced by decreased intracellular ergosterol content, repressed energy status, and related enzyme activities. This was also confirmed by the microscopic observations, which showed abnormal mycelial morphology with more abnormal branches and cell permeabilization under 0.4 g/L P7G treatment. In addition, the in situ results showed that the P7G-treated orange fruit maintained an elevated level of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase) and maintained the higher levels of titratable acidity, ascorbic acid, and glutathione contents. Overall, the present study revealed a possible mechanism of P7G as a natural alternative antifungal agent to control postharvest fungal decay of orange fruit.