Citrus lemon (Citrus limon (L.) Burm. f. cv. Eureka) essential oil controls blue mold in citrus by damaging the cell membrane of Penicillium italicum

As a major postharvest pathogenic fungus of citrus fruit, Penicillium italicum (P. italicum) can cause significant economic losses to the citrus fruit industry. By using steam distillation, we extracted 14 kinds of domestic citrus peel essential oils (EOs) and analyzed the antifungal inhibitory activity of different varieties of EOs. The results showed that Citrus lemon (YLK) EO was the most effective in inhibiting the growth of P. italicum with an MIC and MFC of 0.625 mg/mL and 1.25 mg/mL, respectively. Forty volatile components were identified in YLK EO, and the most prevalent were limonene (46.2%), gamma-terpinene (12.16%), pinene (11.07%), and citral (3.47%). YLK EO treatment significantly inhibited P. italicum spore germination and mycelial growth, disrupted mycelial morphology, and caused reactive oxygen species accumulation and membrane lipid peroxidation in vitro. All these changes disrupt the integrity and permeability of the cell membrane. In addition, in vivo, YLK EO treatment could effectively control and retard the growth and reproduction of P. italicum in citrus fruits. Based on these findings, we can conclude that YLK EO exhibits potent antifungal activity against P. italicum. Its potential antifungal mechanism is likely associated with the damage inflicted on the cell membrane. Therefore, YLK EO can be considered a potential source of natural antifungal agents. •Among 14 varieties of citrus EOs, YLK EO showes the strongest antifungal activity of P. italicum.•YLK EO exhibits antifungal effects against P. italicum in vitro and in vivo.•YLK EO damages the cell membrane of P. italicum.•YLK EO stimulates the accumulation of ROS in the mycelia of P. italicum.