Plasma membrane damage contributes to antifungal activity of citronellal against Penicillium digitatum.

The antifungal activity of citronellal, a typical terpenoid of plant essential oils, against Penicllium digitatum and the possible action mode involved were investigated. Results showed that the mycelial growth and spores' germination of P. digitatum were inhibited by citronellal in a dose-dependent manner. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were determined to be 1.60 µL/mL and 3.20 µL/mL, respectively. It was found that the plasma membrane of citronellal-treated P. digitatum spores was damaged, as confirmed by the propidium iodide stain results, as well as a higher extracellular conductivity and release of cell constituents in citronellal-treated samples than those of control samples. Moreover, in vivo test results demonstrated that wax + citronellal (WC; 10 × MFC) treatment effectively reduced the incidence of green mold after 5 days of storage at 25 ± 2 °C. These findings suggested that the plasma damage mechanism contributed to the antifungal activity of citronellal against P. digitatum. In addition, citronellal was suggested to be a potential alternative to fungicidal agents in controlling green mold of citrus fruit.