Ferulic acid treatment reinforces the resistance of postharvest apple fruit during gray mold infection

Ferulic acid, the most common phenolic acid in plants, is widely used industrially because of its chemical and biological activities. Few studies, however, have examined its mode of action on postharvest diseases caused by Botrytis cinerea. In this study, we therefore investigated the activity and efficacy of ferulic acid treatment on gray mold of apple fruit. ‘Pink Lady’ apple fruits were soaked in 0.80 g l−1 ferulic acid solution for 20 min, incubated for 12 h, and inoculated with 20 μl of a B. cinerea conidial suspension. Distilled water was used instead of ferulic acid as a control. Samples were collected regularly, with the incidence and diameters of lesions surrounding each wound site measured and recorded at the same time. Compared with the control, ferulic acid treatment was found to significantly increase activities of enzymes in the phenylpropanoid pathway (p < 0.05) and thus effectively improve total phenol and flavonoid accumulations. This treatment also affected the activities of enzymes in the lignin biosynthesis pathway, thereby promoting lignin production while decreasing disease incidence and lesion diameters (p < 0.05). The production of hydrogen peroxide and superoxide radicals also decreased. On the basis of these findings, we conclude that ferulic acid treatment can augment the defense response of apple fruit by enhancing the activities of resistance-related enzymes and boosting the accumulation of resistance-related substances, thereby reducing the incidence of gray mold.