Antifungal effect and its mechanism of cinnamaldehyde on Fusarium pernambucanum from postharvest pepper fruit

Rot diseases caused by F. pernambucanum severely reduce the postharvest quality and market value of pepper. This study aimed to investigate the antifungal effect and the inhibition mechanism of cinnamaldehyde against F. pernambucanum by antifungal test in vitro and in vivo, mycelial morphology and spore germination observation, cell leakage detection and respiratory metabolism analysis. Cinnamaldehyde significantly inhibited mycelial growth. It reduced spore germination and mycelial shoot tube length by 27.6 % and 24.2 %, respectively. Mycelia fomulated with cinnamaldehyde showed a wrinkle and deformation under a scanning electron microscopy, and a significantly damage of cellular ultrastructure under a transmission electron microscopy. PI staining showed ruptures on the surface of mycelia fomulated by cinnamaldehyde. The damage also induced leakage of soluble substances from mycelial cells. This results were further exacerbated by the decrease of ergosterol in mycelia. Cinnamaldehyde treatment induced the accumulation of reactive oxygen species (ROS) in mycelium, triggering an increase in malondialdehyde. In addition, cinnamaldehyde had a strong destructive effect on the respiratory metabolism of mycelial cells. After a fumigation with 50 μg L −1 cinnamaldehyde for 3 d, the adenosine triphosphate content, malate dehydrogenase and succinate dehydrogenase enzyme activity of mycelial cell decreased by 45.5 %, 48.2 % and 47.0 %. In vivo tests, cinnamaldehyde fomulation significantly delayed the expansion of disease spots and maintained the quality of pepper fruit. These results will provide a basis to develop biological preservation agent for controlling pepper fruit rot caused by F. pernambucanum . • Cinnamaldehyde exerted direct antifungal activity against Fusarium pernambucanum in vitro. • Cinnamaldehyde destroys the integrity of the cell membrane of Fusarium pernambucanum . • Cinnamaldehyde caused Fusarium pernambucanum impaired respiratory metabolism. • Cinnamaldehyde is expected to be a potential inhibitor to rot disease on pepper fruit in postharvest.