Effect of Cinnamic Acid for Controlling Gray Mold on Table Grape and Its Possible Mechanisms of Action.

Cinnamic acid (CA) is an organic acid and is widely used in food industry as a common food additive. Previous studies showed that CA has the antimicrobial activity in vitro, but little is known about the effect of CA on controlling the fruit decay in vivo. In present study, we showed that application of CA was significantly effective on controlling the gray mold of table grape caused by Botrytis cinerea. CA can directly inhibit the mycelial growth of B. cinerea on potato dextrose agar plates. The mechanisms by which CA inhibited fungal growth were assayed by staining the spores with fluorescent dyes propidium iodide and 7-dichlorodihydrofluorescein diacetate, respectively. The results indicated that CA can damage the integrity of plasma membrane and induce the intracellular reactive oxygen species level of B. cinerea which were responsible for the reduction of growth rate. Meanwhile, CA treatment significantly stimulated the activities of peroxidase and polyphenol oxidase which were closely related to the resistance of plant. Taken together, this study suggested that CA was effective on controlling the gray mold of table grape in postharvest period by inhibiting the growth of pathogen and inducing the resistance of host.