LAUSR

Abstract Black spot rot caused by Alternaria alternata is becoming a main postharvest disease on apple fruit. The objective of this study was to elucidate the antifungal efficiency of ursolic acid (UA) against A. alternata and its application in preserving apple fruit. The results showed that UA induced disturbance of membrane permeability and integrity, as well as intracellular ROS accumulation in A. alternata, result in the sabotaged morphology and lysis of the pathogen, thus exert directly antifungal activity. In addition, the application of UA significantly inhibited the black spot rot development on apple fruit, the increased defense enzyme activities were detected. These results suggested that, in addition to its direct antifungal activity, UA induced the defense responses in apple fruit against the postharvest pathogen invasion. UA is widely distributed in the plant kingdom and could be a promising alternative for Alternata diseases management.