Inhibitory Effect and Antifunal Mechanism of Umbelliferone on Plant Pathogenic Fungi

Low concentrations of 7-hydroxycoumarin (umbelliferone) were found of antifungal activity towards plant pathogenic fungi using growth rate method. Umbelliferone inhibited mycelia growth in Monilia fructigena, Fusarium moniliforme, Botrytis cinerea and Colletotrichum capsici with the minimal inhibitory concentration (MIC) values of 250, 500, 1000, and 2000 μg mL-1, respectively. The results also showed its minimal fungicide concentration (MFC) values of M. fructigena and F moniliforme were both 1000 μg mL-1. But no MFC values towards B. cinerea and C. capsici were obtained in this study. It is noteworthy that umbelliferone was very active against the spore germination of the four fungi. 100% inhibition of spore germination of M. fructigen and F. moniliforme were observed, when the umbelliferone concentrations were up to 1000 μg mL-1 and 2000 μg mL-1, respectively. The antifungal mechanism of umbelliferone was further investigated using scanning electron microscope (SEM) and transmission electron microscope (TEM). After umbelliferone treatment, the fungal mycelia appeared to deform or adhere. The cell structure of fungal mycelium was destroyed, and the cell contents were spilled. Antifungal mechanism of umbelliferone is probably based on its destruction activity towards pathogenic fungal cellular organs. According to our investigation, umbelliferone has the potential to be useful as a phytogenous pesticide.