Antifungal activity and mechanism of tea polyphenols against Rhizopus stolonifer

To investigate the antifungal activity and possible mechanism of tea polyphenols (TPs) against Rhizopus stolonifer, the agent of rotting in nectarines and peaches.

TP inhibited both mycelial growth and spore germination in vitro in a dose-dependent manner, and the morphological changes of the treated hyphae with TP, such as irregularly swollen, increased branching, wrinkled, entwining, collapse and breakage, and of the treated spores, such as swelling of germ tube tips, exfoliation of the surface layer and disorganization of cell organelles, were observed using optical microscopy, scanning electron microscopy and transmission electron microscopy. TP also significantly decreased rhizopus rot on inoculated nectarines and induced the activities of phenylalanine ammonia lyase, polyphenol oxidase, peroxidase, chitinase, and β-1,3-glucanase.

The mechanism of action might be attributed to direct damage of the mycelium and spore and indirect induction of defensive enzyme activities. TP has the potential to be developed as an alternative to control post-harvest disease of fruit caused by R. stolonifer.