Antifungal effect of zinc oxide nanoparticles (ZnO-NPs) on Colletotrichum sp., causal agent of anthracnose in coffee crops.

Coffee cultivation around the world is affected by phytopathogenic fungi, among them Colletotrichum sp., the causative agent of anthracnose. In the present work, therefore, an in vitro study was carried out on the antifungal effect of zinc oxide nanoparticles (ZnO-NPs) obtained by a chemical route on Colletotrichum sp. To this end, the area of growth of the fungus exposed to the action of concentrations of 9 mmolL⁻¹ (730 ppm), 12 mmolL⁻¹ (980 ppm), and 15 mmolL⁻¹ (1200 ppm) of ZnO-NPs was monitored and their behavior was compared with the effect of the fungicide, ciproconazole (positive control) as well as with a sample of the fungus that grew normally (negative control). The ZnO-NPs showed an appreciable percent inhibition of fungal growth, ~96% for the concentration of 15 mmolL⁻¹ at 6 days, causing loss in the continuity of some hyphae and the formation of groups of hyphal structures. Additionally, the ZnO-NPs favored the formation of structures of compact appearance (similar to vacuoles) within the hypha, as well as decreasing the cytoplasmic space. Image 1 • The antifungal activity of ZnO nanoparticles on Colletotrichum spp. was evaluated. • The micro and ultrastructural effects of the ZnO-NPs over fungi were analized. • The evaluated ZnO-NPs significantly inhibited the growth of the Colletotrichum spp. • The synthesized ZnO nanoparticles could potentially be used to protect coffee crops. [ABSTRACT FROM AUTHOR]