Ecofriendly nanomaterials for controlling gray mold of table grapes and maintaining postharvest quality

Biodegradable antifungal nanomaterials are a recent novel measure against plant pathogens. In the present investigation, the synthesis and characterization of some ecofriendly nanomaterials, including silica, chitosan, and copper nanoparticles (NPs) and their combination, were carried out. Their fungicidal activity was studied in vitro and in vivo against Botrytis cinerea, the causal agent of gray mold on table grapes. In addition, the effect of those nanomaterials on physical and chemical properties of grape (TSS, TA, TSS/TA ratio and berries colour) were evaluated. Scanning electron microscopy (SEM) and analysis of DNA-binding profile were used to better understand their mechanism of action. SEM showed that chitosan and silica NPs caused inhibition of hyphal growth and/or alteration of hyphal morphology such as cell wall disruption, withering, and excessive septation. NPs interacted with DNA isolated from fungal mats: the highest concentration of chitosan and silica NPs affected DNA integrity and led to a significant degradation. A single application of chitosan or silica NPs at veraison stage was able to reduce gray mold of table grapes. Although further large scale trials are needed, the promising results of this research suggest nanomaterials compounds, i.e. silica and chitosan NPs, as effective antifungal agents for the control of gray mold of table grapes.