Iron and copper on Botrytis cinerea: new inputs in the cellular characterization of their inhibitory effect.

Certain metals play key roles in infection by the gray mold fungus, Botrytis cinerea. Among them, copper and iron are necessary for redox and catalytic activity of enzymes and metalloproteins, but at high concentrations they are toxic. Understanding the mechanism requires more cell characterization studies for developing new, targeted metal-based fungicides to control fungal diseases on food crops. This study aims to characterize the inhibitory effect of copper and iron on B. cinerea by evaluating mycelial growth, sensitivity to cell wall perturbing agents (congo red and calcofluor white), membrane integrity, adhesion, conidial germination, and virulence. Tests of copper over the range of 2 to 8 mM and iron at 2 to 20 mM revealed that the concentration capable of reducing mycelial growth by 50% (IC50) was 2.87 mM and 9.08 mM for copper and iron, respectively. When mixed at equimolar amounts there was a significant inhibitory effect mostly attributable to copper. The effect of Cu50, Fe50, and Cu50-Fe50 was also studied on the mycelial growth of three wild B. cinerea strains, which were more sensitive to metallic inhibitors. A significant inhibition of conidial germination was correlated with adhesion capacity, indicating potential usefulness in controlling disease at early stages of crop growth. Comparisons of the effects of disruptive agents on the cell wall showed that Cu, Fe, and Cu-Fe did not exert their antifungal effect on the cell wall of B. cinerea. However, a relevant effect was observed on plasma membrane integrity. The pathogenicity test confirmed that virulence was correlated with the individual presence of Cu and Fe. Our results represent an important contribution that could be used to formulate and test metal-based fungicides targeted at early prevention or control of B. cinerea.

Impact on Physicochemical Composition and Antioxidant Activity of the Wild Edible Mushroom Cyttaria espinosae Subjected to Drying.

The wild edible mushroom 'digüeñe' (Cyttaria espinosae) is a mushroom with interesting flavor and nutritional properties, but highly perishable with a consumption very limited, generating inevitable economic losses for their producers. Because of that, the aim of this study was the evaluation of two drying methods (hot-air drying and freeze-drying) in its bioactive and physicochemical composition for its preservation. The best performances of antioxidant capacity were 62 µmol TE g-1 (ORAC) and 14.21 µmol TE g-1 (DPPH), being higher compared with other vegetable sources. Its protein (5.33 %), fiber (5.58 %) and K (2.82 mg g-1 ) content also stands out. ß-Carotene retention was 35.02 and 23.25 % after freeze drying and hot-air, respectively. Freeze-drying seems a good strategy for digüeñe, bioactive compounds, color and structure were better maintained. This work represents the first characterization of dehydrated digüeñe, constituting approaches for its valorization and use in the food industry.