Fungicidal effect of silver nanoparticles on toxigenic fungi in cocoa

Abstract

The objective of this work was to evaluate the microbicidal effect of silver nanoparticles (AgNPs) on potentially toxigenic fungi affecting cocoa (Theobroma cacao) crops. These fungi, isolated from diseased cocoa pods, were characterized phenotypically and genotypically. The microbicidal effect was assessed by measuring radial mycelial growth, in synthetic culture media, and at different AgNP concentrations in plant tissues. The inhibition effect was monitored in Petri dishes, and changes in fungal structures were observed through scanning electron microscopy. Two potentially toxigenic fungi were highly prevalent: Aspergillus flavus and Fusarium solani. The inhibition assays, performed in liquid and solid synthetic culture media, showed that AgNPs did not significantly affect the growth of these fungi, even at the highest concentration (100 ppm). By contrast, they showed a positive inhibitory effect in plant tissues, especially in the cortex, when infected with A. flavus, in which an 80 ppm dose completely inhibited fungal growth. However, once fungi have managed to penetrate inside the pods, their growth is unavoidable, and AgNP effect is reduced. On F. solani, the studied nanomaterial only induced some texture and pigmentation changes. The microbicidal effect of chemically synthesized silver nanoparticles is greater in plant tissues than in culture media.

Silver Nanoparticles Ecofriendly Synthesized by Achyranthes aspera and Scoparia dulcis Leaf Broth as an Effective Fungicide

“…Figure 6b showed the mycelium diameters of A. flavus on various media. On PDA, AA.ext and SD.ext, A. flavus were spread out to 24 [46,47], these results of AA.AgNPs and SD.AgNPs were considered as a similar effect. The silver nanoparticles of the American company MTI (Aladdin, WY, USA) could inhibit the fungus A. flavus effectively at the concentration of 150-200 ppm [46].…”

“…The silver nanoparticles of the American company MTI (Aladdin, WY, USA) could inhibit the fungus A. flavus effectively at the concentration of 150-200 ppm [46]. Differently, silver nanoparticles Biopure-AgNP (NanoComposix, San Diego, CA, USA) could show their successful inhibition at 80 ppm [47].…”

“…Changing to other silver nanoparticles of SD.AgNP20 and SD.AgNP40, the A. flavus diameters on dishes were 19.3 and 15.2 mm after 24 h, 30.3 and 23.3 mm after 48 h, 46.3 and 36.8 mm after 72 h and 65.0 and 52.5 mm after 96 h. So, two kinds of silver nanoparticles all demonstrated high antifungal activity against A. flavus. Looking at the antifungal activity of other silver nanoparticle products against A. flavus[46,47], these results of AA.AgNPs and SD.AgNPs were considered as a similar effect. The silver nanoparticles of the American company MTI (Aladdin, WY, USA) could inhibit the fungus A. flavus effectively at the concentration of 150-…”

The role of nanotechnology for improving crop production

“…Nano-fertilizers can increase crop yields by supplying one or more nutrients whereas nanomaterial-increased fertilizers ameliorate the performance of fertilizers. Nano-fertilizers compared with the conventional fertilizers, are expected to improve growth and yields of crops significantly [30].…”

Diversidad genética de <i>Moniliophthora roreri</i> mediante Polimorfismo de Longitud de Fragmentos Amplificados (AFLPs)

“…En 2012, el área cultivada con cacao en Colombia fue de 158.000 ha, con una productividad de 460 kg ha -1 , que es baja, en comparación con la de Costa de Marfil, el primer productor mundial, con 700 kg ha -1 (Villamizar, 2016).…”