Characterization of biologically synthesized copper nanoparticles by Aspergillus carbonarius and evaluation of their activity in reducing the pathogenic stress of tomatoes infected with Fusarium oxysporum

Abstract

This study was conducted to evaluate the efficiency of the fungus Aspergillus carbonarius in the synthesis of copper nanoparticles (CuNPs) from copper chloride solution, with the characterization of these nanoparticles and the demonstration of their effectiveness in inhibiting the pathogenic fungus Fusarium oxysporum causing tomato root rot disease. The results indicated that the treatment of copper chloride solution at 150 mM with A. carbonarius filtrate led to the production of CuNPs which characterized by a color change from blue to green, with the highest absorbance observed at 300 nm. X-ray diffraction (XRD) results revealed the crystalline structure with peaks at angles 28.47286, 47.43258, and 56.20644 ◦ corresponding to (111), (220), and (311) planes, respectively, matching the JCPDS card number 01-081-1841. Scanning electron microscopy images showed cubic, pyramidal, and prismatic shapes with dimensions ranging from 15 - 84.291 nm. In laboratory experiment, CuNPs inhibited the growth of the pathogenic fungus, with an inhibition zone of 1.6 cm, compared to copper chloride which recorded 0.9 cm. In the field, , the treatment of CuNPs led to an increase in the stress resistance indicators, reaching the highest values for CuNPs when combined with the fungicide Medazim in the American tomato cultivar. The concentrations of total phenols and glutathione in this treatment were 2.56 mg/g and 0.322 µg/g, respectively. The lowest concentration of proline was recorded as 4.31 µg/g in the treatment involving CuNPs against the fungal infection. CuNPs with the fungicide medazim, significantly outperformed other treatments, registering lowest disease severity at 12.22% in the American cultivar, compared to the highest disease severity was recorded in the treatment with the pathogenic fungus alone, reaching 91.16% in the Dutch cultivar. CuNPs significantly increased tomato fruit weight, both in healthy and infected plants. The American, Turkish, and Dutch tomato cultivars infected with the pathogenic fungus and treated with under + medazim showed higher productivity, reaching 6432.55, 6334.34, and 6305.73 g.plant-1, compared to the lowest productivity in the treatment of these cultivars with the pathogenic fungus, reaching 1008.34, 977.45, and 833.78 g.plant-1, respectively

Keywords

• Copper nanoparticles, Aspergillus carbonarius, Fusarium oxysporum, pathogenic stress markers, Rot root disease , Tomato cultivars