Fe-based nanostructured particles affect the biocontrol activity of Trichoderma species by inducing their effector-like and mycoparasitism-associated genes

The use of biocontrol microorganisms is one of the primary techniques used in agriculture to combat the damage caused by phytopathogens. Of these, Trichoderma sp. stand out as fungi species that are naturally present in agricultural soil and can come into contact with various compounds, such as nanostructured particles (NPs), which are starting to be used as pesticides and fertilizers. They can also enter the soil through various anthropogenic activities, such as water treatment, due to the treated water can then be used for crop irrigation. As a result, microorganisms like Trichoderma come into contact with these NPs, and it is unclear whether this will affect their growth and biocontrol ability. In order to determine whether the three adsorbent materials (magnetite (Fe₃O₄), Al-doped magnetite (Al–Fe₃O₄) and silver iron oxide (Ag_2-xFe _xO_4-x) NPs) are toxic or have an impact on the biocontrol activity, the goal of this work was to expose them to two species of Trichoderma. Finding that, at 100 ppm, Trichoderma grows successfully on Fe₃O₄ and Al–Fe₃O₄ but not in the presence of Ag_2-xFe _xO_4-x NPs. However, interestingly, the presence of these nanomaterials helps Trichoderma to better biocontrol two Fusarium species. In addition, Al–Fe₃O₄ and Ag_2-xFe _xO_4-x NPs affected the expression of mycoparasitism-associated genes. These results indicate that the use of these materials and their delivery to the environment would have a synergistic effect with Trichoderma to counteract phytopathogens of agricultural interest. Additionally, the synthesis, microstructural characterization and fluoride adsorption equilibrium of the Ag_2-xFe _xO_4-x NPs are presented.