Evaluation of the beneficial effects of seed treatment with a Trichoderma atroviride isolate on different agricultural crops

In response to the growing need for sustainable alternatives to pesticides and fertilizers, whose intensive exploitation in the last decades caused pollution and biodiversity loss, new biofungicides and biostimulants are continuously under investigation. The fungal genus Trichoderma includes several isolates that can act as both biocontrol agents and biostimulants, enhancing plant defence, growth and stress resilience, to the point these fungi are the most used as active ingredients of commercial products. This study aimed to evaluate a new Trichoderma-based biostimulant the Spanish company Aténs is developing, by analyzing its effects on plant growth, metabolisms and gene expression. Spores of T. atroviride, active ingredient of the new biostimulant, were used alone and with different adhesive – to evaluate their effect on T. atroviride performances - to coat wheat and radish seeds. Germination rate, root elongation, fresh/dry weight and metabolome (by LC-MS) were analyzed. Radish coated seed were also sown under drought stress. Antibiosis and mycoparasitism of T. atroviride vs the wheat pathogen Fusarium graminearum, as well as its ability to endophytically colonize wheat roots and to modulate defence-related gene expression were investigated. Growth parameters and gene expression were analyzed by one-way ANOVA and Tukey's post hoc test, while analysis of variance of the regression and discriminant analysis were used for antagonistic test and metabolic analysis, respectively. According to results here obtained, two adhesivants seem to significantly reduce the performance of T. atroviride, both on wheat and radish in terms of growth parameters. In addition to growth stimulation, T. atroviride showed interesting antagonistic activity, both due to antibiotic volatile and soluble metabolites. Its ability to endophytically colonise wheat roots is reflected to a significant up-regulation of some defence-related genes (pr1, sod). Despite the positive results here collected, further research is needed to clarify the mechanisms behind these effects apparently due to the presence of some adhesivants and to improve the final formulations.