Plant Growth-Promoting and Biocontrol Potential of Aspergillus tubingensis and Talaromyces islandicus

The aim of this study was to screen the plant growth promotion and biocontrol potential of Aspergillus tubingensis and Talaromyces islandicus.

In vitro tests were conducted to assess potassium solubilization, Indole-3-Acetic Acid (IAA) production, and the biological activity of IAA. Subsequently, a greenhouse trial was carried out to evaluate the effect of inoculating Phaseolus vulgaris L. with A. tubingensis or T. islandicus on soil pH, electrical conductivity, and the bioavailability of phosphorus and potassium. Additionally, the impact on plant nutrition in terms of nitrogen, phosphorus, and potassium, chlorophyll content, and biometric parameters were measured. The biocontrol potentiality of both strains against Fusarium spp. was determined. A. tubingensis was selected for the in vivo trial using P. vulgaris L. to study the effect of preventive and curative treatment on disease incidence and severity.

Both strains demonstrated the capability to solubilize potassium (up to 32 mg L⁻¹) and produce IAA (up to 19 μg mL⁻¹). In vivo plant growth promotion assays showed that the presence of both strains in the soil increased the bioavailability of phosphorus and potassium in the rhizosphere. Both strains promoted nutrition, chlorophyll content, and biometric parameters of P. vulgaris L. Moreover, in vitro and in vivo tests confirmed the efficacy of A. tubingensis in controlling Fusarium spp. Preventive inoculation with A. tubingensis controlled up to 80% of disease incidence and severity in plants.

Overall, T. islandicus and A. tubingensis promote plant growth and enhance mineral nutrition of P. vulgaris L., mainly attributed to their capability in potassium solubilization, IAA production, and/or biocontrol potential against Fusarium spp.