The non-pathogenic strain Fusarium oxysporum FO12 enhances sunflower and wheat performance by altering the phytohormone profile and soil properties

Abstract Aims Endophytic fungi (EF) such as the non-pathogenic strain Fusarium oxysporum FO12 have emerged as useful allies for plants as they could promote plant growth and protect from stresses. However, there remain some uncertainties about their performance under natural soil conditions and the effectiveness of some inoculation methods. The objective of this study was to assess the ability of FO12 to enhance plant growth and nutrition in sunflower and wheat plants grown on four different soils with contrasting fertility. Methods To bridge this gap in knowledge, we conducted in vitro and in vivo assays to assess the potential of FO12 for enhancing plant growth and nutrition in sunflower and wheat plants grown on non-calcareous and calcareous soils with contrasting availability of nutrients (Fe, Zn and P); and the effectiveness of two different FO12 application methods: seed dressing (Sd) and soil treatment (St). Results FO12 altered the pH of the culture medium, and increased Fe availability by 202%, Zn availability by 52% and P availability by 7% (in vitro). Both FO12 application methods boosted plant growth in by increasing plant height and sunflower and wheat reproductive biomass by up to 27−31% and 28-34% in non-calcareous and calcareous soils, respectively. FO12 additionally increased macro- and micronutrient uptake, especially with St. Finally, the fungus induced changes in plant phytohormone profile, but mainly with Sd. Conclusions FO12 stimulates plant growth by altering soil properties and physiological plant processes, and its effects on plant nutrition and production depend on the plant species and soil type.