Inhibitory effects of wild Origanum elongatum extracts on Fusarium oxysporum mycelium growth and spores germination: Evidence from in-vitro, in-planta, and in-silico experiments

Fusarium wilt, caused by Fusarium oxysporum, is one of the most devastating diseases to crops including potatoes. This fungus is widespread and dispersed via resistant spores. In this study, organic (methanol, hexane, and chloroform) and aqueous extracts of the aerial parts of wild Origanum elongatum were tested against mycelium and spores of F. oxysporum in both in-vitro (using the poisoned food technique) and in-planta assays. Further, the chemical composition of the extract was identified via HPLC-PDA-MS/MS. Then, molecular modeling was used to clarify the antifungal activity of identified biomolecules. The obtained results showed that organic and aqueous extracts showed significant antifungal and anti-sporulation activities with different effectiveness depending on the extract, concentration, and application test. In in-vitro assays of the aqueous extract, the highest antifungal activity was recorded at concentrations of 10 mg mL⁻¹, while the highest anti-sporulation activity (91.79 %) was observed at 50 mg mL⁻¹. In the organic extracts, methanol was the most effective against fungus with 100 % inhibition of mycelium at 5 mg mL ⁻¹ and the highest anti-sporulation effect (73.58 %) at 20 mg mL⁻¹. In in-planta assays, the methanolic extract at 20 mg mL⁻¹ achieved 0 % disease severity, while the aqueous extract at 50 mg mL⁻¹ reduced severity to 7 %, both significantly more effective than the untreated control. Therefore, methanol was the most effective and these biological properties are supported by a wide range of bioactive molecules, including 56 molecules compared to only 28 molecules in the aqueous extract. These include glycosides of apigenin and kaempferol and salvianolic acid b. However, more research is needed to clarify the inhibition action of the individual components and their synergetic actions in controlled and field conditions.