Potential of Cerrado endophytic fungi in mitigating biotic stress induced by Fusarium oxysporum in cotton plants

Abstract Vascular wilt induced by Fusarium oxysporum hinders water and nutrient circulation in plants, severely affecting the yield of globally important crops such as cotton. In this context, the use of endophytic microorganisms emerges as a promising perspective for the biocontrol of Fusarium wilt. We hypothesized that endophytic fungal strains isolated from the roots of Butia purpurascens , an endemic palm of the Brazilian Cerrado, could control the symptoms caused by F. oxysporum f. sp. vasinfectum in Gossypium hirsutum L. plants. To test this, we induced biotic stress in cotton plants using F. oxysporum and evaluated the effect of inoculating seven fungal strains in mitigating the damage caused by this phytopathogen. Biotic stress was assessed through changes in growth, gas exchange (resulting in increased leaf temperature), chlorophyll a fluorescence, antioxidant enzyme synthesis, proline, malondialdehyde (MDA) levels, and the incidence of necrosis, leaf wilting, and floral abortion. Overall, the inoculation of cotton plants with endophytic fungi significantly mitigated the effects of the pathogen, promoting vegetative growth, maintenance of photosynthetic pigments, improved physiological performance, regulation of antioxidant activity, favorable leaf anatomical changes, and reduction of symptoms such as necrosis, wilting, and floral abortion. Specifically, strains BP10EF and BP52EF ( Gibberella moniliformis ), and BP16EF ( Penicillium purporogenum ) stood out as multifunctional agents in mitigating F. oxysporum wilt in cotton, resulting in responses similar to those observed in healthy plants. These results highlight the potential of these endophytic strains to be explored not only as plant growth-promoting agents but also as resistance inducers in cotton against the stress caused by F. oxysporum .