Protective role of Claroideoglomus etunicatum and Trichoderma harzianum to improve growth and physiological immune responses of Olea europaea tolerance against Fusarium solani

Fusarium solani (FS) is a highly virulent fungus that affects Olea europaea (OE) plants, leading to significant physiological stress, reduced yield, and compromised fruit quality. In our study, FS had a disease index of 87.5% and 85% in 2022 and 2023, respectively. C. etunicatum (CE) and T. harzianum (TH) isolates were used to mitigate the harmful effects of the FS, reducing the disease index to 17.5%, 45%, 15%, and 35% in 2023. OE Plants inoculated with these isolates showed the most favorable conditions for the synthesis of chlorophyll a, b, and carotenoids (15.02, 11.56, and 2.84 mg/g fresh weight), which are essential for photosynthesis and plant health. The highest phenolic and proline concentrations were recorded in the 2023 season in healthy OE plants treated with both treatments. This indicates that this treatment may have provided optimal conditions for phenol synthesis, which is known for its antioxidant properties and role in plant defense mechanisms against FS wilt disease. Furthermore, the highest malondialdehyde (MDA) levels were observed in the OE plant infected with FS and treated with CE in both seasons, demonstrating the induction of substantial oxidative stress. in conclusion: CE and TH provide a foundation for sustainable agricultural practices that can help safeguard olive production against the virulent pathogen FS.