In recent years, natural products have been identified as a major source of secondary metabolites for management of the diseases. The potential use of medicinal plants and their secondary metabolites as a replacement for chemical fungicides is supported by developed research. Luteolin compound is a significant derivative of flavones. In this work, for investigate the effect of luteolin compound on the hyphal structure of Fusarium culmorum and Fusarium pseudograminearum each coverslip was covered with a mixture of Potato Dextrose Agar (PDA) medium and luteolin at different concentrations (40, 60, 80, and 100 μg mL-1), and the fungi were cultured in the center of each coverslip. These coverslip were incubated for 5 days at 28 °C. Using an optical microscope, vegetative fungal growth on PDA containing the luteolin compound was investigated, showing degenerative alterations in the fungal hyphae structures. The control mycelium that was grown on PDA without the luteolin showed typical morphology in the fungi that were assessed. At different concentrations of luteolin, hyphae balloon-shaped cells, deformed, swollen, lysed, vacuolated, broken, and folded were demonstrated. Therefore, the fungal cells treated with luteolin showed irregular cell wall surfaces, indicating that luteolin disrupts the production of cell wall components, which in effect inhibits cell wall synthesis and repair. In general, this study indicated that luteolin, inhibits Fusarium spp. growth and protects wheat plants from this damaging fungi.

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