Control of Wheat Fusarium Head Blight by Heat-Stable Antifungal Factor (HSAF) from <i>Lysobacter enzymogenes</i>

Abstract

Heat-stable antifungal factor (HSAF), which belongs to the polycyclic tetramate macrolactam family, was isolated from <i>Lysobacter enzymogenes</i> fermentations and exhibited inhibitory activities against a wide range of fungal pathogens. In this study, the antifungal activity of HSAF against <i>Fusarium graminearum</i> in vitro and in vivo was investigated. A total of 50% of mycelial growth of <i>F. graminearum</i> was suppressed with 4.1 μg/ml of HSAF (EC₅₀ value). HSAF treatment resulted in abnormal morphology of the hyphae, such as curling, apical swelling, and depolarized growth. Furthermore, HSAF adequately inhibited conidial germination and conidiation of <i>F. graminearum</i> with an inhibition rate of 100% when 1 and 6 μg/ml of HSAF were applied, respectively. HSAF caused ultrastructural changes of <i>F. graminearum</i>, including cell wall thickening and plasmolysis. Moreover, the application of HSAF significantly controlled Fusarium head blight in wheat caused by <i>F. graminearum</i> in the field. Overall, these results indicate that HSAF has potential for development as a fungicide against <i>F. graminearum</i>.