5-Methoxyindole, a Chemical Homolog of Melatonin, Adversely Affects the Phytopathogenic Fungus Fusarium graminearum

Abstract

<i>Fusarium graminearum</i> is a destructive fungal pathogen that threatens the production and quality of wheat, and controlling this pathogen is a significant challenge. As the cost-effective homolog of melatonin, 5-methoxyindole showed strong activity against <i>F. graminearum.</i> In the present study, our results showed the strong adverse activity of 5-methoxyindole against <i>F. graminearum</i> by inhibiting its growth, formation, and conidia germination. In addition, 5-methoxyindole could induce malformation, reactive oxygen species (ROS) accumulation, and cell death in <i>F. graminearum</i> hyphae and conidia. In response to 5-methoxyindole, <i>F. graminearum</i> genes involved in scavenging reactive oxygen species were significantly downregulated. Overall, these findings reveal the mechanism of antifungal action of melatonin-homolog 5-methoxyindole. To the best of our knowledge, this is the first report that a novel melatonin homolog confers strong antifungal activity against <i>F. graminearum</i>, and 5-methoxyindole is a potential compound for protecting wheat plants from <i>F. graminearum</i> infection.