Multiple host infection methods prove Fusarium musae infects plants and animals

Fusarium musae is an emerging potential cross-kingdom fungal pathogen. It causes crown rot in banana fruits and nail and keratitis infection as well as systemic disease in immunocompromised patients. To study F. musae pathogenicity we collected 18 strains isolated worldwide from bananas and human patients. Results showed that all strains can grow at 24°C as well as 37°C in vitro supporting the hypothesis of cross-kingdom pathogenicity of the species. We next aimed to collect experimental proof of multiple host infection to investigate the potential cross-kingdom pathogenicity of F. musae. We developed two in vivo infection models. As plant model we chose banana fruits and infected them by skewering the fruits with toothpicks dipped into spore suspension. We built a specific scale to score disease progression by the presence of brown spots surrounding the point of toothpick insertion. As animal model we chose the “human proxy” Galleria mellonella. Disease progression was assessed by a scoring system based on increased melanisation, loss of activity and cocoon formation. All strains caused consistent disease in both models providing the first experimental proof of the ability of F. musae to invade both plant and animal pathosystems. Our animal and plant models showed comparable level of infection confirming F. musae can be considered as cross-kingdom pathogen. Furthermore, we established animal and plant F. musae infection models with accurate disease indexes for quantifying virulence degrees in the two hosts, posing the bases for the investigation of the host-pathogen interactions of F. musae with its hosts.