Exogenous Iron Induces NADPH Oxidases-Dependent Ferroptosis in the Conidia of Aspergillus flavus

Aspergillus flavus is saprophytic soil fungus that contaminates seed crops with the carcinogenic secondary metabolite aflatoxin, posing a significant threat to humans and animals. Ferrous sulfate is a common iron supplement that is used to the treatment of iron-deficiency anemia. Here, we identified an unexpected inhibitory role of ferrous sulfate on A. flavus. With specific fluorescent dyes, we detected several conidial ferroptosis hallmarks in conidia under the treatment of 1 mM Fe²⁺, including nonapoptosis necrosis, iron-dependent, lipid peroxide accumulation, and ROS burst. However, unlike traditional ferroptosis in mammals, Fe²⁺ triggered conidial ferroptosis in A. flavus was regulated by NADPH oxidase (NOXs) activation instead of Fenton reaction. Transcriptomic and some other bioinformatics analyses showed that NoxA in A. flavus might be a potential target of Fe²⁺, and thus led to the occurrence of conidial ferroptosis. Furthermore, noxA deletion mutant was constructed, and both ROS generation and conidial ferroptosis in ΔnoxA was reduced when exposed to Fe²⁺. Taken together, our study revealed an exogenous Fe²⁺-triggered conidial ferroptosis pathway mediated by NoxA of A. flavus, which greatly contributes to the development of an alternative strategy to control this pathogen.