A novel mitochondrial regulon for ferroptosis during fungal pathogenesis.

Abstract

Ferroptosis remains an underexamined iron- and lipid peroxides-driven cell death modality despite its importance to several human and plant diseases and to immunity thereof. Here, we utilized chemical cell biology, molecular genetics and biochemical analyses to gain insights into how the fungal pathogen Magnaporthe oryzae undergoes ferroptosis strictly in the spore cells to successfully transit to infectious development. We reveal a complex functional interdependency and crosstalk between intrinsic ferroptosis and autophagy-mediated mitochondrial degradation. Mechanistically, the requirement of mitophagy for ferroptotic cell death was attributed to its ability to maintain a pool of metabolically active mitochondria. Pharmacological disruption of the electron transport chain or membrane potential led to complete inhibition of ferroptosis, thus simulating the loss of mitophagy phenotypes. Conversely, increased mitochondrial membrane potential in a mitophagy-defective mutant alleviated the ferroptosis defects therein. Graded inhibition of mitochondrial coenzyme Q biosynthesis with or without ferroptosis inhibitor liproxstatin-1 distinguished its antioxidant function in such regulated cell death. Membrane potential-dependent regulation of ATP synthesis and iron homeostasis, as well as dynamics of tricarboxylic acid cycle enzyme AcoA (aconitase A) in the presence or absence of mitophagy, mitochondrial poisoning or iron chelation further linked mitochondrial metabolism to ferroptosis. Last, we present an important bioenergetics- and redox-based mitochondrial regulon essential for intrinsic ferroptosis and its precise role in fungal pathogenesis leading up to the establishment of the devastating rice blast disease.Abbreviation: 4-CBA: 4 chlorobenzoic acid; AcoA: aconitase A; Atg24: autophagy related 24; CoQ: coenzyme Q; CPX: ciclopirox olamine; ETC: electron transport chain; GSH: glutathione; Gpx4: glutathione peroxidase 4; HPI: hours post inoculation; MMP: mitochondrial membrane potential; MitoQ: Mitoquinone; ROS: reactive oxygen species; TCA: tricarboxylic acid.