PsAF5 functions as an essential adapter for PsPHB2-mediated mitophagy under ROS stress in Phytophthora sojae

Host-derived reactive oxygen species (ROS) is an important defense means to protect against pathogens. Although mitochondria are the main intracellular targets of ROS, how pathogens regulate mitochondrial physiology in response to oxidative stress remains elusive. Prohibitin 2 (PHB2) is an inner mitochondrial membrane (IMM) protein, recognized as a mitophagy receptor in animals and fungi. Here, we found that an ANK and FYVE domain-containing protein PsAF5, as an adapter of PsPHB2, interacting with PsATG8 under ROS stress. Unlike PHB2 can recruit ATG8 directly to mitochondria in animals, PsPHB2 cannot recruit PsATG8 to stressed mitochondria without PsAF5. PsAF5 deletion in P. sojae impairs mitophagy under ROS stress and increases its sensitivity to H2O2, resulting the attenuation of P. sojae pathogenicity. The first discovery of PsPHB2-PsAF5-PsATG8 axis in plant pathogenic oomycetes revealed that the IMM protein as a receptor to mediate mitophagy is conserved in eukaryotes, but with differences in the detail of ATG8 recruitment.