Abstract The mycovirus Cryphonectri a hypovirus 1 (CHV1) and its host, the chestnut blight fungus Cryphonectria parasitica , constitute a well-established biocontrol system . However, the mechanisms by which CHV1 modulates host physiology remain incompletely characterized. This study investigated how CHV1 rescues the phenotypic defects of the SUMOylation-deficient mutant of C. parasitica . Here, we demonstrate that CHV1 infection rescues phenotypic defects in a SUMOylation-deficient mutant of C. parasitica (Δ CpSmt3 ). CHV1 restored mycelial and mitochondrial morphology, suppressed reactive oxygen species (ROS) accumulation, elevated mitochondrial membrane potential (MMP), and inhibited autophagy in the mutant. Both viral proteins, p29 and p48, contributed to the suppression of ROS and the restoration of nuclear division and growth; p48 additionally inhibited autophagy. Proteomic analyses revealed that CHV1 and p48 significantly upregulated proteins associated with translation, mitochondrial function, and protein folding pathway in Δ CpSmt3 . Notably, CHV1 enhanced the expression of CpRho1 . Moreover, the phenotypic characteristics of CHV1-infected Δ CpSmt3 were highly similar to those of CpRho1-overexpressing strains, which suggests that CpRho1 mediates the restorative effects exerted by CHV1. Our results reveal that CHV1 compensates for SUMOylation deficiency primarily through p48, which modulates translation, mitochondrial function, and CpRho1 expression, uncovering a new model of virus-host mutualism.
Li et al. (Mon,) studied this question.