The mitochondrial distribution and morphology family 33 gene () regulates mitochondrial homeostasis by mediating the mitochondrial fission process in yeast. The wheat head blight contains an FgMdm33 protein that is orthologous to Mdm33, albeit its function remains unknown. We have reported here the roles of FgMdm33 in regulating fungal morphogenesis, mitochondrial morphology, autophagy, apoptosis, and fungal pathogenicity. The Δ mutants generated through a homologous recombination strategy in this study exhibited defects in terms of mycelial growth, conidia production, and virulence. Hyphal cells lacking displayed elongated mitochondria and a dispensable respiratory-deficient growth phenotype, indicating the possible involvement of in mitochondrial fission. The Δ mutants displayed a remarkable reduction in the proteolysis of GFP-FgAtg8, whereas the formation of autophagic bodies in the hyphal cells of mutants was recorded under the induction of mitophagy. In addition, the transcriptional expression of the apoptosis-inducing factor 1 gene () was significantly upregulated in the Δ mutants. Cumulatively, these results indicate that is involved in mitochondrial fission, non-selective macroautophagy, and apoptosis and that it regulates fungal growth, conidiation, and pathogenicity of the head blight pathogen.