Ubiquitin-like protein involved in cytoplasm to vacuole transport (Cvt), autophagy vesicles formation, mitophagy, and nucleophagy (By similarity). Conjugation with ATG5 through a ubiquitin-like conjugating system involving also ATG7 as an E1-like activating enzyme and ATG10 as an E2-like conjugating enzyme, is essential for its function (By similarity). The ATG12-ATG5 conjugate acts as an E3-like enzyme which is required for lipidation of ATG8 and ATG8 association to the vesicle membranes (By similarity). ATG12-ATG5 rearranges the ATG3 catalytic center and enhances its E2 activity (By similarity). Autophagy is required for proper vegetative growth, asexual/sexual reproduction, and full virulence (PubMed:28894236). Autophagy is particularly involved in the biosynthesis of deoxynivalenol (DON), an important virulence determinant (PubMed:28894236). Forms a conjugate with ATG5 (By similarity). Forms a thioester bond with the 'Cys-196' of ATG10 (By similarity). Interacts with the ATG7 C-terminal 40 amino acids domain (By similarity). The ATG12-ATG5 conjugate forms a complex with several units of ATG16 (By similarity). The ATG12-ATG5 conjugate associates also with ATG3 (By similarity). Localizes to the isolation membrane (IM), a membrane sac which is generated from the pre-autophagosomal structure (PAS) (By similarity). Ultimately, the IM expands to become a mature autophagosome (By similarity). Localizes also to a dot at the junction between the IM and the vacuolar membrane, termed the vacuole-IM contact site (VICS) (By similarity). Does not significantly decrease the growth rate under nutrient-rich conditions (PubMed:28894236). Causes only mild infection in point-inoculated spikelets of flowering wheat heads and impairs the spreading to nearby spikelets (PubMed:28894236). Reduces strongly the production of deoxynivalenol (DON), an important virulence determinant (PubMed:28894236). Belongs to the ATG12 family.